From f8b683b3ee5ef4b2b84968db9c3023c59bf99220 Mon Sep 17 00:00:00 2001
From: Dmitry Zakharov <comfly@fb.com>
Date: Mon, 15 May 2017 09:12:24 -0700
Subject: [PATCH] Copy-free Source loading implementation

Reviewed By: amnn

Differential Revision: D4914165

fbshipit-source-id: 38851679cb696c41f59edfd0d2005faf37813b23
---
 ReactCommon/cxxreact/JSCExecutor.cpp | 21 +++++++++++++++++++--
 ReactCommon/cxxreact/JSCExecutor.h   |  2 ++
 2 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/ReactCommon/cxxreact/JSCExecutor.cpp b/ReactCommon/cxxreact/JSCExecutor.cpp
index 2aaf9d8e8a9..681914fa0b6 100644
--- a/ReactCommon/cxxreact/JSCExecutor.cpp
+++ b/ReactCommon/cxxreact/JSCExecutor.cpp
@@ -357,9 +357,12 @@ void JSCExecutor::loadApplicationScript(std::unique_ptr<const JSBigString> scrip
     {
       SystraceSection s_("JSCExecutor::loadApplicationScript-createExpectingAscii");
       ReactMarker::logMarker(ReactMarker::JS_BUNDLE_STRING_CONVERT_START);
-      jsScript = jsStringFromBigString(m_context, *script);
+      jsScript = adoptString(std::move(script));
       ReactMarker::logMarker(ReactMarker::JS_BUNDLE_STRING_CONVERT_STOP);
     }
+    #ifdef WITH_FBSYSTRACE
+    fbsystrace_end_section(TRACE_TAG_REACT_CXX_BRIDGE);
+    #endif
 
     SystraceSection s_("JSCExecutor::loadApplicationScript-evaluateScript");
     evaluateScript(m_context, jsScript, jsSourceURL);
@@ -521,13 +524,27 @@ void JSCExecutor::setGlobalVariable(std::string propName, std::unique_ptr<const
   try {
     SystraceSection s("JSCExecutor::setGlobalVariable", "propName", propName);
 
-    auto valueToInject = Value::fromJSON(m_context, jsStringFromBigString(m_context, *jsonValue));
+    auto valueToInject = Value::fromJSON(m_context, adoptString(std::move(jsonValue)));
     Object::getGlobalObject(m_context).setProperty(propName.c_str(), valueToInject);
   } catch (...) {
     std::throw_with_nested(std::runtime_error("Error setting global variable: " + propName));
   }
 }
 
+String JSCExecutor::adoptString(std::unique_ptr<const JSBigString> script) {
+#if defined(WITH_FBJSCEXTENSIONS)
+  const JSBigString* string = script.release();
+  auto jsString = JSStringCreateAdoptingExternal(string->c_str(), string->size(), (void*)string, [](void* s) {
+    delete static_cast<JSBigString*>(s);
+  });
+  return String::adopt(m_context, jsString);
+#else
+  return script->isAscii()
+    ? String::createExpectingAscii(m_context, script->c_str(), script->size())
+    : String(m_context, script->c_str());
+#endif
+}
+
 void* JSCExecutor::getJavaScriptContext() {
   return m_context;
 }
diff --git a/ReactCommon/cxxreact/JSCExecutor.h b/ReactCommon/cxxreact/JSCExecutor.h
index bf5560c90bb..473cca7c754 100644
--- a/ReactCommon/cxxreact/JSCExecutor.h
+++ b/ReactCommon/cxxreact/JSCExecutor.h
@@ -113,6 +113,8 @@ private:
   void flushQueueImmediate(Value&&);
   void loadModule(uint32_t moduleId);
 
+  String adoptString(std::unique_ptr<const JSBigString>);
+
   template<JSValueRef (JSCExecutor::*method)(size_t, const JSValueRef[])>
   void installNativeHook(const char* name);
   JSValueRef getNativeModule(JSObjectRef object, JSStringRef propertyName);