Split up leak detector into two stages for better leak reporting.

third_party/WebKit/Source/web/WebLeakDetector.cpp

 /*
  * Copyright (C) 2014 Google 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 41 matching lines @@
 namespace {
 
 class WebLeakDetectorImpl final : public WebLeakDetector {
 WTF_MAKE_NONCOPYABLE(WebLeakDetectorImpl);
 public:
     explicit WebLeakDetectorImpl(WebLeakDetectorClient* client)
         : m_client(client)
         , m_delayedGCAndReportTimer(this, &WebLeakDetectorImpl::delayedGCAndReport)
         , m_delayedReportTimer(this, &WebLeakDetectorImpl::delayedReport)
         , m_numberOfGCNeeded(0)
+        , m_delayFinalGarbageCollection(false)
     {
         ASSERT(m_client);
     }
 
     ~WebLeakDetectorImpl() override {}
 
     void collectGarbageAndGetDOMCounts(WebLocalFrame*) override;
 
+    void delayFinalGarbageCollection() override { m_delayFinalGarbageCollection = true; }
+    void collectFinalGarbage() override;
+
 private:
     void delayedGCAndReport(Timer<WebLeakDetectorImpl>*);
     void delayedReport(Timer<WebLeakDetectorImpl>*);
 
     WebLeakDetectorClient* m_client;
     Timer<WebLeakDetectorImpl> m_delayedGCAndReportTimer;
     Timer<WebLeakDetectorImpl> m_delayedReportTimer;
     int m_numberOfGCNeeded;
+    bool m_delayFinalGarbageCollection;
 };
 
+void WebLeakDetectorImpl::collectFinalGarbage()
+{
+    ASSERT(m_delayFinalGarbageCollection);
+
+    // Task queue may contain delayed object destruction tasks.
+    // This method is called from navigation hook inside FrameLoader,
+    // so previous document is still held by the loader until the next event loop.
+    // Complete all pending tasks before proceeding to gc.
+    m_numberOfGCNeeded = 2;
+    m_delayedGCAndReportTimer.startOneShot(0, BLINK_FROM_HERE);
+}
+
 void WebLeakDetectorImpl::collectGarbageAndGetDOMCounts(WebLocalFrame* frame)

[haraken, 2015/11/24 23:54:51]

Instead of introducing a notion of "delayed", I'd split this method into two
e.g., disposeBlinkMemory & collectGarabge.

 {
     v8::Isolate* isolate = v8::Isolate::GetCurrent();
     v8::HandleScope handleScope(isolate);
 
     // For example, calling isValidEmailAddress in EmailInputType.cpp with a
     // non-empty string creates a static ScriptRegexp value which holds a
     // V8PerContextData indirectly. This affects the number of V8PerContextData.
     // To ensure that context data is created, call ensureScriptRegexpContext
     // here.
     V8PerIsolateData::from(isolate)->ensureScriptRegexpContext();
 
     WorkerThread::terminateAndWaitForAllWorkers();
     memoryCache()->evictResources();
 
     {
         RefPtrWillBeRawPtr<Document> document = PassRefPtrWillBeRawPtr<Document>(frame->document());
         if (ResourceFetcher* fetcher = document->fetcher())
             fetcher->garbageCollectDocumentResources();
     }
 
     // FIXME: HTML5 Notification should be closed because notification affects the result of number of DOM objects.
 
     V8GCController::collectAllGarbageForTesting(isolate);

[haraken, 2015/11/24 23:54:51]

This will run Oilpan's GC. Doesn't it need to be delayed as well?

     // Note: Oilpan precise GC is scheduled at the end of the event loop.
 
     V8PerIsolateData::from(isolate)->clearScriptRegexpContext();
 
-    // Task queue may contain delayed object destruction tasks.
-    // This method is called from navigation hook inside FrameLoader,
-    // so previous document is still held by the loader until the next event loop.
-    // Complete all pending tasks before proceeding to gc.
-    m_numberOfGCNeeded = 2;
-    m_delayedGCAndReportTimer.startOneShot(0, BLINK_FROM_HERE);
+    if (m_delayFinalGarbageCollection)
+        return;
+
+    collectFinalGarbage();
 }
 
 void WebLeakDetectorImpl::delayedGCAndReport(Timer<WebLeakDetectorImpl>*)
 {
     // We do a second and third GC here to address flakiness
     // The second GC is necessary as Resource GC may have postponed clean-up tasks to next event loop.
     // The third GC is necessary for cleaning up Document after worker object died.
 
     V8GCController::collectAllGarbageForTesting(V8PerIsolateData::mainThreadIsolate());
     // Note: Oilpan precise GC is scheduled at the end of the event loop.
@@ skipping 28 matching lines @@
 }
 
 } // namespace
 
 WebLeakDetector* WebLeakDetector::create(WebLeakDetectorClient* client)
 {
     return new WebLeakDetectorImpl(client);
 }
 
 } // namespace blink