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9717c27492
Because DelayedRunnables are fire-and-forget, there is no way for a targeted EventTarget to clean them up on shutdown. Thus if a timer fires after EventTarget shutdown it will fail to dispatch the timer event, and avoid releasing the timer callback because it's not on the targeted thread. This causes a leak as there is a ref-cycle between nsTimerImpl::mCallback and DelayedRunnable::mTimer. This patch adds nsIDelayedRunnableObserver for a target to observe which DelayedRunnables are relying on their timer to run them. This allows the target to schedule a shutdown task to cancel those timers and release the runnables on the target thread. Supported DelayedRunnable targets with this patch are TaskQueues, eventqueue-based nsThreads and XPCOMThreadWrappers that wrap a supported nsThread. An assertion makes sure at runtime that future new uses of DelayedRunnable target nsIDelayedRunnableObserver-supported event targets. Differential Revision: https://phabricator.services.mozilla.com/D109781
71 lines
2.4 KiB
C++
71 lines
2.4 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef mozilla_ThreadEventTarget_h
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#define mozilla_ThreadEventTarget_h
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#include "mozilla/MemoryReporting.h"
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#include "mozilla/Mutex.h"
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#include "mozilla/SynchronizedEventQueue.h" // for ThreadTargetSink
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#include "nsIDelayedRunnableObserver.h"
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#include "nsISerialEventTarget.h"
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namespace mozilla {
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class DelayedRunnable;
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// ThreadEventTarget handles the details of posting an event to a thread. It can
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// be used with any ThreadTargetSink implementation.
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class ThreadEventTarget final : public nsISerialEventTarget,
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public nsIDelayedRunnableObserver {
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public:
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ThreadEventTarget(ThreadTargetSink* aSink, bool aIsMainThread);
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NS_DECL_THREADSAFE_ISUPPORTS
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NS_DECL_NSIEVENTTARGET_FULL
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// nsIDelayedRunnableObserver
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void OnDelayedRunnableCreated(DelayedRunnable* aRunnable) override;
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void OnDelayedRunnableScheduled(DelayedRunnable* aRunnable) override;
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void OnDelayedRunnableRan(DelayedRunnable* aRunnable) override;
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// Notification from, and on, the owner thread that it is shutting down.
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// Cancels any scheduled DelayedRunnables.
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void NotifyShutdown();
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// Disconnects the target so that it can no longer post events.
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void Disconnect(const MutexAutoLock& aProofOfLock) {
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mSink->Disconnect(aProofOfLock);
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}
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// Sets the thread for which IsOnCurrentThread returns true to the current
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// thread.
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void SetCurrentThread(PRThread* aThread);
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// Call ClearCurrentThread() before the PRThread is deleted on thread join.
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void ClearCurrentThread();
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size_t SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const {
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size_t n = 0;
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if (mSink) {
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n += mSink->SizeOfIncludingThis(aMallocSizeOf);
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}
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return aMallocSizeOf(this) + n;
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}
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private:
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~ThreadEventTarget();
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RefPtr<ThreadTargetSink> mSink;
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bool mIsMainThread;
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// DelayedRunnables (from DelayedDispatch) that are managed by their
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// respective timers, but have not yet run. Accessed only on this nsThread.
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nsTArray<RefPtr<mozilla::DelayedRunnable>> mScheduledDelayedRunnables;
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};
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} // namespace mozilla
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#endif // mozilla_ThreadEventTarget_h
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