Issue #3593, #1197- fix isolate management

src/JsEngine.cpp

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
- * Copyright (C) 2006-2015 Eyeo GmbH
+ * Copyright (C) 2006-2016 Eyeo GmbH
  *
  * Adblock Plus is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 3 as
  * published by the Free Software Foundation.
  *
  * Adblock Plus is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with Adblock Plus.  If not, see <http://www.gnu.org/licenses/>.
  */
 
 #include <AdblockPlus.h>
-
 #include "GlobalJsObject.h"
 #include "JsContext.h"
 #include "JsError.h"
 #include "Utils.h"
 
 namespace
 {
   v8::Handle<v8::Script> CompileScript(v8::Isolate* isolate,
     const std::string& source, const std::string& filename)
   {
@@ skipping 29 matching lines @@
     static void Init()
     {
       // it's threadsafe since C++11 and it will be instantiated only once and
       // destroyed at the application exit
       static V8Initializer initializer;
     }
   };
 }
 
 AdblockPlus::ScopedV8Isolate::ScopedV8Isolate()
-  : isolate(v8::Isolate::New())

[Eric, 2015/08/05 22:29:16]

This is changing the behavior non-trivially, since initializing v8 creates an
isolate by default. Calling 'New()' here would (I think) abandon the default
instance.

Regardless, initialization policy seems like a different issue from getting
order of initialization right.

[sergei, 2015/11/16 16:52:09]

There is no any default isolate. It `v8::Isolate::GetCurrent` returns the
isolate, pointer on which is stored thread local storage.
Sorry, I don't understand about which issues you are talking here. The changes
here are part of updating of v8. In newer v8 one may not use
`v8::Isolate::GetCurrent()` when isolate is not initialized yet, so we need to
create it.

[Eric, 2015/11/17 21:27:43]

Sure there is. See isolate.cc:340
    Isolate* Isolate::default_isolate_ = NULL;
And also see isolate.c:396
    void Isolate::EnsureDefaultIsolate() {

In the current v8 code, each thread has a default isolate. When you call New()
instead of GetCurrent(), you're changing behavior by discarding the default
isolate that's initialized on the thread.

After quite a bit of research, it seems that there's no longer a default
isolate:
    https://code.google.com/p/chromium/issues/detail?id=359977

I'd suggest that a line of documentation is in order here.

-{
+{
+  V8Initializer::Init();
+  isolate = v8::Isolate::New();
 }
 
 AdblockPlus::ScopedV8Isolate::~ScopedV8Isolate()
 {
   isolate->Dispose();

[Eric, 2015/08/05 22:29:16]

If we initialize with 'New()' rather than 'GetCurrent()', then we need to call
'Dispose()'. Otherwise we don't.

Even if we do need it, we don't need it in a destructor of a separate class. v8,
as a Google creature, doesn't do RAII or throw its own exceptions.

[sergei, 2015/11/16 16:52:09]

Do you mean we should create a typedef on `std::shared_ptr` for example?
Google may be does not do RAII in v8 but it's a reason for us to avoid RAII.

[Eric, 2015/11/17 21:27:43]

No.
And I'm not arguing against RAII.

I am arguing that we don't need a separate class for a destructor to call
Dispose() in. Such a destructor can be called in the destructor for JsEngine. 

My point about Google's practice is that Isolate::New() does not throw, so we
can just initialize it in the constructor for JsEngine without any trouble.

   isolate = nullptr;
 }
 
-AdblockPlus::JsEngine::JsEngine()
-{
-}
-
-AdblockPlus::JsEnginePtr AdblockPlus::JsEngine::New(const AppInfo& appInfo)
-{
-  V8Initializer::Init();
-  JsEnginePtr result(new JsEngine());
-
-  const v8::Locker locker(result->isolate);
-  const v8::Isolate::Scope isolateScope(result->isolate);
-  const v8::HandleScope handleScope(result->isolate);
-
-  result->context.reset(result->isolate, v8::Context::New(result->isolate));
+AdblockPlus::JsEngine::JsEngine(const ScopedV8IsolatePtr& isolate)
+  : isolate(isolate)
+{
+}
+
+AdblockPlus::JsEnginePtr AdblockPlus::JsEngine::New(const AppInfo& appInfo, const ScopedV8IsolatePtr& isolate)
+{
+  JsEnginePtr result(new JsEngine(isolate));
+
+  const v8::Locker locker(result->GetIsolate());
+  const v8::Isolate::Scope isolateScope(result->GetIsolate());
+  const v8::HandleScope handleScope(result->GetIsolate());
+
+  result->context.reset(new v8::Persistent<v8::Context>(result->GetIsolate(),
+    v8::Context::New(result->GetIsolate())));
   v8::Local<v8::Object> globalContext = v8::Local<v8::Context>::New(
-    result->isolate, result->context)->Global();
-  AdblockPlus::GlobalJsObject::Setup(result, appInfo,
-    JsValuePtr(new JsValue(result, globalContext)));
+    result->GetIsolate(), *result->context)->Global();
+  result->globalJsObject = JsValuePtr(new JsValue(result, globalContext));
+  AdblockPlus::GlobalJsObject::Setup(result, appInfo, result->globalJsObject);
   return result;
 }
 
