adding module deps + fixing gradle

src/js_list.cpp

@@ -6,7 +6,7 @@
 #include "js_object.hpp"
 #include "js_util.hpp"
 #include "object_accessor.hpp"
-
+laksdlasd
 using RJSAccessor = realm::NativeAccessor<JSValueRef, JSContextRef>;
 using namespace realm;
 

tests/react-test-app/android/app/build.gradle

@@ -1,79 +1,271 @@
-apply plugin: "com.android.application"
+// Copyright 2015-present Facebook. All Rights Reserved.
 
-/**
- * The react.gradle file registers two tasks: bundleDebugJsAndAssets and bundleReleaseJsAndAssets.
- * These basically call `react-native bundle` with the correct arguments during the Android build
- * cycle. By default, bundleDebugJsAndAssets is skipped, as in debug/dev mode we prefer to load the
- * bundle directly from the development server. Below you can see all the possible configurations
- * and their defaults. If you decide to add a configuration block, make sure to add it before the
- * `apply from: "react.gradle"` line.
- *
- * project.ext.react = [
- *   // the name of the generated asset file containing your JS bundle
- *   bundleAssetName: "index.android.bundle",
- *
- *   // the entry file for bundle generation
- *   entryFile: "index.android.js",
- *
- *   // whether to bundle JS and assets in debug mode
- *   bundleInDebug: false,
- *
- *   // whether to bundle JS and assets in release mode
- *   bundleInRelease: true,
- *
- *   // the root of your project, i.e. where "package.json" lives
- *   root: "../../",
- *
- *   // where to put the JS bundle asset in debug mode
- *   jsBundleDirDebug: "$buildDir/intermediates/assets/debug",
- *
- *   // where to put the JS bundle asset in release mode
- *   jsBundleDirRelease: "$buildDir/intermediates/assets/release",
- *
- *   // where to put drawable resources / React Native assets, e.g. the ones you use via
- *   // require('./image.png')), in debug mode
- *   resourcesDirDebug: "$buildDir/intermediates/res/merged/debug",
- *
- *   // where to put drawable resources / React Native assets, e.g. the ones you use via
- *   // require('./image.png')), in release mode
- *   resourcesDirRelease: "$buildDir/intermediates/res/merged/release",
- *
- *   // by default the gradle tasks are skipped if none of the JS files or assets change; this means
- *   // that we don't look at files in android/ or ios/ to determine whether the tasks are up to
- *   // date; if you have any other folders that you want to ignore for performance reasons (gradle
- *   // indexes the entire tree), add them here. Alternatively, if you have JS files in android/
- *   // for example, you might want to remove it from here.
- *   inputExcludes: ["android/**", "ios/**"]
- * ]
- */
+apply plugin: 'com.android.library'
+apply plugin: 'maven'
 
-apply from: "react.gradle"
+apply plugin: 'de.undercouch.download'
+
+import de.undercouch.gradle.tasks.download.Download
+import org.apache.tools.ant.taskdefs.condition.Os
+import org.apache.tools.ant.filters.ReplaceTokens
+
+// We download various C++ open-source dependencies into downloads.
+// We then copy both the downloaded code and our custom makefiles and headers into third-party-ndk.
+// After that we build native code from src/main/jni with module path pointing at third-party-ndk.
+
+def downloadsDir = new File("$buildDir/downloads")
+def thirdPartyNdkDir = new File("$buildDir/third-party-ndk")
+
+task createNativeDepsDirectories {
+    downloadsDir.mkdirs()
+    thirdPartyNdkDir.mkdirs()
+}
+
+task downloadBoost(dependsOn: createNativeDepsDirectories, type: Download) {
+    // Use ZIP version as it's faster this way to selectively extract some parts of the archive
+    src 'https://downloads.sourceforge.net/project/boost/boost/1.57.0/boost_1_57_0.zip'
+    onlyIfNewer true
+    overwrite false
+    dest new File(downloadsDir, 'boost_1_57_0.zip')
+}
+
+task prepareBoost(dependsOn: downloadBoost) {
+    inputs.files downloadBoost.dest, 'src/main/jni/third-party/boost/Android.mk'
+    outputs.dir "$thirdPartyNdkDir/boost"
+    doLast {
+        copy {
+            from { zipTree(downloadBoost.dest) }
+            from 'src/main/jni/third-party/boost/Android.mk'
+            include 'boost_1_57_0/boost/**/*.hpp', 'Android.mk'
+            into "$thirdPartyNdkDir/boost"
+        }
+    }
+}
+
+task downloadDoubleConversion(dependsOn: createNativeDepsDirectories, type: Download) {
+    src 'https://github.com/google/double-conversion/archive/v1.1.1.tar.gz'
+    onlyIfNewer true
+    overwrite false
+    dest new File(downloadsDir, 'double-conversion-1.1.1.tar.gz')
+}
+
+task prepareDoubleConversion(dependsOn: downloadDoubleConversion, type: Copy) {
+    from tarTree(downloadDoubleConversion.dest)
+    from 'src/main/jni/third-party/double-conversion/Android.mk'
+    include 'double-conversion-1.1.1/src/**/*', 'Android.mk'
+    filesMatching('*/src/**/*', {fname -> fname.path = "double-conversion/${fname.name}"})
+    includeEmptyDirs = false
+    into "$thirdPartyNdkDir/double-conversion"
+}
+
+task downloadFolly(dependsOn: createNativeDepsDirectories, type: Download) {
+    src 'https://github.com/facebook/folly/archive/v0.50.0.tar.gz'
+    onlyIfNewer true
+    overwrite false
+    dest new File(downloadsDir, 'folly-0.50.0.tar.gz');
+}
+
+task prepareFolly(dependsOn: downloadFolly, type: Copy) {
+    from tarTree(downloadFolly.dest)
+    from 'src/main/jni/third-party/folly/Android.mk'
+    include 'folly-0.50.0/folly/**/*', 'Android.mk'
+    eachFile {fname -> fname.path = (fname.path - "folly-0.50.0/")}
+    includeEmptyDirs = false
+    into "$thirdPartyNdkDir/folly"
+}
+
+task downloadGlog(dependsOn: createNativeDepsDirectories, type: Download) {
+    src 'https://github.com/google/glog/archive/v0.3.3.tar.gz'
+    onlyIfNewer true
+    overwrite false
+    dest new File(downloadsDir, 'glog-0.3.3.tar.gz')
+}
+
+// Prepare glog sources to be compiled, this task will perform steps that normally shoudl've been
+// executed by automake. This way we can avoid dependencies on make/automake
+task prepareGlog(dependsOn: downloadGlog, type: Copy) {
+    from tarTree(downloadGlog.dest)
+    from 'src/main/jni/third-party/glog/'
+    include 'glog-0.3.3/src/**/*', 'Android.mk', 'config.h'
+    includeEmptyDirs = false
+    filesMatching('**/*.h.in') {
+        filter(ReplaceTokens, tokens: [
+                ac_cv_have_unistd_h: '1',
+                ac_cv_have_stdint_h: '1',
+                ac_cv_have_systypes_h: '1',
+                ac_cv_have_inttypes_h: '1',
+                ac_cv_have_libgflags: '0',
+                ac_google_start_namespace: 'namespace google {',
+                ac_cv_have_uint16_t: '1',
+                ac_cv_have_u_int16_t: '1',
+                ac_cv_have___uint16: '0',
+                ac_google_end_namespace: '}',
+                ac_cv_have___builtin_expect: '1',
+                ac_google_namespace: 'google',
+                ac_cv___attribute___noinline: '__attribute__ ((noinline))',
+                ac_cv___attribute___noreturn: '__attribute__ ((noreturn))',
+                ac_cv___attribute___printf_4_5: '__attribute__((__format__ (__printf__, 4, 5)))'
+        ])
+        it.path = (it.name - '.in')
+    }
+    into "$thirdPartyNdkDir/glog"
+}
+
+task downloadJSCHeaders(type: Download) {
+    def jscAPIBaseURL = 'https://svn.webkit.org/repository/webkit/!svn/bc/174650/trunk/Source/JavaScriptCore/API/'
+    def jscHeaderFiles = ['JSBase.h', 'JSContextRef.h', 'JSObjectRef.h', 'JSRetainPtr.h', 'JSStringRef.h', 'JSValueRef.h', 'WebKitAvailability.h', 'JavaScriptCore.h', 'JavaScript.h', 'JSStringRefCF.h']
+    def output = new File(downloadsDir, 'jsc')
+    output.mkdirs()
+    src(jscHeaderFiles.collect { headerName -> "$jscAPIBaseURL$headerName" })
+    onlyIfNewer true
+    overwrite false
+    dest output
+}
+
+// Create Android.mk library module based on so files from mvn + include headers fetched from webkit.org
+task prepareJSC(dependsOn: downloadJSCHeaders) << {
+    copy {
+        from zipTree(configurations.compile.fileCollection { dep -> dep.name == 'android-jsc' }.singleFile)
+        from {downloadJSCHeaders.dest}
+        from 'src/main/jni/third-party/jsc/Android.mk'
+        include 'jni/**/*.so', '*.h', 'Android.mk'
+        filesMatching('*.h', { fname -> fname.path = "JavaScriptCore/${fname.path}"})
+        into "$thirdPartyNdkDir/jsc";
+    }
+}
+
+def getNdkBuildName() {
+    if (Os.isFamily(Os.FAMILY_WINDOWS)) {
+        return "ndk-build.cmd"
+    } else {
+        return "ndk-build"
+    }
+}
+
+def findNdkBuildFullPath() {
+    // we allow to provide full path to ndk-build tool
+    if (hasProperty('ndk.command')) {
+        return property('ndk.command')
+    }
+    // or just a path to the containing directory
+    if (hasProperty('ndk.path')) {
+        def ndkDir = property('ndk.path')
+        return new File(ndkDir, getNdkBuildName()).getAbsolutePath()
+    }
+    if (System.getenv('ANDROID_NDK') != null) {
+        def ndkDir = System.getenv('ANDROID_NDK')
+        return new File(ndkDir, getNdkBuildName()).getAbsolutePath()
+    }
+    def ndkDir = android.hasProperty('plugin') ? android.plugin.ndkFolder :
+            plugins.getPlugin('com.android.library').sdkHandler.getNdkFolder()
+    if (ndkDir) {
+        return new File(ndkDir, getNdkBuildName()).getAbsolutePath()
+    }
+    return null
+}
+
+def getNdkBuildFullPath() {
+    def ndkBuildFullPath = findNdkBuildFullPath()
+    if (ndkBuildFullPath == null) {
+        throw new GradleScriptException(
+            "ndk-build binary cannot be found, check if you've set " +
+            "\$ANDROID_NDK environment variable correctly or if ndk.dir is " +
+            "setup in local.properties",
+            null)
+    }
+    if (!new File(ndkBuildFullPath).canExecute()) {
+        throw new GradleScriptException(
+            "ndk-build binary " + ndkBuildFullPath + " doesn't exist or isn't executable.\n" +
+            "Check that the \$ANDROID_NDK environment variable, or ndk.dir in local.proerties, is set correctly.\n" +
+            "(On Windows, make sure you escape backslashes in local.properties or use forward slashes, e.g. C:\\\\ndk or C:/ndk rather than C:\\ndk)",
+            null)
+    }
+    return ndkBuildFullPath
+}
+
+task buildReactNdkLib(dependsOn: [prepareJSC, prepareBoost, prepareDoubleConversion, prepareFolly, prepareGlog], type: Exec) {
+    inputs.file('src/main/jni')
+    outputs.dir("$buildDir/react-ndk/all")
+    commandLine getNdkBuildFullPath(),
+            'NDK_PROJECT_PATH=null',
+            "NDK_APPLICATION_MK=$projectDir/src/main/jni/Application.mk",
+            'NDK_OUT=' + temporaryDir,
+            "NDK_LIBS_OUT=$buildDir/react-ndk/all",
+            "THIRD_PARTY_NDK_DIR=$buildDir/third-party-ndk",
+            '-C', file('src/main/jni').absolutePath,
+            '-B',
+            'NDK_LOG=1',
+            '--jobs', Runtime.runtime.availableProcessors()
+}
+
+task cleanReactNdkLib(type: Exec) {
+    commandLine getNdkBuildFullPath(),
+            '-C', file('src/main/jni').absolutePath,
+            'clean'
+}
+
+task packageReactNdkLibs(dependsOn: buildReactNdkLib, type: Copy) {
+    from "$buildDir/react-ndk/all"
+    exclude '**/libjsc.so'
+    into "$buildDir/react-ndk/exported"
+}
 
 android {
     compileSdkVersion 23
     buildToolsVersion "23.0.1"
 
     defaultConfig {
-        applicationId "com.reacttests"
         minSdkVersion 16
         targetSdkVersion 22
         versionCode 1
         versionName "1.0"
+
         ndk {
-            moduleName = "realm-react-android"
-            abiFilters "armeabi-v7a", "x86"
+            moduleName "reactnativejni"
         }
+
+        buildConfigField 'boolean', 'IS_INTERNAL_BUILD', 'false'
     }
-    buildTypes {
-        release {
-            minifyEnabled false  // Set this to true to enable Proguard
-            proguardFiles getDefaultProguardFile("proguard-android.txt"), "proguard-rules.pro"
-        }
+
+    sourceSets.main {
+        jni.srcDirs = []
+        jniLibs.srcDir "$buildDir/react-ndk/exported"
+        res.srcDirs = ['src/main/res/devsupport', 'src/main/res/shell']
+    }
+
+    tasks.withType(JavaCompile) {
+        compileTask -> compileTask.dependsOn packageReactNdkLibs
+    }
+
+    clean.dependsOn cleanReactNdkLib
+
+    lintOptions {
+        abortOnError false
     }
 }
 
 dependencies {
-    compile fileTree(dir: "libs", include: ["*.jar"])
-    compile "com.android.support:appcompat-v7:23.0.1"
-    compile "com.facebook.react:react-native:0.14.+"
+    compile fileTree(dir: 'libs', include: ['*.jar'])
+    compile 'com.android.support:appcompat-v7:23.0.1'
+    compile 'com.android.support:recyclerview-v7:23.0.1'
+    compile 'com.facebook.fresco:fresco:0.8.1'
+    compile 'com.facebook.fresco:imagepipeline-okhttp:0.8.1'
+    compile 'com.facebook.stetho:stetho:1.2.0'
+    compile 'com.facebook.stetho:stetho-okhttp:1.2.0'
+    compile 'com.fasterxml.jackson.core:jackson-core:2.2.3'
+    compile 'com.google.code.findbugs:jsr305:3.0.0'
+    compile 'com.squareup.okhttp:okhttp:2.5.0'
+    compile 'com.squareup.okhttp:okhttp-ws:2.5.0'
+    compile 'com.squareup.okio:okio:1.6.0'
+    compile 'org.webkit:android-jsc:r174650'
+
+    testCompile "junit:junit:${JUNIT_VERSION}"
+    testCompile "org.powermock:powermock-api-mockito:${POWERMOCK_VERSION}"
+    testCompile "org.powermock:powermock-module-junit4-rule:${POWERMOCK_VERSION}"
+    testCompile "org.powermock:powermock-classloading-xstream:${POWERMOCK_VERSION}"
+    testCompile "org.mockito:mockito-core:${MOCKITO_CORE_VERSION}"
+    testCompile "org.easytesting:fest-assert-core:${FEST_ASSERT_CORE_VERSION}"
+    testCompile("org.robolectric:robolectric:${ROBOLECTRIC_VERSION}")
 }
+
+apply from: 'release.gradle'

tests/react-test-app/android/app/gradle.properties

@@ -0,0 +1,14 @@
+VERSION_NAME=0.12.0-SNAPSHOT
+GROUP=com.facebook.react
+
+POM_NAME=ReactNative
+POM_ARTIFACT_ID=react-native
+POM_PACKAGING=aar
+
+android.useDeprecatedNdk=true
+
+MOCKITO_CORE_VERSION=1.+
+POWERMOCK_VERSION=1.6.2
+ROBOLECTRIC_VERSION=3.0
+JUNIT_VERSION=4.12
+FEST_ASSERT_CORE_VERSION=2.0M10

tests/react-test-app/android/app/release.gradle

@@ -0,0 +1,128 @@
+// Copyright 2015-present Facebook. All Rights Reserved.
+
+apply plugin: 'maven'
+apply plugin: 'signing'
+
+// Gradle tasks for publishing to maven
+// 1) To install in local maven repo use :installArchives task
+// 2) To upload artifact to maven central use: :uploadArchives (you'd need to have the permission to do that)
+
+def isReleaseBuild() {
+    return VERSION_NAME.contains('SNAPSHOT') == false
+}
+
+def getRepositoryUrl() {
+    return hasProperty('repositoryUrl') ? property('repositoryUrl') : 'https://oss.sonatype.org/service/local/staging/deploy/maven2/'
+}
+
+def getRepositoryUsername() {
+    return hasProperty('repositoryUsername') ? property('repositoryUsername') : ''
+}
+
+def getRepositoryPassword() {
+    return hasProperty('repositoryPassword') ? property('repositoryPassword') : ''
+}
+
+def configureReactNativePom(def pom) {
+    pom.project {
+        name POM_NAME
+        artifactId POM_ARTIFACT_ID
+        packaging POM_PACKAGING
+        description 'A framework for building native apps with React'
+        url 'https://github.com/facebook/react-native'
+
+        scm {
+            url 'https://github.com/facebook/react-native.git'
+            connection 'scm:git:https://github.com/facebook/react-native.git'
+            developerConnection 'scm:git:git@github.com:facebook/react-native.git'
+        }
+
+        licenses {
+            license {
+                name 'BSD License'
+                url 'https://github.com/facebook/react-native/blob/master/LICENSE'
+                distribution 'repo'
+            }
+        }
+
+        developers {
+            developer {
+                id 'facebook'
+                name 'Facebook'
+            }
+        }
+    }
+}
+
+afterEvaluate { project ->
+
+    task androidJavadoc(type: Javadoc) {
+        source = android.sourceSets.main.java.srcDirs
+        classpath += files(android.bootClasspath)
+        classpath += files(project.getConfigurations().getByName('compile').asList())
+        include '**/*.java'
+        exclude '**/ReactBuildConfig.java'
+    }
+
+    task androidJavadocJar(type: Jar, dependsOn: androidJavadoc) {
+        classifier = 'javadoc'
+        from androidJavadoc.destinationDir
+    }
+
+    task androidSourcesJar(type: Jar) {
+        classifier = 'sources'
+        from android.sourceSets.main.java.srcDirs
+        include '**/*.java'
+    }
+
+    android.libraryVariants.all { variant ->
+        def name = variant.name.capitalize()
+        task "jar${name}"(type: Jar, dependsOn: variant.javaCompile) {
+            from variant.javaCompile.destinationDir
+        }
+    }
+
+    artifacts {
+        archives androidSourcesJar
+        // TODO Make Javadoc generation work with Java 1.8, currently only works with 1.7
+        // archives androidJavadocJar
+    }
+
+    version = VERSION_NAME
+    group = GROUP
+
+    signing {
+        required { isReleaseBuild() && gradle.taskGraph.hasTask('uploadArchives') }
+        sign configurations.archives
+    }
+
+    uploadArchives {
+        configuration = configurations.archives
+        repositories.mavenDeployer {
+            beforeDeployment {
+                MavenDeployment deployment -> signing.signPom(deployment)
+            }
+
+            repository(url: getRepositoryUrl()) {
+                authentication(
+                        userName: getRepositoryUsername(),
+                        password: getRepositoryPassword())
+
+            }
+
+            configureReactNativePom pom
+        }
+    }
+
+    task installArchives(type: Upload) {
+        configuration = configurations.archives
+        repositories.mavenDeployer {
+            beforeDeployment {
+                MavenDeployment deployment -> signing.signPom(deployment)
+            }
+
+            repository url: "file://${System.properties['user.home']}/.m2/repository"
+            configureReactNativePom pom
+        }
+    }
+}

tests/react-test-app/android/app/src/main/AndroidManifest.xml

@@ -1,4 +1,4 @@
-<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+<!-- <manifest xmlns:android="http://schemas.android.com/apk/res/android"
     package="com.reacttests">
 
     <uses-permission android:name="android.permission.INTERNET" />
@@ -19,4 +19,11 @@
       <activity android:name="com.facebook.react.devsupport.DevSettingsActivity" />
     </application>
 
+</manifest> -->
+<manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.reacttests">
+
+    <uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW"/>
+
+    <application />
+
 </manifest>

tests/react-test-app/android/app/src/main/java/com/reacttests/MainActivity.java

@@ -1,78 +1,78 @@
-package com.reacttests;
+// package com.reacttests;
 
-import android.app.Activity;
-import android.os.Bundle;
-import android.view.KeyEvent;
+// import android.app.Activity;
+// import android.os.Bundle;
+// import android.view.KeyEvent;
 
-import com.facebook.react.LifecycleState;
-import com.facebook.react.ReactInstanceManager;
-import com.facebook.react.ReactRootView;
-import com.facebook.react.modules.core.DefaultHardwareBackBtnHandler;
-import com.facebook.react.shell.MainReactPackage;
-import com.facebook.soloader.SoLoader;
+// import com.facebook.react.LifecycleState;
+// import com.facebook.react.ReactInstanceManager;
+// import com.facebook.react.ReactRootView;
+// import com.facebook.react.modules.core.DefaultHardwareBackBtnHandler;
+// import com.facebook.react.shell.MainReactPackage;
+// import com.facebook.soloader.SoLoader;
 
-public class MainActivity extends Activity implements DefaultHardwareBackBtnHandler {
+// public class MainActivity extends Activity implements DefaultHardwareBackBtnHandler {
 
-    private ReactInstanceManager mReactInstanceManager;
-    private ReactRootView mReactRootView;
+//     private ReactInstanceManager mReactInstanceManager;
+//     private ReactRootView mReactRootView;
 
-    @Override
-    protected void onCreate(Bundle savedInstanceState) {
-        super.onCreate(savedInstanceState);
-        mReactRootView = new ReactRootView(this);
+//     @Override
+//     protected void onCreate(Bundle savedInstanceState) {
+//         super.onCreate(savedInstanceState);
+//         mReactRootView = new ReactRootView(this);
 
-        mReactInstanceManager = ReactInstanceManager.builder()
-                .setApplication(getApplication())
-                .setBundleAssetName("index.android.bundle")
-                .setJSMainModuleName("index.android")
-                .addPackage(new MainReactPackage())
-                .setUseDeveloperSupport(BuildConfig.DEBUG)
-                .setInitialLifecycleState(LifecycleState.RESUMED)
-                .build();
+//         mReactInstanceManager = ReactInstanceManager.builder()
+//                 .setApplication(getApplication())
+//                 .setBundleAssetName("index.android.bundle")
+//                 .setJSMainModuleName("index.android")
+//                 .addPackage(new MainReactPackage())
+//                 .setUseDeveloperSupport(BuildConfig.DEBUG)
+//                 .setInitialLifecycleState(LifecycleState.RESUMED)
+//                 .build();
 
-        mReactRootView.startReactApplication(mReactInstanceManager, "ReactTests", null);
+//         mReactRootView.startReactApplication(mReactInstanceManager, "ReactTests", null);
 
-        setContentView(mReactRootView);
-    }
+//         setContentView(mReactRootView);
+//     }
 
-    @Override
-    public boolean onKeyUp(int keyCode, KeyEvent event) {
-        if (keyCode == KeyEvent.KEYCODE_MENU && mReactInstanceManager != null) {
-            mReactInstanceManager.showDevOptionsDialog();
-            return true;
-        }
-        return super.onKeyUp(keyCode, event);
-    }
+//     @Override
+//     public boolean onKeyUp(int keyCode, KeyEvent event) {
+//         if (keyCode == KeyEvent.KEYCODE_MENU && mReactInstanceManager != null) {
+//             mReactInstanceManager.showDevOptionsDialog();
+//             return true;
+//         }
+//         return super.onKeyUp(keyCode, event);
+//     }
 
-    @Override
-    public void onBackPressed() {
-      if (mReactInstanceManager != null) {
-        mReactInstanceManager.onBackPressed();
-      } else {
-        super.onBackPressed();
-      }
-    }
+//     @Override
+//     public void onBackPressed() {
+//       if (mReactInstanceManager != null) {
+//         mReactInstanceManager.onBackPressed();
+//       } else {
+//         super.onBackPressed();
+//       }
+//     }
 
-    @Override
-    public void invokeDefaultOnBackPressed() {
-      super.onBackPressed();
-    }
+//     @Override
+//     public void invokeDefaultOnBackPressed() {
+//       super.onBackPressed();
+//     }
 
-    @Override
-    protected void onPause() {
-        super.onPause();
+//     @Override
+//     protected void onPause() {
+//         super.onPause();
 
-        if (mReactInstanceManager != null) {
-            mReactInstanceManager.onPause();
-        }
-    }
+//         if (mReactInstanceManager != null) {
+//             mReactInstanceManager.onPause();
+//         }
+//     }
 
-    @Override
-    protected void onResume() {
-        super.onResume();
+//     @Override
+//     protected void onResume() {
+//         super.onResume();
 
-        if (mReactInstanceManager != null) {
-            mReactInstanceManager.onResume(this);
-        }
-    }
-}
+//         if (mReactInstanceManager != null) {
+//             mReactInstanceManager.onResume(this);
+//         }
+//     }
+// }

tests/react-test-app/android/app/src/main/jni/Android.mk

@@ -2,7 +2,7 @@ LOCAL_PATH:= $(call my-dir)
 
 include $(CLEAR_VARS)
 
-LOCAL_MODULE := librealmreact
+LOCAL_MODULE := nabil
 
 LOCAL_SRC_FILES := \
   js_list.cpp \
@@ -10,15 +10,9 @@ LOCAL_SRC_FILES := \
   js_init.cpp \
   js_realm.cpp \
   js_util.cpp \
-  realm-react-android.c \
   js_object.cpp \
   js_schema.cpp	\
-  rpc.cpp \	
-
-LOCAL_C_INCLUDES := $(LOCAL_PATH)/..
-LOCAL_EXPORT_C_INCLUDES := $(LOCAL_C_INCLUDES)
-
-LOCAL_CFLAGS := \
+  rpc.cpp \
 
 LOCAL_CFLAGS += -Wall -Werror -fexceptions
 CXX11_FLAGS := -std=c++11
@@ -27,7 +21,7 @@ LOCAL_EXPORT_CPPFLAGS := $(CXX11_FLAGS)
 
 LOCAL_SHARED_LIBRARIES := libjsc
 
-include $(BUILD_STATIC_LIBRARY)
+include $(BUILD_SHARED_LIBRARY)
 
 $(call import-module,jsc)
 

tests/react-test-app/android/app/src/main/jni/Application.mk

@@ -0,0 +1,15 @@
+APP_BUILD_SCRIPT := Android.mk
+
+APP_ABI := armeabi-v7a x86
+APP_PLATFORM := android-9
+
+APP_MK_DIR := $(dir $(lastword $(MAKEFILE_LIST)))
+
+NDK_MODULE_PATH := $(APP_MK_DIR)$(HOST_DIRSEP)$(THIRD_PARTY_NDK_DIR)$(HOST_DIRSEP)$(APP_MK_DIR)first-party
+
+APP_STL := gnustl_shared
+
+# Make sure every shared lib includes a .note.gnu.build-id header
+APP_LDFLAGS := -Wl,--build-id
+
+NDK_TOOLCHAIN_VERSION := 4.8

tests/react-test-app/android/app/src/main/jni/first-party/fb/Android.mk

@@ -0,0 +1,30 @@
+LOCAL_PATH:= $(call my-dir)
+include $(CLEAR_VARS)
+
+LOCAL_SRC_FILES:= \
+       assert.cpp \
+       log.cpp \
+
+LOCAL_C_INCLUDES := $(LOCAL_PATH)/.. $(LOCAL_PATH)/include
+LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/.. $(LOCAL_PATH)/include
+
+LOCAL_CFLAGS := -DLOG_TAG=\"libfb\"
+LOCAL_CFLAGS += -Wall -Werror
+# include/utils/threads.h has unused parameters
+LOCAL_CFLAGS += -Wno-unused-parameter
+ifeq ($(TOOLCHAIN_PERMISSIVE),true)
+  LOCAL_CFLAGS += -Wno-error=unused-but-set-variable
+endif
+LOCAL_CFLAGS += -DHAVE_POSIX_CLOCKS
+
+CXX11_FLAGS := -std=c++11
+LOCAL_CFLAGS += $(CXX11_FLAGS)
+
+LOCAL_EXPORT_CPPFLAGS := $(CXX11_FLAGS)
+
+LOCAL_LDLIBS := -llog -ldl -landroid
+LOCAL_EXPORT_LDLIBS := -llog
+
+LOCAL_MODULE := libfb
+
+include $(BUILD_SHARED_LIBRARY)

tests/react-test-app/android/app/src/main/jni/first-party/fb/Countable.h

@@ -0,0 +1,47 @@
+/*
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+#pragma once
+#include <atomic>
+#include <fb/assert.h>
+#include <fb/noncopyable.h>
+#include <fb/nonmovable.h>
+#include <fb/RefPtr.h>
+
+namespace facebook {
+
+class Countable : public noncopyable, public nonmovable {
+public:
+  // RefPtr expects refcount to start at 0
+  Countable() : m_refcount(0) {}
+  virtual ~Countable()
+  {
+    FBASSERT(m_refcount == 0);
+  }
+
+private:
+  void ref() {
+    ++m_refcount;
+  }
+
+  void unref() {
+    if (0 == --m_refcount) {
+      delete this;
+    }
+  }
+
+  bool hasOnlyOneRef() const {
+    return m_refcount == 1;
+  }
+
+  template <typename T> friend class RefPtr;
+  std::atomic<int> m_refcount;
+};
+
+}

tests/react-test-app/android/app/src/main/jni/first-party/fb/ProgramLocation.h

@@ -0,0 +1,50 @@
+/*
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+#pragma once
+#include <cstring>
+#include <string>
+#include <sstream>
+
+namespace facebook {
+
+#define FROM_HERE facebook::ProgramLocation(__FUNCTION__, __FILE__, __LINE__)
+
+class ProgramLocation {
+public:
+  ProgramLocation() : m_functionName("Unspecified"), m_fileName("Unspecified"), m_lineNumber(0) {}
+
+  ProgramLocation(const char* functionName, const char* fileName, int line) :
+      m_functionName(functionName),
+      m_fileName(fileName),
+      m_lineNumber(line)
+    {}
+
+  const char* functionName() const { return m_functionName; }
+  const char* fileName() const { return m_fileName; }
+  int lineNumber() const { return m_lineNumber; }
+
+  std::string asFormattedString() const {
+    std::stringstream str;
+    str << "Function " << m_functionName << " in file " << m_fileName << ":" << m_lineNumber;
+    return str.str();
+  }
+
+  bool operator==(const ProgramLocation& other) const {
+    // Assumes that the strings are static
+    return (m_functionName == other.m_functionName) && (m_fileName == other.m_fileName) && m_lineNumber == other.m_lineNumber;
+  }
+
+private:
+  const char* m_functionName;
+  const char* m_fileName;
+  int m_lineNumber;
+};
+
+}

