Schedule garbage collection on worker threads using idle tasks

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 28 matching lines @@
 #include "core/workers/WorkerReportingProxy.h"
 #include "core/workers/WorkerThreadStartupData.h"
 #include "platform/PlatformThreadData.h"
 #include "platform/Task.h"
 #include "platform/ThreadSafeFunctional.h"
 #include "platform/ThreadTimers.h"
 #include "platform/heap/SafePoint.h"
 #include "platform/heap/ThreadState.h"
 #include "platform/weborigin/KURL.h"
 #include "public/platform/Platform.h"
+#include "public/platform/WebScheduler.h"
 #include "public/platform/WebThread.h"
 #include "public/platform/WebWaitableEvent.h"
 #include "wtf/Noncopyable.h"
 #include "wtf/WeakPtr.h"
 #include "wtf/text/WTFString.h"
 
 namespace blink {
 
 namespace {
-const int64_t kShortIdleHandlerDelayMs = 1000;
-const int64_t kLongIdleHandlerDelayMs = 10*1000;
+const double kLongIdlePeriodSecs = 1.0;
 
 } // namespace
 
 class WorkerMicrotaskRunner : public WebThread::TaskObserver {
 public:
     explicit WorkerMicrotaskRunner(WorkerThread* workerThread)
         : m_workerThread(workerThread)
     {
     }
 
@@ skipping 190 matching lines @@
     explicit RunDebuggerQueueTask(WorkerThread* thread) : m_thread(thread) { }
 
     WorkerThread* m_thread;
 };
 
 WorkerThread::WorkerThread(PassRefPtr<WorkerLoaderProxy> workerLoaderProxy, WorkerReportingProxy& workerReportingProxy, PassOwnPtr<WorkerThreadStartupData> startupData)
     : m_started(false)
     , m_terminated(false)
     , m_workerLoaderProxy(workerLoaderProxy)
     , m_workerReportingProxy(workerReportingProxy)
+    , m_webScheduler(nullptr)
     , m_startupData(startupData)
     , m_isolate(nullptr)
     , m_shutdownEvent(adoptPtr(Platform::current()->createWaitableEvent()))
     , m_terminationEvent(adoptPtr(Platform::current()->createWaitableEvent()))
 {
     MutexLocker lock(threadSetMutex());
     workerThreads().add(this);
 }
 
 WorkerThread::~WorkerThread()
@@ skipping 19 matching lines @@
         m_workerInspectorController->interruptAndDispatchInspectorCommands();
 }
 
 PlatformThreadId WorkerThread::platformThreadId()
 {
     if (!m_started)
         return 0;
     return backingThread().platformThread().threadId();
 }
 
+// TODO(alexclarke): Use base::Bind instead of this class when the repo's merge. Unfortunately we
+// can't use WTF::bind because the type-erasure for member function pointers with parameters is broken.

[kinuko, 2015/05/13 06:10:52]

Could you give a bit more details about what's broken in WTF::bind? (This one
looks fine, but arbitrarily mixing up base::Bind and WTF::bind in the same code
base could be dangerous and I want to discourage doing so until we have some
guideline. Context: go/thread-safe-blink)

[Sami, 2015/05/13 17:54:19]

This part was written by Alex so I needed to reverse engineer it a bit. I think
the problem was that WTF::bind doesn't derive unbound variables automatically
like base::Bind, e.g.:

void func(int x) { ... }

(*WTF::bind(&func))(123)       // doesn't work because bind returns a
Function<void()>, not Function<void(int)>.

(*WTF::bind<int>(&func))(123)  // works.

I've now taken out this wrapper and replaced it with a bind<double>.

[kinuko, 2015/05/14 06:07:05]

Ah interesting. Thanks for the detail!

+class WorkerThreadIdleTask : public WebThread::IdleTask {
+public:
+    explicit WorkerThreadIdleTask(WorkerThread* thread)
+        : m_thread(thread) { }
+
+    ~WorkerThreadIdleTask() override { }
+
+    void run(double deadlineSeconds) override
+    {
+        m_thread->performIdleWork(deadlineSeconds);
+    }
+
+private:
+    RawPtr<WorkerThread> m_thread; // NOT OWNED
+};
+
 void WorkerThread::initialize()
 {
     KURL scriptURL = m_startupData->m_scriptURL;
     String sourceCode = m_startupData->m_sourceCode;
     WorkerThreadStartMode startMode = m_startupData->m_startMode;
     OwnPtr<Vector<char>> cachedMetaData = m_startupData->m_cachedMetaData.release();
     V8CacheOptions v8CacheOptions = m_startupData->m_v8CacheOptions;
 
+    m_webScheduler = backingThread().platformThread().scheduler();
     {
         MutexLocker lock(m_threadStateMutex);
 
