Adding Pre-PArsing cache & StringRef to iOS 8's JSC

Reviewed By: michalgr

Differential Revision: D3066370

fb-gh-sync-id: 2dabffbd41d4f4f9f2a9ddaca3224ba00498821e
shipit-source-id: 2dabffbd41d4f4f9f2a9ddaca3224ba00498821e

Author: dcaspi

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

@@ -205,19 +205,37 @@ void JSCExecutor::terminateOnJSVMThread() {
   m_context = nullptr;
 }
 
+// Checks if the user is in the pre-parsing cache & StringRef QE.
+// Should be removed when these features are no longer gated.
+bool JSCExecutor::usePreparsingAndStringRef(){
+  return m_jscConfig.getDefault("PreparsingStringRef", true).getBool();
+}
+
 void JSCExecutor::loadApplicationScript(
     const std::string& script,
     const std::string& sourceURL) {
   ReactMarker::logMarker("loadApplicationScript_startStringConvert");
+#if WITH_FBJSCEXTENSIONS
+  JSStringRef jsScriptRef;
+  if (usePreparsingAndStringRef()){
+    jsScriptRef = JSStringCreateWithUTF8CStringExpectAscii(script.c_str(), script.size());
+  } else {
+    jsScriptRef = JSStringCreateWithUTF8CString(script.c_str());
+  }
+
+  String jsScript = String::adopt(jsScriptRef);
+#else
   String jsScript = String::createExpectingAscii(script);
+#endif
+  
   ReactMarker::logMarker("loadApplicationScript_endStringConvert");
 
   String jsSourceURL(sourceURL.c_str());
   #ifdef WITH_FBSYSTRACE
   FbSystraceSection s(TRACE_TAG_REACT_CXX_BRIDGE, "JSCExecutor::loadApplicationScript",
     "sourceURL", sourceURL);
   #endif
-  if (!jsSourceURL) {
+  if (!jsSourceURL || !usePreparsingAndStringRef()) {
     evaluateScript(m_context, jsScript, jsSourceURL);
   } else {
     // If we're evaluating a script, get the device's cache dir

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

@@ -113,6 +113,7 @@ class JSCExecutor : public JSExecutor {
   void receiveMessageFromOwner(const std::string &msgString);
   void terminateOwnedWebWorker(int worker);
   Object createMessageObject(const std::string& msgData);
+  bool usePreparsingAndStringRef();
 
   static JSValueRef nativeStartWorker(
       JSContextRef ctx,

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

@@ -38,7 +38,9 @@ JSValueRef makeJSCException(
 JSValueRef evaluateScript(JSContextRef context, JSStringRef script, JSStringRef source, const char *cachePath) {
   JSValueRef exn, result;
 #if WITH_FBJSCEXTENSIONS
-  if (source){
+  // Only evaluate the script using pre-parsing cache if the script comes from
+  //  a bundle file and a cache path is given.
+  if (source && cachePath){
     // If evaluating an application script, send it through `JSEvaluateScriptWithCache()`
     //  to add cache support.
     result = JSEvaluateScriptWithCache(context, script, NULL, source, 0, &exn, cachePath);