tests/react-test-app/android/app/src/main/jni/first-party/fb/RefPtr.h

@@ -0,0 +1,274 @@
+/*
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+#pragma once
+#include <utility>
+#include <fb/assert.h>
+
+namespace facebook {
+
+// Reference counting smart pointer. This is designed to work with the
+// Countable class or other implementations in the future. It is designed in a
+// way to be both efficient and difficult to misuse. Typical usage is very
+// simple once you learn the patterns (and the compiler will help!):
+//
+// By default, the internal pointer is null.
+//   RefPtr<Foo> ref;
+//
+// Object creation requires explicit construction:
+//   RefPtr<Foo> ref = createNew<Foo>(...);
+//
+// Or if the constructor is not public:
+//   RefPtr<Foo> ref = adoptRef(new Foo(...));
+//
+// But you can implicitly create from nullptr:
+//   RefPtr<Foo> maybeRef = cond ? ref : nullptr;
+//
+// Move/Copy Construction/Assignment are straightforward:
+//   RefPtr<Foo> ref2 = ref;
+//   ref = std::move(ref2);
+//
+// Destruction automatically drops the RefPtr's reference as expected.
+//
+// Upcasting is implicit but downcasting requires an explicit cast:
+//   struct Bar : public Foo {};
+//   RefPtr<Bar> barRef = static_cast<RefPtr<Bar>>(ref);
+//   ref = barRef;
+//
+template <class T>
+class RefPtr {
+public:
+  constexpr RefPtr() :
+    m_ptr(nullptr)
+  {}
+
+  // Allow implicit construction from a pointer only from nullptr
+  constexpr RefPtr(std::nullptr_t ptr) :
+    m_ptr(nullptr)
+  {}
+
+  RefPtr(const RefPtr<T>& ref) :
+    m_ptr(ref.m_ptr)
+  {
+    refIfNecessary(m_ptr);
+  }
+
+  // Only allow implicit upcasts. A downcast will result in a compile error
+  // unless you use static_cast (which will end up invoking the explicit
+  // operator below).
+  template <typename U>
+  RefPtr(const RefPtr<U>& ref, typename std::enable_if<std::is_base_of<T,U>::value, U>::type* = nullptr) :
+    m_ptr(ref.get())
+  {
+    refIfNecessary(m_ptr);
+  }
+
+  RefPtr(RefPtr<T>&& ref) :
+    m_ptr(nullptr)
+  {
+    *this = std::move(ref);
+  }
+
+  // Only allow implicit upcasts. A downcast will result in a compile error
+  // unless you use static_cast (which will end up invoking the explicit
+  // operator below).
+  template <typename U>
+  RefPtr(RefPtr<U>&& ref, typename std::enable_if<std::is_base_of<T,U>::value, U>::type* = nullptr) :
+    m_ptr(nullptr)
+  {
+    *this = std::move(ref);
+  }
+
+  ~RefPtr() {
+    unrefIfNecessary(m_ptr);
+    m_ptr = nullptr;
+  }
+
+  RefPtr<T>& operator=(const RefPtr<T>& ref) {
+    if (m_ptr != ref.m_ptr) {
+      unrefIfNecessary(m_ptr);
+      m_ptr = ref.m_ptr;
+      refIfNecessary(m_ptr);
+    }
+    return *this;
+  }
+
+  // The STL assumes rvalue references are unique and for simplicity's sake, we
+  // make the same assumption here, that &ref != this.
+  RefPtr<T>& operator=(RefPtr<T>&& ref) {
+    unrefIfNecessary(m_ptr);
+    m_ptr = ref.m_ptr;
+    ref.m_ptr = nullptr;
+    return *this;
+  }
+
+  template <typename U>
+  RefPtr<T>& operator=(RefPtr<U>&& ref) {
+    unrefIfNecessary(m_ptr);
+    m_ptr = ref.m_ptr;
+    ref.m_ptr = nullptr;
+    return *this;
+  }
+
+  void reset() {
+    unrefIfNecessary(m_ptr);
+    m_ptr = nullptr;
+  }
+
+  T* get() const {
+    return m_ptr;
+  }
+
+  T* operator->() const {
+    return m_ptr;
+  }
+
+  T& operator*() const {
+    return *m_ptr;
+  }
+
+  template <typename U>
+  explicit operator RefPtr<U> () const;
+
+  explicit operator bool() const {
+    return m_ptr ? true : false;
+  }
+
+  bool isTheLastRef() const {
+    FBASSERT(m_ptr);
+    return m_ptr->hasOnlyOneRef();
+  }
+
+  // Creates a strong reference from a raw pointer, assuming that is already
+  // referenced from some other RefPtr. This should be used sparingly.
+  static inline RefPtr<T> assumeAlreadyReffed(T* ptr) {
+    return RefPtr<T>(ptr, ConstructionMode::External);
+  }
+
+  // Creates a strong reference from a raw pointer, assuming that it points to a
+  // freshly-created object. See the documentation for RefPtr for usage.
+  static inline RefPtr<T> adoptRef(T* ptr) {
+    return RefPtr<T>(ptr, ConstructionMode::Adopted);
+  }
+
+private:
+  enum class ConstructionMode {
+    Adopted,
+    External
+  };
+
+  RefPtr(T* ptr, ConstructionMode mode) :
+    m_ptr(ptr)
+  {
+    FBASSERTMSGF(ptr, "Got null pointer in %s construction mode", mode == ConstructionMode::Adopted ? "adopted" : "external");
+    ptr->ref();
+    if (mode == ConstructionMode::Adopted) {
+      FBASSERT(ptr->hasOnlyOneRef());
+    }
+  }
+
+  static inline void refIfNecessary(T* ptr) {
+    if (ptr) {
+      ptr->ref();
+    }
+  }
+  static inline void unrefIfNecessary(T* ptr) {
+    if (ptr) {
+      ptr->unref();
+    }
+  }
+
+  template <typename U> friend class RefPtr;
+
+  T* m_ptr;
+};
+
+// Creates a strong reference from a raw pointer, assuming that is already
+// referenced from some other RefPtr and that it is non-null. This should be
+// used sparingly.
+template <typename T>
+static inline RefPtr<T> assumeAlreadyReffed(T* ptr) {
+  return RefPtr<T>::assumeAlreadyReffed(ptr);
+}
+
+// As above, but tolerant of nullptr.
+template <typename T>
+static inline RefPtr<T> assumeAlreadyReffedOrNull(T* ptr) {
+  return ptr ? RefPtr<T>::assumeAlreadyReffed(ptr) : nullptr;
+}
+
+// Creates a strong reference from a raw pointer, assuming that it points to a
+// freshly-created object. See the documentation for RefPtr for usage.
+template <typename T>
+static inline RefPtr<T> adoptRef(T* ptr) {
+  return RefPtr<T>::adoptRef(ptr);
+}
+
+template <typename T, typename ...Args>
+static inline RefPtr<T> createNew(Args&&... arguments) {
+  return RefPtr<T>::adoptRef(new T(std::forward<Args>(arguments)...));
+}
+
+template <typename T> template <typename U>
+RefPtr<T>::operator RefPtr<U>() const {
+  static_assert(std::is_base_of<T, U>::value, "Invalid static cast");
+  return assumeAlreadyReffedOrNull<U>(static_cast<U*>(m_ptr));
+}
+
+template <typename T, typename U>
+inline bool operator==(const RefPtr<T>& a, const RefPtr<U>& b) {
+  return a.get() == b.get();
+}
+
+template <typename T, typename U>
+inline bool operator!=(const RefPtr<T>& a, const RefPtr<U>& b) {
+  return a.get() != b.get();
+}
+
+template <typename T, typename U>
+inline bool operator==(const RefPtr<T>& ref, U* ptr) {
+  return ref.get() == ptr;
+}
+
+template <typename T, typename U>
+inline bool operator!=(const RefPtr<T>& ref, U* ptr) {
+  return ref.get() != ptr;
+}
+
+template <typename T, typename U>
+inline bool operator==(U* ptr, const RefPtr<T>& ref) {
+  return ref.get() == ptr;
+}
+
+template <typename T, typename U>
+inline bool operator!=(U* ptr, const RefPtr<T>& ref) {
+  return ref.get() != ptr;
+}
+
+template <typename T>
+inline bool operator==(const RefPtr<T>& ref, std::nullptr_t ptr) {
+  return ref.get() == ptr;
+}
+
+template <typename T>
+inline bool operator!=(const RefPtr<T>& ref, std::nullptr_t ptr) {
+  return ref.get() != ptr;
+}
+
+template <typename T>
+inline bool operator==(std::nullptr_t ptr, const RefPtr<T>& ref) {
+  return ref.get() == ptr;
+}
+
+template <typename T>
+inline bool operator!=(std::nullptr_t ptr, const RefPtr<T>& ref) {
+  return ref.get() != ptr;
+}
+
+}

tests/react-test-app/android/app/src/main/jni/first-party/fb/StaticInitialized.h

@@ -0,0 +1,40 @@
+/*
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+#pragma once
+#include <fb/assert.h>
+#include <utility>
+
+namespace facebook {
+
+// Class that lets you declare a global but does not add a static constructor
+// to the binary. Eventually I'd like to have this auto-initialize in a
+// multithreaded environment but for now it's easiest just to use manual
+// initialization.
+template <typename T>
+class StaticInitialized {
+public:
+  constexpr StaticInitialized() :
+    m_instance(nullptr)
+  {}
+
+  template <typename ...Args>
+  void initialize(Args&&... arguments) {
+    FBASSERT(!m_instance);
+    m_instance = new T(std::forward<Args>(arguments)...);
+  }
+
+  T* operator->() const {
+    return m_instance;
+  }
+private:
+  T* m_instance;
+};
+
+}

tests/react-test-app/android/app/src/main/jni/first-party/fb/ThreadLocal.h

@@ -0,0 +1,118 @@
+/*
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+#pragma once
+
+#include <pthread.h>
+#include <errno.h>
+
+#include <fb/assert.h>
+
+namespace facebook {
+
+///////////////////////////////////////////////////////////////////////////////
+
+/**
+ * A thread-local object is a "global" object within a thread. This is useful
+ * for writing apartment-threaded code, where nothing is actullay shared
+ * between different threads (hence no locking) but those variables are not
+ * on stack in local scope. To use it, just do something like this,
+ *
+ *   ThreadLocal<MyClass> static_object;
+ *     static_object->data_ = ...;
+ *     static_object->doSomething();
+ *
+ *   ThreadLocal<int> static_number;
+ *     int value = *static_number;
+ *
+ * So, syntax-wise it's similar to pointers. T can be primitive types, and if
+ * it's a class, there has to be a default constructor.
+ */
+template<typename T>
+class ThreadLocal {
+public:
+  /**
+   * Constructor that has to be called from a thread-neutral place.
+   */
+  ThreadLocal() :
+    m_key(0),
+    m_cleanup(OnThreadExit) {
+    initialize();
+  }
+
+  /**
+   * As above but with a custom cleanup function
+   */
+  typedef void (*CleanupFunction)(void* obj);
+  explicit ThreadLocal(CleanupFunction cleanup) :
+    m_key(0),
+    m_cleanup(cleanup) {
+    FBASSERT(cleanup);
+    initialize();
+  }
+
+  /**
+   * Access object's member or method through this operator overload.
+   */
+  T *operator->() const {
+    return get();
+  }
+
+  T &operator*() const {
+    return *get();
+  }
+
+  T *get() const {
+    return (T*)pthread_getspecific(m_key);
+  }
+
+  T* release() {
+    T* obj = get();
+    pthread_setspecific(m_key, NULL);
+    return obj;
+  }
+
+  void reset(T* other = NULL) {
+    T* old = (T*)pthread_getspecific(m_key);
+    if (old != other) {
+      FBASSERT(m_cleanup);
+      m_cleanup(old);
+      pthread_setspecific(m_key, other);
+    }
+  }
+
+private:
+  void initialize() {
+    int ret = pthread_key_create(&m_key, m_cleanup);
+    if (ret != 0) {
+      const char *msg = "(unknown error)";
+      switch (ret) {
+      case EAGAIN:
+        msg = "PTHREAD_KEYS_MAX (1024) is exceeded";
+        break;
+      case ENOMEM:
+        msg = "Out-of-memory";
+        break;
+      }
+      (void) msg;
+      FBASSERTMSGF(0, "pthread_key_create failed: %d %s", ret, msg);
+    }
+  }
+
+  static void OnThreadExit(void *obj) {
+    if (NULL != obj) {
+      delete (T*)obj;
+    }
+  }
+
+  pthread_key_t m_key;
+  CleanupFunction m_cleanup;
+};
+
+}

tests/react-test-app/android/app/src/main/jni/first-party/fb/assert.cpp

@@ -0,0 +1,41 @@
+/*
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+#include <cstdarg>
+#include <stdio.h>
+
+#include <fb/assert.h>
+#include <fb/log.h>
+
+namespace facebook {
+
+#define ASSERT_BUF_SIZE 4096
+static char sAssertBuf[ASSERT_BUF_SIZE];
+static AssertHandler gAssertHandler;
+
+void assertInternal(const char* formatstr ...) {
+    va_list va_args;
+    va_start(va_args, formatstr);
+    vsnprintf(sAssertBuf, sizeof(sAssertBuf), formatstr, va_args);
+    va_end(va_args);
+    if (gAssertHandler != NULL) {
+        gAssertHandler(sAssertBuf);
+    }
+    FBLOG(LOG_FATAL, "fbassert", "%s", sAssertBuf);
+    // crash at this specific address so that we can find our crashes easier
+    *(int*)0xdeadb00c = 0;
+    // let the compiler know we won't reach the end of the function
+     __builtin_unreachable();
+}
+
+void setAssertHandler(AssertHandler assertHandler) {
+    gAssertHandler = assertHandler;
+}
+
+} // namespace facebook

tests/react-test-app/android/app/src/main/jni/first-party/fb/include/fb/assert.h

@@ -0,0 +1,34 @@
+/*
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+#ifndef FBASSERT_H
+#define FBASSERT_H
+
+namespace facebook {
+#define ENABLE_FBASSERT 1
+
+#if ENABLE_FBASSERT
+#define FBASSERTMSGF(expr, msg, ...) !(expr) ? facebook::assertInternal("Assert (%s:%d): " msg, __FILE__, __LINE__, ##__VA_ARGS__) : (void) 0
+#else
+#define FBASSERTMSGF(expr, msg, ...)
+#endif // ENABLE_FBASSERT
+
+#define FBASSERT(expr) FBASSERTMSGF(expr, "%s", #expr)
+
+#define FBCRASH(msg, ...) facebook::assertInternal("Fatal error (%s:%d): " msg, __FILE__, __LINE__, ##__VA_ARGS__)
+#define FBUNREACHABLE() facebook::assertInternal("This code should be unreachable (%s:%d)", __FILE__, __LINE__)
+
+void assertInternal(const char* formatstr, ...) __attribute__((noreturn));
+
+// This allows storing the assert message before the current process terminates due to a crash
+typedef void (*AssertHandler)(const char* message);
+void setAssertHandler(AssertHandler assertHandler);
+
+} // namespace facebook
+#endif // FBASSERT_H

tests/react-test-app/android/app/src/main/jni/first-party/fb/include/fb/log.h

@@ -0,0 +1,361 @@
+/*
+ * Copyright (C) 2005 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/*
+ * FB Wrapper for logging functions.
+ *
+ * The android logging API uses the macro "LOG()" for its logic, which means
+ * that it conflicts with random other places that use LOG for their own
+ * purposes and doesn't work right half the places you include it
+ *
+ * FBLOG uses exactly the same semantics (FBLOGD for debug etc) but because of
+ * the FB prefix it's strictly better. FBLOGV also gets stripped out based on
+ * whether NDEBUG is set, but can be overridden by FBLOG_NDEBUG
+ *
+ * Most of the rest is a copy of <cutils/log.h> with minor changes.
+ */
+
+//
+// C/C++ logging functions.  See the logging documentation for API details.
+//
+// We'd like these to be available from C code (in case we import some from
+// somewhere), so this has a C interface.
+//
+// The output will be correct when the log file is shared between multiple
+// threads and/or multiple processes so long as the operating system
+// supports O_APPEND.  These calls have mutex-protected data structures
+// and so are NOT reentrant.  Do not use LOG in a signal handler.
+//
+#pragma once
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+    
+#ifdef ANDROID
+#include <android/log.h>
+#else
+    // These declarations are needed for our internal use even on non-Android builds.
+    // (they are borrowed from <android/log.h>)
+    
+    /*
+     * Android log priority values, in ascending priority order.
+     */
+    typedef enum android_LogPriority {
+        ANDROID_LOG_UNKNOWN = 0,
+        ANDROID_LOG_DEFAULT,    /* only for SetMinPriority() */
+        ANDROID_LOG_VERBOSE,
+        ANDROID_LOG_DEBUG,
+        ANDROID_LOG_INFO,
+        ANDROID_LOG_WARN,
+        ANDROID_LOG_ERROR,
+        ANDROID_LOG_FATAL,
+        ANDROID_LOG_SILENT,     /* only for SetMinPriority(); must be last */
+    } android_LogPriority;
+    
+    /*
+     * Send a simple string to the log.
+     */
+    int __android_log_write(int prio, const char *tag, const char *text);
+    
+    /*
+     * Send a formatted string to the log, used like printf(fmt,...)
+     */
+    int __android_log_print(int prio, const char *tag,  const char *fmt, ...)
+#if defined(__GNUC__)
+    __attribute__ ((format(printf, 3, 4)))
+#endif
+    ;
+
+#endif
+
+// ---------------------------------------------------------------------
+
+/*
+ * Normally we strip FBLOGV (VERBOSE messages) from release builds.
+ * You can modify this (for example with "#define FBLOG_NDEBUG 0"
+ * at the top of your source file) to change that behavior.
+ */
+#ifndef FBLOG_NDEBUG
+#ifdef NDEBUG
+#define FBLOG_NDEBUG 1
+#else
+#define FBLOG_NDEBUG 0
+#endif
+#endif
+
+/*
+ * This is the local tag used for the following simplified
+ * logging macros.  You can change this preprocessor definition
+ * before using the other macros to change the tag.
+ */
+#ifndef LOG_TAG
+#define LOG_TAG NULL
+#endif
+
+// ---------------------------------------------------------------------
+
+/*
+ * Simplified macro to send a verbose log message using the current LOG_TAG.
+ */
+#ifndef FBLOGV
+#if FBLOG_NDEBUG
+#define FBLOGV(...)   ((void)0)
+#else
+#define FBLOGV(...) ((void)FBLOG(LOG_VERBOSE, LOG_TAG, __VA_ARGS__))
+#endif
+#endif
+
+#define CONDITION(cond)     (__builtin_expect((cond)!=0, 0))
+
+#ifndef FBLOGV_IF
+#if FBLOG_NDEBUG
+#define FBLOGV_IF(cond, ...)   ((void)0)
+#else
+#define FBLOGV_IF(cond, ...) \
+    ( (CONDITION(cond)) \
+    ? ((void)FBLOG(LOG_VERBOSE, LOG_TAG, __VA_ARGS__)) \
+    : (void)0 )
+#endif
+#endif
+
+/*
+ * Simplified macro to send a debug log message using the current LOG_TAG.
+ */
+#ifndef FBLOGD
+#define FBLOGD(...) ((void)FBLOG(LOG_DEBUG, LOG_TAG, __VA_ARGS__))
+#endif
+
+#ifndef FBLOGD_IF
+#define FBLOGD_IF(cond, ...) \
+    ( (CONDITION(cond)) \
+    ? ((void)FBLOG(LOG_DEBUG, LOG_TAG, __VA_ARGS__)) \
+    : (void)0 )
+#endif
+
+/*
+ * Simplified macro to send an info log message using the current LOG_TAG.
+ */
+#ifndef FBLOGI
+#define FBLOGI(...) ((void)FBLOG(LOG_INFO, LOG_TAG, __VA_ARGS__))
+#endif
+
+#ifndef FBLOGI_IF
+#define FBLOGI_IF(cond, ...) \
+    ( (CONDITION(cond)) \
+    ? ((void)FBLOG(LOG_INFO, LOG_TAG, __VA_ARGS__)) \
+    : (void)0 )
+#endif
+
+/*
+ * Simplified macro to send a warning log message using the current LOG_TAG.
+ */
+#ifndef FBLOGW
+#define FBLOGW(...) ((void)FBLOG(LOG_WARN, LOG_TAG, __VA_ARGS__))
+#endif
+
+#ifndef FBLOGW_IF
+#define FBLOGW_IF(cond, ...) \
+    ( (CONDITION(cond)) \
+    ? ((void)FBLOG(LOG_WARN, LOG_TAG, __VA_ARGS__)) \
+    : (void)0 )
+#endif
+
+/*
+ * Simplified macro to send an error log message using the current LOG_TAG.
+ */
+#ifndef FBLOGE
+#define FBLOGE(...) ((void)FBLOG(LOG_ERROR, LOG_TAG, __VA_ARGS__))
+#endif
+
+#ifndef FBLOGE_IF
+#define FBLOGE_IF(cond, ...) \
+    ( (CONDITION(cond)) \
+    ? ((void)FBLOG(LOG_ERROR, LOG_TAG, __VA_ARGS__)) \
+    : (void)0 )
+#endif
+
+// ---------------------------------------------------------------------
+
+/*
+ * Conditional based on whether the current LOG_TAG is enabled at
+ * verbose priority.
+ */
+#ifndef IF_FBLOGV
+#if FBLOG_NDEBUG
+#define IF_FBLOGV() if (false)
+#else
+#define IF_FBLOGV() IF_FBLOG(LOG_VERBOSE, LOG_TAG)
+#endif
+#endif
+
+/*
+ * Conditional based on whether the current LOG_TAG is enabled at
+ * debug priority.
+ */
+#ifndef IF_FBLOGD
+#define IF_FBLOGD() IF_FBLOG(LOG_DEBUG, LOG_TAG)
+#endif
+
+/*
+ * Conditional based on whether the current LOG_TAG is enabled at
+ * info priority.
+ */
+#ifndef IF_FBLOGI
+#define IF_FBLOGI() IF_FBLOG(LOG_INFO, LOG_TAG)
+#endif
+
+/*
+ * Conditional based on whether the current LOG_TAG is enabled at
+ * warn priority.
+ */
+#ifndef IF_FBLOGW
+#define IF_FBLOGW() IF_FBLOG(LOG_WARN, LOG_TAG)
+#endif
+
+/*
+ * Conditional based on whether the current LOG_TAG is enabled at
+ * error priority.
+ */
+#ifndef IF_FBLOGE
+#define IF_FBLOGE() IF_FBLOG(LOG_ERROR, LOG_TAG)
+#endif
+
+
+// ---------------------------------------------------------------------
+
+/*
+ * Log a fatal error.  If the given condition fails, this stops program
+ * execution like a normal assertion, but also generating the given message.
+ * It is NOT stripped from release builds.  Note that the condition test
+ * is -inverted- from the normal assert() semantics.
+ */
+#define FBLOG_ALWAYS_FATAL_IF(cond, ...) \
+    ( (CONDITION(cond)) \
+    ? ((void)fb_printAssert(#cond, LOG_TAG, __VA_ARGS__)) \
+    : (void)0 )
+
+#define FBLOG_ALWAYS_FATAL(...) \
+    ( ((void)fb_printAssert(NULL, LOG_TAG, __VA_ARGS__)) )
+
+/*
+ * Versions of LOG_ALWAYS_FATAL_IF and LOG_ALWAYS_FATAL that
+ * are stripped out of release builds.
+ */
+#if FBLOG_NDEBUG
+
+#define FBLOG_FATAL_IF(cond, ...) ((void)0)
+#define FBLOG_FATAL(...) ((void)0)
+
+#else
+
+#define FBLOG_FATAL_IF(cond, ...) FBLOG_ALWAYS_FATAL_IF(cond, __VA_ARGS__)
+#define FBLOG_FATAL(...) FBLOG_ALWAYS_FATAL(__VA_ARGS__)
+
+#endif
+
+/*
+ * Assertion that generates a log message when the assertion fails.
+ * Stripped out of release builds.  Uses the current LOG_TAG.
+ */
+#define FBLOG_ASSERT(cond, ...) FBLOG_FATAL_IF(!(cond), __VA_ARGS__)
+//#define LOG_ASSERT(cond) LOG_FATAL_IF(!(cond), "Assertion failed: " #cond)
+
+// ---------------------------------------------------------------------
+
+/*
+ * Basic log message macro.
+ *
+ * Example:
+ *  FBLOG(LOG_WARN, NULL, "Failed with error %d", errno);
+ *
+ * The second argument may be NULL or "" to indicate the "global" tag.
+ */
+#ifndef FBLOG
+#define FBLOG(priority, tag, ...) \
+    FBLOG_PRI(ANDROID_##priority, tag, __VA_ARGS__)
+#endif
+
+#ifndef FBLOG_BY_DELIMS
+#define FBLOG_BY_DELIMS(priority, tag, delims, msg, ...) \
+    logPrintByDelims(ANDROID_##priority, tag, delims, msg, ##__VA_ARGS__)
+#endif
+
+/*
+ * Log macro that allows you to specify a number for the priority.
+ */
+#ifndef FBLOG_PRI
+#define FBLOG_PRI(priority, tag, ...) \
+    fb_printLog(priority, tag, __VA_ARGS__)
+#endif
+
+/*
+ * Log macro that allows you to pass in a varargs ("args" is a va_list).
+ */
+#ifndef FBLOG_PRI_VA
+#define FBLOG_PRI_VA(priority, tag, fmt, args) \
+    fb_vprintLog(priority, NULL, tag, fmt, args)
+#endif
+
+/*
+ * Conditional given a desired logging priority and tag.
+ */
+#ifndef IF_FBLOG
+#define IF_FBLOG(priority, tag) \
+    if (fb_testLog(ANDROID_##priority, tag))
+#endif
+
+typedef void (*LogHandler)(int priority, const char* tag, const char* message);
+void setLogHandler(LogHandler logHandler);
+
+/*
+ * ===========================================================================
+ *
+ * The stuff in the rest of this file should not be used directly.
+ */
+int fb_printLog(int prio, const char *tag,  const char *fmt, ...)
+#if defined(__GNUC__)
+    __attribute__ ((format(printf, 3, 4)))
+#endif
+;
+
+#define fb_vprintLog(prio, cond, tag, fmt...) \
+    __android_log_vprint(prio, tag, fmt)
+
+#define fb_printAssert(cond, tag, fmt...) \
+    __android_log_assert(cond, tag, fmt)
+
+#define fb_writeLog(prio, tag, text) \
+    __android_log_write(prio, tag, text)
+
+#define fb_bWriteLog(tag, payload, len) \
+    __android_log_bwrite(tag, payload, len)
+#define fb_btWriteLog(tag, type, payload, len) \
+    __android_log_btwrite(tag, type, payload, len)
+
+#define fb_testLog(prio, tag) (1)
+
+/*
+ * FB extensions
+ */
+void logPrintByDelims(int priority, const char* tag, const char* delims,
+                      const char* msg, ...);
+
+
+#ifdef __cplusplus
+}
+#endif
+

tests/react-test-app/android/app/src/main/jni/first-party/fb/log.cpp

@@ -0,0 +1,100 @@
+/*
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+#include <fb/log.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <string.h>
+
+#define LOG_BUFFER_SIZE 4096
+static LogHandler gLogHandler;
+
+void setLogHandler(LogHandler logHandler) {
+  gLogHandler = logHandler;
+}
+
+int fb_printLog(int prio, const char *tag,  const char *fmt, ...) {
+  char logBuffer[LOG_BUFFER_SIZE];
+
+  va_list va_args;
+  va_start(va_args, fmt);
+  int result = vsnprintf(logBuffer, sizeof(logBuffer), fmt, va_args);
+  va_end(va_args);
+  if (gLogHandler != NULL) {
+      gLogHandler(prio, tag, logBuffer);
+  }
+  __android_log_write(prio, tag, logBuffer);
+  return result;
+}
+
+void logPrintByDelims(int priority, const char* tag, const char* delims,
+        const char* msg, ...)
+{
+    va_list ap;
+    char buf[32768];
+    char* context;
+    char* tok;
+
+    va_start(ap, msg);
+    vsnprintf(buf, sizeof(buf), msg, ap);
+    va_end(ap);
+
+    tok = strtok_r(buf, delims, &context);
+
+    if (!tok) {
+        return;
+    }
+
+    do {
+        __android_log_write(priority, tag, tok);
+    } while ((tok = strtok_r(NULL, delims, &context)));
+}
+
+#ifndef ANDROID
+
+// Implementations of the basic android logging functions for non-android platforms.
+
+static char logTagChar(int prio) {
+  switch (prio) {
+    default:
+    case ANDROID_LOG_UNKNOWN:
+    case ANDROID_LOG_DEFAULT:
+    case ANDROID_LOG_SILENT:
+      return ' ';
+    case ANDROID_LOG_VERBOSE:
+      return 'V';
+    case ANDROID_LOG_DEBUG:
+      return 'D';
+    case ANDROID_LOG_INFO:
+      return 'I';
+    case ANDROID_LOG_WARN:
+      return 'W';
+    case ANDROID_LOG_ERROR:
+      return 'E';
+    case ANDROID_LOG_FATAL:
+      return 'F';
+  }
+}
+
+int __android_log_write(int prio, const char *tag, const char *text) {
+  return fprintf(stderr, "[%c/%.16s] %s\n", logTagChar(prio), tag, text);
+}
+
+int __android_log_print(int prio, const char *tag,  const char *fmt, ...) {
+  va_list ap;
+  va_start(ap, fmt);
+
+  int res = fprintf(stderr, "[%c/%.16s] ", logTagChar(prio), tag);
+  res += vfprintf(stderr, "%s\n", ap);
+
+  va_end(ap);
+  return res;
+}
+
+#endif

tests/react-test-app/android/app/src/main/jni/first-party/fb/noncopyable.h

@@ -0,0 +1,21 @@
+/*
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+#pragma once
+
+namespace facebook {
+
+struct noncopyable {
+  noncopyable(const noncopyable&) = delete;
+  noncopyable& operator=(const noncopyable&) = delete;
+protected:
+  noncopyable() = default;
+};
+
+}

tests/react-test-app/android/app/src/main/jni/first-party/fb/nonmovable.h

@@ -0,0 +1,21 @@
+/*
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+#pragma once
+
+namespace facebook {
+
+struct nonmovable {
+  nonmovable(nonmovable&&) = delete;
+  nonmovable& operator=(nonmovable&&) = delete;
+protected:
+  nonmovable() = default;
+};
+
+}

tests/react-test-app/android/app/src/main/jni/first-party/jni/ALog.h

@@ -0,0 +1,83 @@
+/*
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+/** @file ALog.h
+ *
+ *  Very simple android only logging. Define LOG_TAG to enable the macros.
+ */
+
+#pragma once
+
+#ifdef __ANDROID__
+
+#include <android/log.h>
+
+namespace facebook {
+namespace alog {
+
+template<typename... ARGS>
+inline void log(int level, const char* tag, const char* msg, ARGS... args) noexcept {
+  __android_log_print(level, tag, msg, args...);
+}
+
+template<typename... ARGS>
+inline void log(int level, const char* tag, const char* msg) noexcept {
+  __android_log_write(level, tag, msg);
+}
+
+template<typename... ARGS>
+inline void logv(const char* tag, const char* msg, ARGS... args) noexcept {
+  log(ANDROID_LOG_VERBOSE, tag, msg, args...);
+}
+
+template<typename... ARGS>
+inline void logd(const char* tag, const char* msg, ARGS... args) noexcept {
+  log(ANDROID_LOG_DEBUG, tag, msg, args...);
+}
+
+template<typename... ARGS>
+inline void logi(const char* tag, const char* msg, ARGS... args) noexcept {
+  log(ANDROID_LOG_INFO, tag, msg, args...);
+}
+
+template<typename... ARGS>
+inline void logw(const char* tag, const char* msg, ARGS... args) noexcept {
+  log(ANDROID_LOG_WARN, tag, msg, args...);
+}
+
+template<typename... ARGS>
+inline void loge(const char* tag, const char* msg, ARGS... args) noexcept {
+  log(ANDROID_LOG_ERROR, tag, msg, args...);
+}
+
+template<typename... ARGS>
+inline void logf(const char* tag, const char* msg, ARGS... args) noexcept {
+  log(ANDROID_LOG_FATAL, tag, msg, args...);
+}
+
+
+#ifdef LOG_TAG
+# define ALOGV(...) ::facebook::alog::logv(LOG_TAG, __VA_ARGS__)
+# define ALOGD(...) ::facebook::alog::logd(LOG_TAG, __VA_ARGS__)
+# define ALOGI(...) ::facebook::alog::logi(LOG_TAG, __VA_ARGS__)
+# define ALOGW(...) ::facebook::alog::logw(LOG_TAG, __VA_ARGS__)
+# define ALOGE(...) ::facebook::alog::loge(LOG_TAG, __VA_ARGS__)
+# define ALOGF(...) ::facebook::alog::logf(LOG_TAG, __VA_ARGS__)
+#endif
+
+}}
+
+#else
+# define ALOGV(...) ((void)0)
+# define ALOGD(...) ((void)0)
+# define ALOGI(...) ((void)0)
+# define ALOGW(...) ((void)0)
+# define ALOGE(...) ((void)0)
+# define ALOGF(...) ((void)0)
+#endif

tests/react-test-app/android/app/src/main/jni/first-party/jni/Android.mk

@@ -0,0 +1,35 @@
+LOCAL_PATH:= $(call my-dir)
+include $(CLEAR_VARS)
+
+LOCAL_SRC_FILES:= \
+       Countable.cpp \
+       Environment.cpp \
+       fbjni.cpp \
+       jni_helpers.cpp \
+       LocalString.cpp \
+       OnLoad.cpp \
+       WeakReference.cpp \
+       fbjni/Exceptions.cpp \
+       fbjni/Hybrid.cpp \
+       fbjni/References.cpp
+
+LOCAL_C_INCLUDES := $(LOCAL_PATH)/..
+LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/..
+
+LOCAL_CFLAGS := -DLOG_TAG=\"fbjni\" -fexceptions -frtti
+LOCAL_CFLAGS += -Wall -Werror
+
+CXX11_FLAGS := -std=gnu++11
+LOCAL_CFLAGS += $(CXX11_FLAGS)
+
+LOCAL_EXPORT_CPPFLAGS := $(CXX11_FLAGS)
+
+LOCAL_LDLIBS := -landroid
+
+LOCAL_SHARED_LIBRARIES := libfb
+
+LOCAL_MODULE := libfbjni
+
+include $(BUILD_SHARED_LIBRARY)
+
+$(call import-module,fb)

tests/react-test-app/android/app/src/main/jni/first-party/jni/Countable.cpp

@@ -0,0 +1,69 @@
+/*
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+#include <cstdint>
+#include <jni/Countable.h>
+#include <jni/Environment.h>
+#include <jni/Registration.h>
+
+namespace facebook {
+namespace jni {
+
+static jfieldID gCountableNativePtr;
+
+static RefPtr<Countable>* rawCountableFromJava(JNIEnv* env, jobject obj) {
+  FBASSERT(obj);
+  return reinterpret_cast<RefPtr<Countable>*>(env->GetLongField(obj, gCountableNativePtr));
+}
+
+const RefPtr<Countable>& countableFromJava(JNIEnv* env, jobject obj) {
+  FBASSERT(obj);
+  return *rawCountableFromJava(env, obj);
+}
+
+void setCountableForJava(JNIEnv* env, jobject obj, RefPtr<Countable>&& countable) {
+  int oldValue = env->GetLongField(obj, gCountableNativePtr);
+  FBASSERTMSGF(oldValue == 0, "Cannot reinitialize object; expected nullptr, got %x", oldValue);
+
+  FBASSERT(countable);
+  uintptr_t fieldValue = (uintptr_t) new RefPtr<Countable>(std::move(countable));
+  env->SetLongField(obj, gCountableNativePtr, fieldValue);
+}
+
+/**
+ * NB: THREAD SAFETY (this comment also exists at Countable.java)
+ *
+ * This method deletes the corresponding native object on whatever thread the method is called
+ * on. In the common case when this is called by Countable#finalize(), this will be called on the
+ * system finalizer thread. If you manually call dispose on the Java object, the native object
+ * will be deleted synchronously on that thread.
+ */
+void dispose(JNIEnv* env, jobject obj) {
+  // Grab the pointer
+  RefPtr<Countable>* countable = rawCountableFromJava(env, obj);
+  if (!countable) {
+    // That was easy.
+    return;
+  }
+
+  // Clear out the old value to avoid double-frees
+  env->SetLongField(obj, gCountableNativePtr, 0);
+
+  delete countable;
+}
+
+void CountableOnLoad(JNIEnv* env) {
+  jclass countable = env->FindClass("com/facebook/jni/Countable");
+  gCountableNativePtr = env->GetFieldID(countable, "mInstance", "J");
+  registerNatives(env, countable, {
+    { "dispose", "()V", (void*) dispose },
+  });
+}
+
+} }

tests/react-test-app/android/app/src/main/jni/first-party/jni/Countable.h

@@ -0,0 +1,33 @@
+/*
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+#pragma once
+#include <jni.h>
+#include <fb/Countable.h>
+#include <fb/RefPtr.h>
+
+namespace facebook {
+namespace jni {
+
+const RefPtr<Countable>& countableFromJava(JNIEnv* env, jobject obj);
+
+template <typename T> RefPtr<T> extractRefPtr(JNIEnv* env, jobject obj) {
+  return static_cast<RefPtr<T>>(countableFromJava(env, obj));
+}
+
+template <typename T> RefPtr<T> extractPossiblyNullRefPtr(JNIEnv* env, jobject obj) {
+  return obj ? extractRefPtr<T>(env, obj) : nullptr;
+}
+
+void setCountableForJava(JNIEnv* env, jobject obj, RefPtr<Countable>&& countable);
+
+void CountableOnLoad(JNIEnv* env);
+
+} }
+