 AdblockPlus::JsValuePtr AdblockPlus::JsEngine::Evaluate(const std::string& source,
     const std::string& filename)
 {
   const JsContext context(shared_from_this());
   const v8::TryCatch tryCatch;
-  const v8::Handle<v8::Script> script = CompileScript(isolate, source,
+  const v8::Handle<v8::Script> script = CompileScript(GetIsolate(), source,
     filename);
   CheckTryCatch(tryCatch);
   v8::Local<v8::Value> result = script->Run();
   CheckTryCatch(tryCatch);
   return JsValuePtr(new JsValue(shared_from_this(), result));
 }
 
 void AdblockPlus::JsEngine::SetEventCallback(const std::string& eventName,
     AdblockPlus::JsEngine::EventCallback callback)
 {
@@ skipping 14 matching lines @@
 
 void AdblockPlus::JsEngine::Gc()
 {
   while (!v8::V8::IdleNotification());
 }
 
 AdblockPlus::JsValuePtr AdblockPlus::JsEngine::NewValue(const std::string& val)
 {
   const JsContext context(shared_from_this());
   return JsValuePtr(new JsValue(shared_from_this(),
-    Utils::ToV8String(isolate, val)));
+    Utils::ToV8String(GetIsolate(), val)));
 }
 
 AdblockPlus::JsValuePtr AdblockPlus::JsEngine::NewValue(int64_t val)
 {
   const JsContext context(shared_from_this());
   return JsValuePtr(new JsValue(shared_from_this(),
-    v8::Number::New(isolate, val)));
+    v8::Number::New(GetIsolate(), val)));
 }
 
 AdblockPlus::JsValuePtr AdblockPlus::JsEngine::NewValue(bool val)
 {
   const JsContext context(shared_from_this());
   return JsValuePtr(new JsValue(shared_from_this(), v8::Boolean::New(val)));
 }
 
 AdblockPlus::JsValuePtr AdblockPlus::JsEngine::NewObject()
 {
   const JsContext context(shared_from_this());
   return JsValuePtr(new JsValue(shared_from_this(), v8::Object::New()));
 }
 
 AdblockPlus::JsValuePtr AdblockPlus::JsEngine::NewCallback(
     v8::InvocationCallback callback)
 {
   const JsContext context(shared_from_this());
 
   // Note: we are leaking this weak pointer, no obvious way to destroy it when
   // it's no longer used
-  std::tr1::weak_ptr<JsEngine>* data =
-      new std::tr1::weak_ptr<JsEngine>(shared_from_this());
+  std::weak_ptr<JsEngine>* data =
+      new std::weak_ptr<JsEngine>(shared_from_this());
   v8::Local<v8::FunctionTemplate> templ = v8::FunctionTemplate::New(callback,
       v8::External::New(data));
   return JsValuePtr(new JsValue(shared_from_this(), templ->GetFunction()));
 }
 
 AdblockPlus::JsEnginePtr AdblockPlus::JsEngine::FromArguments(const v8::Arguments& arguments)
 {
   const v8::Local<const v8::External> external =
       v8::Local<const v8::External>::Cast(arguments.Data());
-  std::tr1::weak_ptr<JsEngine>* data =
-      static_cast<std::tr1::weak_ptr<JsEngine>*>(external->Value());
+  std::weak_ptr<JsEngine>* data =
+      static_cast<std::weak_ptr<JsEngine>*>(external->Value());
   JsEnginePtr result = data->lock();
   if (!result)
     throw std::runtime_error("Oops, our JsEngine is gone, how did that happen?");
   return result;
 }
 
 AdblockPlus::JsValueList AdblockPlus::JsEngine::ConvertArguments(const v8::Arguments& arguments)
 {
   const JsContext context(shared_from_this());
   JsValueList list;
@@ skipping 39 matching lines @@
   return logSystem;
 }
 
 void AdblockPlus::JsEngine::SetLogSystem(AdblockPlus::LogSystemPtr val)
 {
   if (!val)
     throw std::runtime_error("LogSystem cannot be null");
 
   logSystem = val;
 }
+
+
+void AdblockPlus::JsEngine::SetGlobalProperty(const std::string& name, 
+                                              AdblockPlus::JsValuePtr value)
+{
+  if (!globalJsObject)
+    throw std::runtime_error("Global object cannot be null");
+
+  globalJsObject->SetProperty(name, value);
+}