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/WebThreadSupportingGC.h"
+#include "public/platform/Platform.h"
+#include "public/platform/WebTraceLocation.h"
+
+namespace blink {
+
+WorkerBackingThread::WorkerBackingThread(const char* name, bool shouldCallGCOnShutdown)
+    : m_backingThread(WebThreadSupportingGC::create(name))
+    , m_isOwningThread(true)
+    , m_shouldCallGCOnShutdown(shouldCallGCOnShutdown)
+{
+}
+
+WorkerBackingThread::WorkerBackingThread(WebThread* thread, bool shouldCallGCOnShutdown)
+    : m_backingThread(WebThreadSupportingGC::createForThread(thread))
+    , m_isOwningThread(false)
+    , m_shouldCallGCOnShutdown(shouldCallGCOnShutdown)
+{
+}
+
+WorkerBackingThread::~WorkerBackingThread()
+{

[haraken, 2016/04/06 09:23:16]

Shall we add:

  ASSERT(m_workerScriptCount == 0);

?

[yhirano, 2016/04/07 08:12:40]

Done.

+}
+
+void WorkerBackingThread::attach()
+{
+    ASSERT(m_backingThread->isCurrentThread());

[haraken, 2016/04/06 09:23:17]

I think this ASSERT needs to be protected by the MutexLocker. I guess the access
to m_backingThread will race.

[yhirano, 2016/04/07 08:12:40]

After WebThread::shutdown is called, you mean? Then we need to track
m_backingThread's status in a thread-safe manner, and I think it's too much. I
Removed assertions and added a comment.

+    {
+        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::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();
+}
+
+void WorkerBackingThread::shutdown()
+{
+    ASSERT(m_backingThread->isCurrentThread());
+    if (m_isOwningThread)
+        Platform::current()->willStopWorkerThread();
+
+    V8PerIsolateData::willBeDestroyed(m_isolate);
+    // TODO(yhirano): Remove this when https://crbug.com/v8/1428 is fixed.
+    if (m_shouldCallGCOnShutdown) {
+        // This statement runs only in tests.
+        V8GCController::collectAllGarbageForTesting(m_isolate);
+    }
+
+    m_backingThread->shutdown();
+
+    V8PerIsolateData::destroy(m_isolate);

[haraken, 2016/04/06 09:23:16]

We initialize m_backingThread and then V8PerIsolateData. So we should destroy
V8PerIsolateData and then m_backingThread. (Things should get destroyed in a
reverse order in which they get initialized.)

[yhirano, 2016/04/07 08:12:40]

Done.

+    m_isolate = nullptr;
+}
+
+} // namespace blink