tests/react-test-app/android/app/src/main/jni/first-party/jni/Doxyfile

@@ -0,0 +1,18 @@
+PROJECT_NAME           = "Facebook JNI"
+PROJECT_BRIEF          = "Helper library to provide safe and convenient access to JNI with very low overhead"
+JAVADOC_AUTOBRIEF      = YES
+EXTRACT_ALL            = YES
+RECURSIVE              = YES
+EXCLUDE                = tests Asserts.h Countable.h GlobalReference.h LocalReference.h LocalString.h Registration.h WeakReference.h jni_helpers.h Environment.h
+EXCLUDE_PATTERNS       = *-inl.h *.cpp
+GENERATE_HTML          = YES
+GENERATE_LATEX         = NO
+ENABLE_PREPROCESSING   = YES
+HIDE_UNDOC_MEMBERS     = YES
+HIDE_SCOPE_NAMES       = YES
+HIDE_FRIEND_COMPOUNDS  = YES
+HIDE_UNDOC_CLASSES     = YES
+SHOW_INCLUDE_FILES     = NO
+PREDEFINED             = LOG_TAG=fbjni
+EXAMPLE_PATH           = samples
+#ENABLED_SECTIONS       = INTERNAL

tests/react-test-app/android/app/src/main/jni/first-party/jni/Environment.cpp

@@ -0,0 +1,89 @@
+/*
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+#include <pthread.h>
+#include <fb/log.h>
+#include <fb/StaticInitialized.h>
+#include <fb/ThreadLocal.h>
+#include <jni/Environment.h>
+
+namespace facebook {
+namespace jni {
+
+static StaticInitialized<ThreadLocal<JNIEnv>> g_env;
+static JavaVM* g_vm = nullptr;
+
+/* static */
+JNIEnv* Environment::current() {
+  JNIEnv* env = g_env->get();
+  if ((env == nullptr) && (g_vm != nullptr)) {
+    if (g_vm->GetEnv((void**) &env, JNI_VERSION_1_6) != JNI_OK) {
+      FBLOGE("Error retrieving JNI Environment, thread is probably not attached to JVM");
+      env = nullptr;
+    } else {
+      g_env->reset(env);
+    }
+  }
+  return env;
+}
+
+/* static */
+void Environment::detachCurrentThread() {
+  auto env = g_env->get();
+  if (env) {
+    FBASSERT(g_vm);
+    g_vm->DetachCurrentThread();
+    g_env->reset();
+  }
+}
+
+struct EnvironmentInitializer {
+  EnvironmentInitializer(JavaVM* vm) {
+      FBASSERT(!g_vm);
+      FBASSERT(vm);
+      g_vm = vm;
+      g_env.initialize([] (void*) {});
+  }
+};
+
+/* static */
+void Environment::initialize(JavaVM* vm) {
+  static EnvironmentInitializer init(vm);
+}
+
+/* static */
+JNIEnv* Environment::ensureCurrentThreadIsAttached() {
+  auto env = g_env->get();
+  if (!env) {
+    FBASSERT(g_vm);
+    g_vm->AttachCurrentThread(&env, nullptr);
+    g_env->reset(env);
+  }
+  return env;
+}
+
+ThreadScope::ThreadScope()
+    : attachedWithThisScope_(false) {
+  JNIEnv* env = nullptr;
+  if (g_vm->GetEnv((void**) &env, JNI_VERSION_1_6) != JNI_EDETACHED) {
+    return;
+  }
+  env = facebook::jni::Environment::ensureCurrentThreadIsAttached();
+  FBASSERT(env);
+  attachedWithThisScope_ = true;
+}
+
+ThreadScope::~ThreadScope() {
+  if (attachedWithThisScope_) {
+    Environment::detachCurrentThread();
+  }
+}
+
+} }
+

tests/react-test-app/android/app/src/main/jni/first-party/jni/Environment.h

@@ -0,0 +1,61 @@
+/*
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+#pragma once
+#include <string>
+#include <jni.h>
+
+namespace facebook {
+namespace jni {
+
+// Keeps a thread-local reference to the current thread's JNIEnv.
+struct Environment {
+  // May be null if this thread isn't attached to the JVM
+  static JNIEnv* current();
+  static void initialize(JavaVM* vm);
+  static JNIEnv* ensureCurrentThreadIsAttached();
+  static void detachCurrentThread();
+};
+
+/**
+ * RAII Object that attaches a thread to the JVM. Failing to detach from a thread before it
+ * exits will cause a crash, as will calling Detach an extra time, and this guard class helps
+ * keep that straight. In addition, it remembers whether it performed the attach or not, so it
+ * is safe to nest it with itself or with non-fbjni code that manages the attachment correctly.
+ *
+ * Potential concerns:
+ *  - Attaching to the JVM is fast (~100us on MotoG), but ideally you would attach while the
+ *    app is not busy.
+ *  - Having a thread detach at arbitrary points is not safe in Dalvik; you need to be sure that
+ *    there is no Java code on the current stack or you run the risk of a crash like:
+ *      ERROR: detaching thread with interp frames (count=18)
+ *    (More detail at https://groups.google.com/forum/#!topic/android-ndk/2H8z5grNqjo)
+ *    ThreadScope won't do a detach if the thread was already attached before the guard is
+ *    instantiated, but there's probably some usage that could trip this up.
+ *  - Newly attached C++ threads only get the bootstrap class loader -- i.e. java language
+ *    classes, not any of our application's classes. This will be different behavior than threads
+ *    that were initiated on the Java side. A workaround is to pass a global reference for a
+ *    class or instance to the new thread; this bypasses the need for the class loader.
+ *    (See http://docs.oracle.com/javase/7/docs/technotes/guides/jni/spec/invocation.html#attach_current_thread)
+ */
+class ThreadScope {
+ public:
+  ThreadScope();
+  ThreadScope(ThreadScope&) = delete;
+  ThreadScope(ThreadScope&&) = default;
+  ThreadScope& operator=(ThreadScope&) = delete;
+  ThreadScope& operator=(ThreadScope&&) = delete;
+  ~ThreadScope();
+
+ private:
+  bool attachedWithThisScope_;
+};
+
+} }
+

tests/react-test-app/android/app/src/main/jni/first-party/jni/GlobalReference.h

@@ -0,0 +1,91 @@
+/*
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+#pragma once
+
+#include <memory>
+#include <type_traits>
+
+#include <jni.h>
+
+#include <jni/Environment.h>
+
+namespace facebook { namespace jni {
+
+template<typename T>
+class GlobalReference {
+  static_assert(std::is_convertible<T, jobject>::value,
+                "GlobalReference<T> instantiated with type that is not "
+                "convertible to jobject");
+
+ public:
+  explicit GlobalReference(T globalReference) :
+    reference_(globalReference? Environment::current()->NewGlobalRef(globalReference) : nullptr) {
+  }
+
+  ~GlobalReference() {
+    reset();
+  }
+
+  GlobalReference() :
+    reference_(nullptr) {
+  }
+
+  // enable move constructor and assignment
+  GlobalReference(GlobalReference&& rhs) :
+    reference_(std::move(rhs.reference_)) {
+    rhs.reference_ = nullptr;
+  }
+
+  GlobalReference& operator=(GlobalReference&& rhs) {
+    if (this != &rhs) {
+      reset();
+      reference_ = std::move(rhs.reference_);
+      rhs.reference_ = nullptr;
+    }
+    return *this;
+  }
+
+  GlobalReference(const GlobalReference<T>& rhs) :
+    reference_{} {
+    reset(rhs.get());
+  }
+
+  GlobalReference& operator=(const GlobalReference<T>& rhs) {
+    if (this == &rhs) {
+      return *this;
+    }
+    reset(rhs.get());
+    return *this;
+  }
+
+  explicit operator bool() const {
+    return (reference_ != nullptr);
+  }
+
+  T get() const {
+    return reinterpret_cast<T>(reference_);
+  }
+
+  void reset(T globalReference = nullptr) {
+    if (reference_) {
+      Environment::current()->DeleteGlobalRef(reference_);
+    }
+    if (globalReference) {
+      reference_ = Environment::current()->NewGlobalRef(globalReference);
+    } else {
+      reference_ = nullptr;
+    }
+  }
+
+ private:
+  jobject reference_;
+};
+
+}}

tests/react-test-app/android/app/src/main/jni/first-party/jni/LocalReference.h

@@ -0,0 +1,37 @@
+/*
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+#pragma once
+
+#include <memory>
+#include <type_traits>
+
+#include <jni.h>
+
+#include <jni/Environment.h>
+
+namespace facebook {
+namespace jni {
+
+template<class T>
+struct LocalReferenceDeleter {
+  static_assert(std::is_convertible<T, jobject>::value,
+    "LocalReferenceDeleter<T> instantiated with type that is not convertible to jobject");
+  void operator()(T localReference) {
+    if (localReference != nullptr) {
+      Environment::current()->DeleteLocalRef(localReference);
+    }
+  }
+ };
+
+template<class T>
+using LocalReference =
+  std::unique_ptr<typename std::remove_pointer<T>::type, LocalReferenceDeleter<T>>;
+
+} }

tests/react-test-app/android/app/src/main/jni/first-party/jni/LocalString.cpp

@@ -0,0 +1,242 @@
+/*
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+#include <jni/LocalString.h>
+#include <jni/Environment.h>
+#include <fb/assert.h>
+
+#include <vector>
+
+namespace facebook {
+namespace jni {
+
+namespace {
+
+inline void encode3ByteUTF8(char32_t code, uint8_t* out) {
+  FBASSERTMSGF((code & 0xffff0000) == 0, "3 byte utf-8 encodings only valid for up to 16 bits");
+
+  out[0] = 0xE0 | (code >> 12);
+  out[1] = 0x80 | ((code >> 6) & 0x3F);
+  out[2] = 0x80 | (code & 0x3F);
+}
+
+inline char32_t decode3ByteUTF8(const uint8_t* in) {
+  return (((in[0] & 0x0f) << 12) |
+          ((in[1] & 0x3f) << 6) |
+          ( in[2] & 0x3f));
+}
+
+inline void encode4ByteUTF8(char32_t code, std::string& out, size_t offset) {
+  FBASSERTMSGF((code & 0xfff80000) == 0, "4 byte utf-8 encodings only valid for up to 21 bits");
+
+  out[offset] =     (char) (0xF0 | (code >> 18));
+  out[offset + 1] = (char) (0x80 | ((code >> 12) & 0x3F));
+  out[offset + 2] = (char) (0x80 | ((code >> 6) & 0x3F));
+  out[offset + 3] = (char) (0x80 | (code & 0x3F));
+}
+
+template <typename T>
+inline bool isFourByteUTF8Encoding(const T* utf8) {
+  return ((*utf8 & 0xF8) == 0xF0);
+}
+
+}
+
+namespace detail {
+
+size_t modifiedLength(const std::string& str) {
+  // Scan for supplementary characters
+  size_t j = 0;
+  for (size_t i = 0; i < str.size(); ) {
+    if (str[i] == 0) {
+      i += 1;
+      j += 2;
+    } else if (i + 4 > str.size() ||
+               !isFourByteUTF8Encoding(&(str[i]))) {
+      // See the code in utf8ToModifiedUTF8 for what's happening here.
+      i += 1;
+      j += 1;
+    } else {
+      i += 4;
+      j += 6;
+    }
+  }
+
+  return j;
+}
+
+// returns modified utf8 length; *length is set to strlen(str)
+size_t modifiedLength(const uint8_t* str, size_t* length) {
+  // NUL-terminated: Scan for length and supplementary characters
+  size_t i = 0;
+  size_t j = 0;
+  while (str[i] != 0) {
+    if (str[i + 1] == 0 ||
+        str[i + 2] == 0 ||
+        str[i + 3] == 0 ||
+        !isFourByteUTF8Encoding(&(str[i]))) {
+      i += 1;
+      j += 1;
+    } else {
+      i += 4;
+      j += 6;
+    }
+  }
+
+  *length = i;
+  return j;
+}
+
+void utf8ToModifiedUTF8(const uint8_t* utf8, size_t len, uint8_t* modified, size_t modifiedBufLen)
+{
+  size_t j = 0;
+  for (size_t i = 0; i < len; ) {
+    FBASSERTMSGF(j < modifiedBufLen, "output buffer is too short");
+    if (utf8[i] == 0) {
+      FBASSERTMSGF(j + 1 < modifiedBufLen, "output buffer is too short");
+      modified[j] = 0xc0;
+      modified[j + 1] = 0x80;
+      i += 1;
+      j += 2;
+      continue;
+    }
+
+    if (i + 4 > len ||
+        !isFourByteUTF8Encoding(utf8 + i)) {
+      // If the input is too short for this to be a four-byte
+      // encoding, or it isn't one for real, just copy it on through.
+      modified[j] = utf8[i];
+      i++;
+      j++;
+      continue;
+    }
+
+    // Convert 4 bytes of input to 2 * 3 bytes of output
+    char32_t code = (((utf8[i]     & 0x07) << 18) |
+                     ((utf8[i + 1] & 0x3f) << 12) |
+                     ((utf8[i + 2] & 0x3f) << 6) |
+                     ( utf8[i + 3] & 0x3f));
+    char32_t first;
+    char32_t second;
+
+    if (code > 0x10ffff) {
+      // These could be valid utf-8, but cannot be represented as modified UTF-8, due to the 20-bit
+      // limit on that representation.  Encode two replacement characters, so the expected output
+      // length lines up.
+      const char32_t kUnicodeReplacementChar = 0xfffd;
+      first = kUnicodeReplacementChar;
+      second = kUnicodeReplacementChar;
+    } else {
+      // split into surrogate pair
+      first = ((code - 0x010000) >> 10) | 0xd800;
+      second = ((code - 0x010000) & 0x3ff) | 0xdc00;
+    }
+
+    // encode each as a 3 byte surrogate value
+    FBASSERTMSGF(j + 5 < modifiedBufLen, "output buffer is too short");
+    encode3ByteUTF8(first, modified + j);
+    encode3ByteUTF8(second, modified + j + 3);
+    i += 4;
+    j += 6;
+  }
+
+  FBASSERTMSGF(j < modifiedBufLen, "output buffer is too short");
+  modified[j++] = '\0';
+}
+
+std::string modifiedUTF8ToUTF8(const uint8_t* modified, size_t len) {
+  // Converting from modified utf8 to utf8 will always shrink, so this will always be sufficient
+  std::string utf8(len, 0);
+  size_t j = 0;
+  for (size_t i = 0; i < len; ) {
+    // surrogate pair: 1101 10xx  xxxx xxxx  1101 11xx  xxxx xxxx
+    // encoded pair: 1110 1101  1010 xxxx  10xx xxxx  1110 1101  1011 xxxx  10xx xxxx
+
+    if (len >= i + 6 &&
+        modified[i] == 0xed &&
+        (modified[i + 1] & 0xf0) == 0xa0 &&
+        modified[i + 3] == 0xed &&
+        (modified[i + 4] & 0xf0) == 0xb0) {
+      // Valid surrogate pair
+      char32_t pair1 = decode3ByteUTF8(modified + i);
+      char32_t pair2 = decode3ByteUTF8(modified + i + 3);
+      char32_t ch = 0x10000 + (((pair1 & 0x3ff) << 10) |
+                               ( pair2 & 0x3ff));
+      encode4ByteUTF8(ch, utf8, j);
+      i += 6;
+      j += 4;
+      continue;
+    } else if (len >= i + 2 &&
+               modified[i] == 0xc0 &&
+               modified[i + 1] == 0x80) {
+      utf8[j] = 0;
+      i += 2;
+      j += 1;
+      continue;
+    }
+
+    // copy one byte.  This might be a one, two, or three-byte encoding.  It might be an invalid
+    // encoding of some sort, but garbage in garbage out is ok.
+
+    utf8[j] = (char) modified[i];
+    i++;
+    j++;
+  }
+
+  utf8.resize(j);
+
+  return utf8;
+}
+
+}
+
+LocalString::LocalString(const std::string& str)
+{
+  size_t modlen = detail::modifiedLength(str);
+  if (modlen == str.size()) {
+    // no supplementary characters, build jstring from input buffer
+    m_string = Environment::current()->NewStringUTF(str.data());
+    return;
+  }
+  auto modified = std::vector<char>(modlen + 1); // allocate extra byte for \0
+  detail::utf8ToModifiedUTF8(
+    reinterpret_cast<const uint8_t*>(str.data()), str.size(),
+    reinterpret_cast<uint8_t*>(modified.data()), modified.size());
+  m_string = Environment::current()->NewStringUTF(modified.data());
+}
+
+LocalString::LocalString(const char* str)
+{
+  size_t len;
+  size_t modlen = detail::modifiedLength(reinterpret_cast<const uint8_t*>(str), &len);
+  if (modlen == len) {
+    // no supplementary characters, build jstring from input buffer
+    m_string = Environment::current()->NewStringUTF(str);
+    return;
+  }
+  auto modified = std::vector<char>(modlen + 1); // allocate extra byte for \0
+  detail::utf8ToModifiedUTF8(
+    reinterpret_cast<const uint8_t*>(str), len,
+    reinterpret_cast<uint8_t*>(modified.data()), modified.size());
+  m_string = Environment::current()->NewStringUTF(modified.data());
+}
+
+LocalString::~LocalString() {
+  Environment::current()->DeleteLocalRef(m_string);
+}
+
+std::string fromJString(JNIEnv* env, jstring str) {
+  const char* modified = env->GetStringUTFChars(str, NULL);
+  jsize length = env->GetStringUTFLength(str);
+  std::string s = detail::modifiedUTF8ToUTF8(reinterpret_cast<const uint8_t*>(modified), length);
+  env->ReleaseStringUTFChars(str, modified);
+  return s;
+}
+
+} }

tests/react-test-app/android/app/src/main/jni/first-party/jni/LocalString.h

@@ -0,0 +1,61 @@
+/*
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+#pragma once
+#include <string>
+#include <jni.h>
+
+namespace facebook {
+namespace jni {
+
+namespace detail {
+
+void utf8ToModifiedUTF8(const uint8_t* bytes, size_t len, uint8_t* modified, size_t modifiedLength);
+size_t modifiedLength(const std::string& str);
+size_t modifiedLength(const uint8_t* str, size_t* length);
+std::string modifiedUTF8ToUTF8(const uint8_t* modified, size_t len);
+
+}
+
+// JNI represents strings encoded with modified version of UTF-8.  The difference between UTF-8 and
+// Modified UTF-8 is that the latter support only 1-byte, 2-byte, and 3-byte formats. Supplementary
+// character (4 bytes in unicode) needs to be represented in the form of surrogate pairs. To create
+// a Modified UTF-8 surrogate pair that Dalvik would understand we take 4-byte unicode character,
+// encode it with UTF-16 which gives us two 2 byte chars (surrogate pair) and then we encode each
+// pair as UTF-8. This result in 2 x 3 byte characters.  To convert modified UTF-8 to standard
+// UTF-8, this mus tbe reversed.
+//
+// The second difference is that Modified UTF-8 is encoding NUL byte in 2-byte format.
+//
+// In order to avoid complex error handling, only a minimum of validity checking is done to avoid
+// crashing.  If the input is invalid, the output may be invalid as well.
+//
+// Relevant links:
+//  - http://docs.oracle.com/javase/7/docs/technotes/guides/jni/spec/functions.html
+//  - https://docs.oracle.com/javase/6/docs/api/java/io/DataInput.html#modified-utf-8
+
+class LocalString {
+public:
+  // Assumes UTF8 encoding and make a required convertion to modified UTF-8 when the string
+  // contains unicode supplementary characters.
+  explicit LocalString(const std::string& str);
+  explicit LocalString(const char* str);
+  jstring string() const {
+    return m_string;
+  }
+  ~LocalString();
+private:
+  jstring m_string;
+};
+
+// The string from JNI is converted to standard UTF-8 if the string contains supplementary
+// characters.
+std::string fromJString(JNIEnv* env, jstring str);
+
+} }

tests/react-test-app/android/app/src/main/jni/first-party/jni/OnLoad.cpp

@@ -0,0 +1,23 @@
+/*
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+#include <jni.h>
+#include <fb/assert.h>
+#include <jni/Countable.h>
+#include <jni/Environment.h>
+#include <jni/fbjni.h>
+
+using namespace facebook::jni;
+
+JNIEXPORT jint JNI_OnLoad(JavaVM* vm, void* reserved) {
+  return facebook::jni::initialize(vm, [] {
+      CountableOnLoad(Environment::current());
+      HybridDataOnLoad();
+    });
+}

tests/react-test-app/android/app/src/main/jni/first-party/jni/Registration.h

@@ -0,0 +1,27 @@
+/*
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+#pragma once
+#include <jni.h>
+#include <initializer_list>
+#include <fb/assert.h>
+
+namespace facebook {
+namespace jni {
+
+static inline void registerNatives(JNIEnv* env, jclass cls, std::initializer_list<JNINativeMethod> methods) {
+  auto result = env->RegisterNatives(cls, methods.begin(), methods.size());
+  FBASSERT(result == 0);
+}
+
+static inline void registerNatives(JNIEnv* env, const char* cls, std::initializer_list<JNINativeMethod> list) {
+  registerNatives(env, env->FindClass(cls), list);
+}
+
+} }

tests/react-test-app/android/app/src/main/jni/first-party/jni/WeakReference.cpp

@@ -0,0 +1,43 @@
+/*
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+#include <jni/Environment.h>
+#include <jni/WeakReference.h>
+
+namespace facebook {
+namespace jni {
+
+WeakReference::WeakReference(jobject strongRef) :
+  m_weakReference(Environment::current()->NewWeakGlobalRef(strongRef))
+{
+}
+
+WeakReference::~WeakReference() {
+  auto env = Environment::current();
+  FBASSERTMSGF(env, "Attempt to delete jni::WeakReference from non-JNI thread");
+  env->DeleteWeakGlobalRef(m_weakReference);
+}
+
+ResolvedWeakReference::ResolvedWeakReference(jobject weakRef) :
+  m_strongReference(Environment::current()->NewLocalRef(weakRef))
+{
+}
+
+ResolvedWeakReference::ResolvedWeakReference(const RefPtr<WeakReference>& weakRef) :
+  m_strongReference(Environment::current()->NewLocalRef(weakRef->weakRef()))
+{
+}
+
+ResolvedWeakReference::~ResolvedWeakReference() {
+  if (m_strongReference)
+    Environment::current()->DeleteLocalRef(m_strongReference);
+}
+
+} }
+

tests/react-test-app/android/app/src/main/jni/first-party/jni/WeakReference.h

@@ -0,0 +1,53 @@
+/*
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+#pragma once
+#include <string>
+#include <jni.h>
+#include <fb/noncopyable.h>
+#include <fb/Countable.h>
+
+namespace facebook {
+namespace jni {
+
+class WeakReference : public Countable {
+public:
+  typedef RefPtr<WeakReference> Ptr;
+  WeakReference(jobject strongRef);
+  ~WeakReference();
+  jweak weakRef() {
+    return m_weakReference;
+  }
+
+private:
+  jweak m_weakReference;
+};
+
+// This class is intended to take a weak reference and turn it into a strong
+// local reference. Consequently, it should only be allocated on the stack.
+class ResolvedWeakReference : public noncopyable {
+public:
+  ResolvedWeakReference(jobject weakRef);
+  ResolvedWeakReference(const RefPtr<WeakReference>& weakRef);
+  ~ResolvedWeakReference();
+
+  operator jobject () {
+    return m_strongReference;
+  }
+
+  explicit operator bool () {
+    return m_strongReference != nullptr;
+  }
+
+private:
+  jobject m_strongReference;
+};
+
+} }
+

tests/react-test-app/android/app/src/main/jni/first-party/jni/fbjni.cpp

@@ -0,0 +1,206 @@
+/*
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+#include "fbjni.h"
+
+#include <mutex>
+#include <vector>
+#include <jni/LocalString.h>
+
+namespace facebook {
+namespace jni {
+
+template<typename... Args>
+static void log(Args... args) {
+// TODO (7623232) Migrate to glog
+#ifdef __ANDROID__
+  facebook::alog::loge("fbjni", args...);
+#endif
+}
+
+jint initialize(JavaVM* vm, void(*init_fn)()) noexcept {
+  static std::once_flag init_flag;
+  static auto failed = false;
+
+  std::call_once(init_flag, [vm] {
+    try {
+      Environment::initialize(vm);
+      internal::initExceptionHelpers();
+    } catch (std::exception& ex) {
+      log("Failed to initialize fbjni: %s", ex.what());
+      failed = true;
+    } catch (...) {
+      log("Failed to initialize fbjni");
+      failed = true;
+    }
+  });
+
+  if (failed) {
+    return JNI_ERR;
+  }
+
+  try {
+    init_fn();
+  } catch (...) {
+    translatePendingCppExceptionToJavaException();
+    // So Java will handle the translated exception, fall through and
+    // return a good version number.
+  }
+  return JNI_VERSION_1_6;
+}
+
+alias_ref<jclass> findClassStatic(const char* name) {
+  const auto env = internal::getEnv();
+  auto cls = env->FindClass(name);
+  FACEBOOK_JNI_THROW_EXCEPTION_IF(!cls);
+  auto leaking_ref = (jclass)env->NewGlobalRef(cls);
+  FACEBOOK_JNI_THROW_EXCEPTION_IF(!leaking_ref);
+  return wrap_alias(leaking_ref);
+}
+
+local_ref<jclass> findClassLocal(const char* name) {
+  const auto env = internal::getEnv();
+  auto cls = env->FindClass(name);
+  FACEBOOK_JNI_THROW_EXCEPTION_IF(!cls);
+  return adopt_local(cls);
+}
+
+
+// jstring /////////////////////////////////////////////////////////////////////////////////////////
+
+std::string JObjectWrapper<jstring>::toStdString() const {
+  const auto env = internal::getEnv();
+  auto modified = env->GetStringUTFChars(self(), nullptr);
+  auto length = env->GetStringUTFLength(self());
+  auto string = detail::modifiedUTF8ToUTF8(reinterpret_cast<const uint8_t*>(modified), length);
+  env->ReleaseStringUTFChars(self(), modified);
+  return string;
+}
+
+local_ref<jstring> make_jstring(const char* utf8) {
+  if (!utf8) {
+    return {};
+  }
+  const auto env = internal::getEnv();
+  size_t len;
+  size_t modlen = detail::modifiedLength(reinterpret_cast<const uint8_t*>(utf8), &len);
+  jstring result;
+  if (modlen == len) {
+    // The only difference between utf8 and modifiedUTF8 is in encoding 4-byte UTF8 chars
+    // and '\0' that is encoded on 2 bytes.
+    //
+    // Since modifiedUTF8-encoded string can be no shorter than it's UTF8 conterpart we
+    // know that if those two strings are of the same length we don't need to do any
+    // conversion -> no 4-byte chars nor '\0'.
+    result = env->NewStringUTF(utf8);
+  } else {
+    auto modified = std::vector<char>(modlen + 1); // allocate extra byte for \0
+    detail::utf8ToModifiedUTF8(
+      reinterpret_cast<const uint8_t*>(utf8), len,
+      reinterpret_cast<uint8_t*>(modified.data()), modified.size());
+    result = env->NewStringUTF(modified.data());
+  }
+  FACEBOOK_JNI_THROW_PENDING_EXCEPTION();
+  return adopt_local(result);
+}
+
+
+// PinnedPrimitiveArray ///////////////////////////////////////////////////////////////////////////
+
+// TODO(T7847300): Allow array to be specified as constant so that JNI_ABORT can be passed
+// on release, as opposed to 0, which results in unnecessary copying.
+#pragma push_macro("DEFINE_PRIMITIVE_METHODS")
+#undef DEFINE_PRIMITIVE_METHODS
+#define DEFINE_PRIMITIVE_METHODS(TYPE, NAME)                                                \
+template<>                                                                                  \
+TYPE* PinnedPrimitiveArray<TYPE>::get() {                                                   \
+  FACEBOOK_JNI_THROW_EXCEPTION_IF(array_.get() == nullptr);                                 \
+  const auto env = internal::getEnv();                                                      \
+  elements_ = env->Get ## NAME ## ArrayElements(                                            \
+      static_cast<TYPE ## Array>(array_.get()), &isCopy_);                                  \
+  size_ = array_->size();                                                                   \
+  return elements_;                                                                         \
+}                                                                                           \
+template<>                                                                                  \
+void PinnedPrimitiveArray<TYPE>::release() {                                                \
+  FACEBOOK_JNI_THROW_EXCEPTION_IF(array_.get() == nullptr);                                 \
+  const auto env = internal::getEnv();                                                      \
+  env->Release ## NAME ## ArrayElements(                                                    \
+      static_cast<TYPE ## Array>(array_.get()), elements_, 0);                              \
+  elements_ = nullptr;                                                                      \
+  size_ = 0;                                                                                \
+}
+
+DEFINE_PRIMITIVE_METHODS(jboolean, Boolean)
+DEFINE_PRIMITIVE_METHODS(jbyte, Byte)
+DEFINE_PRIMITIVE_METHODS(jchar, Char)
+DEFINE_PRIMITIVE_METHODS(jshort, Short)
+DEFINE_PRIMITIVE_METHODS(jint, Int)
+DEFINE_PRIMITIVE_METHODS(jlong, Long)
+DEFINE_PRIMITIVE_METHODS(jfloat, Float)
+DEFINE_PRIMITIVE_METHODS(jdouble, Double)
+#pragma pop_macro("DEFINE_PRIMITIVE_METHODS")
+
+
+#define DEFINE_PRIMITIVE_ARRAY_UTILS(TYPE, NAME)                                                \
+                                                                                                \
+local_ref<j ## TYPE ## Array> make_ ## TYPE ## _array(jsize size) {                             \
+  auto array = internal::getEnv()->New ## NAME ## Array(size);                                  \
+  FACEBOOK_JNI_THROW_EXCEPTION_IF(!array);                                                      \
+  return adopt_local(array);                                                                    \
+}                                                                                               \
+                                                                                                \
+local_ref<j ## TYPE ## Array> JArray ## NAME::newArray(size_t count) {                          \
+  return make_ ## TYPE ## _array(count);                                                        \
+}                                                                                               \
+                                                                                                \
+j ## TYPE* JArray ## NAME::getRegion(jsize start, jsize length, j ## TYPE* buf) {               \
+  internal::getEnv()->Get ## NAME ## ArrayRegion(self(), start, length, buf);                   \
+  FACEBOOK_JNI_THROW_PENDING_EXCEPTION();                                                       \
+  return buf;                                                                                   \
+}                                                                                               \
+                                                                                                \
+std::unique_ptr<j ## TYPE[]> JArray ## NAME::getRegion(jsize start, jsize length) {             \
+  auto buf = std::unique_ptr<j ## TYPE[]>{new j ## TYPE[length]};                               \
+  internal::getEnv()->Get ## NAME ## ArrayRegion(self(), start, length, buf.get());             \
+  FACEBOOK_JNI_THROW_PENDING_EXCEPTION();                                                       \
+  return buf;                                                                                   \
+}                                                                                               \
+                                                                                                \
+void JArray ## NAME::setRegion(jsize start, jsize length, const j ## TYPE* buf) {               \
+  internal::getEnv()->Set ## NAME ## ArrayRegion(self(), start, length, buf);                   \
+  FACEBOOK_JNI_THROW_PENDING_EXCEPTION();                                                       \
+}                                                                                               \
+                                                                                                \
+PinnedPrimitiveArray<j ## TYPE> JArray ## NAME::pin() {                                         \
+  return PinnedPrimitiveArray<j ## TYPE>{self()};                                               \
+}                                                                                               \
+
+DEFINE_PRIMITIVE_ARRAY_UTILS(boolean, Boolean)
+DEFINE_PRIMITIVE_ARRAY_UTILS(byte, Byte)
+DEFINE_PRIMITIVE_ARRAY_UTILS(char, Char)
+DEFINE_PRIMITIVE_ARRAY_UTILS(short, Short)
+DEFINE_PRIMITIVE_ARRAY_UTILS(int, Int)
+DEFINE_PRIMITIVE_ARRAY_UTILS(long, Long)
+DEFINE_PRIMITIVE_ARRAY_UTILS(float, Float)
+DEFINE_PRIMITIVE_ARRAY_UTILS(double, Double)
+
+
+// Internal debug /////////////////////////////////////////////////////////////////////////////////
+
+namespace internal {
+ReferenceStats g_reference_stats;
+
+void facebook::jni::internal::ReferenceStats::reset() noexcept {
+  locals_deleted = globals_deleted = weaks_deleted = 0;
+}
+}
+
+}}
+

tests/react-test-app/android/app/src/main/jni/first-party/jni/fbjni.h

@@ -0,0 +1,23 @@
+/*
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+#pragma once
+
+#include <jni.h>
+
+#include "Environment.h"
+#include "ALog.h"
+#include "fbjni/Common.h"
+#include "fbjni/Exceptions.h"
+#include "fbjni/ReferenceAllocators.h"
+#include "fbjni/References.h"
+#include "fbjni/Meta.h"
+#include "fbjni/CoreClasses.h"
+#include "fbjni/Hybrid.h"
+#include "fbjni/Registration.h"

tests/react-test-app/android/app/src/main/jni/first-party/jni/fbjni/Common.h

@@ -0,0 +1,68 @@
+/*
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+/** @file Common.h
+ *
+ * Defining the stuff that don't deserve headers of their own...
+ */
+
+#pragma once
+
+#include <jni.h>
+
+#include <jni/Environment.h>
+#include <jni/ALog.h>
+
+/// @cond INTERNAL
+
+namespace facebook {
+namespace jni {
+
+/**
+ * This needs to be called at library load time, typically in your JNI_OnLoad method.
+ *
+ * The intended use is to return the result of initialize() directly
+ * from JNI_OnLoad and to do nothing else there. Library specific
+ * initialization code should go in the function passed to initialize
+ * (which can be, and probably should be, a C++ lambda). This approach
+ * provides correct error handling and translation errors during
+ * initialization into Java exceptions when appropriate.
+ *
+ * Failure to call this will cause your code to crash in a remarkably
+ * unhelpful way (typically a segfault) while trying to handle an exception
+ * which occurs later.
+ */
+jint initialize(JavaVM*, void(*)()) noexcept;
+
+namespace internal {
+
+/**
+ * Retrieve a pointer the JNI environment of the current thread.
+ *
+ * @pre The current thread must be attached to the VM
+ */
+inline JNIEnv* getEnv() noexcept {
+  // TODO(T6594868) Benchmark against raw JNI access
+  return Environment::current();
+}
+
+// Define to get extremely verbose logging of references and to enable reference stats
+#if defined(__ANDROID__) && defined(FBJNI_DEBUG_REFS)
+template<typename... Args>
+inline void dbglog(Args... args) noexcept {
+  facebook::alog::logv("fbjni_ref", args...);
+}
+#else
+template<typename... Args>
+inline void dbglog(Args...) noexcept {}
+#endif
+
+}}}
+
+/// @endcond

tests/react-test-app/android/app/src/main/jni/first-party/jni/fbjni/CoreClasses-inl.h

