Drop V8RecursionScope dependency on ExecutionContext

Source/core/workers/WorkerThread.cpp

 /*
  * Copyright (C) 2008 Apple Inc. All Rights Reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 268 matching lines @@
     InspectorInstrumentation::willEvaluateWorkerScript(workerGlobalScope(), startMode);
     script->evaluate(ScriptSourceCode(sourceCode, scriptURL));
 
     postInitialize();
 
     postDelayedTask(createSameThreadTask(&WorkerThread::idleHandler, this), kShortIdleHandlerDelayMs);
 }
 
 void WorkerThread::cleanup()
 {
-
     // This should be called before we start the shutdown procedure.
     workerReportingProxy().willDestroyWorkerGlobalScope();
 
     // The below assignment will destroy the context, which will in turn notify messaging proxy.
     // We cannot let any objects survive past thread exit, because no other thread will run GC or otherwise destroy them.
     // If Oilpan is enabled, we detach of the context/global scope, with the final heap cleanup below sweeping it out.
 #if !ENABLE(OILPAN)
     ASSERT(m_workerGlobalScope->hasOneRef());
 #endif
     m_workerGlobalScope->dispose();

[haraken, 2014/09/11 01:18:54]

I think you can call willBeDestroyed here (between line 298 and 299).

[jsbell, 2014/09/11 22:14:52]

Agreed, doing it here in cleanup() would be better and make worker thread
shutdown more similar to the main thread. The complication is that the path to
the isolate (WorkerGlobalScope -> WorkerScriptController -> v8::Isolate) is
broken by the WorkerThreadShutdownFinishTask which runs before cleanup() - line
343 calls workerGlobalScope->clearScript();

I considered passing the isolate through in the closure, but how about (latest
patch) moving the call into WorkerScriptController itself, since that is
responsible for initializing the V8PerContextData in the first place?

     m_workerGlobalScope = nullptr;
 

[haraken, 2014/09/11 01:18:54]

I think you can call willBeDestroyed here.

     ThreadState::current()->removeInterruptor(m_messageLoopInterruptor.get());
 
     // Detach the ThreadState, cleaning out the thread's heap by
     // performing a final GC. The cleanup operation will at the end
     // assert that the heap is empty. If the heap does not become
     // empty, there are still pointers into the heap and those
     // pointers will be dangling after thread termination because we
     // are destroying the heap. It is important to detach while the
     // thread is still valid. In particular, finalizers for objects in
     // the heap for this thread will need to access thread local data.
@@ skipping 18 matching lines @@
 class WorkerThreadShutdownFinishTask : public ExecutionContextTask {
 public:
     static PassOwnPtr<WorkerThreadShutdownFinishTask> create()
     {
         return adoptPtr(new WorkerThreadShutdownFinishTask());
     }
 
     virtual void performTask(ExecutionContext *context)
     {
         WorkerGlobalScope* workerGlobalScope = toWorkerGlobalScope(context);
+
+        V8PerIsolateData::willBeDestroyed(workerGlobalScope->script()->isolate());

[haraken, 2014/09/11 01:18:54]

Can we call this in WorkerThread::cleanup()? We want to call
V8PerIsolateData::willBeDestroyed at the very end of the thread execution but
before starting detaching the thread.

         workerGlobalScope->clearInspector();
         // It's not safe to call clearScript until all the cleanup tasks posted by functions initiated by WorkerThreadShutdownStartTask have completed.
         workerGlobalScope->clearScript();
         workerGlobalScope->thread()->m_thread->postTask(new Task(WTF::bind(&WorkerThread::cleanup, workerGlobalScope->thread())));
     }
 
     virtual bool isCleanupTask() const { return true; }
 };
 
 class WorkerThreadShutdownStartTask : public ExecutionContextTask {
@@ skipping 140 matching lines @@
     InspectorInstrumentation::didLeaveNestedRunLoop(m_workerGlobalScope.get());
 }
 
 void WorkerThread::setWorkerInspectorController(WorkerInspectorController* workerInspectorController)
 {
     MutexLocker locker(m_workerInspectorControllerMutex);
     m_workerInspectorController = workerInspectorController;
 }
 
 } // namespace blink