Refactor TimeBase to post tasks. Workers to use real Idle tasks.

Source/core/workers/WorkerThread.cpp

Index: Source/core/workers/WorkerThread.cpp
diff --git a/Source/core/workers/WorkerThread.cpp b/Source/core/workers/WorkerThread.cpp
index f59a49182a66ff3dcd4b57653f081d209767d181..292b10a626e8a442a8a9c1515a71c8b095555c95 100644
--- a/Source/core/workers/WorkerThread.cpp
+++ b/Source/core/workers/WorkerThread.cpp
@@ -38,14 +38,13 @@
 #include "core/workers/WorkerClients.h"
 #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"
@@ -55,8 +54,7 @@
 namespace blink {
 
 namespace {
-const int64_t kShortIdleHandlerDelayMs = 1000;
-const int64_t kLongIdleHandlerDelayMs = 10*1000;
+const double kLongIdleHandlerDelaySecs = 1.0;
 
 class MicrotaskRunner : public WebThread::TaskObserver {
 public:
@@ -101,100 +99,6 @@ unsigned WorkerThread::workerThreadCount()
     return workerThreads().size();
 }
 
-class WorkerThreadCancelableTask final : public ExecutionContextTask {
-    WTF_MAKE_NONCOPYABLE(WorkerThreadCancelableTask); WTF_MAKE_FAST_ALLOCATED(WorkerThreadCancelableTask);
-public:
-    static PassOwnPtr<WorkerThreadCancelableTask> create(PassOwnPtr<Closure> closure)
-    {
-        return adoptPtr(new WorkerThreadCancelableTask(closure));
-    }
-
-    virtual ~WorkerThreadCancelableTask() { }
-
-    virtual void performTask(ExecutionContext*) override
-    {
-        if (!m_taskCanceled)
-            (*m_closure)();
-    }
-
-    WeakPtr<WorkerThreadCancelableTask> createWeakPtr() { return m_weakFactory.createWeakPtr(); }
-    void cancelTask() { m_taskCanceled = true; }
-
-private:
-    explicit WorkerThreadCancelableTask(PassOwnPtr<Closure> closure)
-        : m_closure(closure)
-        , m_weakFactory(this)
-        , m_taskCanceled(false)
-    { }
-
-    OwnPtr<Closure> m_closure;
-    WeakPtrFactory<WorkerThreadCancelableTask> m_weakFactory;
-    bool m_taskCanceled;
-};
-
-class WorkerSharedTimer : public SharedTimer {
-public:
-    explicit WorkerSharedTimer(WorkerThread* workerThread)
-        : m_workerThread(workerThread)
-        , m_running(false)
-    { }
-
-    typedef void (*SharedTimerFunction)();
-    virtual void setFiredFunction(SharedTimerFunction func)
-    {
-        m_sharedTimerFunction = func;
-    }
-
-    virtual void setFireInterval(double interval)
-    {
-        ASSERT(m_sharedTimerFunction);
-
-        // See BlinkPlatformImpl::setSharedTimerFireInterval for explanation of
-        // why ceil is used in the interval calculation.
-        int64_t delay = static_cast<int64_t>(ceil(interval * 1000));
-
-        if (delay < 0) {
-            delay = 0;
-        }
-
-        m_running = true;
-
-        if (m_lastQueuedTask.get())
-            m_lastQueuedTask->cancelTask();
-
-        // Now queue the task as a cancellable one.
-        OwnPtr<WorkerThreadCancelableTask> task = WorkerThreadCancelableTask::create(bind(&WorkerSharedTimer::OnTimeout, this));
-        m_lastQueuedTask = task->createWeakPtr();
-        m_workerThread->postDelayedTask(FROM_HERE, task.release(), delay);
-    }
-
-    virtual void stop()
-    {
-        m_running = false;
-        m_lastQueuedTask = nullptr;
-    }
-
-private:
-    void OnTimeout()
-    {
-        ASSERT(m_workerThread->workerGlobalScope());
-
-        m_lastQueuedTask = nullptr;
-
-        if (m_sharedTimerFunction && m_running && !m_workerThread->workerGlobalScope()->isClosing())
-            m_sharedTimerFunction();
-    }
-
-    WorkerThread* m_workerThread;
-    SharedTimerFunction m_sharedTimerFunction;
-    bool m_running;
-
-    // The task to run OnTimeout, if any. While OnTimeout resets
-    // m_lastQueuedTask, this must be a weak pointer because the
-    // worker runloop may delete the task as it is shutting down.
-    WeakPtr<WorkerThreadCancelableTask> m_lastQueuedTask;
-};
-
 class WorkerThreadTask : public blink::WebThread::Task {
     WTF_MAKE_NONCOPYABLE(WorkerThreadTask); WTF_MAKE_FAST_ALLOCATED(WorkerThreadTask);
 public:
@@ -265,6 +169,8 @@ WorkerThread::WorkerThread(const char* threadName, PassRefPtr<WorkerLoaderProxy>
     , m_isolate(nullptr)
     , m_shutdownEvent(adoptPtr(blink::Platform::current()->createWaitableEvent()))
     , m_terminationEvent(adoptPtr(blink::Platform::current()->createWaitableEvent()))
+    , m_webScheduler(nullptr)
+    , m_preShutdown(false)
 {
     MutexLocker lock(threadSetMutex());
     workerThreads().add(this);
@@ -283,6 +189,7 @@ void WorkerThread::start()
         return;
 