@@ -0,0 +1,443 @@
+/*
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+#pragma once
+
+#include <string.h>
+#include <type_traits>
+
+#include "Common.h"
+#include "Exceptions.h"
+
+namespace facebook {
+namespace jni {
+
+inline bool isSameObject(alias_ref<jobject> lhs, alias_ref<jobject> rhs) noexcept {
+  return internal::getEnv()->IsSameObject(lhs.get(), rhs.get()) != JNI_FALSE;
+}
+
+
+// jobject /////////////////////////////////////////////////////////////////////////////////////////
+
+inline JObjectWrapper<jobject>::JObjectWrapper(jobject reference) noexcept
+  : this_{reference}
+{}
+
+inline JObjectWrapper<jobject>::JObjectWrapper(const JObjectWrapper<jobject>& other) noexcept
+  : this_{other.this_} {
+  internal::dbglog("wrapper copy from this=%p ref=%p other=%p", this, other.this_, &other);
+}
+
+inline local_ref<jclass> JObjectWrapper<jobject>::getClass() const noexcept {
+  return adopt_local(internal::getEnv()->GetObjectClass(self()));
+}
+
+inline bool JObjectWrapper<jobject>::isInstanceOf(alias_ref<jclass> cls) const noexcept {
+  return internal::getEnv()->IsInstanceOf(self(), cls.get()) != JNI_FALSE;
+}
+
+template<typename T>
+inline T JObjectWrapper<jobject>::getFieldValue(JField<T> field) const noexcept {
+  return field.get(self());
+}
+
+template<typename T>
+inline local_ref<T*> JObjectWrapper<jobject>::getFieldValue(JField<T*> field) noexcept {
+  return adopt_local(field.get(self()));
+}
+
+template<typename T>
+inline void JObjectWrapper<jobject>::setFieldValue(JField<T> field, T value) noexcept {
+  field.set(self(), value);
+}
+
+inline std::string JObjectWrapper<jobject>::toString() const {
+  static auto method = findClassLocal("java/lang/Object")->getMethod<jstring()>("toString");
+
+  return method(self())->toStdString();
+}
+
+inline void JObjectWrapper<jobject>::set(jobject reference) noexcept {
+  this_ = reference;
+}
+
+inline jobject JObjectWrapper<jobject>::get() const noexcept {
+  return this_;
+}
+
+inline jobject JObjectWrapper<jobject>::self() const noexcept {
+  return this_;
+}
+
+inline void swap(JObjectWrapper<jobject>& a, JObjectWrapper<jobject>& b) noexcept {
+  using std::swap;
+  swap(a.this_, b.this_);
+}
+
+
+// jclass //////////////////////////////////////////////////////////////////////////////////////////
+
+namespace detail {
+
+// This is not a real type.  It is used so people won't accidentally
+// use a void* to initialize a NativeMethod.
+struct NativeMethodWrapper;
+
+};
+
+struct NativeMethod {
+  const char* name;
+  std::string descriptor;
+  detail::NativeMethodWrapper* wrapper;
+};
+
+inline local_ref<jclass> JObjectWrapper<jclass>::getSuperclass() const noexcept {
+  return adopt_local(internal::getEnv()->GetSuperclass(self()));
+}
+
+inline void JObjectWrapper<jclass>::registerNatives(std::initializer_list<NativeMethod> methods) {
+  const auto env = internal::getEnv();
+
+  JNINativeMethod jnimethods[methods.size()];
+  size_t i = 0;
+  for (auto it = methods.begin(); it < methods.end(); ++it, ++i) {
+    jnimethods[i].name = it->name;
+    jnimethods[i].signature = it->descriptor.c_str();
+    jnimethods[i].fnPtr = reinterpret_cast<void*>(it->wrapper);
+  }
+
+  auto result = env->RegisterNatives(self(), jnimethods, methods.size());
+  FACEBOOK_JNI_THROW_EXCEPTION_IF(result != JNI_OK);
+}
+
+inline bool JObjectWrapper<jclass>::isAssignableFrom(alias_ref<jclass> other) const noexcept {
+  const auto env = internal::getEnv();
+  const auto result = env->IsAssignableFrom(self(), other.get());
+  return result;
+}
+
+template<typename F>
+inline JConstructor<F> JObjectWrapper<jclass>::getConstructor() const {
+  return getConstructor<F>(jmethod_traits<F>::constructor_descriptor().c_str());
+}
+
+template<typename F>
+inline JConstructor<F> JObjectWrapper<jclass>::getConstructor(const char* descriptor) const {
+  constexpr auto constructor_method_name = "<init>";
+  return getMethod<F>(constructor_method_name, descriptor);
+}
+
+template<typename F>
+inline JMethod<F> JObjectWrapper<jclass>::getMethod(const char* name) const {
+  return getMethod<F>(name, jmethod_traits<F>::descriptor().c_str());
+}
+
+template<typename F>
+inline JMethod<F> JObjectWrapper<jclass>::getMethod(
+    const char* name,
+    const char* descriptor) const {
+  const auto env = internal::getEnv();
+  const auto method = env->GetMethodID(self(), name, descriptor);
+  FACEBOOK_JNI_THROW_EXCEPTION_IF(!method);
+  return JMethod<F>{method};
+}
+
+template<typename F>
+inline JStaticMethod<F> JObjectWrapper<jclass>::getStaticMethod(const char* name) const {
+  return getStaticMethod<F>(name, jmethod_traits<F>::descriptor().c_str());
+}
+
+template<typename F>
+inline JStaticMethod<F> JObjectWrapper<jclass>::getStaticMethod(
+    const char* name,
+    const char* descriptor) const {
+  const auto env = internal::getEnv();
+  const auto method = env->GetStaticMethodID(self(), name, descriptor);
+  FACEBOOK_JNI_THROW_EXCEPTION_IF(!method);
+  return JStaticMethod<F>{method};
+}
+
+template<typename F>
+inline JNonvirtualMethod<F> JObjectWrapper<jclass>::getNonvirtualMethod(const char* name) const {
+  return getNonvirtualMethod<F>(name, jmethod_traits<F>::descriptor().c_str());
+}
+
+template<typename F>
+inline JNonvirtualMethod<F> JObjectWrapper<jclass>::getNonvirtualMethod(
+    const char* name,
+    const char* descriptor) const {
+  const auto env = internal::getEnv();
+  const auto method = env->GetMethodID(self(), name, descriptor);
+  FACEBOOK_JNI_THROW_EXCEPTION_IF(!method);
+  return JNonvirtualMethod<F>{method};
+}
+
+template<typename T>
+inline JField<enable_if_t<IsJniScalar<T>(), T>>
+JObjectWrapper<jclass>::getField(const char* name) const {
+  return getField<T>(name, jtype_traits<T>::descriptor().c_str());
+}
+
+template<typename T>
+inline JField<enable_if_t<IsJniScalar<T>(), T>> JObjectWrapper<jclass>::getField(
+    const char* name,
+    const char* descriptor) const {
+  const auto env = internal::getEnv();
+  auto field = env->GetFieldID(self(), name, descriptor);
+  FACEBOOK_JNI_THROW_EXCEPTION_IF(!field);
+  return JField<T>{field};
+}
+
+template<typename T>
+inline JStaticField<enable_if_t<IsJniScalar<T>(), T>> JObjectWrapper<jclass>::getStaticField(
+    const char* name) const {
+  return getStaticField<T>(name, jtype_traits<T>::descriptor().c_str());
+}
+
+template<typename T>
+inline JStaticField<enable_if_t<IsJniScalar<T>(), T>> JObjectWrapper<jclass>::getStaticField(
+    const char* name,
+    const char* descriptor) const {
+  const auto env = internal::getEnv();
+  auto field = env->GetStaticFieldID(self(), name, descriptor);
+  FACEBOOK_JNI_THROW_EXCEPTION_IF(!field);
+  return JStaticField<T>{field};
+}
+
+template<typename T>
+inline T JObjectWrapper<jclass>::getStaticFieldValue(JStaticField<T> field) const noexcept {
+  return field.get(self());
+}
+
+template<typename T>
+inline local_ref<T*> JObjectWrapper<jclass>::getStaticFieldValue(JStaticField<T*> field) noexcept {
+  return adopt_local(field.get(self()));
+}
+
+template<typename T>
+inline void JObjectWrapper<jclass>::setStaticFieldValue(JStaticField<T> field, T value) noexcept {
+  field.set(self(), value);
+}
+
+template<typename R, typename... Args>
+inline local_ref<R> JObjectWrapper<jclass>::newObject(
+    JConstructor<R(Args...)> constructor,
+    Args... args) const {
+  const auto env = internal::getEnv();
+  auto object = env->NewObject(self(), constructor.getId(), args...);
+  FACEBOOK_JNI_THROW_EXCEPTION_IF(!object);
+  return adopt_local(static_cast<R>(object));
+}
+
+inline jclass JObjectWrapper<jclass>::self() const noexcept {
+  return static_cast<jclass>(this_);
+}
+
+inline void registerNatives(const char* name, std::initializer_list<NativeMethod> methods) {
+  findClassLocal(name)->registerNatives(methods);
+}
+
+
+// jstring /////////////////////////////////////////////////////////////////////////////////////////
+
+inline local_ref<jstring> make_jstring(const std::string& modifiedUtf8) {
+  return make_jstring(modifiedUtf8.c_str());
+}
+
+inline jstring JObjectWrapper<jstring>::self() const noexcept {
+  return static_cast<jstring>(this_);
+}
+
+
+// jthrowable //////////////////////////////////////////////////////////////////////////////////////
+
+inline jthrowable JObjectWrapper<jthrowable>::self() const noexcept {
+  return static_cast<jthrowable>(this_);
+}
+
+
+// jtypeArray //////////////////////////////////////////////////////////////////////////////////////
+template<typename T>
+inline ElementProxy<T>::ElementProxy(
+    JObjectWrapper<_jtypeArray<T>*>* target,
+    size_t idx)
+    : target_{target}, idx_{idx} {}
+
+template<typename T>
+inline ElementProxy<T>& ElementProxy<T>::operator=(const T& o) {
+  target_->setElement(idx_, o);
+  return *this;
+}
+
+template<typename T>
+inline ElementProxy<T>& ElementProxy<T>::operator=(alias_ref<T>& o) {
+  target_->setElement(idx_, o.get());
+  return *this;
+}
+
+template<typename T>
+inline ElementProxy<T>& ElementProxy<T>::operator=(alias_ref<T>&& o) {
+  target_->setElement(idx_, o.get());
+  return *this;
+}
+
+template<typename T>
+inline ElementProxy<T>& ElementProxy<T>::operator=(const ElementProxy<T>& o) {
+  auto src = o.target_->getElement(o.idx_);
+  target_->setElement(idx_, src.get());
+  return *this;
+}
+
+template<typename T>
+inline ElementProxy<T>::ElementProxy::operator const local_ref<T> () const {
+  return target_->getElement(idx_);
+}
+
+template<typename T>
+inline ElementProxy<T>::ElementProxy::operator local_ref<T> () {
+  return target_->getElement(idx_);
+}
+
+template<typename T>
+local_ref<jtypeArray<T>> JObjectWrapper<jtypeArray<T>>::newArray(size_t size) {
+  static auto elementClass = findClassStatic(jtype_traits<T>::base_name().c_str());
+  const auto env = internal::getEnv();
+  auto rawArray = env->NewObjectArray(size, elementClass.get(), nullptr);
+  FACEBOOK_JNI_THROW_EXCEPTION_IF(!rawArray);
+  return adopt_local(static_cast<jtypeArray<T>>(rawArray));
+}
+
+template<typename T>
+inline void JObjectWrapper<jtypeArray<T>>::setElement(size_t idx, const T& value) {
+  const auto env = internal::getEnv();
+  env->SetObjectArrayElement(static_cast<jobjectArray>(self()), idx, value);
+}
+
+template<typename T>
+inline local_ref<T> JObjectWrapper<jtypeArray<T>>::getElement(size_t idx) {
+  const auto env = internal::getEnv();
+  auto rawElement = env->GetObjectArrayElement(static_cast<jobjectArray>(self()), idx);
+  return adopt_local(static_cast<T>(rawElement));
+}
+
+template<typename T>
+inline size_t JObjectWrapper<jtypeArray<T>>::size() {
+  const auto env = internal::getEnv();
+  return env->GetArrayLength(static_cast<jobjectArray>(self()));
+}
+
+template<typename T>
+inline ElementProxy<T> JObjectWrapper<jtypeArray<T>>::operator[](size_t index) {
+  return ElementProxy<T>(this, index);
+}
+
+template<typename T>
+inline jtypeArray<T> JObjectWrapper<jtypeArray<T>>::self() const noexcept {
+  return static_cast<jtypeArray<T>>(this_);
+}
+
+
+// jarray /////////////////////////////////////////////////////////////////////////////////////////
+
+inline size_t JObjectWrapper<jarray>::size() const noexcept {
+  const auto env = internal::getEnv();
+  return env->GetArrayLength(self());
+}
+
+inline jarray JObjectWrapper<jarray>::self() const noexcept {
+  return static_cast<jarray>(this_);
+}
+
+
+// PinnedPrimitiveArray ///////////////////////////////////////////////////////////////////////////
+
+template<typename T>
+inline PinnedPrimitiveArray<T>::PinnedPrimitiveArray(alias_ref<jarray> array) noexcept
+  : array_{array} {
+  get();
+}
+
+template<typename T>
+PinnedPrimitiveArray<T>::PinnedPrimitiveArray(PinnedPrimitiveArray&& o) noexcept {
+  array_ = std::move(o.array_);
+  elements_ = o.elements_;
+  isCopy_ = o.isCopy_;
+  size_ = o.size_;
+  o.elements_ = nullptr;
+  o.isCopy_ = false;
+  o.size_ = 0;
+}
+
+template<typename T>
+PinnedPrimitiveArray<T>&
+PinnedPrimitiveArray<T>::operator=(PinnedPrimitiveArray&& o) noexcept {
+  array_ = std::move(o.array_);
+  elements_ = o.elements_;
+  isCopy_ = o.isCopy_;
+  size_ = o.size_;
+  o.elements_ = nullptr;
+  o.isCopy_ = false;
+  o.size_ = 0;
+  return *this;
+}
+
+template<typename T>
+inline T& PinnedPrimitiveArray<T>::operator[](size_t index) {
+  FACEBOOK_JNI_THROW_EXCEPTION_IF(elements_ == nullptr);
+  return elements_[index];
+}
+
+template<typename T>
+inline bool PinnedPrimitiveArray<T>::isCopy() const noexcept {
+  return isCopy_ == JNI_TRUE;
+}
+
+template<typename T>
+inline size_t PinnedPrimitiveArray<T>::size() const noexcept {
+  return size_;
+}
+
+template<typename T>
+inline PinnedPrimitiveArray<T>::~PinnedPrimitiveArray() noexcept {
+  if (elements_) {
+    release();
+  }
+}
+
+#pragma push_macro("DECLARE_PRIMITIVE_METHODS")
+#undef DECLARE_PRIMITIVE_METHODS
+#define DECLARE_PRIMITIVE_METHODS(TYPE, NAME)          \
+template<> TYPE* PinnedPrimitiveArray<TYPE>::get();    \
+template<> void PinnedPrimitiveArray<TYPE>::release(); \
+
+DECLARE_PRIMITIVE_METHODS(jboolean, Boolean)
+DECLARE_PRIMITIVE_METHODS(jbyte, Byte)
+DECLARE_PRIMITIVE_METHODS(jchar, Char)
+DECLARE_PRIMITIVE_METHODS(jshort, Short)
+DECLARE_PRIMITIVE_METHODS(jint, Int)
+DECLARE_PRIMITIVE_METHODS(jlong, Long)
+DECLARE_PRIMITIVE_METHODS(jfloat, Float)
+DECLARE_PRIMITIVE_METHODS(jdouble, Double)
+#pragma pop_macro("DECLARE_PRIMITIVE_METHODS")
+
+
+template<typename T, typename Base>
+inline alias_ref<jclass> JavaClass<T, Base>::javaClassStatic() {
+  static auto cls = findClassStatic(
+    std::string(T::kJavaDescriptor + 1, strlen(T::kJavaDescriptor) - 2).c_str());
+  return cls;
+}
+
+template<typename T, typename Base>
+inline local_ref<jclass> JavaClass<T, Base>::javaClassLocal() {
+  std::string className(T::kJavaDescriptor + 1, strlen(T::kJavaDescriptor) - 2);
+  return findClassLocal(className.c_str());
+}
+
+}}

tests/react-test-app/android/app/src/main/jni/first-party/jni/fbjni/CoreClasses.h

@@ -0,0 +1,510 @@
+/*
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+#pragma once
+
+/** @file CoreClasses.h
+ *
+ * In CoreClasses.h wrappers for the core classes (jobject, jclass, and jstring) is defined
+ * to provide access to corresponding JNI functions + some conveniance.
+ */
+
+#include "Meta.h"
+#include "References.h"
+
+#include <memory>
+
+#include <jni.h>
+
+namespace facebook {
+namespace jni {
+
+/// Lookup a class by name. Note this functions returns an alias_ref that
+/// points to a leaked global reference.  This is appropriate for classes
+/// that are never unloaded (which is any class in an Android app and most
+/// Java programs).
+///
+/// The most common use case for this is storing the result
+/// in a "static auto" variable, or a static global.
+///
+/// @return Returns a leaked global reference to the class
+alias_ref<jclass> findClassStatic(const char* name);
+
+/// Lookup a class by name. Note this functions returns a local reference,
+/// which means that it must not be stored in a static variable.
+///
+/// The most common use case for this is one-time initialization
+/// (like caching method ids).
+///
+/// @return Returns a global reference to the class
+local_ref<jclass> findClassLocal(const char* name);
+
+/// Check to see if two references refer to the same object. Comparison with nullptr
+/// returns true if and only if compared to another nullptr. A weak reference that
+/// refers to a reclaimed object count as nullptr.
+bool isSameObject(alias_ref<jobject> lhs, alias_ref<jobject> rhs) noexcept;
+
+
+/// Wrapper to provide functionality to jobject references
+template<>
+class JObjectWrapper<jobject> {
+ public:
+  /// Java type descriptor
+  static constexpr const char* kJavaDescriptor = "Ljava/lang/Object;";
+
+  static constexpr const char* get_instantiated_java_descriptor() { return nullptr; }
+
+  /// Wrap an existing JNI reference
+  JObjectWrapper(jobject reference = nullptr) noexcept;
+
+  // Copy constructor
+  JObjectWrapper(const JObjectWrapper& other) noexcept;
+
+  /// Get a @ref local_ref of the object's class
+  local_ref<jclass> getClass() const noexcept;
+
+  /// Checks if the object is an instance of a class
+  bool isInstanceOf(alias_ref<jclass> cls) const noexcept;
+
+  /// Get the primitive value of a field
+  template<typename T>
+  T getFieldValue(JField<T> field) const noexcept;
+
+  /// Get and wrap the value of a field in a @ref local_ref
+  template<typename T>
+  local_ref<T*> getFieldValue(JField<T*> field) noexcept;
+
+  /// Set the value of field. Any Java type is accepted, including the primitive types
+  /// and raw reference types.
+  template<typename T>
+  void setFieldValue(JField<T> field, T value) noexcept;
+
+  /// Convenience method to create a std::string representing the object
+  std::string toString() const;
+
+ protected:
+  jobject this_;
+
+ private:
+  template<typename T, typename A>
+  friend class base_owned_ref;
+
+  template<typename T>
+  friend class alias_ref;
+
+  friend void swap(JObjectWrapper<jobject>& a, JObjectWrapper<jobject>& b) noexcept;
+
+  void set(jobject reference) noexcept;
+  jobject get() const noexcept;
+  jobject self() const noexcept;
+};
+
+using JObject = JObjectWrapper<jobject>;
+
+void swap(JObjectWrapper<jobject>& a, JObjectWrapper<jobject>& b) noexcept;
+
+
+/// Wrapper to provide functionality to jclass references
+struct NativeMethod;
+
+template<>
+class JObjectWrapper<jclass> : public JObjectWrapper<jobject> {
+ public:
+  /// Java type descriptor
+  static constexpr const char* kJavaDescriptor = "Ljava/lang/Class;";
+
+  using JObjectWrapper<jobject>::JObjectWrapper;
+
+  /// Get a @local_ref to the super class of this class
+  local_ref<jclass> getSuperclass() const noexcept;
+
+  /// Register native methods for the class.  Usage looks like this:
+  ///
+  /// classRef->registerNatives({
+  ///     makeNativeMethod("nativeMethodWithAutomaticDescriptor",
+  ///                      methodWithAutomaticDescriptor),
+  ///     makeNativeMethod("nativeMethodWithExplicitDescriptor",
+  ///                      "(Lcom/facebook/example/MyClass;)V",
+  ///                      methodWithExplicitDescriptor),
+  ///  });
+  ///
+  /// By default, C++ exceptions raised will be converted to Java exceptions.
+  /// To avoid this and get the "standard" JNI behavior of a crash when a C++
+  /// exception is crashing out of the JNI method, declare the method noexcept.
+  void registerNatives(std::initializer_list<NativeMethod> methods);
+
+  /// Check to see if the class is assignable from another class
+  /// @pre cls != nullptr
+  bool isAssignableFrom(alias_ref<jclass> cls) const noexcept;
+
+  /// Convenience method to lookup the constructor with descriptor as specified by the
+  /// type arguments
+  template<typename F>
+  JConstructor<F> getConstructor() const;
+
+  /// Convenience method to lookup the constructor with specified descriptor
+  template<typename F>
+  JConstructor<F> getConstructor(const char* descriptor) const;
+
+  /// Look up the method with given name and descriptor as specified with the type arguments
+  template<typename F>
+  JMethod<F> getMethod(const char* name) const;
+
+  /// Look up the method with given name and descriptor
+  template<typename F>
+  JMethod<F> getMethod(const char* name, const char* descriptor) const;
+
+  /// Lookup the field with the given name and deduced descriptor
+  template<typename T>
+  JField<enable_if_t<IsJniScalar<T>(), T>> getField(const char* name) const;
+
+  /// Lookup the field with the given name and descriptor
+  template<typename T>
+  JField<enable_if_t<IsJniScalar<T>(), T>> getField(const char* name, const char* descriptor) const;
+
+  /// Lookup the static field with the given name and deduced descriptor
+  template<typename T>
+  JStaticField<enable_if_t<IsJniScalar<T>(), T>> getStaticField(const char* name) const;
+
+  /// Lookup the static field with the given name and descriptor
+  template<typename T>
+  JStaticField<enable_if_t<IsJniScalar<T>(), T>> getStaticField(
+      const char* name,
+      const char* descriptor) const;
+
+  /// Get the primitive value of a static field
+  template<typename T>
+  T getStaticFieldValue(JStaticField<T> field) const noexcept;
+
+  /// Get and wrap the value of a field in a @ref local_ref
+  template<typename T>
+  local_ref<T*> getStaticFieldValue(JStaticField<T*> field) noexcept;
+
+  /// Set the value of field. Any Java type is accepted, including the primitive types
+  /// and raw reference types.
+  template<typename T>
+  void setStaticFieldValue(JStaticField<T> field, T value) noexcept;
+
+  /// Allocates a new object and invokes the specified constructor
+  template<typename R, typename... Args>
+  local_ref<R> newObject(JConstructor<R(Args...)> constructor, Args... args) const;
+
+  /// Look up the static method with given name and descriptor as specified with the type arguments
+  template<typename F>
+  JStaticMethod<F> getStaticMethod(const char* name) const;
+
+  /// Look up the static method with given name and descriptor
+  template<typename F>
+  JStaticMethod<F> getStaticMethod(const char* name, const char* descriptor) const;
+
+  /// Look up the non virtual method with given name and descriptor as specified with the
+  /// type arguments
+  template<typename F>
+  JNonvirtualMethod<F> getNonvirtualMethod(const char* name) const;
+
+  /// Look up the non virtual method with given name and descriptor
+  template<typename F>
+  JNonvirtualMethod<F> getNonvirtualMethod(const char* name, const char* descriptor) const;
+
+ private:
+  jclass self() const noexcept;
+};
+
+using JClass = JObjectWrapper<jclass>;
+
+// Convenience method to register methods on a class without holding
+// onto the class object.
+void registerNatives(const char* name, std::initializer_list<NativeMethod> methods);
+
+/// Wrapper to provide functionality to jstring references
+template<>
+class JObjectWrapper<jstring> : public JObjectWrapper<jobject> {
+ public:
+  /// Java type descriptor
+  static constexpr const char* kJavaDescriptor = "Ljava/lang/String;";
+
+  using JObjectWrapper<jobject>::JObjectWrapper;
+
+  /// Convenience method to convert a jstring object to a std::string
+  std::string toStdString() const;
+
+ private:
+  jstring self() const noexcept;
+};
+
+/// Convenience functions to convert a std::string or const char* into a @ref local_ref to a
+/// jstring
+local_ref<jstring> make_jstring(const char* modifiedUtf8);
+local_ref<jstring> make_jstring(const std::string& modifiedUtf8);
+
+using JString = JObjectWrapper<jstring>;
+
+/// Wrapper to provide functionality to jthrowable references
+template<>
+class JObjectWrapper<jthrowable> : public JObjectWrapper<jobject> {
+ public:
+  /// Java type descriptor
+  static constexpr const char* kJavaDescriptor = "Ljava/lang/Throwable;";
+
+  using JObjectWrapper<jobject>::JObjectWrapper;
+
+ private:
+  jthrowable self() const noexcept;
+};
+
+
+/// @cond INTERNAL
+template<class T> class _jtypeArray : public _jobjectArray {};
+// @endcond
+/// Wrapper to provide functionality for arrays of j-types
+template<class T> using jtypeArray = _jtypeArray<T>*;
+
+template<typename T>
+class ElementProxy {
+   private:
+    JObjectWrapper<_jtypeArray<T>*>* target_;
+    size_t idx_;
+
+   public:
+    ElementProxy(JObjectWrapper<_jtypeArray<T>*>* target, size_t idx);
+
+    ElementProxy<T>& operator=(const T& o);
+
+    ElementProxy<T>& operator=(alias_ref<T>& o);
+
+    ElementProxy<T>& operator=(alias_ref<T>&& o);
+
+    ElementProxy<T>& operator=(const ElementProxy<T>& o);
+
+    operator const local_ref<T> () const;
+
+    operator local_ref<T> ();
+  };
+
+template<typename T>
+class JObjectWrapper<jtypeArray<T>> : public JObjectWrapper<jobject> {
+ public:
+  static constexpr const char* kJavaDescriptor = nullptr;
+  static std::string get_instantiated_java_descriptor() {
+    return "[" + jtype_traits<T>::descriptor();
+  };
+
+  using JObjectWrapper<jobject>::JObjectWrapper;
+
+  /// Allocate a new array from Java heap, for passing as a JNI parameter or return value.
+  /// NOTE: if using as a return value, you want to call release() instead of get() on the
+  /// smart pointer.
+  static local_ref<jtypeArray<T>> newArray(size_t count);
+
+  /// Assign an object to the array.
+  /// Typically you will use the shorthand (*ref)[idx]=value;
+  void setElement(size_t idx, const T& value);
+
+  /// Read an object from the array.
+  /// Typically you will use the shorthand
+  ///   T value = (*ref)[idx];
+  /// If you use auto, you'll get an ElementProxy, which may need to be cast.
+  local_ref<T> getElement(size_t idx);
+
+  /// Get the size of the array.
+  size_t size();
+
+  /// EXPERIMENTAL SUBSCRIPT SUPPORT
+  /// This implementation of [] returns a proxy object which then has a bunch of specializations
+  /// (adopt_local free function, operator= and casting overloads on the ElementProxy) that can
+  /// make code look like it is dealing with a T rather than an obvious proxy. In particular, the
+  /// proxy in this iteration does not read a value and therefore does not create a LocalRef
+  /// until one of these other operators is used. There are certainly holes that you may find
+  /// by using idioms that haven't been tried yet. Consider yourself warned. On the other hand,
+  /// it does make for some idiomatic assignment code; see TestBuildStringArray in fbjni_tests
+  /// for some examples.
+  ElementProxy<T> operator[](size_t idx);
+
+ private:
+  jtypeArray<T> self() const noexcept;
+};
+
+template <class T>
+using JArrayClass = JObjectWrapper<jtypeArray<T>>;
+
+template<typename T>
+local_ref<jtypeArray<T>> adopt_local_array(jobjectArray ref) {
+  return adopt_local(static_cast<jtypeArray<T>>(ref));
+}
+
+template<typename T>
+local_ref<T> adopt_local(ElementProxy<T> elementProxy) {
+  return static_cast<local_ref<T>>(elementProxy);
+}
+
+/// Wrapper to provide functionality to jarray references.
+/// This is an empty holder by itself. Construct a PinnedPrimitiveArray to actually interact with
+/// the elements of the array.
+template<>
+class JObjectWrapper<jarray> : public JObjectWrapper<jobject> {
+ public:
+  static constexpr const char* kJavaDescriptor = nullptr;
+
+  using JObjectWrapper<jobject>::JObjectWrapper;
+  size_t size() const noexcept;
+
+ private:
+  jarray self() const noexcept;
+};
+
+using JArray = JObjectWrapper<jarray>;
+
+template <typename T>
+class PinnedPrimitiveArray;
+
+#pragma push_macro("DECLARE_PRIMITIVE_ARRAY_UTILS")
+#undef DECLARE_PRIMITIVE_ARRAY_UTILS
+#define DECLARE_PRIMITIVE_ARRAY_UTILS(TYPE, NAME, DESC)                \
+                                                                       \
+local_ref<j ## TYPE ## Array> make_ ## TYPE ## _array(jsize size);     \
+                                                                       \
+template<> class JObjectWrapper<j ## TYPE ## Array> : public JArray {  \
+ public:                                                               \
+  static constexpr const char* kJavaDescriptor = "[" # DESC;           \
+                                                                       \
+  using JArray::JArray;                                                \
+                                                                       \
+  static local_ref<j ## TYPE ## Array> newArray(size_t count);         \
+                                                                       \
+  j ## TYPE* getRegion(jsize start, jsize length, j ## TYPE* buf);     \
+  std::unique_ptr<j ## TYPE[]> getRegion(jsize start, jsize length);   \
+  void setRegion(jsize start, jsize length, const j ## TYPE* buf);     \
+  PinnedPrimitiveArray<j ## TYPE> pin();                               \
+                                                                       \
+ private:                                                              \
+  j ## TYPE ## Array self() const noexcept {                           \
+    return static_cast<j ## TYPE ## Array>(this_);                     \
+  }                                                                    \
+};                                                                     \
+                                                                       \
+using JArray ## NAME = JObjectWrapper<j ## TYPE ## Array>              \
+
+
+DECLARE_PRIMITIVE_ARRAY_UTILS(boolean, Boolean, "Z");
+DECLARE_PRIMITIVE_ARRAY_UTILS(byte, Byte, "B");
+DECLARE_PRIMITIVE_ARRAY_UTILS(char, Char, "C");
+DECLARE_PRIMITIVE_ARRAY_UTILS(short, Short, "S");
+DECLARE_PRIMITIVE_ARRAY_UTILS(int, Int, "I");
+DECLARE_PRIMITIVE_ARRAY_UTILS(long, Long, "J");
+DECLARE_PRIMITIVE_ARRAY_UTILS(float, Float, "F");
+DECLARE_PRIMITIVE_ARRAY_UTILS(double, Double, "D");
+
+#pragma pop_macro("DECLARE_PRIMITIVE_ARRAY_UTILS")
+
+
+/// RAII class for pinned primitive arrays
+/// This currently only supports read/write access to existing java arrays. You can't create a
+/// primitive array this way yet. This class also pins the entire array into memory during the
+/// lifetime of the PinnedPrimitiveArray. If you need to unpin the array manually, call the
+/// release() function. During a long-running block of code, you should unpin the array as soon
+/// as you're done with it, to avoid holding up the Java garbage collector.
+template <typename T>
+class PinnedPrimitiveArray {
+  public:
+   static_assert(is_jni_primitive<T>::value,
+       "PinnedPrimitiveArray requires primitive jni type.");
+
+   PinnedPrimitiveArray(PinnedPrimitiveArray&&) noexcept;
+   PinnedPrimitiveArray(const PinnedPrimitiveArray&) = delete;
+   ~PinnedPrimitiveArray() noexcept;
+
+   PinnedPrimitiveArray& operator=(PinnedPrimitiveArray&&) noexcept;
+   PinnedPrimitiveArray& operator=(const PinnedPrimitiveArray&) = delete;
+
+   T* get();
+   void release();
+
+   const T& operator[](size_t index) const;
+   T& operator[](size_t index);
+   bool isCopy() const noexcept;
+   size_t size() const noexcept;
+
+  private:
+   alias_ref<jarray> array_;
+   T* elements_;
+   jboolean isCopy_;
+   size_t size_;
+
+   PinnedPrimitiveArray(alias_ref<jarray>) noexcept;
+
+   friend class JObjectWrapper<jbooleanArray>;
+   friend class JObjectWrapper<jbyteArray>;
+   friend class JObjectWrapper<jcharArray>;
+   friend class JObjectWrapper<jshortArray>;
+   friend class JObjectWrapper<jintArray>;
+   friend class JObjectWrapper<jlongArray>;
+   friend class JObjectWrapper<jfloatArray>;
+   friend class JObjectWrapper<jdoubleArray>;
+};
+
+
+namespace detail {
+
+class BaseJavaClass {
+public:
+  typedef _jobject _javaobject;
+  typedef _javaobject* javaobject;
+};
+
+}
+
+// Together, these classes allow convenient use of any class with the fbjni
+// helpers.  To use:
+//
+// struct MyClass : public JavaClass<MyClass> {
+//   constexpr static auto kJavaDescriptor = "Lcom/example/package/MyClass;";
+// };
+//
+// alias_ref<MyClass::javaobject> myClass = foo();
+
+template <typename T, typename Base = detail::BaseJavaClass>
+class JavaClass {
+public:
+  // JNI pattern for jobject assignable pointer
+  struct _javaobject : public Base::_javaobject {
+    typedef T javaClass;
+  };
+  typedef _javaobject* javaobject;
+
+  static alias_ref<jclass> javaClassStatic();
+  static local_ref<jclass> javaClassLocal();
+};
+
+template <typename T>
+class JObjectWrapper<T,
+    typename std::enable_if<
+      is_plain_jni_reference<T>::value &&
+      std::is_class<typename std::remove_pointer<T>::type::javaClass>::value
+    >::type>
+  : public JObjectWrapper<jobject> {
+public:
+  static constexpr const char* kJavaDescriptor =
+    std::remove_pointer<T>::type::javaClass::kJavaDescriptor;
+
+  using JObjectWrapper<jobject>::JObjectWrapper;
+
+  template<typename U>
+  JObjectWrapper(const JObjectWrapper<U>& w)
+    : JObjectWrapper<jobject>(w) {
+    static_assert(std::is_convertible<U, T>::value,
+                  "U must be convertible to T");
+  }
+};
+
+}}
+
+#include "CoreClasses-inl.h"
+// This is here because code in Meta-inl.h uses alias_ref, which
+// requires JObjectWrapper<jobject> to be concrete before it can work.
+#include "Meta-inl.h"

tests/react-test-app/android/app/src/main/jni/first-party/jni/fbjni/Exceptions.cpp

