WebWorkers: Allow native modules to be notified when executors are unregistered

Summary: This will allow them to clean up resources when a web worker goes away.

Reviewed By: mhorowitz, lexs

Differential Revision: D2994721

fb-gh-sync-id: c7ca1afc7290e85038cf692a139f6478dba0ef61
shipit-source-id: c7ca1afc7290e85038cf692a139f6478dba0ef61

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

@@ -222,8 +222,10 @@ public class CatalystInstanceImpl implements CatalystInstance {
       Systrace.unregisterListener(mTraceListener);
 
       synchronouslyDisposeBridgeOnJSThread();
-      mReactQueueConfiguration.destroy();
     }
+
+    mReactQueueConfiguration.destroy();
+
     boolean wasIdle = (mPendingJSCalls.getAndSet(0) == 0);
     if (!wasIdle && !mBridgeIdleListeners.isEmpty()) {
       for (NotThreadSafeBridgeIdleDebugListener listener : mBridgeIdleListeners) {
@@ -293,12 +295,12 @@ public class CatalystInstanceImpl implements CatalystInstance {
   @Override
   public void handleMemoryPressure(final MemoryPressure level) {
     mReactQueueConfiguration.getJSQueueThread().runOnQueue(
-        new Runnable() {
-          @Override
-          public void run() {
-            Assertions.assertNotNull(mBridge).handleMemoryPressure(level);
-          }
-        });
+      new Runnable() {
+        @Override
+        public void run() {
+          Assertions.assertNotNull(mBridge).handleMemoryPressure(level);
+        }
+      });
   }
 
   /**
@@ -399,12 +401,14 @@ public class CatalystInstanceImpl implements CatalystInstance {
     public void call(ExecutorToken executorToken, int moduleId, int methodId, ReadableNativeArray parameters) {
       mReactQueueConfiguration.getNativeModulesQueueThread().assertIsOnThread();
 
-      // Suppress any callbacks if destroyed - will only lead to sadness.
-      if (mDestroyed) {
-        return;
-      }
+      synchronized (mTeardownLock) {
+        // Suppress any callbacks if destroyed - will only lead to sadness.
+        if (mDestroyed) {
+          return;
+        }
 
-      mJavaRegistry.call(CatalystInstanceImpl.this, executorToken, moduleId, methodId, parameters);
+        mJavaRegistry.call(CatalystInstanceImpl.this, executorToken, moduleId, methodId, parameters);
+      }
     }
 
     @Override
@@ -415,17 +419,38 @@ public class CatalystInstanceImpl implements CatalystInstance {
       // native modules could be in a bad state so we don't want to call anything on them. We
       // still want to trigger the debug listener since it allows instrumentation tests to end and
       // check their assertions without waiting for a timeout.
-      if (!mDestroyed) {
-        Systrace.beginSection(Systrace.TRACE_TAG_REACT_JAVA_BRIDGE, "onBatchComplete");
-        try {
-          mJavaRegistry.onBatchComplete();
-        } finally {
-          Systrace.endSection(Systrace.TRACE_TAG_REACT_JAVA_BRIDGE);
+      synchronized (mTeardownLock) {
+        if (!mDestroyed) {
+          Systrace.beginSection(Systrace.TRACE_TAG_REACT_JAVA_BRIDGE, "onBatchComplete");
+          try {
+            mJavaRegistry.onBatchComplete();
+          } finally {
+            Systrace.endSection(Systrace.TRACE_TAG_REACT_JAVA_BRIDGE);
+          }
         }
       }
 
       decrementPendingJSCalls();
     }
+
+    @Override
+    public void onExecutorUnregistered(ExecutorToken executorToken) {
+      mReactQueueConfiguration.getNativeModulesQueueThread().assertIsOnThread();
+
+      // Since onCatalystInstanceDestroy happens on the UI thread, we don't want to also execute
+      // this callback on the native modules thread at the same time. Longer term, onCatalystInstanceDestroy
+      // should probably be executed on the native modules thread as well instead.
+      synchronized (mTeardownLock) {
+        if (!mDestroyed) {
+          Systrace.beginSection(Systrace.TRACE_TAG_REACT_JAVA_BRIDGE, "onExecutorUnregistered");
+          try {
+            mJavaRegistry.onExecutorUnregistered(executorToken);
+          } finally {
+            Systrace.endSection(Systrace.TRACE_TAG_REACT_JAVA_BRIDGE);
+          }
+        }
+      }
+    }
   }
 
   private class NativeExceptionHandler implements QueueThreadExceptionHandler {

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

@@ -30,6 +30,7 @@ public class NativeModuleRegistry {
   private final List<ModuleDefinition> mModuleTable;
   private final Map<Class<? extends NativeModule>, NativeModule> mModuleInstances;
   private final ArrayList<OnBatchCompleteListener> mBatchCompleteListenerModules;
+  private final ArrayList<OnExecutorUnregisteredListener> mOnExecutorUnregisteredListenerModules;
 
   private NativeModuleRegistry(
       List<ModuleDefinition> moduleTable,
@@ -37,12 +38,16 @@ public class NativeModuleRegistry {
     mModuleTable = moduleTable;
     mModuleInstances = moduleInstances;
 
-    mBatchCompleteListenerModules = new ArrayList<OnBatchCompleteListener>(mModuleTable.size());
+    mBatchCompleteListenerModules = new ArrayList<>(mModuleTable.size());
+    mOnExecutorUnregisteredListenerModules = new ArrayList<>(mModuleTable.size());
     for (int i = 0; i < mModuleTable.size(); i++) {
       ModuleDefinition definition = mModuleTable.get(i);
       if (definition.target instanceof OnBatchCompleteListener) {
         mBatchCompleteListenerModules.add((OnBatchCompleteListener) definition.target);
       }
+      if (definition.target instanceof OnExecutorUnregisteredListener) {
+        mOnExecutorUnregisteredListenerModules.add((OnExecutorUnregisteredListener) definition.target);
+      }
     }
   }
 
@@ -135,6 +140,12 @@ public class NativeModuleRegistry {
     }
   }
 
+  public void onExecutorUnregistered(ExecutorToken executorToken) {
+    for (int i = 0; i < mOnExecutorUnregisteredListenerModules.size(); i++) {
+      mOnExecutorUnregisteredListenerModules.get(i).onExecutorDestroyed(executorToken);
+    }
+  }
+
   public <T extends NativeModule> T getModule(Class<T> moduleInterface) {
     return (T) Assertions.assertNotNull(mModuleInstances.get(moduleInterface));
   }

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

@@ -0,0 +1,22 @@
+/**
+ * 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;
+
+/**
+ * Interface for a module that will be notified when JS executors have been unregistered from the bridge.
+ * Note that this will NOT notify listeners about the main executor being destroyed: use
+ * {@link NativeModule#onCatalystInstanceDestroy()} for that. Once a module has received a
+ * {@link NativeModule#onCatalystInstanceDestroy()} call, it will not receive any onExecutorUnregistered
+ * calls.
+ */
+public interface OnExecutorUnregisteredListener {
+
+  void onExecutorDestroyed(ExecutorToken executorToken);
+}

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

@@ -19,4 +19,7 @@ public interface ReactCallback {
 
   @DoNotStrip
   void onBatchComplete();
+
+  @DoNotStrip
+  void onExecutorUnregistered(ExecutorToken executorToken);
 }