Initialize the Choreographer in ReactChoreographer lazily

Summary:
Today, ReactInstanceManager calls `ReactChoreographer.initialize()` in its constructor. Since `ReactChoreographer` also needs to run on the UI thread, this forces the entire `ReactInstanceManager` to run on the UI thread.

By moving `ReactChoreographer` to lazily set up its Choreographer, we can make `ReactInstanceManager` run on any thread

Reviewed By: mdvacca

Differential Revision: D10097432

fbshipit-source-id: eb8c80aafcba745ea15c86296d11c487329b1df0

ReactAndroid/src/main/java/com/facebook/react/modules/core/ChoreographerCompat.java

@@ -13,6 +13,7 @@ import android.os.Build;
 import android.os.Handler;
 import android.os.Looper;
 import android.view.Choreographer;
+import com.facebook.react.bridge.UiThreadUtil;
 
 /**
  * Wrapper class for abstracting away availability of the JellyBean Choreographer. If Choreographer
@@ -23,13 +24,17 @@ public class ChoreographerCompat {
   private static final long ONE_FRAME_MILLIS = 17;
   private static final boolean IS_JELLYBEAN_OR_HIGHER =
     Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN;
-  private static final ChoreographerCompat INSTANCE = new ChoreographerCompat();
+  private static ChoreographerCompat sInstance;
 
   private Handler mHandler;
   private Choreographer mChoreographer;
 
   public static ChoreographerCompat getInstance() {
-    return INSTANCE;
+    UiThreadUtil.assertOnUiThread();
+    if (sInstance == null){
+      sInstance = new ChoreographerCompat();
+    }
+    return sInstance;
   }
 
   private ChoreographerCompat() {

ReactAndroid/src/main/java/com/facebook/react/modules/core/ReactChoreographer.java

@@ -7,11 +7,12 @@
 
 package com.facebook.react.modules.core;
 
+import com.facebook.react.bridge.UiThreadUtil;
 import java.util.ArrayDeque;
+import javax.annotation.Nullable;
 
 import com.facebook.common.logging.FLog;
 import com.facebook.infer.annotation.Assertions;
-import com.facebook.react.bridge.UiThreadUtil;
 import com.facebook.react.common.ReactConstants;
 
 /**
@@ -65,7 +66,6 @@ public class ReactChoreographer {
 
   public static void initialize() {
     if (sInstance == null) {
-      UiThreadUtil.assertOnUiThread();
       sInstance = new ReactChoreographer();
     }
   }
@@ -75,7 +75,8 @@ public class ReactChoreographer {
     return sInstance;
   }
 
-  private final ChoreographerCompat mChoreographer;
+  // This needs to be volatile due to double checked locking issue - https://fburl.com/z409owpf
+  private @Nullable volatile ChoreographerCompat mChoreographer;
   private final ReactChoreographerDispatcher mReactChoreographerDispatcher;
   private final ArrayDeque<ChoreographerCompat.FrameCallback>[] mCallbackQueues;
 
@@ -83,12 +84,12 @@ public class ReactChoreographer {
   private boolean mHasPostedCallback = false;
 
   private ReactChoreographer() {
-    mChoreographer = ChoreographerCompat.getInstance();
     mReactChoreographerDispatcher = new ReactChoreographerDispatcher();
     mCallbackQueues = new ArrayDeque[CallbackType.values().length];
     for (int i = 0; i < mCallbackQueues.length; i++) {
       mCallbackQueues[i] = new ArrayDeque<>();
     }
+    initializeChoreographer(null);
   }
 
   public synchronized void postFrameCallback(
@@ -98,11 +99,40 @@ public class ReactChoreographer {
     mTotalCallbacks++;
     Assertions.assertCondition(mTotalCallbacks > 0);
     if (!mHasPostedCallback) {
-      mChoreographer.postFrameCallback(mReactChoreographerDispatcher);
-      mHasPostedCallback = true;
+      if (mChoreographer == null) {
+        initializeChoreographer(new Runnable(){
+          @Override
+          public void run() {
+            postFrameCallbackOnChoreographer();
+          }
+        });
+      } else {
+        postFrameCallbackOnChoreographer();
+      }
     }
   }
 
+  public void postFrameCallbackOnChoreographer() {
+    mChoreographer.postFrameCallback(mReactChoreographerDispatcher);
+    mHasPostedCallback = true;
+  }
+
+  public void initializeChoreographer(@Nullable final Runnable runnable) {
+    UiThreadUtil.runOnUiThread(new Runnable() {
+      @Override
+      public void run() {
+        synchronized (ReactChoreographer.class) {
+          if (mChoreographer == null) {
+            mChoreographer = ChoreographerCompat.getInstance();
+          }
+        }
+        if (runnable != null) {
+          runnable.run();
+        }
+      }
+    });
+  }
+
   public synchronized void removeFrameCallback(
     CallbackType type,
     ChoreographerCompat.FrameCallback frameCallback) {
@@ -117,7 +147,9 @@ public class ReactChoreographer {
   private void maybeRemoveFrameCallback() {
     Assertions.assertCondition(mTotalCallbacks >= 0);
     if (mTotalCallbacks == 0 && mHasPostedCallback) {
-      mChoreographer.removeFrameCallback(mReactChoreographerDispatcher);
+      if (mChoreographer != null) {
+        mChoreographer.removeFrameCallback(mReactChoreographerDispatcher);
+      }
       mHasPostedCallback = false;
     }
   }