         // The worker was terminated before the thread had a chance to run.
         if (m_terminated) {
             // Notify the proxy that the WorkerGlobalScope has been disposed of.
             // This can free this thread object, hence it must not be touched afterwards.
             m_workerReportingProxy.workerThreadTerminated();
             return;
         }
@@ skipping 21 matching lines @@
     if (startMode == PauseWorkerGlobalScopeOnStart)
         m_workerGlobalScope->workerInspectorController()->pauseOnStart();
 
     OwnPtr<CachedMetadataHandler> handler(workerGlobalScope()->createWorkerScriptCachedMetadataHandler(scriptURL, cachedMetaData.get()));
     bool success = script->evaluate(ScriptSourceCode(sourceCode, scriptURL), nullptr, handler.get(), v8CacheOptions);
     m_workerGlobalScope->didEvaluateWorkerScript();
     m_workerReportingProxy.didEvaluateWorkerScript(success);
 
     postInitialize();
 
-    postDelayedTask(FROM_HERE, createSameThreadTask(&WorkerThread::idleHandler, this), kShortIdleHandlerDelayMs);
+    m_webScheduler->postIdleTaskAfterWakeup(FROM_HERE, new WorkerThreadIdleTask(this));
 }
 
 void WorkerThread::shutdown()
 {
     MutexLocker lock(m_threadStateMutex);
     ASSERT(isCurrentThread());
 
     PlatformThreadData::current().threadTimers().setSharedTimer(nullptr);
     workerGlobalScope()->dispose();
     willDestroyIsolate();
@@ skipping 98 matching lines @@
 
     for (WorkerThread* thread : threads)
         thread->terminationEvent()->wait();
 }
 
 bool WorkerThread::isCurrentThread()
 {
     return m_started && backingThread().isCurrentThread();
 }
 
-void WorkerThread::idleHandler()
+void WorkerThread::performIdleWork(double deadlineSeconds)
 {
-    ASSERT(m_workerGlobalScope.get());
-    int64_t delay = kLongIdleHandlerDelayMs;
+    double gcDeadlineSeconds = deadlineSeconds;
 
-    // Do a script engine idle notification if the next event is distant enough.
-    const double kMinIdleTimespan = 0.3;
-    const double nextFireTime = PlatformThreadData::current().threadTimers().nextFireTime();
-    if (nextFireTime == 0.0 || nextFireTime > currentTime() + kMinIdleTimespan) {
-        bool hasMoreWork = !isolate()->IdleNotificationDeadline(Platform::current()->monotonicallyIncreasingTime() + 1.0);
-        if (hasMoreWork)
-            delay = kShortIdleHandlerDelayMs;
-    }
+    // The V8 GC does some GC steps (e.g. compaction) only when the idle notification is ~1s.
+    // TODO(rmcilroy): Refactor so extending the deadline like this this isn't needed.
+    if (m_webScheduler->canExceedIdleDeadlineIfRequired())
+        gcDeadlineSeconds = Platform::current()->monotonicallyIncreasingTime() + kLongIdlePeriodSecs;
 
-    postDelayedTask(FROM_HERE, createSameThreadTask(&WorkerThread::idleHandler, this), delay);
+    if (doIdleGc(gcDeadlineSeconds))
+        m_webScheduler->postIdleTaskAfterWakeup(FROM_HERE, new WorkerThreadIdleTask(this));
+    else
+        m_webScheduler->postIdleTask(FROM_HERE, new WorkerThreadIdleTask(this));
+}
+
+bool WorkerThread::doIdleGc(double deadlineSeconds)
+{
+    bool gcFinished = false;
+    if (deadlineSeconds > Platform::current()->monotonicallyIncreasingTime())
+        gcFinished = isolate()->IdleNotificationDeadline(deadlineSeconds);
+    return gcFinished;
 }
 
 void WorkerThread::postTask(const WebTraceLocation& location, PassOwnPtr<ExecutionContextTask> task)
 {
     backingThread().postTask(location, WorkerThreadTask::create(*this, task, true).leakPtr());
 }
 
 void WorkerThread::postDelayedTask(const WebTraceLocation& location, PassOwnPtr<ExecutionContextTask> task, long long delayMs)
 {
     backingThread().postDelayedTask(location, WorkerThreadTask::create(*this, task, true).leakPtr(), delayMs);
@@ skipping 73 matching lines @@
     InspectorInstrumentation::didLeaveNestedRunLoop(m_workerGlobalScope.get());
 }
 
 void WorkerThread::setWorkerInspectorController(WorkerInspectorController* workerInspectorController)
 {
     MutexLocker locker(m_workerInspectorControllerMutex);
     m_workerInspectorController = workerInspectorController;
 }
 
 } // namespace blink