@@ -0,0 +1,399 @@
+/*
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+#include "Exceptions.h"
+#include "CoreClasses.h"
+#include <jni/ALog.h>
+
+#include <fb/assert.h>
+
+#include <alloca.h>
+#include <cstdlib>
+#include <ios>
+#include <stdexcept>
+#include <stdio.h>
+#include <string>
+#include <system_error>
+
+#include <jni.h>
+
+namespace facebook {
+namespace jni {
+
+// CommonJniExceptions /////////////////////////////////////////////////////////////////////////////
+
+class CommonJniExceptions {
+ public:
+  static void init();
+
+  static jclass getThrowableClass() {
+    return throwableClass_;
+  }
+
+  static jclass getUnknownCppExceptionClass() {
+    return unknownCppExceptionClass_;
+  }
+
+  static jthrowable getUnknownCppExceptionObject() {
+    return unknownCppExceptionObject_;
+  }
+
+  static jthrowable getRuntimeExceptionObject() {
+    return runtimeExceptionObject_;
+  }
+
+ private:
+  static jclass throwableClass_;
+  static jclass unknownCppExceptionClass_;
+  static jthrowable unknownCppExceptionObject_;
+  static jthrowable runtimeExceptionObject_;
+};
+
+// The variables in this class are all JNI global references and are intentionally leaked because
+// we assume this library cannot be unloaded. These global references are created manually instead
+// of using global_ref from References.h to avoid circular dependency.
+jclass CommonJniExceptions::throwableClass_ = nullptr;
+jclass CommonJniExceptions::unknownCppExceptionClass_ = nullptr;
+jthrowable CommonJniExceptions::unknownCppExceptionObject_ = nullptr;
+jthrowable CommonJniExceptions::runtimeExceptionObject_ = nullptr;
+
+
+// Variable to guarantee that fallback exceptions have been initialized early. We don't want to
+// do pure dynamic initialization -- we want to warn programmers early that they need to run the
+// helpers at library load time instead of lazily getting them when the exception helpers are
+// first used.
+static std::atomic<bool> gIsInitialized(false);
+
+void CommonJniExceptions::init() {
+  JNIEnv* env = internal::getEnv();
+  FBASSERTMSGF(env, "Could not get JNI Environment");
+
+  // Throwable class
+  jclass localThrowableClass = env->FindClass("java/lang/Throwable");
+  FBASSERT(localThrowableClass);
+  throwableClass_ = static_cast<jclass>(env->NewGlobalRef(localThrowableClass));
+  FBASSERT(throwableClass_);
+  env->DeleteLocalRef(localThrowableClass);
+
+  // UnknownCppException class
+  jclass localUnknownCppExceptionClass = env->FindClass("com/facebook/jni/UnknownCppException");
+  FBASSERT(localUnknownCppExceptionClass);
+  jmethodID unknownCppExceptionConstructorMID = env->GetMethodID(
+      localUnknownCppExceptionClass,
+      "<init>",
+      "()V");
+  FBASSERT(unknownCppExceptionConstructorMID);
+  unknownCppExceptionClass_ = static_cast<jclass>(env->NewGlobalRef(localUnknownCppExceptionClass));
+  FBASSERT(unknownCppExceptionClass_);
+  env->DeleteLocalRef(localUnknownCppExceptionClass);
+
+  // UnknownCppException object
+  jthrowable localUnknownCppExceptionObject = static_cast<jthrowable>(env->NewObject(
+      unknownCppExceptionClass_,
+      unknownCppExceptionConstructorMID));
+  FBASSERT(localUnknownCppExceptionObject);
+  unknownCppExceptionObject_ = static_cast<jthrowable>(env->NewGlobalRef(
+      localUnknownCppExceptionObject));
+  FBASSERT(unknownCppExceptionObject_);
+  env->DeleteLocalRef(localUnknownCppExceptionObject);
+
+  // RuntimeException object
+  jclass localRuntimeExceptionClass = env->FindClass("java/lang/RuntimeException");
+  FBASSERT(localRuntimeExceptionClass);
+
+  jmethodID runtimeExceptionConstructorMID = env->GetMethodID(
+      localRuntimeExceptionClass,
+      "<init>",
+      "()V");
+  FBASSERT(runtimeExceptionConstructorMID);
+  jthrowable localRuntimeExceptionObject = static_cast<jthrowable>(env->NewObject(
+      localRuntimeExceptionClass,
+      runtimeExceptionConstructorMID));
+  FBASSERT(localRuntimeExceptionObject);
+  runtimeExceptionObject_ = static_cast<jthrowable>(env->NewGlobalRef(localRuntimeExceptionObject));
+  FBASSERT(runtimeExceptionObject_);
+
+  env->DeleteLocalRef(localRuntimeExceptionClass);
+  env->DeleteLocalRef(localRuntimeExceptionObject);
+}
+
+
+// initExceptionHelpers() //////////////////////////////////////////////////////////////////////////
+
+void internal::initExceptionHelpers() {
+  CommonJniExceptions::init();
+  gIsInitialized.store(true, std::memory_order_seq_cst);
+}
+
+void assertIfExceptionsNotInitialized() {
+  // Use relaxed memory order because we don't need memory barriers.
+  // The real init-once enforcement is done by the compiler for the
+  // "static" in initExceptionHelpers.
+  FBASSERTMSGF(gIsInitialized.load(std::memory_order_relaxed),
+               "initExceptionHelpers was never called!");
+}
+
+// Exception throwing & translating functions //////////////////////////////////////////////////////
+
+// Functions that throw Java exceptions
+
+namespace {
+
+void setJavaExceptionAndAbortOnFailure(jthrowable throwable) noexcept {
+  assertIfExceptionsNotInitialized();
+  JNIEnv* env = internal::getEnv();
+  if (throwable) {
+    env->Throw(throwable);
+  }
+  if (env->ExceptionCheck() != JNI_TRUE) {
+    std::abort();
+  }
+}
+
+void setDefaultException() noexcept {
+  assertIfExceptionsNotInitialized();
+  setJavaExceptionAndAbortOnFailure(CommonJniExceptions::getRuntimeExceptionObject());
+}
+
+void setCppSystemErrorExceptionInJava(const std::system_error& ex) noexcept {
+  assertIfExceptionsNotInitialized();
+  JNIEnv* env = internal::getEnv();
+  jclass cppSystemErrorExceptionClass = env->FindClass(
+      "com/facebook/jni/CppSystemErrorException");
+  if (!cppSystemErrorExceptionClass) {
+    setDefaultException();
+    return;
+  }
+  jmethodID constructorMID = env->GetMethodID(
+      cppSystemErrorExceptionClass,
+      "<init>",
+      "(Ljava/lang/String;I)V");
+  if (!constructorMID) {
+    setDefaultException();
+    return;
+  }
+  jthrowable cppSystemErrorExceptionObject = static_cast<jthrowable>(env->NewObject(
+      cppSystemErrorExceptionClass,
+      constructorMID,
+      env->NewStringUTF(ex.what()),
+      ex.code().value()));
+  setJavaExceptionAndAbortOnFailure(cppSystemErrorExceptionObject);
+}
+
+template<typename... ARGS>
+void setNewJavaException(jclass exceptionClass, const char* fmt, ARGS... args) {
+  assertIfExceptionsNotInitialized();
+  int msgSize = snprintf(nullptr, 0, fmt, args...);
+  JNIEnv* env = internal::getEnv();
+
+  try {
+    char *msg = (char*) alloca(msgSize);
+    snprintf(msg, kMaxExceptionMessageBufferSize, fmt, args...);
+    env->ThrowNew(exceptionClass, msg);
+  } catch (...) {
+    env->ThrowNew(exceptionClass, "");
+  }
+
+  if (env->ExceptionCheck() != JNI_TRUE) {
+    setDefaultException();
+  }
+}
+
+void setNewJavaException(jclass exceptionClass, const char* msg) {
+  assertIfExceptionsNotInitialized();
+  setNewJavaException(exceptionClass, "%s", msg);
+}
+
+template<typename... ARGS>
+void setNewJavaException(const char* className, const char* fmt, ARGS... args) {
+  assertIfExceptionsNotInitialized();
+  JNIEnv* env = internal::getEnv();
+  jclass exceptionClass = env->FindClass(className);
+  if (env->ExceptionCheck() != JNI_TRUE && !exceptionClass) {
+    // If FindClass() has failed but no exception has been thrown, throw a default exception.
+    setDefaultException();
+    return;
+  }
+  setNewJavaException(exceptionClass, fmt, args...);
+}
+
+}
+
+// Functions that throw C++ exceptions
+
+// TODO(T6618159) Take a stack dump here to save context if it results in a crash when propagated
+void throwPendingJniExceptionAsCppException() {
+  assertIfExceptionsNotInitialized();
+  JNIEnv* env = internal::getEnv();
+  if (env->ExceptionCheck() == JNI_FALSE) {
+    return;
+  }
+
+  jthrowable throwable = env->ExceptionOccurred();
+  if (!throwable) {
+    throw std::runtime_error("Unable to get pending JNI exception.");
+  }
+
+  env->ExceptionClear();
+  throw JniException(throwable);
+}
+
+void throwCppExceptionIf(bool condition) {
+  assertIfExceptionsNotInitialized();
+  if (!condition) {
+    return;
+  }
+
+  JNIEnv* env = internal::getEnv();
+  if (env->ExceptionCheck() == JNI_TRUE) {
+    throwPendingJniExceptionAsCppException();
+    return;
+  }
+
+  throw JniException();
+}
+
+void throwNewJavaException(jthrowable throwable) {
+  throw JniException(throwable);
+}
+
+void throwNewJavaException(const char* throwableName, const char* msg) {
+  // If anything of the fbjni calls fail, an exception of a suitable
+  // form will be thrown, which is what we want.
+  auto throwableClass = findClassLocal(throwableName);
+  auto throwable = throwableClass->newObject(
+    throwableClass->getConstructor<jthrowable(jstring)>(),
+    make_jstring(msg).release());
+  throwNewJavaException(throwable.get());
+}
+
+// Translate C++ to Java Exception
+
+void translatePendingCppExceptionToJavaException() noexcept {
+  assertIfExceptionsNotInitialized();
+  try {
+    try {
+      throw;
+    } catch(const JniException& ex) {
+      ex.setJavaException();
+    } catch(const std::ios_base::failure& ex) {
+      setNewJavaException("java/io/IOException", ex.what());
+    } catch(const std::bad_alloc& ex) {
+      setNewJavaException("java/lang/OutOfMemoryError", ex.what());
+    } catch(const std::out_of_range& ex) {
+      setNewJavaException("java/lang/ArrayIndexOutOfBoundsException", ex.what());
+    } catch(const std::system_error& ex) {
+      setCppSystemErrorExceptionInJava(ex);
+    } catch(const std::runtime_error& ex) {
+      setNewJavaException("java/lang/RuntimeException", ex.what());
+    } catch(const std::exception& ex) {
+      setNewJavaException("com/facebook/jni/CppException", ex.what());
+    } catch(const char* msg) {
+      setNewJavaException(CommonJniExceptions::getUnknownCppExceptionClass(), msg);
+    } catch(...) {
+      setJavaExceptionAndAbortOnFailure(CommonJniExceptions::getUnknownCppExceptionObject());
+    }
+  } catch(...) {
+    // This block aborts the program, if something bad happens when handling exceptions, thus
+    // keeping this function noexcept.
+    std::abort();
+  }
+}
+
+// JniException ////////////////////////////////////////////////////////////////////////////////////
+
+const std::string JniException::kExceptionMessageFailure_ = "Unable to get exception message.";
+
+JniException::JniException() : JniException(CommonJniExceptions::getRuntimeExceptionObject()) { }
+
+JniException::JniException(jthrowable throwable) : isMessageExtracted_(false) {
+  assertIfExceptionsNotInitialized();
+  throwableGlobalRef_ = static_cast<jthrowable>(internal::getEnv()->NewGlobalRef(throwable));
+  if (!throwableGlobalRef_) {
+    throw std::bad_alloc();
+  }
+}
+
+JniException::JniException(JniException &&rhs)
+    : throwableGlobalRef_(std::move(rhs.throwableGlobalRef_)),
+      what_(std::move(rhs.what_)),
+      isMessageExtracted_(rhs.isMessageExtracted_) {
+  rhs.throwableGlobalRef_ = nullptr;
+}
+
+JniException::JniException(const JniException &rhs)
+    : what_(rhs.what_), isMessageExtracted_(rhs.isMessageExtracted_) {
+  JNIEnv* env = internal::getEnv();
+  if (rhs.getThrowable()) {
+    throwableGlobalRef_ = static_cast<jthrowable>(env->NewGlobalRef(rhs.getThrowable()));
+    if (!throwableGlobalRef_) {
+      throw std::bad_alloc();
+    }
+  } else {
+    throwableGlobalRef_ = nullptr;
+  }
+}
+
+JniException::~JniException() noexcept {
+  if (throwableGlobalRef_) {
+    internal::getEnv()->DeleteGlobalRef(throwableGlobalRef_);
+  }
+}
+
+jthrowable JniException::getThrowable() const noexcept {
+  return throwableGlobalRef_;
+}
+
+// TODO 6900503: consider making this thread-safe.
+void JniException::populateWhat() const noexcept {
+  JNIEnv* env = internal::getEnv();
+
+  jmethodID toStringMID = env->GetMethodID(
+      CommonJniExceptions::getThrowableClass(),
+      "toString",
+      "()Ljava/lang/String;");
+  jstring messageJString = (jstring) env->CallObjectMethod(
+      throwableGlobalRef_,
+      toStringMID);
+
+  isMessageExtracted_ = true;
+
+  if (env->ExceptionCheck()) {
+    env->ExceptionClear();
+    what_ = kExceptionMessageFailure_;
+    return;
+  }
+
+  const char* chars = env->GetStringUTFChars(messageJString, nullptr);
+  if (!chars) {
+    what_ = kExceptionMessageFailure_;
+    return;
+  }
+
+  try {
+    what_ = std::string(chars);
+  } catch(...) {
+    what_ = kExceptionMessageFailure_;
+  }
+
+  env->ReleaseStringUTFChars(messageJString, chars);
+}
+
+const char* JniException::what() const noexcept {
+  if (!isMessageExtracted_) {
+    populateWhat();
+  }
+  return what_.c_str();
+}
+
+void JniException::setJavaException() const noexcept {
+  setJavaExceptionAndAbortOnFailure(throwableGlobalRef_);
+}
+
+}}

tests/react-test-app/android/app/src/main/jni/first-party/jni/fbjni/Exceptions.h

@@ -0,0 +1,130 @@
+/*
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+/**
+ * @file Exceptions.h
+ *
+ * After invoking a JNI function that can throw a Java exception, the macro
+ * @ref FACEBOOK_JNI_THROW_PENDING_EXCEPTION() or @ref FACEBOOK_JNI_THROW_EXCEPTION_IF()
+ * should be invoked.
+ *
+ * IMPORTANT! IMPORTANT! IMPORTANT! IMPORTANT! IMPORTANT! IMPORTANT! IMPORTANT! IMPORTANT!
+ * To use these methods you MUST call initExceptionHelpers() when your library is loaded.
+ */
+
+#pragma once
+
+#include <alloca.h>
+#include <stdexcept>
+#include <string>
+
+#include <jni.h>
+
+#include "Common.h"
+
+// If a pending JNI Java exception is found, wraps it in a JniException object and throws it as
+// a C++ exception.
+#define FACEBOOK_JNI_THROW_PENDING_EXCEPTION() \
+  ::facebook::jni::throwPendingJniExceptionAsCppException()
+
+// If the condition is true, throws a JniException object, which wraps the pending JNI Java
+// exception if any. If no pending exception is found, throws a JniException object that wraps a
+// RuntimeException throwable. 
+#define FACEBOOK_JNI_THROW_EXCEPTION_IF(CONDITION) \
+  ::facebook::jni::throwCppExceptionIf(CONDITION)
+
+namespace facebook {
+namespace jni {
+
+namespace internal {
+  void initExceptionHelpers();
+}
+
+/**
+ * Before using any of the state initialized above, call this.  It
+ * will assert if initialization has not yet occurred.
+ */
+void assertIfExceptionsNotInitialized();
+
+// JniException ////////////////////////////////////////////////////////////////////////////////////
+
+/**
+ * This class wraps a Java exception into a C++ exception; if the exception is routed back
+ * to the Java side, it can be unwrapped and just look like a pure Java interaction. The class
+ * is resilient to errors while creating the exception, falling back to some pre-allocated
+ * exceptions if a new one cannot be allocated or populated.
+ *
+ * Note: the what() method of this class is not thread-safe (t6900503).
+ */
+class JniException : public std::exception {
+ public:
+  JniException();
+
+  explicit JniException(jthrowable throwable);
+
+  JniException(JniException &&rhs);
+
+  JniException(const JniException &other);
+
+  ~JniException() noexcept;
+
+  jthrowable getThrowable() const noexcept;
+
+  virtual const char* what() const noexcept;
+
+  void setJavaException() const noexcept;
+
+ private:
+  jthrowable throwableGlobalRef_;
+  mutable std::string what_;
+  mutable bool isMessageExtracted_;
+  const static std::string kExceptionMessageFailure_;
+
+  void populateWhat() const noexcept;
+};
+
+// Exception throwing & translating functions //////////////////////////////////////////////////////
+
+// Functions that throw C++ exceptions
+
+void throwPendingJniExceptionAsCppException();
+
+void throwCppExceptionIf(bool condition);
+
+static const int kMaxExceptionMessageBufferSize = 512;
+
+[[noreturn]] void throwNewJavaException(jthrowable);
+
+[[noreturn]] void throwNewJavaException(const char* throwableName, const char* msg);
+
+// These methods are the preferred way to throw a Java exception from
+// a C++ function.  They create and throw a C++ exception which wraps
+// a Java exception, so the C++ flow is interrupted. Then, when
+// translatePendingCppExceptionToJavaException is called at the
+// topmost level of the native stack, the wrapped Java exception is
+// thrown to the java caller.
+template<typename... Args>
+[[noreturn]] void throwNewJavaException(const char* throwableName, const char* fmt, Args... args) {
+  assertIfExceptionsNotInitialized();
+  int msgSize = snprintf(nullptr, 0, fmt, args...);
+
+  char *msg = (char*) alloca(msgSize);
+  snprintf(msg, kMaxExceptionMessageBufferSize, fmt, args...);
+  throwNewJavaException(throwableName, msg);
+}
+
+// Identifies any pending C++ exception and throws it as a Java exception. If the exception can't
+// be thrown, it aborts the program. This is a noexcept function at C++ level.
+void translatePendingCppExceptionToJavaException() noexcept;
+
+// For convenience, some exception names in java.lang are available here.
+
+const char* const gJavaLangIllegalArgumentException = "java/lang/IllegalArgumentException";
+
+}}

tests/react-test-app/android/app/src/main/jni/first-party/jni/fbjni/Hybrid.cpp

@@ -0,0 +1,76 @@
+/*
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+#include "Hybrid.h"
+
+#include "Exceptions.h"
+#include "Registration.h"
+
+namespace facebook {
+namespace jni {
+
+namespace detail {
+
+void setNativePointer(alias_ref<HybridData::javaobject> hybridData,
+                      std::unique_ptr<BaseHybridClass> new_value) {
+  static auto pointerField = hybridData->getClass()->getField<jlong>("mNativePointer");
+  auto* old_value = reinterpret_cast<BaseHybridClass*>(hybridData->getFieldValue(pointerField));
+  if (new_value) {
+    // Modify should only ever be called once with a non-null
+    // new_value.  If this happens again it's a programmer error, so
+    // blow up.
+    FBASSERTMSGF(old_value == 0, "Attempt to set C++ native pointer twice");
+  } else if (old_value == 0) {
+    return;
+  }
+  // delete on a null pointer is defined to be a noop.
+  delete old_value;
+  // This releases ownership from the unique_ptr, and passes the pointer, and
+  // ownership of it, to HybridData which is managed by the java GC.  The
+  // finalizer on hybridData calls resetNative which will delete the object, if
+  // reseetNative has not already been called.
+  hybridData->setFieldValue(pointerField, reinterpret_cast<jlong>(new_value.release()));
+}
+
+BaseHybridClass* getNativePointer(alias_ref<HybridData::javaobject> hybridData) {
+  static auto pointerField = hybridData->getClass()->getField<jlong>("mNativePointer");
+  auto* value = reinterpret_cast<BaseHybridClass*>(hybridData->getFieldValue(pointerField));
+  if (!value) {
+    throwNewJavaException("java/lang/NullPointerException", "java.lang.NullPointerException");
+  }
+  return value;
+}
+
+local_ref<HybridData::javaobject> getHybridData(alias_ref<jobject> jthis,
+                                                JField<HybridData::javaobject> field) {
+  auto hybridData = jthis->getFieldValue(field);
+  if (!hybridData) {
+    throwNewJavaException("java/lang/NullPointerException", "java.lang.NullPointerException");
+  }
+  return hybridData;
+}
+
+}
+
+namespace {
+
+void resetNative(alias_ref<detail::HybridData::javaobject> jthis) {
+  detail::setNativePointer(jthis, nullptr);
+}
+
+}
+
+void HybridDataOnLoad() {
+  registerNatives("com/facebook/jni/HybridData", {
+      makeNativeMethod("resetNative", resetNative),
+  });
+}
+
+}}
+

tests/react-test-app/android/app/src/main/jni/first-party/jni/fbjni/Hybrid.h

@@ -0,0 +1,277 @@
+/*
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+#pragma once
+
+#include <memory>
+#include <type_traits>
+#include <fb/assert.h>
+#include "CoreClasses.h"
+
+namespace facebook {
+namespace jni {
+
+namespace detail {
+
+class BaseHybridClass : public BaseJavaClass {
+public:
+  virtual ~BaseHybridClass() {}
+};
+
+struct HybridData : public JavaClass<HybridData> {
+  constexpr static auto kJavaDescriptor = "Lcom/facebook/jni/HybridData;";
+};
+
+void setNativePointer(alias_ref<HybridData::javaobject> hybridData,
+                      std::unique_ptr<BaseHybridClass> new_value);
+BaseHybridClass* getNativePointer(alias_ref<HybridData::javaobject> hybridData);
+local_ref<HybridData::javaobject> getHybridData(alias_ref<jobject> jthis,
+                                                JField<HybridData::javaobject> field);
+
+// Normally, pass through types unmolested.
+template <typename T, typename Enabled = void>
+struct Convert {
+  typedef T jniType;
+  static jniType fromJni(jniType t) {
+    return t;
+  }
+  static jniType toJniRet(jniType t) {
+    return t;
+  }
+  static jniType toCall(jniType t) {
+    return t;
+  }
+};
+
+// This is needed for return conversion
+template <>
+struct Convert<void> {
+  typedef void jniType;
+};
+
+// convert to std::string from jstring
+template <>
+struct Convert<std::string> {
+  typedef jstring jniType;
+  static std::string fromJni(jniType t) {
+    return wrap_alias(t)->toStdString();
+  }
+  static jniType toJniRet(const std::string& t) {
+    return make_jstring(t).release();
+  }
+  static local_ref<jstring> toCall(const std::string& t) {
+    return make_jstring(t);
+  }
+};
+
+// convert return from const char*
+template <>
+struct Convert<const char*> {
+  typedef jstring jniType;
+  // no automatic synthesis of const char*.  (It can't be freed.)
+  static jniType toJniRet(const char* t) {
+    return make_jstring(t).release();
+  }
+  static local_ref<jstring> toCall(const char* t) {
+    return make_jstring(t);
+  }
+};
+
+// jboolean is an unsigned char, not a bool. Allow it to work either way.
+template<>
+struct Convert<bool> {
+  typedef jboolean jniType;
+  static bool fromJni(jniType t) {
+    return t;
+  }
+  static jniType toJniRet(bool t) {
+    return t;
+  }
+  static jniType toCall(bool t) {
+    return t;
+  }
+};
+
+// convert to alias_ref<T> from T
+template <typename T>
+struct Convert<alias_ref<T>> {
+  typedef T jniType;
+  static alias_ref<jniType> fromJni(jniType t) {
+    return wrap_alias(t);
+  }
+  static jniType toJniRet(alias_ref<jniType> t) {
+    return t.get();
+  }
+  static jniType toCall(alias_ref<jniType> t) {
+    return t.get();
+  }
+};
+
+// convert return from local_ref<T>
+template <typename T>
+struct Convert<local_ref<T>> {
+  typedef T jniType;
+  // No automatic synthesis of local_ref
+  static jniType toJniRet(local_ref<jniType> t) {
+    return t.release();
+  }
+  static jniType toCall(local_ref<jniType> t) {
+    return t.get();
+  }
+};
+
+// convert return from global_ref<T>
+template <typename T>
+struct Convert<global_ref<T>> {
+  typedef T jniType;
+  // No automatic synthesis of global_ref
+  static jniType toJniRet(global_ref<jniType> t) {
+    return t.get();
+  }
+  static jniType toCall(global_ref<jniType> t) {
+    return t.get();
+  }
+};
+
+// In order to avoid potentially filling the jni locals table,
+// temporary objects (right now, this is just jstrings) need to be
+// released.  This is done by returning a holder which autoconverts to
+// jstring.  This is only relevant when the jniType is passed down, as
+// in newObjectJavaArgs.
+
+template <typename T>
+inline T callToJni(T&& t) {
+  return t;
+}
+
+inline jstring callToJni(local_ref<jstring>&& sref) {
+  return sref.get();
+}
+
+struct jstring_holder {
+  local_ref<jstring> s_;
+  jstring_holder(const char* s) : s_(make_jstring(s)) {}
+  operator jstring() { return s_.get(); }
+};
+
+template <typename T, typename Enabled = void>
+struct HybridRoot {};
+
+template <typename T>
+struct HybridRoot<T,
+                  typename std::enable_if<!std::is_base_of<BaseHybridClass, T>::value>::type>
+    : public BaseHybridClass {};
+
+}
+
+template <typename T, typename Base = detail::BaseHybridClass>
+class HybridClass : public Base
+                  , public detail::HybridRoot<Base>
+                  , public JavaClass<T, Base> {
+public:
+  typedef detail::HybridData::javaobject jhybriddata;
+  typedef typename JavaClass<T, Base>::javaobject jhybridobject;
+
+  using JavaClass<T, Base>::javaClassStatic;
+  using JavaClass<T, Base>::javaClassLocal;
+  using JavaClass<T, Base>::javaobject;
+  typedef typename JavaClass<T, Base>::_javaobject _javaobject;
+
+protected:
+  typedef HybridClass HybridBase;
+
+  // This ensures that a C++ hybrid part cannot be created on its own
+  // by default.  If a hybrid wants to enable this, it can provide its
+  // own public ctor, or change the accessibility of this to public.
+  using Base::Base;
+
+  static void registerHybrid(std::initializer_list<NativeMethod> methods) {
+    javaClassStatic()->registerNatives(methods);
+  }
+
+  static local_ref<jhybriddata> makeHybridData(std::unique_ptr<T> cxxPart) {
+    static auto dataCtor = detail::HybridData::javaClassStatic()->getConstructor<jhybriddata()>();
+    auto hybridData = detail::HybridData::javaClassStatic()->newObject(dataCtor);
+    detail::setNativePointer(hybridData, std::move(cxxPart));
+    return hybridData;
+  }
+
+  template <typename... Args>
+  static local_ref<jhybriddata> makeCxxInstance(Args&&... args) {
+    return makeHybridData(std::unique_ptr<T>(new T(std::forward<Args>(args)...)));
+  }
+
+public:
+  // Factory method for creating a hybrid object where the arguments
+  // are used to initialize the C++ part directly without passing them
+  // through java.  This method requires the Java part to have a ctor
+  // which takes a HybridData, and for the C++ part to have a ctor
+  // compatible with the arguments passed here.  For safety, the ctor
+  // can be private, and the hybrid declared a friend of its base, so
+  // the hybrid can only be created from here.
+  //
+  // Exception behavior: This can throw an exception if creating the
+  // C++ object fails, or any JNI methods throw.
+  template <typename... Args>
+  static local_ref<jhybridobject> newObjectCxxArgs(Args&&... args) {
+    auto hybridData = makeCxxInstance(std::forward<Args>(args)...);
+    static auto ctor = javaClassStatic()->template getConstructor<jhybridobject(jhybriddata)>();
+    return javaClassStatic()->newObject(ctor, hybridData.get());
+  }
+
+  // Factory method for creating a hybrid object where the arguments
+  // are passed to the java ctor.
+  template <typename... Args>
+  static local_ref<jhybridobject> newObjectJavaArgs(Args&&... args) {
+    static auto ctor =
+      javaClassStatic()->template getConstructor<
+        jhybridobject(typename detail::Convert<typename std::decay<Args>::type>::jniType...)>();
+    // This can't use the same impl as Convert::toJniRet because that
+    // function sometimes creates and then releases local_refs, which
+    // could potentially cause the locals table to fill.  Instead, we
+    // use two calls, one which can return a local_ref if needed, and
+    // a second which extracts its value.  The lifetime of the
+    // local_ref is the expression, after which it is destroyed and
+    // the local_ref is cleaned up.
+    auto lref =
+      javaClassStatic()->newObject(
+        ctor, detail::callToJni(
+          detail::Convert<typename std::decay<Args>::type>::toCall(args))...);
+    return lref;
+  }
+
+  // If a hybrid class throws an exception which derives from
+  // std::exception, it will be passed to mapException on the hybrid
+  // class, or nearest ancestor.  This allows boilerplate exception
+  // translation code (for example, calling throwNewJavaException on a
+  // particular java class) to be hoisted to a common function.  If
+  // mapException returns, then the std::exception will be translated
+  // to Java.
+  static void mapException(const std::exception& ex) {}
+};
+
+// Given a *_ref object which refers to a hybrid class, this will reach inside
+// of it, find the mHybridData, extract the C++ instance pointer, cast it to
+// the appropriate type, and return it.
+template <typename T>
+inline typename std::remove_pointer<typename T::PlainJniType>::type::javaClass* cthis(T jthis) {
+  static auto dataField =
+    jthis->getClass()->template getField<detail::HybridData::javaobject>("mHybridData");
+  // I'd like to use dynamic_cast here, but -fno-rtti is the default.
+  auto* value = static_cast<typename std::remove_pointer<typename T::PlainJniType>::type::javaClass*>(
+    detail::getNativePointer(detail::getHybridData(jthis, dataField)));
+  // This would require some serious programmer error.
+  FBASSERTMSGF(value != 0, "Incorrect C++ type in hybrid field");
+  return value;
+}
+
+void HybridDataOnLoad();
+
+}
+}

