Add @ReactModule annotation

Reviewed By: astreet

Differential Revision: D3310686

fbshipit-source-id: ec2dc7fdf2dfbb3eedde667d7228fc3241860e35

ReactAndroid/src/main/java/com/facebook/react/bridge/BaseJavaModule.java

@@ -9,7 +9,10 @@
 
 package com.facebook.react.bridge;
 
+import com.facebook.common.logging.FLog;
 import com.facebook.infer.annotation.Assertions;
+import com.facebook.react.bridge.annotations.ReactModule;
+import com.facebook.react.common.ReactConstants;
 import com.facebook.systrace.Systrace;
 import com.facebook.systrace.SystraceMessage;
 
@@ -462,6 +465,17 @@ public abstract class BaseJavaModule implements NativeModule {
     writer.endObject();
   }
 
+  @Override
+  public String getName() {
+    ReactModule module = getClass().getAnnotation(ReactModule.class);
+    if (module == null) {
+      throw new IllegalStateException(
+        getClass().getSimpleName() +
+          "module must have @ReactModule annotation or override getName()");
+    }
+    return module.name();
+  }
+
   @Override
   public void initialize() {
     // do nothing
@@ -469,6 +483,7 @@ public abstract class BaseJavaModule implements NativeModule {
 
   @Override
   public boolean canOverrideExistingModule() {
+    // TODO(t11394819): Make this final and use annotation
     return false;
   }
 
@@ -484,7 +499,15 @@ public abstract class BaseJavaModule implements NativeModule {
 
   @Override
   public boolean supportsWebWorkers() {
-    return false;
+    ReactModule module = getClass().getAnnotation(ReactModule.class);
+    if (module == null) {
+      FLog.w(
+        ReactConstants.TAG,
+        "Module " + getName() +
+          " lacks @ReactModule annotation, assuming false for supportsWebWorkers()");
+      return false;
+    }
+    return module.supportsWebWorkers();
   }
 
   private static char paramTypeToChar(Class paramClass) {

ReactAndroid/src/main/java/com/facebook/react/bridge/annotations/ReactModule.java

@@ -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.
+ */
+
+package com.facebook.react.bridge.annotations;
+
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+
+import com.facebook.react.bridge.BaseJavaModule;
+import com.facebook.react.bridge.ExecutorToken;
+import com.facebook.react.bridge.ReactContext;
+
+import static java.lang.annotation.ElementType.TYPE;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+/**
+ * Annotation for use on {@link BaseJavaModule}s to describe properties for that module.
+ */
+@Retention(RUNTIME)
+@Target(TYPE)
+public @interface ReactModule {
+  /**
+   * Name used to {@code require()} this module from JavaScript.
+   */
+  String name();
+
+  /**
+   * True if you intend to override some other native module that was registered e.g. as part
+   * of a different package (such as the core one). Trying to override without returning true from
+   * this method is considered an error and will throw an exception during initialization. By
+   * default all modules return false.
+   */
+  boolean canOverrideExistingModule() default false;
+
+  /**
+   * In order to support web workers, a module must be aware that it can be invoked from multiple
+   * different JS VMs. Supporting web workers means recognizing things like:
+   *
+   * 1) ids (e.g. timer ids, request ids, etc.) may only unique on a per-VM basis
+   * 2) the module needs to make sure to enqueue callbacks and JS module calls to the correct VM
+   *
+   * In order to facilitate this, modules that support web workers will have all their @ReactMethod-
+   * annotated methods passed a {@link ExecutorToken} as the first parameter before any arguments
+   * from JS. This ExecutorToken internally maps to a specific JS VM and can be used by the
+   * framework to route calls appropriately. In order to make JS module calls correctly, start using
+   * the version of {@link ReactContext#getJSModule(ExecutorToken, Class)} that takes an
+   * ExecutorToken. It will ensure that any calls you dispatch to the returned object will go to
+   * the right VM. For Callbacks, you don't have to do anything special -- the framework
+   * automatically tags them with the correct ExecutorToken when the are created.
+   *
+   * Note: even though calls can come from multiple JS VMs on multiple threads, calls to this module
+   * will still only occur on a single thread.
+   *
+   * @return whether this module supports web workers.
+   */
+  boolean supportsWebWorkers() default false;
+
+  /**
+   * Whether this module needs to be loaded immediately.
+   */
+  boolean needsEagerInit() default false;
+}