Update WebWorkers API to return message object in onmessage

Summary:
public

I wasn't obeying the web workers API correctly: I had missed that the message isn't sent directly but is attached to a message object in a data field.

Reviewed By: lexs

Differential Revision: D2811247

fb-gh-sync-id: 8e51414766e0cfe382ee9bdde8f0d66e269cb83a

ReactAndroid/src/main/jni/react/JSCExecutor.cpp

@@ -239,14 +239,14 @@ std::shared_ptr<JMessageQueueThread> JSCExecutor::getMessageQueueThread() {
 }
 
 void JSCExecutor::onMessageReceived(int workerId, const std::string& json) {
-  Value rebornJSMsg = Value::fromJSON(m_context, String(json.c_str()));
-  JSValueRef args[] = { rebornJSMsg };
   Object& worker = m_webWorkerJSObjs.at(workerId);
 
   Value onmessageValue = worker.getProperty("onmessage");
   if (onmessageValue.isUndefined()) {
     return;
   }
+
+  JSValueRef args[] = { JSCWebWorker::createMessageObject(m_context, json) };
   onmessageValue.asObject().callAsFunction(1, args);
 
   m_flushImmediateCallback(flush(), true);

ReactAndroid/src/main/jni/react/JSCWebWorker.cpp

@@ -53,8 +53,8 @@ void JSCWebWorker::postMessage(JSValueRef msg) {
     if (isFinished()) {
       return;
     }
-    Value rebornJSMsg = Value::fromJSON(context_, String(msgString.c_str()));
-    JSValueRef args[] = { rebornJSMsg };
+
+    JSValueRef args[] = { createMessageObject(context_, msgString) };
     Value onmessageValue = Object::getGlobalObject(context_).getProperty("onmessage");
     onmessageValue.asObject().callAsFunction(1, args);
   });
@@ -111,5 +111,13 @@ JSValueRef JSCWebWorker::nativePostMessage(
   return JSValueMakeUndefined(ctx);
 }
 
+/*static*/
+Object JSCWebWorker::createMessageObject(JSContextRef context, const std::string& msgJson) {
+  Value rebornJSMsg = Value::fromJSON(context, String(msgJson.c_str()));
+  Object messageObject = Object::create(context);
+  messageObject.setProperty("data", rebornJSMsg);
+  return std::move(messageObject);
+}
+
 }
 }

ReactAndroid/src/main/jni/react/JSCWebWorker.h

@@ -58,6 +58,8 @@ public:
   void postMessage(JSValueRef msg);
   void finish();
   bool isFinished();
+
+  static Object createMessageObject(JSContextRef context, const std::string& msgData);
 private:
   void initJSVMAndLoadScript();
   void postRunnableToEventLoop(std::function<void()>&& runnable);

ReactAndroid/src/main/jni/react/Value.cpp

@@ -58,6 +58,10 @@ Object Value::asObject() {
   return std::move(ret);
 }
 
+Object::operator Value() const {
+  return Value(m_context, m_obj);
+}
+
 Value Object::callAsFunction(int nArgs, JSValueRef args[]) {
   JSValueRef exn;
   JSValueRef result = JSObjectCallAsFunction(m_context, m_obj, NULL, nArgs, args, &exn);
@@ -68,7 +72,7 @@ Value Object::callAsFunction(int nArgs, JSValueRef args[]) {
   return Value(m_context, result);
 }
 
-Value Object::getProperty(String propName) const {
+Value Object::getProperty(const String& propName) const {
   JSValueRef exn;
   JSValueRef property = JSObjectGetProperty(m_context, m_obj, propName, &exn);
   if (!property) {
@@ -82,4 +86,26 @@ Value Object::getProperty(const char *propName) const {
   return getProperty(String(propName));
 }
 
+void Object::setProperty(const String& propName, const Value& value) const {
+  JSValueRef exn = NULL;
+  JSObjectSetProperty(m_context, m_obj, propName, value, kJSPropertyAttributeNone, &exn);
+  if (exn) {
+    std::string exceptionText = Value(m_context, exn).toString().str();
+    throwJSExecutionException("Failed to set property: %s", exceptionText.c_str());
+  }
+}
+
+void Object::setProperty(const char *propName, const Value& value) const {
+  setProperty(String(propName), value);
+}
+
+/* static */
+Object Object::create(JSContextRef ctx) {
+  JSObjectRef newObj = JSObjectMake(
+      ctx,
+      NULL, // create instance of default object class
+      NULL); // no private data
+  return Object(ctx, newObj);
+}
+
 } }

ReactAndroid/src/main/jni/react/Value.h

@@ -111,14 +111,18 @@ public:
     return m_obj;
   }
 
+  operator Value() const;
+
   bool isFunction() const {
     return JSObjectIsFunction(m_context, m_obj);
   }
 
   Value callAsFunction(int nArgs, JSValueRef args[]);
 
-  Value getProperty(String propName) const;
+  Value getProperty(const String& propName) const;
   Value getProperty(const char *propName) const;
+  void setProperty(const String& propName, const Value& value) const;
+  void setProperty(const char *propName, const Value& value) const;
 
   void makeProtected() {
     if (!m_isProtected && m_obj) {
@@ -132,6 +136,11 @@ public:
     return Object(ctx, globalObj);
   }
 
+  /**
+   * Creates an instance of the default object class.
+   */
+  static Object create(JSContextRef ctx);
+
 private:
   JSContextRef m_context;
   JSObjectRef m_obj;