tests/react-test-app/android/app/src/main/jni/first-party/jni/fbjni/Meta-inl.h

@@ -0,0 +1,352 @@
+/*
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+#pragma once
+
+#include <jni.h>
+
+#include "Common.h"
+#include "Exceptions.h"
+
+namespace facebook {
+namespace jni {
+
+// JMethod /////////////////////////////////////////////////////////////////////////////////////////
+
+inline JMethodBase::JMethodBase(jmethodID method_id) noexcept
+  : method_id_{method_id}
+{}
+
+inline JMethodBase::operator bool() const noexcept {
+  return method_id_ != nullptr;
+}
+
+inline jmethodID JMethodBase::getId() const noexcept {
+  return method_id_;
+}
+
+template<typename... Args>
+inline void JMethod<void(Args...)>::operator()(alias_ref<jobject> self, Args... args) {
+  const auto env = internal::getEnv();
+        env->CallVoidMethod(self.get(), getId(), args...);
+  FACEBOOK_JNI_THROW_PENDING_EXCEPTION();
+}
+
+#pragma push_macro("DEFINE_PRIMITIVE_CALL")
+#undef DEFINE_PRIMITIVE_CALL
+#define DEFINE_PRIMITIVE_CALL(TYPE, METHOD)                                                 \
+template<typename... Args>                                                                  \
+inline TYPE JMethod<TYPE(Args...)>::operator()(alias_ref<jobject> self, Args... args) {     \
+  const auto env = internal::getEnv();                                                      \
+  auto result = env->Call ## METHOD ## Method(self.get(), getId(), args...);                \
+  FACEBOOK_JNI_THROW_PENDING_EXCEPTION();                                                   \
+  return result;                                                                            \
+}
+
+DEFINE_PRIMITIVE_CALL(jboolean, Boolean)
+DEFINE_PRIMITIVE_CALL(jbyte, Byte)
+DEFINE_PRIMITIVE_CALL(jchar, Char)
+DEFINE_PRIMITIVE_CALL(jshort, Short)
+DEFINE_PRIMITIVE_CALL(jint, Int)
+DEFINE_PRIMITIVE_CALL(jlong, Long)
+DEFINE_PRIMITIVE_CALL(jfloat, Float)
+DEFINE_PRIMITIVE_CALL(jdouble, Double)
+#pragma pop_macro("DEFINE_PRIMITIVE_CALL")
+
+template<typename T, typename... Args>
+inline local_ref<T*> JMethod<T*(Args...)>::operator()(alias_ref<jobject> self, Args... args) {
+  const auto env = internal::getEnv();
+        auto result = env->CallObjectMethod(self.get(), getId(), args...);
+  FACEBOOK_JNI_THROW_PENDING_EXCEPTION();
+        return adopt_local(static_cast<T*>(result));
+}
+
+template<typename... Args>
+inline void JStaticMethod<void(Args...)>::operator()(alias_ref<jclass> cls, Args... args) {
+  const auto env = internal::getEnv();
+  env->CallStaticVoidMethod(cls.get(), getId(), args...);
+  FACEBOOK_JNI_THROW_PENDING_EXCEPTION();
+}
+
+#pragma push_macro("DEFINE_PRIMITIVE_STATIC_CALL")
+#undef DEFINE_PRIMITIVE_STATIC_CALL
+#define DEFINE_PRIMITIVE_STATIC_CALL(TYPE, METHOD)                                          \
+template<typename... Args>                                                                  \
+inline TYPE JStaticMethod<TYPE(Args...)>::operator()(alias_ref<jclass> cls, Args... args) { \
+  const auto env = internal::getEnv();                                                      \
+  auto result = env->CallStatic ## METHOD ## Method(cls.get(), getId(), args...);           \
+  FACEBOOK_JNI_THROW_PENDING_EXCEPTION();                                                   \
+        return result;                                                                      \
+}
+
+DEFINE_PRIMITIVE_STATIC_CALL(jboolean, Boolean)
+DEFINE_PRIMITIVE_STATIC_CALL(jbyte, Byte)
+DEFINE_PRIMITIVE_STATIC_CALL(jchar, Char)
+DEFINE_PRIMITIVE_STATIC_CALL(jshort, Short)
+DEFINE_PRIMITIVE_STATIC_CALL(jint, Int)
+DEFINE_PRIMITIVE_STATIC_CALL(jlong, Long)
+DEFINE_PRIMITIVE_STATIC_CALL(jfloat, Float)
+DEFINE_PRIMITIVE_STATIC_CALL(jdouble, Double)
+#pragma pop_macro("DEFINE_PRIMITIVE_STATIC_CALL")
+
+template<typename T, typename... Args>
+inline local_ref<T*> JStaticMethod<T*(Args...)>::operator()(alias_ref<jclass> cls, Args... args) {
+  const auto env = internal::getEnv();
+  auto result = env->CallStaticObjectMethod(cls.get(), getId(), args...);
+  FACEBOOK_JNI_THROW_PENDING_EXCEPTION();
+  return adopt_local(static_cast<T*>(result));
+}
+
+
+template<typename... Args>
+inline void
+JNonvirtualMethod<void(Args...)>::operator()(alias_ref<jobject> self, jclass cls, Args... args) {
+  const auto env = internal::getEnv();
+  env->CallNonvirtualVoidMethod(self.get(), cls, getId(), args...);
+  FACEBOOK_JNI_THROW_PENDING_EXCEPTION();
+}
+
+#pragma push_macro("DEFINE_PRIMITIVE_NON_VIRTUAL_CALL")
+#undef DEFINE_PRIMITIVE_NON_VIRTUAL_CALL
+#define DEFINE_PRIMITIVE_NON_VIRTUAL_CALL(TYPE, METHOD)                                           \
+template<typename... Args>                                                                        \
+inline TYPE                                                                                       \
+JNonvirtualMethod<TYPE(Args...)>::operator()(alias_ref<jobject> self, jclass cls, Args... args) { \
+  const auto env = internal::getEnv();                                                            \
+  auto result = env->CallNonvirtual ## METHOD ## Method(self.get(), cls, getId(), args...);       \
+  FACEBOOK_JNI_THROW_PENDING_EXCEPTION();                                                         \
+  return result;                                                                                  \
+}
+
+DEFINE_PRIMITIVE_NON_VIRTUAL_CALL(jboolean, Boolean)
+DEFINE_PRIMITIVE_NON_VIRTUAL_CALL(jbyte, Byte)
+DEFINE_PRIMITIVE_NON_VIRTUAL_CALL(jchar, Char)
+DEFINE_PRIMITIVE_NON_VIRTUAL_CALL(jshort, Short)
+DEFINE_PRIMITIVE_NON_VIRTUAL_CALL(jint, Int)
+DEFINE_PRIMITIVE_NON_VIRTUAL_CALL(jlong, Long)
+DEFINE_PRIMITIVE_NON_VIRTUAL_CALL(jfloat, Float)
+DEFINE_PRIMITIVE_NON_VIRTUAL_CALL(jdouble, Double)
+#pragma pop_macro("DEFINE_PRIMITIVE_NON_VIRTUAL_CALL")
+
+template<typename T, typename... Args>
+inline local_ref<T*> JNonvirtualMethod<T*(Args...)>::operator()(
+    alias_ref<jobject> self,
+    jclass cls,
+    Args... args) {
+  const auto env = internal::getEnv();
+  auto result = env->CallNonvirtualObjectMethod(self.get(), cls, getId(), args...);
+  FACEBOOK_JNI_THROW_PENDING_EXCEPTION();
+  return adopt_local(static_cast<T*>(result));
+}
+
+
+// jtype_traits ////////////////////////////////////////////////////////////////////////////////////
+
+/// The generic way to associate a descriptor to a type is to look it up in the
+/// corresponding @ref JObjectWrapper specialization. This makes it easy to add
+/// support for your user defined type.
+template<typename T>
+struct jtype_traits {
+  // The jni type signature (described at
+  // http://docs.oracle.com/javase/1.5.0/docs/guide/jni/spec/types.html).
+  static std::string descriptor() {
+    static const auto descriptor = JObjectWrapper<T>::kJavaDescriptor != nullptr ?
+      std::string{JObjectWrapper<T>::kJavaDescriptor} :
+      JObjectWrapper<T>::get_instantiated_java_descriptor();
+    return descriptor;
+  }
+
+  // The signature used for class lookups. See
+  // http://docs.oracle.com/javase/6/docs/api/java/lang/Class.html#getName().
+  static std::string base_name() {
+    if (JObjectWrapper<T>::kJavaDescriptor != nullptr) {
+      std::string base_name = JObjectWrapper<T>::kJavaDescriptor;
+      return base_name.substr(1, base_name.size() - 2);
+    }
+    return JObjectWrapper<T>::get_instantiated_java_descriptor();
+  }
+};
+
+#pragma push_macro("DEFINE_FIELD_AND_ARRAY_TRAIT")
+#undef DEFINE_FIELD_AND_ARRAY_TRAIT
+
+#define DEFINE_FIELD_AND_ARRAY_TRAIT(TYPE, DSC)                     \
+template<>                                                          \
+struct jtype_traits<TYPE> {                                         \
+  static std::string descriptor() { return std::string{#DSC}; }     \
+  static std::string base_name() { return descriptor(); }           \
+};                                                                  \
+template<>                                                          \
+struct jtype_traits<TYPE ## Array> {                                \
+  static std::string descriptor() { return std::string{"[" #DSC}; } \
+  static std::string base_name() { return descriptor(); }           \
+};
+
+// There is no voidArray, handle that without the macro.
+template<>
+struct jtype_traits<void> {
+  static std::string descriptor() { return std::string{"V"}; };
+};
+
+DEFINE_FIELD_AND_ARRAY_TRAIT(jboolean, Z)
+DEFINE_FIELD_AND_ARRAY_TRAIT(jbyte,    B)
+DEFINE_FIELD_AND_ARRAY_TRAIT(jchar,    C)
+DEFINE_FIELD_AND_ARRAY_TRAIT(jshort,   S)
+DEFINE_FIELD_AND_ARRAY_TRAIT(jint,     I)
+DEFINE_FIELD_AND_ARRAY_TRAIT(jlong,    J)
+DEFINE_FIELD_AND_ARRAY_TRAIT(jfloat,   F)
+DEFINE_FIELD_AND_ARRAY_TRAIT(jdouble,  D)
+
+#pragma pop_macro("DEFINE_FIELD_AND_ARRAY_TRAIT")
+
+
+// JField<T> ///////////////////////////////////////////////////////////////////////////////////////
+
+template<typename T>
+inline JField<T>::JField(jfieldID field) noexcept
+  : field_id_{field}
+{}
+
+template<typename T>
+inline JField<T>::operator bool() const noexcept {
+  return field_id_ != nullptr;
+}
+
+template<typename T>
+inline jfieldID JField<T>::getId() const noexcept {
+  return field_id_;
+}
+
+#pragma push_macro("DEFINE_FIELD_PRIMITIVE_GET_SET")
+#undef DEFINE_FIELD_PRIMITIVE_GET_SET
+#define DEFINE_FIELD_PRIMITIVE_GET_SET(TYPE, METHOD)                 \
+template<>                                                           \
+inline TYPE JField<TYPE>::get(jobject object) const noexcept {       \
+  const auto env = internal::getEnv();                               \
+  return env->Get ## METHOD ## Field(object, field_id_);             \
+}                                                                    \
+                                                                     \
+template<>                                                           \
+inline void JField<TYPE>::set(jobject object, TYPE value) noexcept { \
+  const auto env = internal::getEnv();                               \
+  env->Set ## METHOD ## Field(object, field_id_, value);             \
+}
+
+DEFINE_FIELD_PRIMITIVE_GET_SET(jboolean, Boolean)
+DEFINE_FIELD_PRIMITIVE_GET_SET(jbyte, Byte)
+DEFINE_FIELD_PRIMITIVE_GET_SET(jchar, Char)
+DEFINE_FIELD_PRIMITIVE_GET_SET(jshort, Short)
+DEFINE_FIELD_PRIMITIVE_GET_SET(jint, Int)
+DEFINE_FIELD_PRIMITIVE_GET_SET(jlong, Long)
+DEFINE_FIELD_PRIMITIVE_GET_SET(jfloat, Float)
+DEFINE_FIELD_PRIMITIVE_GET_SET(jdouble, Double)
+#pragma pop_macro("DEFINE_FIELD_PRIMITIVE_GET_SET")
+
+template<typename T>
+inline T JField<T>::get(jobject object) const noexcept {
+  return static_cast<T>(internal::getEnv()->GetObjectField(object, field_id_));
+}
+
+template<typename T>
+inline void JField<T>::set(jobject object, T value) noexcept {
+  internal::getEnv()->SetObjectField(object, field_id_, static_cast<jobject>(value));
+}
+
+// JStaticField<T> /////////////////////////////////////////////////////////////////////////////////
+
+template<typename T>
+inline JStaticField<T>::JStaticField(jfieldID field) noexcept
+  : field_id_{field}
+{}
+
+template<typename T>
+inline JStaticField<T>::operator bool() const noexcept {
+  return field_id_ != nullptr;
+}
+
+template<typename T>
+inline jfieldID JStaticField<T>::getId() const noexcept {
+  return field_id_;
+}
+
+#pragma push_macro("DEFINE_STATIC_FIELD_PRIMITIVE_GET_SET")
+#undef DEFINE_STATIC_FIELD_PRIMITIVE_GET_SET
+#define DEFINE_STATIC_FIELD_PRIMITIVE_GET_SET(TYPE, METHOD)                \
+template<>                                                                 \
+inline TYPE JStaticField<TYPE>::get(jclass jcls) const noexcept {          \
+  const auto env = internal::getEnv();                                     \
+  return env->GetStatic ## METHOD ## Field(jcls, field_id_);               \
+}                                                                          \
+                                                                           \
+template<>                                                                 \
+inline void JStaticField<TYPE>::set(jclass jcls, TYPE value) noexcept {    \
+  const auto env = internal::getEnv();                                     \
+  env->SetStatic ## METHOD ## Field(jcls, field_id_, value);               \
+}
+
+DEFINE_STATIC_FIELD_PRIMITIVE_GET_SET(jboolean, Boolean)
+DEFINE_STATIC_FIELD_PRIMITIVE_GET_SET(jbyte, Byte)
+DEFINE_STATIC_FIELD_PRIMITIVE_GET_SET(jchar, Char)
+DEFINE_STATIC_FIELD_PRIMITIVE_GET_SET(jshort, Short)
+DEFINE_STATIC_FIELD_PRIMITIVE_GET_SET(jint, Int)
+DEFINE_STATIC_FIELD_PRIMITIVE_GET_SET(jlong, Long)
+DEFINE_STATIC_FIELD_PRIMITIVE_GET_SET(jfloat, Float)
+DEFINE_STATIC_FIELD_PRIMITIVE_GET_SET(jdouble, Double)
+#pragma pop_macro("DEFINE_STATIC_FIELD_PRIMITIVE_GET_SET")
+
+template<typename T>
+inline T JStaticField<T>::get(jclass jcls) const noexcept {
+  const auto env = internal::getEnv();
+  return static_cast<T>(env->GetStaticObjectField(jcls, field_id_));
+}
+
+template<typename T>
+inline void JStaticField<T>::set(jclass jcls, T value) noexcept {
+  internal::getEnv()->SetStaticObjectField(jcls, field_id_, value);
+}
+
+
+// jmethod_traits //////////////////////////////////////////////////////////////////////////////////
+
+// TODO(T6608405) Adapt this to implement a register natives method that requires no descriptor
+namespace internal {
+
+template<typename Head>
+inline std::string JavaDescriptor() {
+  return jtype_traits<Head>::descriptor();
+}
+
+template<typename Head, typename Elem, typename... Tail>
+inline std::string JavaDescriptor() {
+  return JavaDescriptor<Head>() + JavaDescriptor<Elem, Tail...>();
+}
+
+template<typename R, typename Arg1, typename... Args>
+inline std::string JMethodDescriptor() {
+  return "(" + JavaDescriptor<Arg1, Args...>() + ")" + JavaDescriptor<R>();
+}
+
+template<typename R>
+inline std::string JMethodDescriptor() {
+  return "()" + JavaDescriptor<R>();
+}
+
+} // internal
+
+template<typename R, typename... Args>
+inline std::string jmethod_traits<R(Args...)>::descriptor() {
+  return internal::JMethodDescriptor<R, Args...>();
+}
+
+template<typename R, typename... Args>
+inline std::string jmethod_traits<R(Args...)>::constructor_descriptor() {
+  return internal::JMethodDescriptor<void, Args...>();
+}
+
+}}

tests/react-test-app/android/app/src/main/jni/first-party/jni/fbjni/Meta.h

@@ -0,0 +1,302 @@
+/*
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+/** @file meta.h
+ *
+ * Provides wrappers for meta data such as methods and fields.
+ */
+
+#pragma once
+
+#include <type_traits>
+#include <string>
+
+#include <jni.h>
+
+#include "References.h"
+
+namespace facebook {
+namespace jni {
+
+/// Wrapper of a jmethodID. Provides a common base for JMethod specializations
+class JMethodBase {
+ public:
+  /// Verify that the method is valid
+  explicit operator bool() const noexcept;
+
+  /// Access the wrapped id
+  jmethodID getId() const noexcept;
+
+ protected:
+  /// Create a wrapper of a method id
+  explicit JMethodBase(jmethodID method_id = nullptr) noexcept;
+
+ private:
+  jmethodID method_id_;
+};
+
+
+/// Representation of a jmethodID
+template<typename F>
+class JMethod;
+
+/// @cond INTERNAL
+#pragma push_macro("DEFINE_PRIMITIVE_METHOD_CLASS")
+
+#undef DEFINE_PRIMITIVE_METHOD_CLASS
+
+// Defining JMethod specializations based on return value
+#define DEFINE_PRIMITIVE_METHOD_CLASS(TYPE)                                      \
+template<typename... Args>                                                       \
+class JMethod<TYPE(Args...)> : public JMethodBase {                              \
+ public:                                                                         \
+  static_assert(std::is_void<TYPE>::value || IsJniPrimitive<TYPE>(),             \
+      "TYPE must be primitive or void");                                         \
+                                                                                 \
+  using JMethodBase::JMethodBase;                                                \
+  JMethod() noexcept {};                                                         \
+  JMethod(const JMethod& other) noexcept = default;                              \
+                                                                                 \
+  TYPE operator()(alias_ref<jobject> self, Args... args);                        \
+                                                                                 \
+  friend class JObjectWrapper<jclass>;                                           \
+}
+
+DEFINE_PRIMITIVE_METHOD_CLASS(void);
+DEFINE_PRIMITIVE_METHOD_CLASS(jboolean);
+DEFINE_PRIMITIVE_METHOD_CLASS(jbyte);
+DEFINE_PRIMITIVE_METHOD_CLASS(jchar);
+DEFINE_PRIMITIVE_METHOD_CLASS(jshort);
+DEFINE_PRIMITIVE_METHOD_CLASS(jint);
+DEFINE_PRIMITIVE_METHOD_CLASS(jlong);
+DEFINE_PRIMITIVE_METHOD_CLASS(jfloat);
+DEFINE_PRIMITIVE_METHOD_CLASS(jdouble);
+
+#pragma pop_macro("DEFINE_PRIMITIVE_METHOD_CLASS")
+/// @endcond
+
+
+/// JMethod specialization for references that wraps the return value in a @ref local_ref
+template<typename T, typename... Args>
+class JMethod<T*(Args...)> : public JMethodBase {
+ public:
+  static_assert(IsPlainJniReference<T*>(), "T* must be a JNI reference");
+
+  using JMethodBase::JMethodBase;
+  JMethod() noexcept {};
+  JMethod(const JMethod& other) noexcept = default;
+
+  /// Invoke a method and return a local reference wrapping the result
+  local_ref<T*> operator()(alias_ref<jobject> self, Args... args);
+
+  friend class JObjectWrapper<jclass>;
+};
+
+
+/// Convenience type representing constructors
+template<typename F>
+using JConstructor = JMethod<F>;
+
+/// Representation of a jStaticMethodID
+template<typename F>
+class JStaticMethod;
+
+/// @cond INTERNAL
+#pragma push_macro("DEFINE_PRIMITIVE_STATIC_METHOD_CLASS")
+
+#undef DEFINE_PRIMITIVE_STATIC_METHOD_CLASS
+
+// Defining JStaticMethod specializations based on return value
+#define DEFINE_PRIMITIVE_STATIC_METHOD_CLASS(TYPE)                          \
+template<typename... Args>                                                  \
+class JStaticMethod<TYPE(Args...)> : public JMethodBase {                   \
+  static_assert(std::is_void<TYPE>::value || IsJniPrimitive<TYPE>(),        \
+      "T must be a JNI primitive or void");                                 \
+                                                                            \
+ public:                                                                    \
+  using JMethodBase::JMethodBase;                                           \
+  JStaticMethod() noexcept {};                                              \
+  JStaticMethod(const JStaticMethod& other) noexcept = default;             \
+                                                                            \
+  TYPE operator()(alias_ref<jclass> cls, Args... args);                     \
+                                                                            \
+  friend class JObjectWrapper<jclass>;                                      \
+}
+
+DEFINE_PRIMITIVE_STATIC_METHOD_CLASS(void);
+DEFINE_PRIMITIVE_STATIC_METHOD_CLASS(jboolean);
+DEFINE_PRIMITIVE_STATIC_METHOD_CLASS(jbyte);
+DEFINE_PRIMITIVE_STATIC_METHOD_CLASS(jchar);
+DEFINE_PRIMITIVE_STATIC_METHOD_CLASS(jshort);
+DEFINE_PRIMITIVE_STATIC_METHOD_CLASS(jint);
+DEFINE_PRIMITIVE_STATIC_METHOD_CLASS(jlong);
+DEFINE_PRIMITIVE_STATIC_METHOD_CLASS(jfloat);
+DEFINE_PRIMITIVE_STATIC_METHOD_CLASS(jdouble);
+
+#pragma pop_macro("DEFINE_PRIMITIVE_STATIC_METHOD_CLASS")
+/// @endcond
+
+
+/// JStaticMethod specialization for references that wraps the return value in a @ref local_ref
+template<typename T, typename... Args>
+class JStaticMethod<T*(Args...)> : public JMethodBase {
+  static_assert(IsPlainJniReference<T*>(), "T* must be a JNI reference");
+
+ public:
+  using JMethodBase::JMethodBase;
+  JStaticMethod() noexcept {};
+  JStaticMethod(const JStaticMethod& other) noexcept = default;
+
+  /// Invoke a method and return a local reference wrapping the result
+  local_ref<T*> operator()(alias_ref<jclass> cls, Args... args);
+
+  friend class JObjectWrapper<jclass>;
+};
+
+/// Representation of a jNonvirtualMethodID
+template<typename F>
+class JNonvirtualMethod;
+
+/// @cond INTERNAL
+#pragma push_macro("DEFINE_PRIMITIVE_NON_VIRTUAL_METHOD_CLASS")
+
+#undef DEFINE_PRIMITIVE_NON_VIRTUAL_METHOD_CLASS
+
+// Defining JNonvirtualMethod specializations based on return value
+#define DEFINE_PRIMITIVE_NON_VIRTUAL_METHOD_CLASS(TYPE)                     \
+template<typename... Args>                                                  \
+class JNonvirtualMethod<TYPE(Args...)> : public JMethodBase {               \
+  static_assert(std::is_void<TYPE>::value || IsJniPrimitive<TYPE>(),        \
+      "T must be a JNI primitive or void");                                 \
+                                                                            \
+ public:                                                                    \
+  using JMethodBase::JMethodBase;                                           \
+  JNonvirtualMethod() noexcept {};                                          \
+  JNonvirtualMethod(const JNonvirtualMethod& other) noexcept = default;     \
+                                                                            \
+  TYPE operator()(alias_ref<jobject> self, jclass cls, Args... args);       \
+                                                                            \
+  friend class JObjectWrapper<jclass>;                                      \
+}
+
+DEFINE_PRIMITIVE_NON_VIRTUAL_METHOD_CLASS(void);
+DEFINE_PRIMITIVE_NON_VIRTUAL_METHOD_CLASS(jboolean);
+DEFINE_PRIMITIVE_NON_VIRTUAL_METHOD_CLASS(jbyte);
+DEFINE_PRIMITIVE_NON_VIRTUAL_METHOD_CLASS(jchar);
+DEFINE_PRIMITIVE_NON_VIRTUAL_METHOD_CLASS(jshort);
+DEFINE_PRIMITIVE_NON_VIRTUAL_METHOD_CLASS(jint);
+DEFINE_PRIMITIVE_NON_VIRTUAL_METHOD_CLASS(jlong);
+DEFINE_PRIMITIVE_NON_VIRTUAL_METHOD_CLASS(jfloat);
+DEFINE_PRIMITIVE_NON_VIRTUAL_METHOD_CLASS(jdouble);
+
+#pragma pop_macro("DEFINE_PRIMITIVE_NON_VIRTUAL_METHOD_CLASS")
+/// @endcond
+
+
+/// JNonvirtualMethod specialization for references that wraps the return value in a @ref local_ref
+template<typename T, typename... Args>
+class JNonvirtualMethod<T*(Args...)> : public JMethodBase {
+  static_assert(IsPlainJniReference<T*>(), "T* must be a JNI reference");
+
+ public:
+  using JMethodBase::JMethodBase;
+  JNonvirtualMethod() noexcept {};
+  JNonvirtualMethod(const JNonvirtualMethod& other) noexcept = default;
+
+  /// Invoke a method and return a local reference wrapping the result
+  local_ref<T*> operator()(alias_ref<jobject> self, jclass cls, Args... args);
+
+  friend class JObjectWrapper<jclass>;
+};
+
+
+/**
+ * JField represents typed fields and simplifies their access. Note that object types return
+ * raw pointers which generally should promptly get a wrap_local treatment.
+ */
+template<typename T>
+class JField {
+  static_assert(IsJniScalar<T>(), "T must be a JNI scalar");
+
+ public:
+  /// Wraps an existing field id
+  explicit JField(jfieldID field = nullptr) noexcept;
+
+  /// Verify that the id is valid
+  explicit operator bool() const noexcept;
+
+  /// Access the wrapped id
+  jfieldID getId() const noexcept;
+
+ private:
+  jfieldID field_id_;
+
+  /// Get field value
+  /// @pre object != nullptr
+  T get(jobject object) const noexcept;
+
+  /// Set field value
+  /// @pre object != nullptr
+  void set(jobject object, T value) noexcept;
+
+  friend class JObjectWrapper<jobject>;
+};
+
+
+/**
+ * JStaticField represents typed fields and simplifies their access. Note that object types
+ * return raw pointers which generally should promptly get a wrap_local treatment.
+ */
+template<typename T>
+class JStaticField {
+  static_assert(IsJniScalar<T>(), "T must be a JNI scalar");
+
+ public:
+  /// Wraps an existing field id
+  explicit JStaticField(jfieldID field = nullptr) noexcept;
+
+  /// Verify that the id is valid
+  explicit operator bool() const noexcept;
+
+  /// Access the wrapped id
+  jfieldID getId() const noexcept;
+
+ private:
+  jfieldID field_id_;
+
+  /// Get field value
+  /// @pre object != nullptr
+  T get(jclass jcls) const noexcept;
+
+  /// Set field value
+  /// @pre object != nullptr
+  void set(jclass jcls, T value) noexcept;
+
+  friend class JObjectWrapper<jclass>;
+
+};
+
+
+/// Type traits for Java types (currently providing Java type descriptors)
+template<typename T>
+struct jtype_traits;
+
+
+/// Type traits for Java methods (currently providing Java type descriptors)
+template<typename F>
+struct jmethod_traits;
+
+/// Template magic to provide @ref jmethod_traits
+template<typename R, typename... Args>
+struct jmethod_traits<R(Args...)> {
+  static std::string descriptor();
+  static std::string constructor_descriptor();
+};
+
+}}

tests/react-test-app/android/app/src/main/jni/first-party/jni/fbjni/ReferenceAllocators-inl.h

@@ -0,0 +1,123 @@
+/*
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+#pragma once
+
+#include <cassert>
+#include <new>
+#include <atomic>
+
+#include "Exceptions.h"
+#include "References.h"
+
+namespace facebook {
+namespace jni {
+
+/// @cond INTERNAL
+namespace internal {
+
+// Statistics mostly provided for test (only updated if FBJNI_DEBUG_REFS is defined)
+struct ReferenceStats {
+  std::atomic_uint locals_deleted, globals_deleted, weaks_deleted;
+
+  void reset() noexcept;
+};
+
+extern ReferenceStats g_reference_stats;
+}
+/// @endcond
+
+
+// LocalReferenceAllocator /////////////////////////////////////////////////////////////////////////
+
+inline jobject LocalReferenceAllocator::newReference(jobject original) const {
+  internal::dbglog("Local new: %p", original);
+  auto ref = internal::getEnv()->NewLocalRef(original);
+  FACEBOOK_JNI_THROW_PENDING_EXCEPTION();
+  return ref;
+}
+
+inline void LocalReferenceAllocator::deleteReference(jobject reference) const noexcept {
+  internal::dbglog("Local release: %p", reference);
+
+  if (reference) {
+    #ifdef FBJNI_DEBUG_REFS
+      ++internal::g_reference_stats.locals_deleted;
+    #endif
+    assert(verifyReference(reference));
+    internal::getEnv()->DeleteLocalRef(reference);
+  }
+}
+
+inline bool LocalReferenceAllocator::verifyReference(jobject reference) const noexcept {
+  if (!reference || !internal::doesGetObjectRefTypeWork()) {
+    return true;
+  }
+  return internal::getEnv()->GetObjectRefType(reference) == JNILocalRefType;
+}
+
+
+// GlobalReferenceAllocator ////////////////////////////////////////////////////////////////////////
+
+inline jobject GlobalReferenceAllocator::newReference(jobject original) const {
+  internal::dbglog("Global new: %p", original);
+  auto ref = internal::getEnv()->NewGlobalRef(original);
+  FACEBOOK_JNI_THROW_PENDING_EXCEPTION();
+  return ref;
+}
+
+inline void GlobalReferenceAllocator::deleteReference(jobject reference) const noexcept {
+  internal::dbglog("Global release: %p", reference);
+
+  if (reference) {
+    #ifdef FBJNI_DEBUG_REFS
+      ++internal::g_reference_stats.globals_deleted;
+    #endif
+    assert(verifyReference(reference));
+    internal::getEnv()->DeleteGlobalRef(reference);
+  }
+}
+
+inline bool GlobalReferenceAllocator::verifyReference(jobject reference) const noexcept {
+  if (!reference || !internal::doesGetObjectRefTypeWork()) {
+    return true;
+  }
+  return internal::getEnv()->GetObjectRefType(reference) == JNIGlobalRefType;
+}
+
+
+// WeakGlobalReferenceAllocator ////////////////////////////////////////////////////////////////////
+
+inline jobject WeakGlobalReferenceAllocator::newReference(jobject original) const {
+  internal::dbglog("Weak global new: %p", original);
+  auto ref = internal::getEnv()->NewWeakGlobalRef(original);
+  FACEBOOK_JNI_THROW_PENDING_EXCEPTION();
+  return ref;
+}
+
+inline void WeakGlobalReferenceAllocator::deleteReference(jobject reference) const noexcept {
+  internal::dbglog("Weak Global release: %p", reference);
+
+  if (reference) {
+    #ifdef FBJNI_DEBUG_REFS
+      ++internal::g_reference_stats.weaks_deleted;
+    #endif
+    assert(verifyReference(reference));
+    internal::getEnv()->DeleteWeakGlobalRef(reference);
+  }
+}
+
+inline bool WeakGlobalReferenceAllocator::verifyReference(jobject reference) const noexcept {
+  if (!reference || !internal::doesGetObjectRefTypeWork()) {
+    return true;
+  }
+  return internal::getEnv()->GetObjectRefType(reference) == JNIWeakGlobalRefType;
+}
+
+}}

tests/react-test-app/android/app/src/main/jni/first-party/jni/fbjni/ReferenceAllocators.h

@@ -0,0 +1,60 @@
+/*
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+/**
+ * @file ReferenceAllocators.h
+ *
+ * Reference allocators are used to create and delete various classes of JNI references (local,
+ * global, and weak global).
+ */
+
+#pragma once
+
+#include "Common.h"
+
+namespace facebook { namespace jni {
+
+/// Allocator that handles local references
+class LocalReferenceAllocator {
+ public:
+  jobject newReference(jobject original) const;
+  void deleteReference(jobject reference) const noexcept;
+  bool verifyReference(jobject reference) const noexcept;
+};
+
+/// Allocator that handles global references
+class GlobalReferenceAllocator {
+ public:
+  jobject newReference(jobject original) const;
+  void deleteReference(jobject reference) const noexcept;
+  bool verifyReference(jobject reference) const noexcept;
+};
+
+/// Allocator that handles weak global references
+class WeakGlobalReferenceAllocator {
+ public:
+  jobject newReference(jobject original) const;
+  void deleteReference(jobject reference) const noexcept;
+  bool verifyReference(jobject reference) const noexcept;
+};
+
+/// @cond INTERNAL
+namespace internal {
+
+/**
+ * @return true iff env->GetObjectRefType is expected to work properly.
+ */
+bool doesGetObjectRefTypeWork();
+
+}
+/// @endcond
+
+}}
+
+#include "ReferenceAllocators-inl.h"

tests/react-test-app/android/app/src/main/jni/first-party/jni/fbjni/References-inl.h