     m_thread = createWebThreadSupportingGC();
+    m_webScheduler = m_thread->platformThread().scheduler();
     m_thread->postTask(FROM_HERE, new Task(threadSafeBind(&WorkerThread::initialize, AllowCrossThreadAccess(this))));
 }
 
@@ -300,6 +207,24 @@ PlatformThreadId WorkerThread::platformThreadId() const
     return m_thread->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.
+class WorkerThreadIdleTask : public WebThread::IdleTask {
+public:
+    explicit WorkerThreadIdleTask(WorkerThread* thread)
+        : m_thread(thread) { }
+
+    ~WorkerThreadIdleTask() override { }
+
+    void run(double deadlineSeconds) override
+    {
+        m_thread->idleTask(deadlineSeconds);
+    }
+
+private:
+    RawPtr<WorkerThread> m_thread; // NOT OWNED
+};
+
 void WorkerThread::initialize()
 {
     KURL scriptURL = m_startupData->m_scriptURL;
@@ -326,8 +251,6 @@ void WorkerThread::initialize()
         m_isolate = initializeIsolate();
         m_workerGlobalScope = createWorkerGlobalScope(m_startupData.release());
         m_workerGlobalScope->scriptLoaded(sourceCode.length(), cachedMetaData.get() ? cachedMetaData->size() : 0);
-
-        PlatformThreadData::current().threadTimers().setSharedTimer(adoptPtr(new WorkerSharedTimer(this)));
     }
 
     // The corresponding call to stopRunLoop() is in ~WorkerScriptController().
@@ -349,7 +272,7 @@ void WorkerThread::initialize()
 
     postInitialize();
 
-    postDelayedTask(FROM_HERE, createSameThreadTask(&WorkerThread::idleHandler, this), kShortIdleHandlerDelayMs);
+    m_webScheduler->postIdleTaskAfterWakeup(FROM_HERE, new WorkerThreadIdleTask(this));
 }
 
 PassOwnPtr<WebThreadSupportingGC> WorkerThread::createWebThreadSupportingGC()
@@ -382,9 +305,6 @@ void WorkerThread::cleanup()
     workerReportingProxy().workerThreadTerminated();
 
     m_terminationEvent->signal();
-
-    // Clean up PlatformThreadData before WTF::WTFThreadData goes away!
-    PlatformThreadData::current().destroy();
 }
 
 class WorkerThreadShutdownFinishTask : public ExecutionContextTask {
@@ -401,7 +321,7 @@ public:
 
         WorkerThread* workerThread = workerGlobalScope->thread();
         workerThread->willDestroyIsolate();
-        workerThread->m_thread->postTask(FROM_HERE, new Task(WTF::bind(&WorkerThread::cleanup, workerThread)));
+        workerThread->m_webScheduler->postShutdownTask(FROM_HERE, new Task(WTF::bind(&WorkerThread::cleanup, workerThread)), 0);
     }
 
     virtual bool isCleanupTask() const { return true; }
@@ -418,7 +338,6 @@ public:
     {
         WorkerGlobalScope* workerGlobalScope = toWorkerGlobalScope(context);
         workerGlobalScope->stopActiveDOMObjects();
-        PlatformThreadData::current().threadTimers().setSharedTimer(nullptr);
 
         // Event listeners would keep DOMWrapperWorld objects alive for too long. Also, they have references to JS objects,
         // which become dangling once Heap is destroyed.
@@ -432,6 +351,41 @@ public:
     virtual bool isCleanupTask() const { return true; }
 };
 
