Add API for sync function calls

Reviewed By: javache

Differential Revision: D3897526

fbshipit-source-id: cadead316996ca7c1dd2b0d60d87945f5452640c

ReactCommon/cxxreact/Instance.h

@@ -55,6 +55,11 @@ class Instance {
   void callJSCallback(ExecutorToken token, uint64_t callbackId, folly::dynamic&& params);
   MethodCallResult callSerializableNativeHook(ExecutorToken token, unsigned int moduleId,
                                               unsigned int methodId, folly::dynamic&& args);
+  // This method is experimental, and may be modified or removed.
+  template <typename T>
+  Value callFunctionSync(const std::string& module, const std::string& method, T&& args) {
+    return nativeToJsBridge_->callFunctionSync(module, method, std::forward<T>(args));
+  }
 
   ExecutorToken getMainExecutorToken();
   void handleMemoryPressureUiHidden();

ReactCommon/cxxreact/JSCExecutor.cpp

@@ -118,7 +118,6 @@ JSCExecutor::JSCExecutor(std::shared_ptr<ExecutorDelegate> delegate,
     folly::dynamic::object
       ("remoteModuleConfig", std::move(nativeModuleConfig));
 
-
   SystraceSection t("setGlobalVariable");
   setGlobalVariable(
     "__fbBatchedBridgeConfig",
@@ -344,6 +343,7 @@ void JSCExecutor::bindBridge() throw(JSException) {
   m_callFunctionReturnFlushedQueueJS = batchedBridge.getProperty("callFunctionReturnFlushedQueue").asObject();
   m_invokeCallbackAndReturnFlushedQueueJS = batchedBridge.getProperty("invokeCallbackAndReturnFlushedQueue").asObject();
   m_flushedQueueJS = batchedBridge.getProperty("flushedQueue").asObject();
+  m_callFunctionReturnResultAndFlushedQueueJS = batchedBridge.getProperty("callFunctionReturnResultAndFlushedQueue").asObject();
 }
 
 void JSCExecutor::callNativeModules(Value&& value) {
@@ -405,6 +405,26 @@ void JSCExecutor::invokeCallback(const double callbackId, const folly::dynamic&
   callNativeModules(std::move(result));
 }
 
+Value JSCExecutor::callFunctionSyncWithValue(
+    const std::string& module, const std::string& method, Value args) {
+  SystraceSection s("JSCExecutor::callFunction");
+
+  Object result = m_callFunctionReturnResultAndFlushedQueueJS->callAsFunction({
+    Value(m_context, String::createExpectingAscii(module)),
+    Value(m_context, String::createExpectingAscii(method)),
+    std::move(args),
+  }).asObject();
+
+  Value length = result.getProperty("length");
+
+  if (!length.isNumber() || length.asInteger() != 2) {
+    std::runtime_error("Return value of a callFunction must be an array of size 2");
+  }
+
+  callNativeModules(result.getPropertyAtIndex(1));
+  return result.getPropertyAtIndex(0);
+}
+
 void JSCExecutor::setGlobalVariable(std::string propName, std::unique_ptr<const JSBigString> jsonValue) {
   try {
     SystraceSection s("JSCExecutor.setGlobalVariable",

ReactCommon/cxxreact/JSCExecutor.h

@@ -74,6 +74,12 @@ public:
   virtual void invokeCallback(
     const double callbackId,
     const folly::dynamic& arguments) override;
+  template <typename T>
+  Value callFunctionSync(
+      const std::string& module, const std::string& method, T&& args) {
+    return callFunctionSyncWithValue(module, method,
+                                     toValue(m_context, std::forward<T>(args)));
+  }
   virtual void setGlobalVariable(
     std::string propName,
     std::unique_ptr<const JSBigString> jsonValue) override;
@@ -101,6 +107,7 @@ private:
   folly::Optional<Object> m_invokeCallbackAndReturnFlushedQueueJS;
   folly::Optional<Object> m_callFunctionReturnFlushedQueueJS;
   folly::Optional<Object> m_flushedQueueJS;
+  folly::Optional<Object> m_callFunctionReturnResultAndFlushedQueueJS;
 
   /**
    * WebWorker constructor. Must be invoked from thread this Executor will run on.
@@ -115,6 +122,9 @@ private:
       const folly::dynamic& jscConfig);
 
   void initOnJSVMThread() throw(JSException);
+  // This method is experimental, and may be modified or removed.
+  Value callFunctionSyncWithValue(
+    const std::string& module, const std::string& method, Value value);
   void terminateOnJSVMThread();
   void bindBridge() throw(JSException);
   void callNativeModules(Value&&);

ReactCommon/cxxreact/NativeToJsBridge.h

@@ -11,6 +11,7 @@
 
 #include "Executor.h"
 #include "ExecutorToken.h"
+#include "JSCExecutor.h"
 #include "JSModulesUnbundle.h"
 #include "MessageQueueThread.h"
 #include "MethodCall.h"
@@ -80,6 +81,35 @@ public:
    */
   void invokeCallback(ExecutorToken executorToken, double callbackId, folly::dynamic&& args);
 
+  /**
+   * Executes a JS method on the given executor synchronously, returning its
+   * return value.  JSException will be thrown if JS throws an exception;
+   * another standard exception may be thrown for C++ bridge failures, or if
+   * the executor is not capable of synchronous calls.
+   *
+   * This method is experimental, and may be modified or removed.
+   *
+   * loadApplicationScriptSync() must be called and finished executing
+   * before callFunctionSync().
+   */
+  template <typename T>
+  Value callFunctionSync(const std::string& module, const std::string& method, T&& args) {
+    if (*m_destroyed) {
+      throw std::logic_error(
+        folly::to<std::string>("Synchronous call to ", module, ".", method,
+                               " after bridge is destroyed"));
+    }
+
+    JSCExecutor *jscExecutor = dynamic_cast<JSCExecutor*>(m_mainExecutor);
+    if (!jscExecutor) {
+      throw std::invalid_argument(
+        folly::to<std::string>("Executor type ", typeid(*m_mainExecutor).name(),
+                               " does not support synchronous calls"));
+    }
+
+    return jscExecutor->callFunctionSync(module, method, std::forward<T>(args));
+  }
+
   /**
    * Starts the JS application.  If unbundle is non-null, then it is
    * used to fetch JavaScript modules as individual scripts.