@@ -0,0 +1,387 @@
+/*
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+#pragma once
+
+#include <new>
+#include "CoreClasses.h"
+
+namespace facebook {
+namespace jni {
+
+template<typename T>
+inline enable_if_t<IsPlainJniReference<T>(), local_ref<T>> adopt_local(T ref) noexcept {
+  return local_ref<T>{ref};
+}
+
+template<typename T>
+inline enable_if_t<IsPlainJniReference<T>(), global_ref<T>> adopt_global(T ref) noexcept {
+  return global_ref<T>{ref};
+}
+
+template<typename T>
+inline enable_if_t<IsPlainJniReference<T>(), weak_ref<T>> adopt_weak_global(T ref) noexcept {
+  return weak_ref<T>{ref};
+}
+
+
+template<typename T>
+inline enable_if_t<IsPlainJniReference<T>(), alias_ref<T>> wrap_alias(T ref) noexcept {
+  return alias_ref<T>(ref);
+}
+
+
+template<typename T>
+enable_if_t<IsPlainJniReference<T>(), alias_ref<T>> wrap_alias(T ref) noexcept;
+
+
+template<typename T>
+inline enable_if_t<IsPlainJniReference<T>(), T> getPlainJniReference(T ref) {
+  return ref;
+}
+
+template<typename T>
+inline T getPlainJniReference(alias_ref<T> ref) {
+  return ref.get();
+}
+
+template<typename T, typename A>
+inline T getPlainJniReference(const base_owned_ref<T, A>& ref) {
+  return ref.getPlainJniReference();
+}
+
+
+namespace internal {
+
+template<typename T, typename Alloc>
+enable_if_t<IsNonWeakReference<T>(), plain_jni_reference_t<T>> make_ref(const T& reference) {
+  auto old_reference = getPlainJniReference(reference);
+  if (!old_reference) {
+    return nullptr;
+  }
+
+  auto ref = Alloc{}.newReference(old_reference);
+  if (!ref) {
+    // Note that we end up here if we pass a weak ref that refers to a collected object.
+    // Thus, it's hard to come up with a reason why this function should be used with
+    // weak references.
+    throw std::bad_alloc{};
+  }
+
+  return static_cast<plain_jni_reference_t<T>>(ref);
+}
+
+}
+
+template<typename T>
+enable_if_t<IsNonWeakReference<T>(), local_ref<plain_jni_reference_t<T>>>
+make_local(const T& ref) {
+  return adopt_local(internal::make_ref<T, LocalReferenceAllocator>(ref));
+}
+
+template<typename T>
+enable_if_t<IsNonWeakReference<T>(), global_ref<plain_jni_reference_t<T>>>
+make_global(const T& ref) {
+  return adopt_global(internal::make_ref<T, GlobalReferenceAllocator>(ref));
+}
+
+template<typename T>
+enable_if_t<IsNonWeakReference<T>(), weak_ref<plain_jni_reference_t<T>>>
+make_weak(const T& ref) {
+  return adopt_weak_global(internal::make_ref<T, WeakGlobalReferenceAllocator>(ref));
+}
+
+template<typename T1, typename T2>
+inline enable_if_t<IsNonWeakReference<T1>() && IsNonWeakReference<T2>(), bool>
+operator==(const T1& a, const T2& b) {
+  return isSameObject(getPlainJniReference(a), getPlainJniReference(b));
+}
+
+template<typename T1, typename T2>
+inline enable_if_t<IsNonWeakReference<T1>() && IsNonWeakReference<T2>(), bool>
+operator!=(const T1& a, const T2& b) {
+  return !(a == b);
+}
+
+
+// base_owned_ref ///////////////////////////////////////////////////////////////////////
+
+template<typename T, typename Alloc>
+inline constexpr base_owned_ref<T, Alloc>::base_owned_ref() noexcept
+  : object_{nullptr}
+{}
+
+template<typename T, typename Alloc>
+inline constexpr base_owned_ref<T, Alloc>::base_owned_ref(
+    std::nullptr_t t) noexcept
+  : object_{nullptr}
+{}
+
+template<typename T, typename Alloc>
+inline base_owned_ref<T, Alloc>::base_owned_ref(
+    const base_owned_ref& other)
+  : object_{Alloc{}.newReference(other.getPlainJniReference())}
+{}
+
+template<typename T, typename Alloc>
+template<typename U>
+inline base_owned_ref<T, Alloc>::base_owned_ref(const base_owned_ref<U, Alloc>& other)
+  : object_{Alloc{}.newReference(other.getPlainJniReference())}
+{}
+
+template<typename T, typename Alloc>
+inline facebook::jni::base_owned_ref<T, Alloc>::base_owned_ref(
+    T reference) noexcept
+  : object_{reference} {
+  assert(Alloc{}.verifyReference(reference));
+  internal::dbglog("New wrapped ref=%p this=%p", getPlainJniReference(), this);
+}
+
+template<typename T, typename Alloc>
+inline base_owned_ref<T, Alloc>::base_owned_ref(
+    base_owned_ref<T, Alloc>&& other) noexcept
+  : object_{other.object_} {
+  internal::dbglog("New move from ref=%p other=%p", other.getPlainJniReference(), &other);
+  internal::dbglog("New move to ref=%p this=%p", getPlainJniReference(), this);
+  // JObjectWrapper is a simple type and does not support move semantics so we explicitly
+  // clear other
+  other.object_.set(nullptr);
+}
+
+template<typename T, typename Alloc>
+template<typename U>
+base_owned_ref<T, Alloc>::base_owned_ref(base_owned_ref<U, Alloc>&& other) noexcept
+  : object_{other.object_} {
+  internal::dbglog("New move from ref=%p other=%p", other.getPlainJniReference(), &other);
+  internal::dbglog("New move to ref=%p this=%p", getPlainJniReference(), this);
+  // JObjectWrapper is a simple type and does not support move semantics so we explicitly
+  // clear other
+  other.object_.set(nullptr);
+}
+
+template<typename T, typename Alloc>
+inline base_owned_ref<T, Alloc>::~base_owned_ref() noexcept {
+  reset();
+  internal::dbglog("Ref destruct ref=%p this=%p", getPlainJniReference(), this);
+}
+
+template<typename T, typename Alloc>
+inline T base_owned_ref<T, Alloc>::release() noexcept {
+  auto value = getPlainJniReference();
+  internal::dbglog("Ref release ref=%p this=%p", value, this);
+  object_.set(nullptr);
+  return value;
+}
+
+template<typename T, typename Alloc>
+inline void base_owned_ref<T,Alloc>::reset() noexcept {
+  reset(nullptr);
+}
+
+template<typename T, typename Alloc>
+inline void base_owned_ref<T,Alloc>::reset(T reference) noexcept {
+  if (getPlainJniReference()) {
+    assert(Alloc{}.verifyReference(reference));
+    Alloc{}.deleteReference(getPlainJniReference());
+  }
+  object_.set(reference);
+}
+
+template<typename T, typename Alloc>
+inline T base_owned_ref<T, Alloc>::getPlainJniReference() const noexcept {
+  return static_cast<T>(object_.get());
+}
+
+
+// weak_ref ///////////////////////////////////////////////////////////////////////
+
+template<typename T>
+inline weak_ref<T>& weak_ref<T>::operator=(
+    const weak_ref& other) {
+  auto otherCopy = other;
+  swap(*this, otherCopy);
+  return *this;
+}
+
+template<typename T>
+inline weak_ref<T>& weak_ref<T>::operator=(
+    weak_ref<T>&& other) noexcept {
+  internal::dbglog("Op= move ref=%p this=%p oref=%p other=%p",
+      getPlainJniReference(), this, other.getPlainJniReference(), &other);
+  reset(other.release());
+  return *this;
+}
+
+template<typename T>
+local_ref<T> weak_ref<T>::lockLocal() {
+  return adopt_local(static_cast<T>(LocalReferenceAllocator{}.newReference(getPlainJniReference())));
+}
+
+template<typename T>
+global_ref<T> weak_ref<T>::lockGlobal() {
+  return adopt_global(static_cast<T>(GlobalReferenceAllocator{}.newReference(getPlainJniReference())));
+}
+
+template<typename T>
+inline void swap(
+    weak_ref<T>& a,
+    weak_ref<T>& b) noexcept {
+  internal::dbglog("Ref swap a.ref=%p a=%p b.ref=%p b=%p",
+      a.getPlainJniReference(), &a, b.getPlainJniReference(), &b);
+  using std::swap;
+  swap(a.object_, b.object_);
+}
+
+
+// basic_strong_ref ////////////////////////////////////////////////////////////////////////////
+
+template<typename T, typename Alloc>
+inline basic_strong_ref<T, Alloc>& basic_strong_ref<T, Alloc>::operator=(
+    const basic_strong_ref& other) {
+  auto otherCopy = other;
+  swap(*this, otherCopy);
+  return *this;
+}
+
+template<typename T, typename Alloc>
+inline basic_strong_ref<T, Alloc>& basic_strong_ref<T, Alloc>::operator=(
+    basic_strong_ref<T, Alloc>&& other) noexcept {
+  internal::dbglog("Op= move ref=%p this=%p oref=%p other=%p",
+      getPlainJniReference(), this, other.getPlainJniReference(), &other);
+  reset(other.release());
+  return *this;
+}
+
+template<typename T, typename Alloc>
+inline alias_ref<T> basic_strong_ref<T, Alloc>::releaseAlias() noexcept {
+  return wrap_alias(release());
+}
+
+template<typename T, typename Alloc>
+inline basic_strong_ref<T, Alloc>::operator bool() const noexcept {
+  return get() != nullptr;
+}
+
+template<typename T, typename Alloc>
+inline T basic_strong_ref<T, Alloc>::get() const noexcept {
+  return getPlainJniReference();
+}
+
+template<typename T, typename Alloc>
+inline JObjectWrapper<T>* basic_strong_ref<T, Alloc>::operator->() noexcept {
+  return &object_;
+}
+
+template<typename T, typename Alloc>
+inline const JObjectWrapper<T>* basic_strong_ref<T, Alloc>::operator->() const noexcept {
+  return &object_;
+}
+
+template<typename T, typename Alloc>
+inline JObjectWrapper<T>& basic_strong_ref<T, Alloc>::operator*() noexcept {
+  return object_;
+}
+
+template<typename T, typename Alloc>
+inline const JObjectWrapper<T>& basic_strong_ref<T, Alloc>::operator*() const noexcept {
+  return object_;
+}
+
+template<typename T, typename Alloc>
+inline void swap(
+    basic_strong_ref<T, Alloc>& a,
+    basic_strong_ref<T, Alloc>& b) noexcept {
+  internal::dbglog("Ref swap a.ref=%p a=%p b.ref=%p b=%p",
+      a.getPlainJniReference(), &a, b.getPlainJniReference(), &b);
+  using std::swap;
+  swap(a.object_, b.object_);
+}
+
+
+// alias_ref //////////////////////////////////////////////////////////////////////////////
+
+template<typename T>
+inline constexpr alias_ref<T>::alias_ref() noexcept
+  : object_{nullptr}
+{}
+
+template<typename T>
+inline constexpr alias_ref<T>::alias_ref(std::nullptr_t) noexcept
+  : object_{nullptr}
+{}
+
+template<typename T>
+inline alias_ref<T>::alias_ref(const alias_ref& other) noexcept
+  : object_{other.object_}
+{}
+
+
+template<typename T>
+inline alias_ref<T>::alias_ref(T ref) noexcept
+  : object_{ref} {
+  assert(
+      LocalReferenceAllocator{}.verifyReference(ref) ||
+      GlobalReferenceAllocator{}.verifyReference(ref));
+}
+
+template<typename T>
+template<typename TOther, typename /* for SFINAE */>
+inline alias_ref<T>::alias_ref(alias_ref<TOther> other) noexcept
+  : object_{other.get()}
+{}
+
+template<typename T>
+template<typename TOther, typename AOther, typename /* for SFINAE */>
+inline alias_ref<T>::alias_ref(const basic_strong_ref<TOther, AOther>& other) noexcept
+  : object_{other.get()}
+{}
+
+template<typename T>
+inline alias_ref<T>& alias_ref<T>::operator=(alias_ref other) noexcept {
+  swap(*this, other);
+  return *this;
+}
+
+template<typename T>
+inline alias_ref<T>::operator bool() const noexcept {
+  return get() != nullptr;
+}
+
+template<typename T>
+inline T facebook::jni::alias_ref<T>::get() const noexcept {
+  return static_cast<T>(object_.get());
+}
+
+template<typename T>
+inline JObjectWrapper<T>* alias_ref<T>::operator->() noexcept {
+  return &object_;
+}
+
+template<typename T>
+inline const JObjectWrapper<T>* alias_ref<T>::operator->() const noexcept {
+  return &object_;
+}
+
+template<typename T>
+inline JObjectWrapper<T>& alias_ref<T>::operator*() noexcept {
+  return object_;
+}
+
+template<typename T>
+inline const JObjectWrapper<T>& alias_ref<T>::operator*() const noexcept {
+  return object_;
+}
+
+template<typename T>
+inline void swap(alias_ref<T>& a, alias_ref<T>& b) noexcept {
+  using std::swap;
+  swap(a.object_, b.object_);
+}
+
+}}

tests/react-test-app/android/app/src/main/jni/first-party/jni/fbjni/References.cpp

@@ -0,0 +1,41 @@
+/*
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+#include "References.h"
+
+namespace facebook {
+namespace jni {
+
+JniLocalScope::JniLocalScope(JNIEnv* env, jint capacity)
+    : env_(env) {
+  hasFrame_ = false;
+  auto pushResult = env->PushLocalFrame(capacity);
+  FACEBOOK_JNI_THROW_EXCEPTION_IF(pushResult < 0);
+  hasFrame_ = true;
+}
+
+JniLocalScope::~JniLocalScope() {
+  if (hasFrame_) {
+    env_->PopLocalFrame(nullptr);
+  }
+}
+
+namespace internal {
+
+// Default implementation always returns true.
+// Platform-specific sources can override this.
+bool doesGetObjectRefTypeWork() __attribute__ ((weak));
+bool doesGetObjectRefTypeWork() {
+  return true;
+}
+
+}
+
+}
+}

tests/react-test-app/android/app/src/main/jni/first-party/jni/fbjni/References.h

@@ -0,0 +1,515 @@
+/*
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+
+/** @file References.h
+ *
+ * Functionality similar to smart pointers, but for references into the VM. Four main reference
+ * types are provided: local_ref, global_ref, weak_ref, and alias_ref. All are generic
+ * templates that and refer to objects in the jobject hierarchy. The type of the referred objects
+ * are specified using the template parameter. All reference types except alias_ref own their
+ * underlying reference, just as a std smart pointer owns the underlying raw pointer. In the context
+ * of std smart pointers, these references behave like unique_ptr, and have basically the same
+ * interface. Thus, when the reference is destructed, the plain JNI reference, i.e. the underlying
+ * JNI reference (like the parameters passed directly to JNI functions), is released. The alias
+ * references provides no ownership and is a simple wrapper for plain JNI references.
+ *
+ * All but the weak references provides access to the underlying object using dereferencing, and a
+ * get() method. It is also possible to convert these references to booleans to test for nullity.
+ * To access the underlying object of a weak reference, the reference must either be released, or
+ * the weak reference can be used to create a local or global reference.
+ *
+ * An owning reference is created either by moving the reference from an existing owned reference,
+ * by copying an existing owned reference (which creates a new underlying reference), by using the
+ * default constructor which initialize the reference to nullptr, or by using a helper function. The
+ * helper function exist in two flavors: make_XXX or adopt_XXX.
+ *
+ * Adopting takes a plain JNI reference and wrap it in an owned reference. It takes ownership of the
+ * plain JNI reference so be sure that no one else owns the reference when you adopt it, and make
+ * sure that you know what kind of reference it is.
+ *
+ * New owned references can be created from existing plain JNI references, alias references, local
+ * references, and global references (i.e. non-weak references) using the make_local, make_global,
+ * and make_weak functions.
+ *
+ * Alias references can be implicitly initialized using global, local and plain JNI references using
+ * the wrap_alias function. Here, we don't assume ownership of the passed-in reference, but rather
+ * create a separate reference that we do own, leaving the passed-in reference to its fate.
+ *
+ * Similar rules apply for assignment. An owned reference can be copy or move assigned using a smart
+ * reference of the same type. In the case of copy assignment a new reference is created. Alias
+ * reference can also be assigned new values, but since they are simple wrappers of plain JNI
+ * references there is no move semantics involved.
+ *
+ * Alias references are special in that they do not own the object and can therefore safely be
+ * converted to and from its corresponding plain JNI reference. They are useful as parameters of
+ * functions that do not affect the lifetime of a reference. Usage can be compared with using plain
+ * JNI pointers as parameters where a function does not take ownership of the underlying object.
+ *
+ * The local, global, and alias references makes it possible to access methods in the underlying
+ * objects. A core set of classes are implemented in CoreClasses.h, and user defined wrappers are
+ * supported (see example below). The wrappers also supports inheritance so a wrapper can inherit
+ * from another wrapper to gain access to its functionality. As an example the jstring wrapper
+ * inherits from the jobject wrapper, so does the jclass wrapper. That means that you can for
+ * example call the toString() method using the jclass wrapper, or any other class that inherits
+ * from the jobject wrapper.
+ *
+ * Note that the wrappers are parameterized on the static type of your (jobject) pointer, thus if
+ * you have a jobject that refers to a Java String you will need to cast it to jstring to get the
+ * jstring wrapper. This also mean that if you make a down cast that is invalid there will be no one
+ * stopping you and the wrappers currently does not detect this which can cause crashes. Thus, cast
+ * wisely.
+ *
+ * @include WrapperSample.cpp
+ */
+
+#pragma once
+
+#include <cassert>
+#include <cstddef>
+#include <type_traits>
+
+#include <jni.h>
+
+#include "ReferenceAllocators.h"
+#include "TypeTraits.h"
+
+namespace facebook {
+namespace jni {
+
+/**
+ * The JObjectWrapper is specialized to provide functionality for various Java classes, some
+ * specializations are provided, and it is easy to add your own. See example
+ * @sample WrapperSample.cpp
+ */
+template<typename T, typename Enable = void>
+class JObjectWrapper;
+
+
+template<typename T, typename Alloc>
+class base_owned_ref;
+
+template<typename T, typename Alloc>
+class basic_strong_ref;
+
+template<typename T>
+class weak_ref;
+
+template<typename T>
+class alias_ref;
+
+
+/// A smart unique reference owning a local JNI reference
+template<typename T>
+using local_ref = basic_strong_ref<T, LocalReferenceAllocator>;
+
+/// A smart unique reference owning a global JNI reference
+template<typename T>
+using global_ref = basic_strong_ref<T, GlobalReferenceAllocator>;
+
+
+/// Convenience function to wrap an existing local reference
+template<typename T>
+enable_if_t<IsPlainJniReference<T>(), local_ref<T>> adopt_local(T ref) noexcept;
+
+/// Convenience function to wrap an existing global reference
+template<typename T>
+enable_if_t<IsPlainJniReference<T>(), global_ref<T>> adopt_global(T ref) noexcept;
+
+/// Convenience function to wrap an existing weak reference
+template<typename T>
+enable_if_t<IsPlainJniReference<T>(), weak_ref<T>> adopt_weak_global(T ref) noexcept;
+
+
+/**
+ * Create a new local reference from an existing reference
+ *
+ * @param ref a plain JNI, alias, or strong reference
+ * @return an owned local reference (referring to null if the input does)
+ * @throws std::bad_alloc if the JNI reference could not be created
+ */
+template<typename T>
+enable_if_t<IsNonWeakReference<T>(), local_ref<plain_jni_reference_t<T>>>
+make_local(const T& r);
+
+/**
+ * Create a new global reference from an existing reference
+ *
+ * @param ref a plain JNI, alias, or strong reference
+ * @return an owned global reference (referring to null if the input does)
+ * @throws std::bad_alloc if the JNI reference could not be created
+ */
+template<typename T>
+enable_if_t<IsNonWeakReference<T>(), global_ref<plain_jni_reference_t<T>>>
+make_global(const T& r);
+
+/**
+ * Create a new weak global reference from an existing reference
+ *
+ * @param ref a plain JNI, alias, or strong reference
+ * @return an owned weak global reference (referring to null if the input does)
+ * @throws std::bad_alloc if the returned reference is null
+ */
+template<typename T>
+enable_if_t<IsNonWeakReference<T>(), weak_ref<plain_jni_reference_t<T>>>
+make_weak(const T& r);
+
+
+/// Swaps two owning references of the same type
+template<typename T>
+void swap(weak_ref<T>& a, weak_ref<T>& b) noexcept;
+
+/// Swaps two owning references of the same type
+template<typename T, typename Alloc>
+void swap(basic_strong_ref<T, Alloc>& a, basic_strong_ref<T, Alloc>& b) noexcept;
+
+/**
+ * Retrieve the plain reference from a plain reference.
+ */
+template<typename T>
+enable_if_t<IsPlainJniReference<T>(), T> getPlainJniReference(T ref);
+
+/**
+ * Retrieve the plain reference from an alias reference.
+ */
+template<typename T>
+T getPlainJniReference(alias_ref<T> ref);
+
+/**
+ * Retrieve the plain JNI reference from any reference owned reference.
+ */
+template<typename T, typename Alloc>
+T getPlainJniReference(const base_owned_ref<T, Alloc>& ref);
+
+/**
+ * Compare two references to see if they refer to the same object
+ */
+template<typename T1, typename T2>
+enable_if_t<IsNonWeakReference<T1>() && IsNonWeakReference<T2>(), bool>
+operator==(const T1& a, const T2& b);
+
+/**
+ * Compare two references to see if they don't refer to the same object
+ */
+template<typename T1, typename T2>
+enable_if_t<IsNonWeakReference<T1>() && IsNonWeakReference<T2>(), bool>
+operator!=(const T1& a, const T2& b);
+
+
+template<typename T, typename Alloc>
+class base_owned_ref {
+
+  static_assert(IsPlainJniReference<T>(), "T must be a JNI reference");
+
+ public:
+
+  /**
+   * Release the ownership and set the reference to null. Thus no deleter is invoked.
+   * @return Returns the reference
+   */
+  T release() noexcept;
+
+  /**
+   * Reset the reference to refer to nullptr.
+   */
+  void reset() noexcept;
+
+ protected:
+
+  JObjectWrapper<T> object_;
+
+  /*
+   * Wrap an existing reference and transfers its ownership to the newly created unique reference.
+   * NB! Does not create a new reference
+   */
+  explicit base_owned_ref(T reference) noexcept;
+
+  /// Create a null reference
+  constexpr base_owned_ref() noexcept;
+
+  /// Create a null reference
+  constexpr explicit base_owned_ref(std::nullptr_t) noexcept;
+
+  /// Copy constructor (note creates a new reference)
+  base_owned_ref(const base_owned_ref& other);
+  template<typename U>
+  base_owned_ref(const base_owned_ref<U, Alloc>& other);
+
+  /// Transfers ownership of an underlying reference from one unique reference to another
+  base_owned_ref(base_owned_ref&& other) noexcept;
+  template<typename U>
+  base_owned_ref(base_owned_ref<U, Alloc>&& other) noexcept;
+
+  /// The delete the underlying reference if applicable
+  ~base_owned_ref() noexcept;
+
+
+  /// Assignment operator (note creates a new reference)
+  base_owned_ref& operator=(const base_owned_ref& other);
+
+  /// Assignment by moving a reference thus not creating a new reference
+  base_owned_ref& operator=(base_owned_ref&& rhs) noexcept;
+
+
+  T getPlainJniReference() const noexcept;
+
+  void reset(T reference) noexcept;
+
+
+  friend T jni::getPlainJniReference<>(const base_owned_ref& ref);
+
+  template<typename U, typename UAlloc>
+  friend class base_owned_ref;
+};
+
+
+/**
+ * A smart reference that owns its underlying JNI reference. The class provides basic
+ * functionality to handle a reference but gives no access to it unless the reference is
+ * released, thus no longer owned. The API is stolen with pride from unique_ptr and the
+ * semantics should be basically the same. This class should not be used directly, instead use
+ * @ref weak_ref
+ */
+template<typename T>
+class weak_ref : public base_owned_ref<T, WeakGlobalReferenceAllocator> {
+
+  static_assert(IsPlainJniReference<T>(), "T must be a JNI reference");
+
+ public:
+
+  using PlainJniType = T;
+  using Allocator = WeakGlobalReferenceAllocator;
+
+  // This inherits non-default, non-copy, non-move ctors.
+  using base_owned_ref<T, Allocator>::base_owned_ref;
+
+  /// Create a null reference
+  constexpr weak_ref() noexcept
+    : base_owned_ref<T, Allocator>{} {}
+
+  /// Create a null reference
+  constexpr explicit weak_ref(std::nullptr_t) noexcept
+    : base_owned_ref<T, Allocator>{nullptr} {}
+
+  /// Copy constructor (note creates a new reference)
+  weak_ref(const weak_ref& other)
+    : base_owned_ref<T, Allocator>{other} {}
+
+  /// Transfers ownership of an underlying reference from one unique reference to another
+  weak_ref(weak_ref&& other) noexcept
+    : base_owned_ref<T, Allocator>{std::move(other)} {}
+
+
+  /// Assignment operator (note creates a new reference)
+  weak_ref& operator=(const weak_ref& other);
+
+  /// Assignment by moving a reference thus not creating a new reference
+  weak_ref& operator=(weak_ref&& rhs) noexcept;
+
+
+  // Creates an owned local reference to the referred object or to null if the object is reclaimed
+  local_ref<T> lockLocal();
+
+  // Creates an owned global reference to the referred object or to null if the object is reclaimed
+  global_ref<T> lockGlobal();
+
+ private:
+
+  using base_owned_ref<T, Allocator>::getPlainJniReference;
+
+  /*
+   * Wrap an existing reference and transfers its ownership to the newly created unique reference.
+   * NB! Does not create a new reference
+   */
+  explicit weak_ref(T reference) noexcept
+    : base_owned_ref<T, Allocator>{reference} {}
+
+
+  template<typename T2> friend class weak_ref;
+  friend weak_ref<enable_if_t<IsPlainJniReference<T>(), T>>
+    adopt_weak_global<T>(T ref) noexcept;
+  friend void swap<T>(weak_ref& a, weak_ref& b) noexcept;
+};
+
+
+/**
+ * A class representing owned strong references to Java objects. This class
+ * should not be used directly, instead use @ref local_ref, or @ref global_ref.
+ */
+template<typename T, typename Alloc>
+class basic_strong_ref : public base_owned_ref<T, Alloc> {
+
+  static_assert(IsPlainJniReference<T>(), "T must be a JNI reference");
+
+ public:
+
+  using PlainJniType = T;
+  using Allocator = Alloc;
+
+  // This inherits non-default, non-copy, non-move ctors.
+  using base_owned_ref<T, Alloc>::base_owned_ref;
+  using base_owned_ref<T, Alloc>::release;
+  using base_owned_ref<T, Alloc>::reset;
+
+  /// Create a null reference
+  constexpr basic_strong_ref() noexcept
+    : base_owned_ref<T, Alloc>{} {}
+
+  /// Create a null reference
+  constexpr explicit basic_strong_ref(std::nullptr_t) noexcept
+    : base_owned_ref<T, Alloc>{nullptr} {}
+
+  /// Copy constructor (note creates a new reference)
+  basic_strong_ref(const basic_strong_ref& other)
+    : base_owned_ref<T, Alloc>{other} {}
+
+  /// Transfers ownership of an underlying reference from one unique reference to another
+  basic_strong_ref(basic_strong_ref&& other) noexcept
+    : base_owned_ref<T, Alloc>{std::move(other)} {}
+
+  /// Assignment operator (note creates a new reference)
+  basic_strong_ref& operator=(const basic_strong_ref& other);
+
+  /// Assignment by moving a reference thus not creating a new reference
+  basic_strong_ref& operator=(basic_strong_ref&& rhs) noexcept;
+
+
+  /// Release the ownership of the reference and return the wrapped reference in an alias
+  alias_ref<T> releaseAlias() noexcept;
+
+  /// Checks if the reference points to a non-null object
+  explicit operator bool() const noexcept;
+
+  /// Get the plain JNI reference
+  T get() const noexcept;
+
+  /// Access the functionality provided by the object wrappers
+  JObjectWrapper<T>* operator->() noexcept;
+
+  /// Access the functionality provided by the object wrappers
+  const JObjectWrapper<T>* operator->() const noexcept;
+
+  /// Provide a reference to the underlying wrapper (be sure that it is non-null before invoking)
+  JObjectWrapper<T>& operator*() noexcept;
+
+  /// Provide a const reference to the underlying wrapper (be sure that it is non-null
+  /// before invoking)
+  const JObjectWrapper<T>& operator*() const noexcept;
+
+ private:
+
+  using base_owned_ref<T, Alloc>::object_;
+  using base_owned_ref<T, Alloc>::getPlainJniReference;
+
+  /*
+   * Wrap an existing reference and transfers its ownership to the newly created unique reference.
+   * NB! Does not create a new reference
+   */
+  explicit basic_strong_ref(T reference) noexcept
+    : base_owned_ref<T, Alloc>{reference} {}
+
+
+  friend enable_if_t<IsPlainJniReference<T>(), local_ref<T>> adopt_local<T>(T ref) noexcept;
+  friend enable_if_t<IsPlainJniReference<T>(), global_ref<T>> adopt_global<T>(T ref) noexcept;
+  friend void swap<T, Alloc>(basic_strong_ref& a, basic_strong_ref& b) noexcept;
+};
+
+
+template<typename T>
+enable_if_t<IsPlainJniReference<T>(), alias_ref<T>> wrap_alias(T ref) noexcept;
+
+/// Swaps to alias referencec of the same type
+template<typename T>
+void swap(alias_ref<T>& a, alias_ref<T>& b) noexcept;
+
+/**
+ * A non-owning variant of the smart references (a dumb reference). These references still provide
+ * access to the functionality of the @ref JObjectWrapper specializations including exception
+ * handling and ease of use. Use this representation when you don't want to claim ownership of the
+ * underlying reference (compare to using raw pointers instead of smart pointers.) For symmetry use
+ * @ref alias_ref instead of this class.
+ */
+template<typename T>
+class alias_ref {
+
+  static_assert(IsPlainJniReference<T>(), "T must be a JNI reference");
+
+ public:
+
+  using PlainJniType = T;
+
+
+  /// Create a null reference
+  constexpr alias_ref() noexcept;
+
+  /// Create a null reference
+  constexpr alias_ref(std::nullptr_t) noexcept;
+
+  /// Copy constructor
+  alias_ref(const alias_ref& other) noexcept;
+
+  /// Wrap an existing plain JNI reference
+  alias_ref(T ref) noexcept;
+
+  /// Wrap an existing smart reference of any type convertible to T
+  template<typename TOther, typename = enable_if_t<IsConvertible<TOther, T>(), T>>
+  alias_ref(alias_ref<TOther> other) noexcept;
+
+  /// Wrap an existing alias reference of a type convertible to T
+  template<typename TOther, typename AOther, typename = enable_if_t<IsConvertible<TOther, T>(), T>>
+  alias_ref(const basic_strong_ref<TOther, AOther>& other) noexcept;
+
+
+  /// Assignment operator
+  alias_ref& operator=(alias_ref other) noexcept;
+
+  /// Checks if the reference points to a non-null object
+  explicit operator bool() const noexcept;
+
+  /// Converts back to a plain JNI reference
+  T get() const noexcept;
+
+  /// Access the functionality provided by the object wrappers
+  JObjectWrapper<T>* operator->() noexcept;
+
+  /// Access the functionality provided by the object wrappers
+  const JObjectWrapper<T>* operator->() const noexcept;
+
+  /// Provide a guaranteed non-null reference (be sure that it is non-null before invoking)
+  JObjectWrapper<T>& operator*() noexcept;
+
+  /// Provide a guaranteed non-null reference (be sure that it is non-null before invoking)
+  const JObjectWrapper<T>& operator*() const noexcept;
+
+ private:
+  JObjectWrapper<T> object_;
+
+  friend void swap<T>(alias_ref& a, alias_ref& b) noexcept;
+};
+
+
+/**
+ * RAII object to create a local JNI frame, using PushLocalFrame/PopLocalFrame.
+ *
+ * This is useful when you have a call which is initiated from C++-land, and therefore
+ * doesn't automatically get a local JNI frame managed for you by the JNI framework.
+ */
+class JniLocalScope {
+public:
+  JniLocalScope(JNIEnv* p_env, jint capacity);
+  ~JniLocalScope();
+
+private:
+  JNIEnv* env_;
+  bool hasFrame_;
+};
+
+}}
+
+#include "References-inl.h"

tests/react-test-app/android/app/src/main/jni/first-party/jni/fbjni/Registration-inl.h

@@ -0,0 +1,193 @@
+/*
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+#pragma once
+
+#include "Exceptions.h"
+#include "Hybrid.h"
+
+namespace facebook {
+namespace jni {
+
+namespace detail {
+
+// convert to HybridClass* from jhybridobject
+template <typename T>
+struct Convert<
+  T, typename std::enable_if<
+    std::is_base_of<BaseHybridClass, typename std::remove_pointer<T>::type>::value>::type> {
+  typedef typename std::remove_pointer<T>::type::jhybridobject jniType;
+  static T fromJni(jniType t) {
+    if (t == nullptr) {
+      return nullptr;
+    }
+    return facebook::jni::cthis(wrap_alias(t));
+  }
+  // There is no automatic return conversion for objects.
+};
+
+// registration wrapper for legacy JNI-style functions
+
+template<typename F, F func, typename C, typename... Args>
+inline NativeMethodWrapper* exceptionWrapJNIMethod(void (*)(JNIEnv*, C, Args... args)) {
+  struct funcWrapper {
+    static void call(JNIEnv* env, jobject obj, Args... args) {
+      // Note that if func was declared noexcept, then both gcc and clang are smart
+      // enough to elide the try/catch.
+      try {
+        (*func)(env, static_cast<C>(obj), args...);
+      } catch (...) {
+        translatePendingCppExceptionToJavaException();
+      }
+    }
+  };
+
+  // This intentionally erases the real type; JNI will do it anyway
+  return reinterpret_cast<NativeMethodWrapper*>(&(funcWrapper::call));
+}
+
+template<typename F, F func, typename C, typename R, typename... Args>
+inline NativeMethodWrapper* exceptionWrapJNIMethod(R (*)(JNIEnv*, C, Args... args)) {
+  struct funcWrapper {
+    static R call(JNIEnv* env, jobject obj, Args... args) {
+      try {
+        return (*func)(env, static_cast<C>(obj), args...);
+      } catch (...) {
+        translatePendingCppExceptionToJavaException();
+        return R{};
+      }
+    }
+  };
+
+  // This intentionally erases the real type; JNI will do it anyway
+  return reinterpret_cast<NativeMethodWrapper*>(&(funcWrapper::call));
+}
+
+// registration wrappers for functions, with autoconversion of arguments.
+
+template<typename F, F func, typename C, typename... Args>
+inline NativeMethodWrapper* exceptionWrapJNIMethod(void (*)(alias_ref<C>, Args... args)) {
+  struct funcWrapper {
+    static void call(JNIEnv*, jobject obj,
+                     typename Convert<typename std::decay<Args>::type>::jniType... args) {
+      try {
+        (*func)(static_cast<C>(obj), Convert<typename std::decay<Args>::type>::fromJni(args)...);
+      } catch (...) {
+        translatePendingCppExceptionToJavaException();
+      }
+    }
+  };
+
+  // This intentionally erases the real type; JNI will do it anyway
+  return reinterpret_cast<NativeMethodWrapper*>(&(funcWrapper::call));
+}
+
+template<typename F, F func, typename C, typename R, typename... Args>
+inline NativeMethodWrapper* exceptionWrapJNIMethod(R (*)(alias_ref<C>, Args... args)) {
+  struct funcWrapper {
+    typedef typename Convert<typename std::decay<R>::type>::jniType jniRet;
+
+    static jniRet call(JNIEnv*, jobject obj,
+                       typename Convert<typename std::decay<Args>::type>::jniType... args) {
+      try {
+        return Convert<typename std::decay<R>::type>::toJniRet(
+          (*func)(static_cast<C>(obj), Convert<typename std::decay<Args>::type>::fromJni(args)...));
+      } catch (...) {
+        translatePendingCppExceptionToJavaException();
+        return jniRet{};
+      }
+    }
+  };
+
+  // This intentionally erases the real type; JNI will do it anyway
+  return reinterpret_cast<NativeMethodWrapper*>(&(funcWrapper::call));
+}
+
+// registration wrappers for non-static methods, with autoconvertion of arguments.
+
+template<typename M, M method, typename C, typename... Args>
+inline NativeMethodWrapper* exceptionWrapJNIMethod(void (C::*method0)(Args... args)) {
+  struct funcWrapper {
+    static void call(JNIEnv* env, jobject obj,
+                     typename Convert<typename std::decay<Args>::type>::jniType... args) {
+      try {
+        try {
+          auto aref = wrap_alias(static_cast<typename C::jhybridobject>(obj));
+          // This is usually a noop, but if the hybrid object is a
+          // base class of other classes which register JNI methods,
+          // this will get the right type for the registered method.
+          auto cobj = static_cast<C*>(facebook::jni::cthis(aref));
+          (cobj->*method)(Convert<typename std::decay<Args>::type>::fromJni(args)...);
+        } catch (const std::exception& ex) {
+          C::mapException(ex);
+          throw;
+        }
+      } catch (...) {
+        translatePendingCppExceptionToJavaException();
+      }
+    }
+  };
+
+  // This intentionally erases the real type; JNI will do it anyway
+  return reinterpret_cast<NativeMethodWrapper*>(&(funcWrapper::call));
+}
+
+template<typename M, M method, typename C, typename R, typename... Args>
+inline NativeMethodWrapper* exceptionWrapJNIMethod(R (C::*method0)(Args... args)) {
+  struct funcWrapper {
+    typedef typename Convert<typename std::decay<R>::type>::jniType jniRet;
+
+    static jniRet call(JNIEnv* env, jobject obj,
+                       typename Convert<typename std::decay<Args>::type>::jniType... args) {
+      try {
+        try {
+          auto aref = wrap_alias(static_cast<typename C::jhybridobject>(obj));
+          // This is usually a noop, but if the hybrid object is a
+          // base class of other classes which register JNI methods,
+          // this will get the right type for the registered method.
+          auto cobj = static_cast<C*>(facebook::jni::cthis(aref));
+          return Convert<typename std::decay<R>::type>::toJniRet(
+            (cobj->*method)(Convert<typename std::decay<Args>::type>::fromJni(args)...));
+        } catch (const std::exception& ex) {
+          C::mapException(ex);
+          throw;
+        }
+      } catch (...) {
+        translatePendingCppExceptionToJavaException();
+        return jniRet{};
+      }
+    }
+  };
+
+  // This intentionally erases the real type; JNI will do it anyway
+  return reinterpret_cast<NativeMethodWrapper*>(&(funcWrapper::call));
+}
+
+template<typename R, typename C, typename... Args>
+inline std::string makeDescriptor(R (*)(JNIEnv*, C, Args... args)) {
+  return jmethod_traits<R(Args...)>::descriptor();
+}
+
+template<typename R, typename C, typename... Args>
+inline std::string makeDescriptor(R (*)(alias_ref<C>, Args... args)) {
+  typedef typename Convert<typename std::decay<R>::type>::jniType jniRet;
+  return jmethod_traits<jniRet(typename Convert<typename std::decay<Args>::type>::jniType...)>
+    ::descriptor();
+}
+
+template<typename R, typename C, typename... Args>
+inline std::string makeDescriptor(R (C::*)(Args... args)) {
+  typedef typename Convert<typename std::decay<R>::type>::jniType jniRet;
+  return jmethod_traits<jniRet(typename Convert<typename std::decay<Args>::type>::jniType...)>
+    ::descriptor();
+}
+
+}
+
+}}

tests/react-test-app/android/app/src/main/jni/first-party/jni/fbjni/Registration.h

