compositor-worker: Share a thread and an isolate for compositor workers.

Source/core/workers/WorkerThread.h

 /*
  * 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 14 matching lines @@
  */
 
 #ifndef WorkerThread_h
 #define WorkerThread_h
 
 #include "core/CoreExport.h"
 #include "core/dom/ExecutionContextTask.h"
 #include "core/frame/csp/ContentSecurityPolicy.h"
 #include "core/workers/WorkerGlobalScope.h"
 #include "core/workers/WorkerLoaderProxy.h"
+#include "core/workers/WorkerV8Isolate.h"
 #include "platform/WebThreadSupportingGC.h"
 #include "platform/weborigin/SecurityOrigin.h"
 #include "wtf/Forward.h"
 #include "wtf/MessageQueue.h"
 #include "wtf/OwnPtr.h"
 #include "wtf/PassRefPtr.h"
 #include "wtf/RefCounted.h"
 #include <v8.h>
 
 namespace blink {
@@ skipping 17 matching lines @@
     virtual ~WorkerThread();
 
     virtual void start(PassOwnPtr<WorkerThreadStartupData>);
     virtual void stop();
 
     // Returns the thread this worker runs on. Some implementations can create
     // a new thread on the first call (e.g. shared, dedicated workers), whereas
     // some implementations can use an existing thread that is already being
     // used by other workers (e.g.  compositor workers).
     virtual WebThreadSupportingGC& backingThread() = 0;
-
-    virtual void didStartRunLoop();
     virtual void didStopRunLoop();
 
-    v8::Isolate* isolate() const { return m_isolate; }
+    v8::Isolate* isolate();
 
     // Can be used to wait for this worker thread to shut down.
     // (This is signalled on the main thread, so it's assumed to be waited on the worker context thread)
     WebWaitableEvent* shutdownEvent() { return m_shutdownEvent.get(); }
 
     WebWaitableEvent* terminationEvent() { return m_terminationEvent.get(); }
     void terminateAndWait();
     static void terminateAndWaitForAllWorkers();
 
     bool isCurrentThread();
@@ skipping 28 matching lines @@
     void setWorkerInspectorController(WorkerInspectorController*);
 
 protected:
     WorkerThread(PassRefPtr<WorkerLoaderProxy>, WorkerReportingProxy&);
 
     // Factory method for creating a new worker context for the thread.
     virtual PassRefPtrWillBeRawPtr<WorkerGlobalScope> createWorkerGlobalScope(PassOwnPtr<WorkerThreadStartupData>) = 0;
 
     virtual void postInitialize() { }
 
-    virtual v8::Isolate* initializeIsolate();
-    virtual void willDestroyIsolate();
-    virtual void destroyIsolate();
+    virtual OwnPtr<WorkerV8Isolate>& workerIsolate() = 0;

[kinuko, 2015/05/29 17:45:18]

Returning OwnPtr but not for the caller to take ownership looks a bit uncommon
to me... hmm.

I think the functionality wise this change (or previous change) looks good to
me, but in general I'm feeling that the WorkerThread's interface is getting less
and less organized.  I can't come up with a good plan for now though.

[sadrul, 2015/05/29 18:26:32]

With this change:

. For managing the WebThread: WorkerThread now has initializeBackingThread(),
shutdownBackingThread(), and backingThread(). (I am not counting
didStartRunLoop() and didStopRunLoop(), since these are more about setting
things up in chrome-land than managing the thread)

. For managing the v8::Isolate: WorkerThread now has workerIsolate(),
terminateV8Execution(), and isolate() (since this CL is also removing some
now-unnecessary isolate-managing functions).

Both of the sets are fairly small, and pretty self-explanatory. Is there
anything specific you think looks ugly/untidy that I could address?

     virtual void terminateV8Execution();
 
+    virtual void didStartRunLoop();

[kinuko, 2015/05/29 17:45:18]

nit: I think this can be public as far as didStartRunLoop() is public, mainly
for symmetricity and readability.

[sadrul, 2015/05/29 18:26:32]

Acknowledged. Will make this change.

[sadrul, 2015/06/01 05:24:11]

Done.

+    virtual void initializeBackingThread();
+    virtual void shutdownBackingThread();
+
     // This is protected virtual for testing.
     virtual bool doIdleGc(double deadlineSeconds);
 
 private:
     friend class WorkerSharedTimer;
     friend class WorkerMicrotaskRunner;
 
     void stopInShutdownSequence();
     void stopInternal();
 
     void initialize(PassOwnPtr<WorkerThreadStartupData>);
     void shutdown();
     void performIdleWork(double deadlineSeconds);
     void postDelayedTask(const WebTraceLocation&, PassOwnPtr<ExecutionContextTask>, long long delayMs);
 
     bool m_started;
     bool m_terminated;
     bool m_shutdown;
     MessageQueue<WebThread::Task> m_debuggerMessageQueue;
     OwnPtr<WebThread::TaskObserver> m_microtaskRunner;
 
     RefPtr<WorkerLoaderProxy> m_workerLoaderProxy;
     WorkerReportingProxy& m_workerReportingProxy;
     RawPtr<WebScheduler> m_webScheduler; // Not owned.
 
     RefPtrWillBePersistent<WorkerInspectorController> m_workerInspectorController;
     Mutex m_workerInspectorControllerMutex;
 
-    // This lock protects |m_workerGlobalScope|, |m_terminated|, |m_isolate| and |m_microtaskRunner|.
+    // This lock protects |m_workerGlobalScope|, and |m_terminated|.
     Mutex m_threadStateMutex;
 
     RefPtrWillBePersistent<WorkerGlobalScope> m_workerGlobalScope;
 
-    v8::Isolate* m_isolate;
-    OwnPtr<V8IsolateInterruptor> m_interruptor;
-
     // Used to signal thread shutdown.
     OwnPtr<WebWaitableEvent> m_shutdownEvent;
 
     // Used to signal thread termination.
     OwnPtr<WebWaitableEvent> m_terminationEvent;
 };
 
 } // namespace blink
 
 #endif // WorkerThread_h