remove activities from module constructors

Summary:
Refactor modules that take activities (or activities that implement some interface) as constructor args to not do that. Expose `getCurrentActivity()` in `ReactContext` and use that wherever the activity is needed.

public

Reviewed By: astreet

Differential Revision: D2680462

fb-gh-sync-id: f263b3fe5b422b7aab9fdadd051cef4e82797b0a

ReactAndroid/src/main/java/com/facebook/react/ReactInstanceManager.java

@@ -47,6 +47,18 @@ import com.facebook.react.uimanager.ViewManager;
  * have a static method, and so cannot (in Java < 8), be one.
  */
 public abstract class ReactInstanceManager {
+
+  /**
+   * Listener interface for react instance events.
+   */
+  public interface ReactInstanceEventListener {
+    /**
+     * Called when the react context is initialized (all modules registered). Always called on the
+     * UI thread.
+     */
+    void onReactContextInitialized(ReactContext context);
+  }
+
   public abstract DevSupportManager getDevSupportManager();
 
   /**
@@ -118,6 +130,11 @@ public abstract class ReactInstanceManager {
   public abstract List<ViewManager> createAllViewManagers(
     ReactApplicationContext catalystApplicationContext);
 
+  /**
+   * Add a listener to be notified of react instance events.
+   */
+  public abstract void addReactInstanceEventListener(ReactInstanceEventListener listener);
+
   @VisibleForTesting
   public abstract @Nullable ReactContext getCurrentReactContext();
 

ReactAndroid/src/main/java/com/facebook/react/ReactInstanceManagerImpl.java

@@ -12,10 +12,11 @@ package com.facebook.react;
 import javax.annotation.Nullable;
 
 import java.util.ArrayList;
+import java.util.Collection;
 import java.util.List;
+import java.util.concurrent.ConcurrentLinkedQueue;
 
 import android.app.Activity;
-import android.app.Application;
 import android.content.Context;
 import android.content.Intent;
 import android.os.AsyncTask;
@@ -95,6 +96,8 @@ import com.facebook.systrace.Systrace;
   private @Nullable DefaultHardwareBackBtnHandler mDefaultBackButtonImpl;
   private String mSourceUrl;
   private @Nullable Activity mCurrentActivity;
+  private final Collection<ReactInstanceEventListener> mReactInstanceEventListeners =
+      new ConcurrentLinkedQueue<>();
   private volatile boolean mHasStartedCreatingInitialContext = false;
   private final UIImplementationProvider mUIImplementationProvider;
 
@@ -406,6 +409,7 @@ import com.facebook.systrace.Systrace;
       mCurrentReactContext = null;
       mHasStartedCreatingInitialContext = false;
     }
+    mCurrentActivity = null;
   }
 
   @Override
@@ -482,6 +486,11 @@ import com.facebook.systrace.Systrace;
     }
   }
 
+  @Override
+  public void addReactInstanceEventListener(ReactInstanceEventListener listener) {
+    mReactInstanceEventListeners.add(listener);
+  }
+
   @VisibleForTesting
   @Override
   public @Nullable ReactContext getCurrentReactContext() {
@@ -535,6 +544,10 @@ import com.facebook.systrace.Systrace;
     for (ReactRootView rootView : mAttachedRootViews) {
       attachMeasuredRootViewToInstance(rootView, catalystInstance);
     }
+
+    for (ReactInstanceEventListener listener : mReactInstanceEventListeners) {
+      listener.onReactContextInitialized(reactContext);
+    }
   }
 
   private void attachMeasuredRootViewToInstance(

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

@@ -146,7 +146,6 @@ public class ReactContext extends ContextWrapper {
    */
   public void onPause() {
     UiThreadUtil.assertOnUiThread();
-    mCurrentActivity = null;
     for (LifecycleEventListener listener : mLifecycleEventListeners) {
       listener.onHostPause();
     }
@@ -163,6 +162,7 @@ public class ReactContext extends ContextWrapper {
     if (mCatalystInstance != null) {
       mCatalystInstance.destroy();
     }
+    mCurrentActivity = null;
   }
 
   /**
@@ -239,4 +239,13 @@ public class ReactContext extends ContextWrapper {
     mCurrentActivity.startActivityForResult(intent, code, bundle);
     return true;
   }
+
+  /**
+   * Get the activity to which this context is currently attached, or {@code null} if not attached.
+   * DO NOT HOLD LONG-LIVED REFERENCES TO THE OBJECT RETURNED BY THIS METHOD, AS THIS WILL CAUSE
+   * MEMORY LEAKS.
+   */
+  /* package */ @Nullable Activity getCurrentActivity() {
+    return mCurrentActivity;
+  }
 }

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

@@ -9,6 +9,10 @@
 
 package com.facebook.react.bridge;
 
+import javax.annotation.Nullable;
+
+import android.app.Activity;
+
 /**
  * Base class for Catalyst native modules that require access to the {@link ReactContext}
  * instance.
@@ -27,4 +31,17 @@ public abstract class ReactContextBaseJavaModule extends BaseJavaModule {
   protected final ReactApplicationContext getReactApplicationContext() {
     return mReactApplicationContext;
   }
+
+  /**
+   * Get the activity to which this context is currently attached, or {@code null} if not attached.
+   *
+   * DO NOT HOLD LONG-LIVED REFERENCES TO THE OBJECT RETURNED BY THIS METHOD, AS THIS WILL CAUSE
+   * MEMORY LEAKS.
+   *
+   * For example, never store the value returned by this method in a member variable. Instead, call
+   * this method whenever you actually need the Activity and make sure to check for {@code null}.
+   */
+  protected @Nullable final Activity getCurrentActivity() {
+    return mReactApplicationContext.getCurrentActivity();
+  }
 }