@@ -0,0 +1,87 @@
+/*
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+#pragma once
+
+#include <jni.h>
+#include "References.h"
+
+namespace facebook {
+namespace jni {
+
+namespace detail {
+
+// This uses the real JNI function as a non-type template parameter to
+// cause a (static member) function to exist with the same signature,
+// but with try/catch exception translation.
+template<typename F, F func, typename C, typename... Args>
+NativeMethodWrapper* exceptionWrapJNIMethod(void (*func0)(JNIEnv*, jobject, Args... args));
+
+// Same as above, but for non-void return types.
+template<typename F, F func, typename C, typename R, typename... Args>
+NativeMethodWrapper* exceptionWrapJNIMethod(R (*func0)(JNIEnv*, jobject, Args... args));
+
+// Automatically wrap object argument, and don't take env explicitly.
+template<typename F, F func, typename C, typename... Args>
+NativeMethodWrapper* exceptionWrapJNIMethod(void (*func0)(alias_ref<C>, Args... args));
+
+// Automatically wrap object argument, and don't take env explicitly,
+// non-void return type.
+template<typename F, F func, typename C, typename R, typename... Args>
+NativeMethodWrapper* exceptionWrapJNIMethod(R (*func0)(alias_ref<C>, Args... args));
+
+// Extract C++ instance from object, and invoke given method on it.
+template<typename M, M method, typename C, typename... Args>
+NativeMethodWrapper* exceptionWrapJNIMethod(void (C::*method0)(Args... args));
+
+// Extract C++ instance from object, and invoke given method on it,
+// non-void return type
+template<typename M, M method, typename C, typename R, typename... Args>
+NativeMethodWrapper* exceptionWrapJNIMethod(R (C::*method0)(Args... args));
+
+// This uses deduction to figure out the descriptor name if the types
+// are primitive or have JObjectWrapper specializations.
+template<typename R, typename C, typename... Args>
+std::string makeDescriptor(R (*func)(JNIEnv*, C, Args... args));
+
+// This uses deduction to figure out the descriptor name if the types
+// are primitive or have JObjectWrapper specializations.
+template<typename R, typename C, typename... Args>
+std::string makeDescriptor(R (*func)(alias_ref<C>, Args... args));
+
+// This uses deduction to figure out the descriptor name if the types
+// are primitive or have JObjectWrapper specializations.
+template<typename R, typename C, typename... Args>
+std::string makeDescriptor(R (C::*method0)(Args... args));
+
+}
+
+// We have to use macros here, because the func needs to be used
+// as both a decltype expression argument and as a non-type template
+// parameter, since C++ provides no way for translateException
+// to deduce the type of its non-type template parameter.
+// The empty string in the macros below ensures that name
+// is always a string literal (because that syntax is only
+// valid when name is a string literal).
+#define makeNativeMethod2(name, func)                                   \
+  { name "", ::facebook::jni::detail::makeDescriptor(&func),            \
+      ::facebook::jni::detail::exceptionWrapJNIMethod<decltype(&func), &func>(&func) }
+
+#define makeNativeMethod3(name, desc, func)                             \
+  { name "", desc,                                                      \
+      ::facebook::jni::detail::exceptionWrapJNIMethod<decltype(&func), &func>(&func) }
+
+// Variadic template hacks to get macros with different numbers of
+// arguments. Usage instructions are in CoreClasses.h.
+#define makeNativeMethodN(a, b, c, count, ...) makeNativeMethod ## count
+#define makeNativeMethod(...) makeNativeMethodN(__VA_ARGS__, 3, 2)(__VA_ARGS__)
+
+}}
+
+#include "Registration-inl.h"

tests/react-test-app/android/app/src/main/jni/first-party/jni/fbjni/TypeTraits.h

@@ -0,0 +1,149 @@
+/*
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+#pragma once
+
+#include <type_traits>
+
+namespace facebook {
+namespace jni {
+
+/// Generic std::enable_if helper
+template<bool B, typename T>
+using enable_if_t = typename std::enable_if<B, T>::type;
+
+/// Generic std::is_convertible helper
+template<typename From, typename To>
+constexpr bool IsConvertible() {
+  return std::is_convertible<From, To>::value;
+}
+
+template<template<typename...> class TT, typename T>
+struct is_instantiation_of : std::false_type {};
+
+template<template<typename...> class TT, typename... Ts>
+struct is_instantiation_of<TT, TT<Ts...>> : std::true_type {};
+
+template<template<typename...> class TT, typename... Ts>
+constexpr bool IsInstantiationOf() {
+  return is_instantiation_of<TT, Ts...>::value;
+}
+
+/// Metafunction to determine whether a type is a JNI reference or not
+template<typename T>
+struct is_plain_jni_reference :
+  std::integral_constant<bool,
+      std::is_pointer<T>::value &&
+      std::is_base_of<
+        typename std::remove_pointer<jobject>::type,
+        typename std::remove_pointer<T>::type>::value> {};
+
+/// Helper to simplify use of is_plain_jni_reference
+template<typename T>
+constexpr bool IsPlainJniReference() {
+  return is_plain_jni_reference<T>::value;
+}
+
+/// Metafunction to determine whether a type is a primitive JNI type or not
+template<typename T>
+struct is_jni_primitive :
+  std::integral_constant<bool,
+    std::is_same<jboolean, T>::value ||
+    std::is_same<jbyte, T>::value ||
+    std::is_same<jchar, T>::value ||
+    std::is_same<jshort, T>::value ||
+    std::is_same<jint, T>::value ||
+    std::is_same<jlong, T>::value ||
+    std::is_same<jfloat, T>::value ||
+    std::is_same<jdouble, T>::value> {};
+
+/// Helper to simplify use of is_jni_primitive
+template<typename T>
+constexpr bool IsJniPrimitive() {
+  return is_jni_primitive<T>::value;
+}
+
+/// Metafunction to determine if a type is a scalar (primitive or reference) JNI type
+template<typename T>
+struct is_jni_scalar :
+  std::integral_constant<bool,
+    is_plain_jni_reference<T>::value ||
+    is_jni_primitive<T>::value> {};
+
+/// Helper to simplify use of is_jni_scalar
+template<typename T>
+constexpr bool IsJniScalar() {
+  return is_jni_scalar<T>::value;
+}
+
+// Metafunction to determine if a type is a JNI type
+template<typename T>
+struct is_jni_type :
+  std::integral_constant<bool,
+    is_jni_scalar<T>::value ||
+    std::is_void<T>::value> {};
+
+/// Helper to simplify use of is_jni_type
+template<typename T>
+constexpr bool IsJniType() {
+  return is_jni_type<T>::value;
+}
+
+template<typename T>
+class weak_global_ref;
+
+template<typename T, typename Alloc>
+class basic_strong_ref;
+
+template<typename T>
+class alias_ref;
+
+template<typename T>
+struct is_non_weak_reference :
+  std::integral_constant<bool,
+    IsPlainJniReference<T>() ||
+    IsInstantiationOf<basic_strong_ref, T>() ||
+    IsInstantiationOf<alias_ref, T>()> {};
+
+template<typename T>
+constexpr bool IsNonWeakReference() {
+  return is_non_weak_reference<T>::value;
+}
+
+template<typename T>
+struct is_any_reference :
+  std::integral_constant<bool,
+    IsPlainJniReference<T>() ||
+    IsInstantiationOf<weak_global_ref, T>() ||
+    IsInstantiationOf<basic_strong_ref, T>() ||
+    IsInstantiationOf<alias_ref, T>()> {};
+
+template<typename T>
+constexpr bool IsAnyReference() {
+  return is_any_reference<T>::value;
+}
+
+template<typename T>
+struct reference_traits {
+  static_assert(IsPlainJniReference<T>(), "Need a plain JNI reference");
+  using plain_jni_reference_t = T;
+};
+
+template<template <typename...> class R, typename T, typename... A>
+struct reference_traits<R<T, A...>> {
+  static_assert(IsAnyReference<T>(), "Need an fbjni reference");
+  using plain_jni_reference_t = T;
+};
+
+template<typename T>
+using plain_jni_reference_t = typename reference_traits<T>::plain_jni_reference_t;
+
+}
+}
+

tests/react-test-app/android/app/src/main/jni/first-party/jni/jni_helpers.cpp

@@ -0,0 +1,195 @@
+/*
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+#include <jni.h>
+#include <stddef.h>
+#include <cstdio>
+
+#define MSG_SIZE 1024
+
+namespace facebook {
+
+/**
+ * Instructs the JNI environment to throw an exception.
+ *
+ * @param pEnv JNI environment
+ * @param szClassName class name to throw
+ * @param szFmt sprintf-style format string
+ * @param ... sprintf-style args
+ * @return 0 on success; a negative value on failure
+ */
+jint throwException(JNIEnv* pEnv, const char* szClassName, const char* szFmt, va_list va_args) {
+  char szMsg[MSG_SIZE];
+  vsnprintf(szMsg, MSG_SIZE, szFmt, va_args);
+  jclass exClass = pEnv->FindClass(szClassName);
+  return pEnv->ThrowNew(exClass, szMsg);
+}
+
+/**
+ * Instructs the JNI environment to throw a NoClassDefFoundError.
+ *
+ * @param pEnv JNI environment
+ * @param szFmt sprintf-style format string
+ * @param ... sprintf-style args
+ * @return 0 on success; a negative value on failure
+ */
+jint throwNoClassDefError(JNIEnv* pEnv, const char* szFmt, ...) {
+  va_list va_args;
+  va_start(va_args, szFmt);
+  jint ret = throwException(pEnv, "java/lang/NoClassDefFoundError", szFmt, va_args);
+  va_end(va_args);
+  return ret;
+}
+
+/**
+ * Instructs the JNI environment to throw a RuntimeException.
+ *
+ * @param pEnv JNI environment
+ * @param szFmt sprintf-style format string
+ * @param ... sprintf-style args
+ * @return 0 on success; a negative value on failure
+ */
+jint throwRuntimeException(JNIEnv* pEnv, const char* szFmt, ...) {
+  va_list va_args;
+  va_start(va_args, szFmt);
+  jint ret = throwException(pEnv, "java/lang/RuntimeException", szFmt, va_args);
+  va_end(va_args);
+  return ret;
+}
+
+/**
+ * Instructs the JNI environment to throw an IllegalArgumentException.
+ *
+ * @param pEnv JNI environment
+ * @param szFmt sprintf-style format string
+ * @param ... sprintf-style args
+ * @return 0 on success; a negative value on failure
+ */
+jint throwIllegalArgumentException(JNIEnv* pEnv, const char* szFmt, ...) {
+  va_list va_args;
+  va_start(va_args, szFmt);
+  jint ret = throwException(pEnv, "java/lang/IllegalArgumentException", szFmt, va_args);
+  va_end(va_args);
+  return ret;
+}
+
+/**
+ * Instructs the JNI environment to throw an IllegalStateException.
+ *
+ * @param pEnv JNI environment
+ * @param szFmt sprintf-style format string
+ * @param ... sprintf-style args
+ * @return 0 on success; a negative value on failure
+ */
+jint throwIllegalStateException(JNIEnv* pEnv, const char* szFmt, ...) {
+  va_list va_args;
+  va_start(va_args, szFmt);
+  jint ret = throwException(pEnv, "java/lang/IllegalStateException", szFmt, va_args);
+  va_end(va_args);
+  return ret;
+}
+
+/**
+ * Instructs the JNI environment to throw an OutOfMemoryError.
+ *
+ * @param pEnv JNI environment
+ * @param szFmt sprintf-style format string
+ * @param ... sprintf-style args
+ * @return 0 on success; a negative value on failure
+ */
+jint throwOutOfMemoryError(JNIEnv* pEnv, const char* szFmt, ...) {
+  va_list va_args;
+  va_start(va_args, szFmt);
+  jint ret = throwException(pEnv, "java/lang/OutOfMemoryError", szFmt, va_args);
+  va_end(va_args);
+  return ret;
+}
+
+/**
+ * Instructs the JNI environment to throw an AssertionError.
+ *
+ * @param pEnv JNI environment
+ * @param szFmt sprintf-style format string
+ * @param ... sprintf-style args
+ * @return 0 on success; a negative value on failure
+ */
+jint throwAssertionError(JNIEnv* pEnv, const char* szFmt, ...) {
+  va_list va_args;
+  va_start(va_args, szFmt);
+  jint ret = throwException(pEnv, "java/lang/AssertionError", szFmt, va_args);
+  va_end(va_args);
+  return ret;
+}
+
+/**
+ * Instructs the JNI environment to throw an IOException.
+ *
+ * @param pEnv JNI environment
+ * @param szFmt sprintf-style format string
+ * @param ... sprintf-style args
+ * @return 0 on success; a negative value on failure
+ */
+jint throwIOException(JNIEnv* pEnv, const char* szFmt, ...) {
+  va_list va_args;
+  va_start(va_args, szFmt);
+  jint ret = throwException(pEnv, "java/io/IOException", szFmt, va_args);
+  va_end(va_args);
+  return ret;
+}
+
+/**
+ * Finds the specified class. If it's not found, instructs the JNI environment to throw an
+ * exception.
+ *
+ * @param pEnv JNI environment
+ * @param szClassName the classname to find in JNI format (e.g. "java/lang/String")
+ * @return the class or NULL if not found (in which case a pending exception will be queued). This
+ *     returns a global reference (JNIEnv::NewGlobalRef).
+ */
+jclass findClassOrThrow(JNIEnv* pEnv, const char* szClassName) {
+  jclass clazz = pEnv->FindClass(szClassName);
+  if (!clazz) {
+    return NULL;
+  }
+  return (jclass) pEnv->NewGlobalRef(clazz);
+}
+
+/**
+ * Finds the specified field of the specified class. If it's not found, instructs the JNI
+ * environment to throw an exception.
+ *
+ * @param pEnv JNI environment
+ * @param clazz the class to lookup the field in
+ * @param szFieldName the name of the field to find
+ * @param szSig the signature of the field
+ * @return the field or NULL if not found (in which case a pending exception will be queued)
+ */
+jfieldID getFieldIdOrThrow(JNIEnv* pEnv, jclass clazz, const char* szFieldName, const char* szSig) {
+  return pEnv->GetFieldID(clazz, szFieldName, szSig);
+}
+
+/**
+ * Finds the specified method of the specified class. If it's not found, instructs the JNI
+ * environment to throw an exception.
+ *
+ * @param pEnv JNI environment
+ * @param clazz the class to lookup the method in
+ * @param szMethodName the name of the method to find
+ * @param szSig the signature of the method
+ * @return the method or NULL if not found (in which case a pending exception will be queued)
+ */
+jmethodID getMethodIdOrThrow(
+    JNIEnv* pEnv,
+    jclass clazz,
+    const char* szMethodName,
+    const char* szSig) {
+  return pEnv->GetMethodID(clazz, szMethodName, szSig);
+}
+
+} // namespace facebook

tests/react-test-app/android/app/src/main/jni/first-party/jni/jni_helpers.h

@@ -0,0 +1,137 @@
+/*
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+#pragma once
+
+#include <jni.h>
+
+namespace facebook {
+
+/**
+ * Instructs the JNI environment to throw an exception.
+ *
+ * @param pEnv JNI environment
+ * @param szClassName class name to throw
+ * @param szFmt sprintf-style format string
+ * @param ... sprintf-style args
+ * @return 0 on success; a negative value on failure
+ */
+jint throwException(JNIEnv* pEnv, const char* szClassName, const char* szFmt, va_list va_args);
+
+/**
+ * Instructs the JNI environment to throw a NoClassDefFoundError.
+ *
+ * @param pEnv JNI environment
+ * @param szFmt sprintf-style format string
+ * @param ... sprintf-style args
+ * @return 0 on success; a negative value on failure
+ */
+jint throwNoClassDefError(JNIEnv* pEnv, const char* szFmt, ...);
+
+/**
+ * Instructs the JNI environment to throw a RuntimeException.
+ *
+ * @param pEnv JNI environment
+ * @param szFmt sprintf-style format string
+ * @param ... sprintf-style args
+ * @return 0 on success; a negative value on failure
+ */
+jint throwRuntimeException(JNIEnv* pEnv, const char* szFmt, ...);
+
+/**
+ * Instructs the JNI environment to throw a IllegalArgumentException.
+ *
+ * @param pEnv JNI environment
+ * @param szFmt sprintf-style format string
+ * @param ... sprintf-style args
+ * @return 0 on success; a negative value on failure
+ */
+jint throwIllegalArgumentException(JNIEnv* pEnv, const char* szFmt, ...);
+
+/**
+ * Instructs the JNI environment to throw a IllegalStateException.
+ *
+ * @param pEnv JNI environment
+ * @param szFmt sprintf-style format string
+ * @param ... sprintf-style args
+ * @return 0 on success; a negative value on failure
+ */
+jint throwIllegalStateException(JNIEnv* pEnv, const char* szFmt, ...);
+
+/**
+ * Instructs the JNI environment to throw an IOException.
+ *
+ * @param pEnv JNI environment
+ * @param szFmt sprintf-style format string
+ * @param ... sprintf-style args
+ * @return 0 on success; a negative value on failure
+ */
+jint throwIOException(JNIEnv* pEnv, const char* szFmt, ...);
+
+/**
+ * Instructs the JNI environment to throw an AssertionError.
+ *
+ * @param pEnv JNI environment
+ * @param szFmt sprintf-style format string
+ * @param ... sprintf-style args
+ * @return 0 on success; a negative value on failure
+ */
+jint throwAssertionError(JNIEnv* pEnv, const char* szFmt, ...);
+
+/**
+ * Instructs the JNI environment to throw an OutOfMemoryError.
+ *
+ * @param pEnv JNI environment
+ * @param szFmt sprintf-style format string
+ * @param ... sprintf-style args
+ * @return 0 on success; a negative value on failure
+ */
+jint throwOutOfMemoryError(JNIEnv* pEnv, const char* szFmt, ...);
+
+/**
+ * Finds the specified class. If it's not found, instructs the JNI environment to throw an
+ * exception.
+ *
+ * @param pEnv JNI environment
+ * @param szClassName the classname to find in JNI format (e.g. "java/lang/String")
+ * @return the class or NULL if not found (in which case a pending exception will be queued). This
+ *     returns a global reference (JNIEnv::NewGlobalRef).
+ */
+jclass findClassOrThrow(JNIEnv *pEnv, const char* szClassName);
+
+/**
+ * Finds the specified field of the specified class. If it's not found, instructs the JNI
+ * environment to throw an exception.
+ *
+ * @param pEnv JNI environment
+ * @param clazz the class to lookup the field in
+ * @param szFieldName the name of the field to find
+ * @param szSig the signature of the field
+ * @return the field or NULL if not found (in which case a pending exception will be queued)
+ */
+jfieldID getFieldIdOrThrow(JNIEnv* pEnv, jclass clazz, const char* szFieldName, const char* szSig);
+
+/**
+ * Finds the specified method of the specified class. If it's not found, instructs the JNI
+ * environment to throw an exception.
+ *
+ * @param pEnv JNI environment
+ * @param clazz the class to lookup the method in
+ * @param szMethodName the name of the method to find
+ * @param szSig the signature of the method
+ * @return the method or NULL if not found (in which case a pending exception will be queued)
+ */
+jmethodID getMethodIdOrThrow(
+    JNIEnv* pEnv,
+    jclass clazz,
+    const char* szMethodName,
+    const char* szSig);
+
+} // namespace facebook
+

tests/react-test-app/android/app/src/main/jni/third-party/boost/Android.mk

@@ -0,0 +1,11 @@
+LOCAL_PATH:= $(call my-dir)
+include $(CLEAR_VARS)
+
+LOCAL_C_INCLUDES := $(LOCAL_PATH)/boost_1_57_0
+LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/boost_1_57_0
+CXX11_FLAGS := -std=gnu++11
+LOCAL_EXPORT_CPPFLAGS := $(CXX11_FLAGS)
+
+LOCAL_MODULE    := boost
+
+include $(BUILD_STATIC_LIBRARY)

tests/react-test-app/android/app/src/main/jni/third-party/double-conversion/Android.mk

@@ -0,0 +1,23 @@
+LOCAL_PATH:= $(call my-dir)
+
+include $(CLEAR_VARS)
+
+LOCAL_MODULE := double-conversion
+
+LOCAL_SRC_FILES := \
+  double-conversion/bignum.cc \
+  double-conversion/bignum-dtoa.cc \
+  double-conversion/cached-powers.cc \
+  double-conversion/diy-fp.cc \
+  double-conversion/double-conversion.cc \
+  double-conversion/fast-dtoa.cc \
+  double-conversion/fixed-dtoa.cc \
+  double-conversion/strtod.cc
+
+LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)
+
+CXX11_FLAGS := -std=c++11 -Wno-unused-variable -Wno-unused-local-typedefs
+LOCAL_CFLAGS += $(CXX11_FLAGS)
+LOCAL_EXPORT_CPPFLAGS := $(CXX11_FLAGS)
+
+include $(BUILD_STATIC_LIBRARY)

tests/react-test-app/android/app/src/main/jni/third-party/folly/Android.mk

@@ -0,0 +1,41 @@
+LOCAL_PATH:= $(call my-dir)
+include $(CLEAR_VARS)
+
+LOCAL_SRC_FILES:= \
+	folly/json.cpp \
+	folly/Unicode.cpp \
+	folly/Conv.cpp \
+  folly/detail/FunctionalExcept.cpp \
+  folly/detail/MallocImpl.cpp \
+  folly/Malloc.cpp \
+  folly/StringBase.cpp \
+  folly/dynamic.cpp \
+
+LOCAL_C_INCLUDES := $(LOCAL_PATH)
+LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)
+
+LOCAL_CFLAGS += -fexceptions -fno-omit-frame-pointer -frtti
+LOCAL_CFLAGS += -Wall -Werror -std=c++11
+
+CXX11_FLAGS := -std=gnu++11
+LOCAL_CFLAGS += $(CXX11_FLAGS)
+
+FOLLY_FLAGS := -DFOLLY_NO_CONFIG=1 -DFOLLY_HAVE_CLOCK_GETTIME=1
+LOCAL_CFLAGS += $(FOLLY_FLAGS)
+
+LOCAL_EXPORT_CPPFLAGS := $(CXX11_FLAGS) $(FOLLY_FLAGS)
+
+LOCAL_MODULE := libfolly_json
+
+LOCAL_SHARED_LIBRARIES := libglog libdouble-conversion
+# Boost is header-only library we pretend to link is statically as
+# this way android makefile will automatically setup path to boost header
+# file, but except from that this will have no effect, as no c/cpp files
+# are part of this static library
+LOCAL_STATIC_LIBRARIES := libboost
+
+include $(BUILD_SHARED_LIBRARY)
+
+$(call import-module,glog)
+$(call import-module,double-conversion)
+$(call import-module,boost)

tests/react-test-app/android/app/src/main/jni/third-party/glog/Android.mk

@@ -0,0 +1,32 @@
+LOCAL_PATH:= $(call my-dir)
+
+include $(CLEAR_VARS)
+
+LOCAL_SRC_FILES := \
+  glog-0.3.3/src/demangle.cc \
+  glog-0.3.3/src/logging.cc \
+  glog-0.3.3/src/raw_logging.cc \
+  glog-0.3.3/src/signalhandler.cc \
+  glog-0.3.3/src/symbolize.cc \
+  glog-0.3.3/src/utilities.cc \
+  glog-0.3.3/src/vlog_is_on.cc
+
+LOCAL_C_INCLUDES += $(LOCAL_PATH) $(LOCAL_PATH)/.. $(LOCAL_PATH)/glog-0.3.3/src/
+
+LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/.. $(LOCAL_PATH)/glog-0.3.3/src/
+
+LOCAL_CFLAGS += \
+  -Wall \
+  -Wwrite-strings \
+  -Woverloaded-virtual \
+  -Wno-sign-compare \
+  -DNDEBUG \
+  -g \
+  -O2 \
+  -D_START_GOOGLE_NAMESPACE_="namespace google {" \
+  -D_END_GOOGLE_NAMESPACE_="}"
+
+
+LOCAL_MODULE    := glog
+
+include $(BUILD_SHARED_LIBRARY)

tests/react-test-app/android/app/src/main/jni/third-party/glog/config.h

@@ -0,0 +1,179 @@
+/* src/config.h.  Generated from config.h.in by configure.  */
+/* src/config.h.in.  Generated from configure.ac by autoheader.  */
+
+/* define if glog doesn't use RTTI */
+#define DISABLE_RTTI 1
+
+/* Namespace for Google classes */
+#define GOOGLE_NAMESPACE google
+
+/* Define if you have the `dladdr' function */
+#define HAVE_DLADDR 1
+
+/* Define to 1 if you have the <dlfcn.h> header file. */
+#define HAVE_DLFCN_H 1
+
+/* Define to 1 if you have the <execinfo.h> header file. */
+/* #undef HAVE_EXECINFO_H */
+
+/* Define if you have the `fcntl' function */
+#define HAVE_FCNTL 1
+
+/* Define to 1 if you have the <glob.h> header file. */
+/* #undef HAVE_GLOB_H */
+
+/* Define to 1 if you have the <inttypes.h> header file. */
+#define HAVE_INTTYPES_H 1
+
+/* Define to 1 if you have the `pthread' library (-lpthread). */
+/* #undef HAVE_LIBPTHREAD */
+
+/* Define to 1 if you have the <libunwind.h> header file. */
+/* #undef HAVE_LIBUNWIND_H */
+
+/* define if you have google gflags library */
+/* #undef HAVE_LIB_GFLAGS */
+
+/* define if you have google gmock library */
+/* #undef HAVE_LIB_GMOCK */
+
+/* define if you have google gtest library */
+/* #undef HAVE_LIB_GTEST */
+
+/* define if you have libunwind */
+/* #undef HAVE_LIB_UNWIND */
+
+/* Define to 1 if you have the <memory.h> header file. */
+#define HAVE_MEMORY_H 1
+
+/* define if the compiler implements namespaces */
+#define HAVE_NAMESPACES 1
+
+/* Define if you have POSIX threads libraries and header files. */
+#define HAVE_PTHREAD 1
+
+/* Define to 1 if you have the <pwd.h> header file. */
+#define HAVE_PWD_H 1
+
+/* define if the compiler implements pthread_rwlock_* */
+#define HAVE_RWLOCK 1
+
+/* Define if you have the `sigaltstack' function */
+#define HAVE_SIGALTSTACK 1
+
+/* Define to 1 if you have the <stdint.h> header file. */
+#define HAVE_STDINT_H 1
+
+/* Define to 1 if you have the <stdlib.h> header file. */
+#define HAVE_STDLIB_H 1
+
+/* Define to 1 if you have the <strings.h> header file. */
+#define HAVE_STRINGS_H 1
+
+/* Define to 1 if you have the <string.h> header file. */
+#define HAVE_STRING_H 1
+
+/* Define to 1 if you have the <syscall.h> header file. */
+/* #undef HAVE_SYSCALL_H */
+
+/* Define to 1 if you have the <syslog.h> header file. */
+#define HAVE_SYSLOG_H 1
+
+/* Define to 1 if you have the <sys/stat.h> header file. */
+#define HAVE_SYS_STAT_H 1
+
+/* Define to 1 if you have the <sys/syscall.h> header file. */
+#define HAVE_SYS_SYSCALL_H 1
+
+/* Define to 1 if you have the <sys/time.h> header file. */
+#define HAVE_SYS_TIME_H 1
+
+/* Define to 1 if you have the <sys/types.h> header file. */
+#define HAVE_SYS_TYPES_H 1
+
+/* Define to 1 if you have the <sys/ucontext.h> header file. */
+/* #undef HAVE_SYS_UCONTEXT_H */
+
+/* Define to 1 if you have the <sys/utsname.h> header file. */
+#define HAVE_SYS_UTSNAME_H 1
+
+/* Define to 1 if you have the <ucontext.h> header file. */
+/* #undef HAVE_UCONTEXT_H */
+
+/* Define to 1 if you have the <unistd.h> header file. */
+#define HAVE_UNISTD_H 1
+
+/* Define to 1 if you have the <unwind.h> header file. */
+#define HAVE_UNWIND_H 1
+
+/* define if the compiler supports using expression for operator */
+#define HAVE_USING_OPERATOR 1
+
+/* define if your compiler has __attribute__ */
+#define HAVE___ATTRIBUTE__ 1
+
+/* define if your compiler has __builtin_expect */
+#define HAVE___BUILTIN_EXPECT 1
+
+/* define if your compiler has __sync_val_compare_and_swap */
+#define HAVE___SYNC_VAL_COMPARE_AND_SWAP 1
+
+/* Define to the sub-directory in which libtool stores uninstalled libraries.
+   */
+#define LT_OBJDIR ".libs/"
+
+/* Name of package */
+#define PACKAGE "glog"
+
+/* Define to the address where bug reports for this package should be sent. */
+#define PACKAGE_BUGREPORT "opensource@google.com"
+
+/* Define to the full name of this package. */
+#define PACKAGE_NAME "glog"
+
+/* Define to the full name and version of this package. */
+#define PACKAGE_STRING "glog 0.3.3"
+
+/* Define to the one symbol short name of this package. */
+#define PACKAGE_TARNAME "glog"
+
+/* Define to the home page for this package. */
+#define PACKAGE_URL ""
+
+/* Define to the version of this package. */
+#define PACKAGE_VERSION "0.3.3"
+
+/* How to access the PC from a struct ucontext */
+/* #undef PC_FROM_UCONTEXT */
+
+/* Define to necessary symbol if this constant uses a non-standard name on
+   your system. */
+/* #undef PTHREAD_CREATE_JOINABLE */
+
+/* The size of `void *', as computed by sizeof. */
+#define SIZEOF_VOID_P 4
+
+/* Define to 1 if you have the ANSI C header files. */
+/* #undef STDC_HEADERS */
+
+/* the namespace where STL code like vector<> is defined */
+#define STL_NAMESPACE std
+
+/* location of source code */
+#define TEST_SRC_DIR "."
+
+/* Version number of package */
+#define VERSION "0.3.3"
+
+/* Stops putting the code inside the Google namespace */
+#define _END_GOOGLE_NAMESPACE_ }
+
+/* Puts following code inside the Google namespace */
+#define _START_GOOGLE_NAMESPACE_ namespace google {
+
+
+/* TODO(vjn/dreiss): revisit these when use the android-21 (or newer) NDK platform. */
+#undef HAVE_SYSCALL_H
+#undef HAVE_SYS_SYSCALL_H
+#undef OS_LINUX
+#undef OS_MACOSX

tests/react-test-app/android/app/src/main/jni/third-party/jsc/Android.mk

@@ -0,0 +1,6 @@
+LOCAL_PATH:= $(call my-dir)
+include $(CLEAR_VARS)
+LOCAL_MODULE:= jsc
+LOCAL_SRC_FILES := jni/$(TARGET_ARCH_ABI)/libjsc.so
+LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)
+include $(PREBUILT_SHARED_LIBRARY)

tests/react-test-app/android/build.gradle

@@ -6,6 +6,7 @@ buildscript {
     }
     dependencies {
         classpath 'com.android.tools.build:gradle:1.3.1'
+        classpath 'de.undercouch:gradle-download-task:1.2'
 
         // NOTE: Do not place your application dependencies here; they belong
         // in the individual module build.gradle files