BREAKING: Only call batchDidComplete when there were actually native calls dispatched

Summary: This is breaking because it affects the contract for onBatchComplete, but modules really shouldn't (and probably aren't) depending on it being called without any actual native module method calls having happened.

Reviewed By: javache

Differential Revision: D4715656

fbshipit-source-id: 53ddd4a26c9949de86f5111d214b3e5002ca2e94

ReactCommon/cxxreact/NativeToJsBridge.cpp

@@ -49,6 +49,8 @@ public:
       JSExecutor& executor, folly::dynamic&& calls, bool isEndOfBatch) override {
     ExecutorToken token = m_nativeToJs->getTokenForExecutor(executor);
     m_nativeQueue->runOnQueue([this, token, calls=std::move(calls), isEndOfBatch] () mutable {
+      m_batchHadNativeModuleCalls = m_batchHadNativeModuleCalls || !calls.empty();
+
       // An exception anywhere in here stops processing of the batch.  This
       // was the behavior of the Android bridge, and since exception handling
       // terminates the whole bridge, there's not much point in continuing.
@@ -57,7 +59,10 @@ public:
           token, call.moduleId, call.methodId, std::move(call.arguments), call.callId);
       }
       if (isEndOfBatch) {
-        m_callback->onBatchComplete();
+        if (m_batchHadNativeModuleCalls) {
+          m_callback->onBatchComplete();
+          m_batchHadNativeModuleCalls = false;
+        }
         m_callback->decrementPendingJSCalls();
       }
     });
@@ -85,6 +90,7 @@ private:
   std::shared_ptr<ModuleRegistry> m_registry;
   std::unique_ptr<MessageQueueThread> m_nativeQueue;
   std::shared_ptr<InstanceCallback> m_callback;
+  bool m_batchHadNativeModuleCalls = false;
 };
 
 NativeToJsBridge::NativeToJsBridge(