Add GuardedResultAsyncTask

Reviewed By: andreicoman11

Differential Revision: D2679459

fb-gh-sync-id: 8a9ec170ce76bbc3340c9e8872e19b78ae5a5c2d

Author: lexs

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

@@ -16,9 +16,8 @@
  * handled by the {@link com.facebook.react.bridge.NativeModuleCallExceptionHandler} registered if
  * the app is in dev mode.
  *
- * This class doesn't allow doInBackground to return a results. This is mostly because when this
- * class was written that functionality wasn't used and it would require some extra code to make
- * work correctly with caught exceptions. Don't let that stop you from adding it if you need it :)
+ * This class doesn't allow doInBackground to return a results. If you need this
+ * use GuardedResultAsyncTask instead.
  */
 public abstract class GuardedAsyncTask<Params, Progress>
     extends AsyncTask<Params, Progress, Void> {

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

@@ -0,0 +1,43 @@
+// Copyright 2004-present Facebook. All Rights Reserved.
+
+package com.facebook.react.bridge;
+
+import android.os.AsyncTask;
+
+/**
+ * Abstract base for a AsyncTask with result support that should have any RuntimeExceptions it
+ * throws handled by the {@link com.facebook.react.bridge.NativeModuleCallExceptionHandler}
+ * registered if the app is in dev mode.
+ */
+public abstract class GuardedResultAsyncTask<Result>
+    extends AsyncTask<Void, Void, Result> {
+
+  private final ReactContext mReactContext;
+
+  protected GuardedResultAsyncTask(ReactContext reactContext) {
+    mReactContext = reactContext;
+  }
+
+  @Override
+  protected final Result doInBackground(Void... params) {
+    try {
+      return doInBackgroundGuarded();
+    } catch (RuntimeException e) {
+      mReactContext.handleException(e);
+      throw e;
+    }
+  }
+
+  @Override
+  protected final void onPostExecute(Result result) {
+    try {
+      onPostExecuteGuarded(result);
+    } catch (RuntimeException e) {
+      mReactContext.handleException(e);
+    }
+  }
+
+  protected abstract Result doInBackgroundGuarded();
+  protected abstract void onPostExecuteGuarded(Result result);
+
+}