Refactoring WorkletThreadBackingHolder with template pattern

third_party/WebKit/Source/modules/webaudio/AudioWorkletThread.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 "modules/webaudio/AudioWorkletThread.h"
 
 #include "core/workers/WorkerBackingThread.h"
 #include "core/workers/WorkerThreadStartupData.h"
-#include "core/workers/WorkletBackingThreadHolder.h"
 #include "modules/webaudio/AudioWorkletGlobalScope.h"
 #include "platform/CrossThreadFunctional.h"
 #include "platform/WaitableEvent.h"
 #include "platform/WebThreadSupportingGC.h"
 #include "platform/tracing/TraceEvent.h"
 #include "platform/weborigin/SecurityOrigin.h"
 #include "public/platform/Platform.h"
 #include "wtf/Assertions.h"
 #include "wtf/PtrUtil.h"
 #include <memory>
 
 namespace blink {
 
-namespace {
-
-// TODO(hongchan): consider refactoring static methods in this class into
-// a template class.
-class AudioWorkletThreadHolder final : public WorkletBackingThreadHolder {
- public:
-  static AudioWorkletThreadHolder* instance() {
-    MutexLocker locker(holderInstanceMutex());
-    return s_instance;
-  }
-
-  static void ensureInstance() {
-    if (!s_instance)
-      s_instance = new AudioWorkletThreadHolder;
-  }
-
-  static void clear() {
-    MutexLocker locker(holderInstanceMutex());
-    if (s_instance) {
-      s_instance->shutdownAndWait();
-      delete s_instance;
-      s_instance = nullptr;
-    }
-  }
-
-  static void createForTest() {
-    MutexLocker locker(holderInstanceMutex());
-    DCHECK_EQ(nullptr, s_instance);
-    s_instance =
-        new AudioWorkletThreadHolder(WorkerBackingThread::createForTest(

[nhiroki, 2016/10/25 22:39:33]

Ah, we removed this part :p

In unit tests, we need to create WorkerBackingThread by
WorkerBackingThread::createForTest(). This suppresses leak reports. See
https://cs.chromium.org/chromium/src/third_party/WebKit/Source/core/workers/W...

-            "AudioWorkletThread", BlinkGC::PerThreadHeapMode));
-  }
-
- private:
-  AudioWorkletThreadHolder(
-      std::unique_ptr<WorkerBackingThread> backingThread = nullptr)
-      : WorkletBackingThreadHolder(
-            backingThread
-                ? std::move(backingThread)
-                : WorkerBackingThread::create("AudioWorkletThread",
-                                              BlinkGC::PerThreadHeapMode)) {}
-
-  static Mutex& holderInstanceMutex() {
-    DEFINE_THREAD_SAFE_STATIC_LOCAL(Mutex, holderMutex, new Mutex);
-    return holderMutex;
-  }
-
-  void initializeOnThread() {
-    MutexLocker locker(holderInstanceMutex());
-    DCHECK(!m_initialized);
-    m_thread->initialize();
-    m_initialized = true;
-  }
-
-  static AudioWorkletThreadHolder* s_instance;
-};
-
-AudioWorkletThreadHolder* AudioWorkletThreadHolder::s_instance = nullptr;
-
-}  // namespace
+template class WorkletThreadHolder<AudioWorkletThread>;
 
 std::unique_ptr<AudioWorkletThread> AudioWorkletThread::create(
     PassRefPtr<WorkerLoaderProxy> workerLoaderProxy,
     WorkerReportingProxy& workerReportingProxy) {
   TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("audio-worklet"),
                "AudioWorkletThread::create");
   DCHECK(isMainThread());
   return wrapUnique(new AudioWorkletThread(std::move(workerLoaderProxy),
                                            workerReportingProxy));
 }
 
 AudioWorkletThread::AudioWorkletThread(
     PassRefPtr<WorkerLoaderProxy> workerLoaderProxy,
     WorkerReportingProxy& workerReportingProxy)
     : WorkerThread(std::move(workerLoaderProxy), workerReportingProxy) {}
 
 AudioWorkletThread::~AudioWorkletThread() {}
 
 WorkerBackingThread& AudioWorkletThread::workerBackingThread() {
-  return *AudioWorkletThreadHolder::instance()->thread();
+  return *WorkletThreadHolder<AudioWorkletThread>::threadHolderInstance()
+              ->thread();
 }
 
 void collectAllGarbageOnAudioWorkletThread(WaitableEvent* doneEvent) {
   blink::ThreadState::current()->collectAllGarbage();
   doneEvent->signal();
 }
 
 void AudioWorkletThread::collectAllGarbage() {
   DCHECK(isMainThread());
   WaitableEvent doneEvent;
-  AudioWorkletThreadHolder* instance = AudioWorkletThreadHolder::instance();
-  if (!instance)
+  WorkletThreadHolder<AudioWorkletThread>* threadHolderInstance =
+      WorkletThreadHolder<AudioWorkletThread>::threadHolderInstance();
+  if (!threadHolderInstance)
     return;
-  instance->thread()->backingThread().postTask(
+  threadHolderInstance->thread()->backingThread().postTask(
       BLINK_FROM_HERE, crossThreadBind(&collectAllGarbageOnAudioWorkletThread,
                                        crossThreadUnretained(&doneEvent)));
   doneEvent.wait();
 }
 
 void AudioWorkletThread::ensureSharedBackingThread() {
   DCHECK(isMainThread());
-  AudioWorkletThreadHolder::ensureInstance();
+  WorkletThreadHolder<AudioWorkletThread>::ensureInstance(
+      "AudioWorkletThread", BlinkGC::PerThreadHeapMode);
 }
 
 void AudioWorkletThread::clearSharedBackingThread() {

[nhiroki, 2016/10/26 08:08:17]

Copied from https://codereview.chromium.org/2448863002/

On 2016/10/26 07:41:49, haraken wrote:
Good point. It looks like that this is correctly called in unit tests, but it's
not called in production codes.

   DCHECK(isMainThread());
-  AudioWorkletThreadHolder::clear();
-}
-
-void AudioWorkletThread::createSharedBackingThreadForTest() {
-  AudioWorkletThreadHolder::createForTest();
+  WorkletThreadHolder<AudioWorkletThread>::clearInstance();
 }
 
 WorkerOrWorkletGlobalScope* AudioWorkletThread::createWorkerGlobalScope(
     std::unique_ptr<WorkerThreadStartupData> startupData) {
   TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("audio-worklet"),
                "AudioWorkletThread::createWorkerGlobalScope");
 
   RefPtr<SecurityOrigin> securityOrigin =
       SecurityOrigin::create(startupData->m_scriptURL);
   if (startupData->m_starterOriginPrivilegeData) {
     securityOrigin->transferPrivilegesFrom(
         std::move(startupData->m_starterOriginPrivilegeData));
   }
 
   return AudioWorkletGlobalScope::create(
       startupData->m_scriptURL, startupData->m_userAgent,
       securityOrigin.release(), this->isolate(), this);
 }
 
 }  // namespace blink