+class PreShutDownTask : public WebThread::Task {
+public:
+    PreShutDownTask(WebWaitableEvent* completion, WebScheduler* webScheduler)
+        : m_completion(completion)
+        , m_webScheduler(webScheduler) { }
+
+    ~PreShutDownTask() override { }
+
+    void run()
+    {
+        m_webScheduler->preShutdown();
+        m_completion->signal();
+    }
+
+private:
+    RawPtr<WebWaitableEvent> m_completion; // NOT OWNED.
+    RawPtr<WebScheduler> m_webScheduler; // NOT OWNED.
+};
+
+void WorkerThread::preShutdown()
+{
+    MutexLocker lock(m_preShutdownMutex);
+    if (m_preShutdown || !m_webScheduler)
+        return;
+    m_preShutdown = true;
+
+    if (m_thread->isCurrentThread()) {
+        m_webScheduler->preShutdown();
+    } else {
+        OwnPtr<WebWaitableEvent> completion(adoptPtr(blink::Platform::current()->createWaitableEvent()));
+        m_thread->postTask(FROM_HERE, new PreShutDownTask(completion.get(), m_webScheduler.get()));
+        completion->wait();
+    }
+}
+
 void WorkerThread::stop()
 {
     // Prevent the deadlock between GC and an attempt to stop a thread.
@@ -459,26 +413,30 @@ bool WorkerThread::terminated()
 void WorkerThread::stopInternal()
 {
     // Protect against this method and initialize() racing each other.
-    MutexLocker lock(m_threadCreationMutex);
+    {
+        MutexLocker lock(m_threadCreationMutex);
 
-    // If stop has already been called, just return.
-    if (m_terminated)
-        return;
-    m_terminated = true;
+        // If stop has already been called, just return.
+        if (m_terminated)
+            return;
+        m_terminated = true;
 
-    // Signal the thread to notify that the thread's stopping.
-    if (m_shutdownEvent)
-        m_shutdownEvent->signal();
+        // Signal the thread to notify that the thread's stopping.
+        if (m_shutdownEvent)
+            m_shutdownEvent->signal();
 
-    if (!m_workerGlobalScope)
-        return;
+        if (!m_workerGlobalScope)
+            return;
 
-    // Ensure that tasks are being handled by thread event loop. If script execution weren't forbidden, a while(1) loop in JS could keep the thread alive forever.
-    terminateV8Execution();
+        // Ensure that tasks are being handled by thread event loop. If script execution weren't forbidden, a while(1) loop in JS could keep the thread alive forever.
+        terminateV8Execution();
 
-    InspectorInstrumentation::didKillAllExecutionContextTasks(m_workerGlobalScope.get());
-    m_debuggerMessageQueue.kill();
-    postTask(FROM_HERE, WorkerThreadShutdownStartTask::create());
+        InspectorInstrumentation::didKillAllExecutionContextTasks(m_workerGlobalScope.get());
+        m_debuggerMessageQueue.kill();
+        postTask(FROM_HERE, WorkerThreadShutdownStartTask::create());
+    }
+    // Prevent further execution of non-shutdown tasks on the thread.  Must happen after any v8 task has been terminated.
+    preShutdown();
 }
 
 void WorkerThread::didStartRunLoop()
@@ -510,31 +468,46 @@ bool WorkerThread::isCurrentThread() const
     return m_thread && m_thread->isCurrentThread();
 }
 
-void WorkerThread::idleHandler()
+void WorkerThread::idleTask(double deadlineSeconds)
 {
-    ASSERT(m_workerGlobalScope.get());
-    int64_t delay = kLongIdleHandlerDelayMs;
+    if (terminated())
+        return;
 
-    // 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;
-    }
+    double gcDeadlineSeconds = deadlineSeconds;
 
-    postDelayedTask(FROM_HERE, createSameThreadTask(&WorkerThread::idleHandler, this), delay);
+    // 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() + kLongIdleHandlerDelaySecs;
+
+    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)
 {
-    m_thread->postTask(location, WorkerThreadTask::create(*this, task, true).leakPtr());
+    if (task->isCleanupTask())
+        m_webScheduler->postShutdownTask(location, WorkerThreadTask::create(*this, task, true).leakPtr(), 0);
+    else
+        m_thread->postTask(location, WorkerThreadTask::create(*this, task, true).leakPtr());
 }
 
 void WorkerThread::postDelayedTask(const WebTraceLocation& location, PassOwnPtr<ExecutionContextTask> task, long long delayMs)
 {
-    m_thread->postDelayedTask(location, WorkerThreadTask::create(*this, task, true).leakPtr(), delayMs);
+    if (task->isCleanupTask())
+        m_webScheduler->postShutdownTask(location, WorkerThreadTask::create(*this, task, true).leakPtr(), delayMs);
+    else
+        m_thread->postDelayedTask(location, WorkerThreadTask::create(*this, task, true).leakPtr(), delayMs);
 }
 
 v8::Isolate* WorkerThread::initializeIsolate()