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| author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-19 01:47:29 +0000 |
|---|---|---|
| committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-19 01:47:29 +0000 |
| commit | 0ebf5bdf043a27fd3dfb7f92e0cb63d88954c44d (patch) | |
| tree | a31f07c9bcca9d56ce61e9a1ffd30ef350d513aa /xpcom/threads/SynchronizedEventQueue.h | |
| parent | Initial commit. (diff) | |
| download | firefox-esr-upstream/115.8.0esr.tar.xz firefox-esr-upstream/115.8.0esr.zip | |
Adding upstream version 115.8.0esr.upstream/115.8.0esr
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to '')
| -rw-r--r-- | xpcom/threads/SynchronizedEventQueue.h | 131 |
1 files changed, 131 insertions, 0 deletions
diff --git a/xpcom/threads/SynchronizedEventQueue.h b/xpcom/threads/SynchronizedEventQueue.h new file mode 100644 index 0000000000..e4cf1a62af --- /dev/null +++ b/xpcom/threads/SynchronizedEventQueue.h @@ -0,0 +1,131 @@ +/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ +/* vim: set ts=8 sts=2 et sw=2 tw=80: */ +/* This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ + +#ifndef mozilla_SynchronizedEventQueue_h +#define mozilla_SynchronizedEventQueue_h + +#include "mozilla/AlreadyAddRefed.h" +#include "mozilla/EventQueue.h" +#include "mozilla/MemoryReporting.h" +#include "mozilla/Mutex.h" +#include "nsIThreadInternal.h" +#include "nsCOMPtr.h" +#include "nsTObserverArray.h" + +class nsIEventTarget; +class nsISerialEventTarget; +class nsIThreadObserver; + +namespace mozilla { + +// A SynchronizedEventQueue is an abstract class for event queues that can be +// used across threads. A SynchronizedEventQueue implementation will typically +// use locks and condition variables to guarantee consistency. The methods of +// SynchronizedEventQueue are split between ThreadTargetSink (which contains +// methods for posting events) and SynchronizedEventQueue (which contains +// methods for getting events). This split allows event targets (specifically +// ThreadEventTarget) to use a narrow interface, since they only need to post +// events. +// +// ThreadEventQueue is the canonical implementation of +// SynchronizedEventQueue. When Quantum DOM is implemented, we will use a +// different synchronized queue on the main thread, SchedulerEventQueue, which +// will handle the cooperative threading model. + +class ThreadTargetSink { + public: + NS_INLINE_DECL_THREADSAFE_REFCOUNTING(ThreadTargetSink) + + virtual bool PutEvent(already_AddRefed<nsIRunnable>&& aEvent, + EventQueuePriority aPriority) = 0; + + // After this method is called, no more events can be posted. + virtual void Disconnect(const MutexAutoLock& aProofOfLock) = 0; + + virtual nsresult RegisterShutdownTask(nsITargetShutdownTask* aTask) = 0; + virtual nsresult UnregisterShutdownTask(nsITargetShutdownTask* aTask) = 0; + + size_t SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) { + return aMallocSizeOf(this) + SizeOfExcludingThis(aMallocSizeOf); + } + + // Not const because overrides may need to take a lock + virtual size_t SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) = 0; + + protected: + virtual ~ThreadTargetSink() = default; +}; + +class SynchronizedEventQueue : public ThreadTargetSink { + public: + virtual already_AddRefed<nsIRunnable> GetEvent( + bool aMayWait, mozilla::TimeDuration* aLastEventDelay = nullptr) = 0; + virtual bool HasPendingEvent() = 0; + + // This method atomically checks if there are pending events and, if there are + // none, forbids future events from being posted. It returns true if there + // were no pending events. + virtual bool ShutdownIfNoPendingEvents() = 0; + + // These methods provide access to an nsIThreadObserver, whose methods are + // called when posting and processing events. SetObserver should only be + // called on the thread that processes events. GetObserver can be called from + // any thread. GetObserverOnThread must be used from the thread that processes + // events; it does not acquire a lock. + virtual already_AddRefed<nsIThreadObserver> GetObserver() = 0; + virtual already_AddRefed<nsIThreadObserver> GetObserverOnThread() = 0; + virtual void SetObserver(nsIThreadObserver* aObserver) = 0; + + void AddObserver(nsIThreadObserver* aObserver); + void RemoveObserver(nsIThreadObserver* aObserver); + const nsTObserverArray<nsCOMPtr<nsIThreadObserver>>& EventObservers(); + + size_t SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) override { + // Normally we'd return + // mEventObservers.ShallowSizeOfExcludingThis(aMallocSizeOf); However, + // mEventObservers may be being mutated on another thread, and we don't lock + // around access, so locking here wouldn't help. They're small, so + return 0; + } + + /** + * This method causes any events currently enqueued on the thread to be + * suppressed until PopEventQueue is called, and any event dispatched to this + * thread's nsIEventTarget will queue as well. Calls to PushEventQueue may be + * nested and must each be paired with a call to PopEventQueue in order to + * restore the original state of the thread. The returned nsIEventTarget may + * be used to push events onto the nested queue. Dispatching will be disabled + * once the event queue is popped. The thread will only ever process pending + * events for the innermost event queue. Must only be called on the target + * thread. + */ + virtual already_AddRefed<nsISerialEventTarget> PushEventQueue() = 0; + + /** + * Revert a call to PushEventQueue. When an event queue is popped, any events + * remaining in the queue are appended to the elder queue. This also causes + * the nsIEventTarget returned from PushEventQueue to stop dispatching events. + * Must only be called on the target thread, and with the innermost event + * queue. + */ + virtual void PopEventQueue(nsIEventTarget* aTarget) = 0; + + /** + * Flush the list of shutdown tasks which were previously registered. After + * this is called, new shutdown tasks cannot be registered. + */ + virtual void RunShutdownTasks() = 0; + + protected: + virtual ~SynchronizedEventQueue() = default; + + private: + nsTObserverArray<nsCOMPtr<nsIThreadObserver>> mEventObservers; +}; + +} // namespace mozilla + +#endif // mozilla_SynchronizedEventQueue_h |