Introduce WorkerBackingThread

third_party/WebKit/Source/core/workers/WorkerBackingThread.cpp

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "core/workers/WorkerBackingThread.h"
+
+#include "bindings/core/v8/V8Binding.h"
+#include "bindings/core/v8/V8GCController.h"
+#include "bindings/core/v8/V8IdleTaskRunner.h"
+#include "bindings/core/v8/V8Initializer.h"
+#include "bindings/core/v8/V8PerIsolateData.h"
+#include "platform/RuntimeEnabledFeatures.h"
+#include "platform/ThreadSafeFunctional.h"
+#include "platform/WaitableEvent.h"
+#include "platform/WebThreadSupportingGC.h"
+#include "public/platform/Platform.h"
+#include "public/platform/WebTraceLocation.h"
+
+namespace blink {
+
+namespace {
+
+void noop(PassOwnPtr<WebThreadSupportingGC> thread) {}
+
+} // namespace
+
+WorkerBackingThread::WorkerBackingThread(const char* name)
+    : m_backingThread(WebThreadSupportingGC::create(name))
+    , m_isOwningThread(true)
+{
+}
+
+WorkerBackingThread::WorkerBackingThread(WebThread* thread)
+    : m_backingThread(WebThreadSupportingGC::createForThread(thread))
+    , m_isOwningThread(false)
+{
+}
+
+WorkerBackingThread::~WorkerBackingThread()
+{
+    ASSERT(!workerScriptCount());
+    if (!isMainThread()) {
+        // We need to destroy the backing thread in the main thread.
+        Platform::current()->mainThread()->taskRunner()->postTask(BLINK_FROM_HERE, threadSafeBind(&noop, m_backingThread.release()));

[kinuko, 2016/02/29 09:32:53]

So we make this class thread-safe-refcounted and post task here basically to
make the lifetime management self-contained within this class (and for making
things work for compositor worker)?  Posting tasks in dtor everywhere makes me
feel a bit nervous (as we're also introducing one in WebThreadSupportingGC), it
tends to make things harder to track... I feel making these explicit and have
each worker container own WorkerBackingThread solely on the main thread could be
better?

[yhirano, 2016/02/29 23:47:32]

When the WebThreadSuppotingGC changes are landed we will not need this call.

+    }
+}
+
+void WorkerBackingThread::attach()
+{
+    ASSERT(m_backingThread->isCurrentThread());
+    {
+        MutexLocker locker(m_mutex);
+        if (++m_workerScriptCount > 1)
+            return;
+    }
+    initialize();
+}
+
+void WorkerBackingThread::detach()
+{
+    ASSERT(m_backingThread->isCurrentThread());
+    {
+        MutexLocker locker(m_mutex);
+        if (--m_workerScriptCount > 0)
+            return;
+    }
+    shutdown();
+}
+
+void WorkerBackingThread::setInitializationEventForTest()
+{
+    m_initializationEventForTest = adoptPtr(new WaitableEvent);
+}
+
+void WorkerBackingThread::initialize()
+{
+    ASSERT(m_backingThread->isCurrentThread());
+    ASSERT(!m_isolate);
+    m_backingThread->initialize();
+    m_isolate = V8PerIsolateData::initialize();
+    V8Initializer::initializeWorker(m_isolate);
+
+    OwnPtr<V8IsolateInterruptor> interruptor = adoptPtr(new V8IsolateInterruptor(m_isolate));
+    ThreadState::current()->addInterruptor(interruptor.release());
+    ThreadState::current()->registerTraceDOMWrappers(m_isolate, V8GCController::traceDOMWrappers);
+    if (RuntimeEnabledFeatures::v8IdleTasksEnabled())
+        V8PerIsolateData::enableIdleTasks(m_isolate, adoptPtr(new V8IdleTaskRunner(backingThread().platformThread().scheduler())));
+    if (m_isOwningThread)
+        Platform::current()->didStartWorkerThread();
+
+    if (m_initializationEventForTest)
+        m_initializationEventForTest->signal();
+}
+
+void WorkerBackingThread::shutdown()
+{
+    ASSERT(m_backingThread->isCurrentThread());
+    if (m_isOwningThread)
+        Platform::current()->willStopWorkerThread();
+
+    V8PerIsolateData::willBeDestroyed(m_isolate);
+    m_backingThread->shutdown();
+    V8PerIsolateData::destroy(m_isolate);
+    m_isolate = nullptr;
+}
+
+} // namespace blink