gecko-dev/xpcom/threads/ThreadEventQueue.h

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/* -*- 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_ThreadEventQueue_h
#define mozilla_ThreadEventQueue_h
#include "mozilla/AbstractEventQueue.h"
#include "mozilla/CondVar.h"
#include "mozilla/SynchronizedEventQueue.h"
#include "nsCOMPtr.h"
#include "nsTArray.h"
class nsIEventTarget;
class nsISerialEventTarget;
class nsIThreadObserver;
namespace mozilla {
class EventQueue;
template<typename InnerQueueT>
class PrioritizedEventQueue;
class LabeledEventQueue;
class ThreadEventTarget;
// A ThreadEventQueue implements normal monitor-style synchronization over the
// InnerQueueT AbstractEventQueue. It also implements PushEventQueue and
// PopEventQueue for workers (see the documentation below for an explanation of
// those). All threads use a ThreadEventQueue as their event queue. InnerQueueT
// is a template parameter to avoid virtual dispatch overhead.
template<class InnerQueueT>
class ThreadEventQueue final : public SynchronizedEventQueue
{
public:
explicit ThreadEventQueue(UniquePtr<InnerQueueT> aQueue);
bool PutEvent(already_AddRefed<nsIRunnable>&& aEvent,
EventPriority aPriority) final;
already_AddRefed<nsIRunnable> GetEvent(bool aMayWait,
EventPriority* aPriority) final;
bool HasPendingEvent() final;
bool ShutdownIfNoPendingEvents() final;
void Disconnect(const MutexAutoLock& aProofOfLock) final {}
void EnableInputEventPrioritization() final;
void FlushInputEventPrioritization() final;
void SuspendInputEventPrioritization() final;
void ResumeInputEventPrioritization() final;
/**
* 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.
*/
already_AddRefed<nsISerialEventTarget> PushEventQueue();
/**
* 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.
*/
void PopEventQueue(nsIEventTarget* aTarget);
already_AddRefed<nsIThreadObserver> GetObserver() final;
already_AddRefed<nsIThreadObserver> GetObserverOnThread() final;
void SetObserver(nsIThreadObserver* aObserver) final;
Mutex& MutexRef() { return mLock; }
private:
class NestedSink;
virtual ~ThreadEventQueue();
bool PutEventInternal(already_AddRefed<nsIRunnable>&& aEvent,
EventPriority aPriority,
NestedSink* aQueue);
UniquePtr<InnerQueueT> mBaseQueue;
struct NestedQueueItem
{
UniquePtr<EventQueue> mQueue;
RefPtr<ThreadEventTarget> mEventTarget;
NestedQueueItem(UniquePtr<EventQueue> aQueue,
ThreadEventTarget* aEventTarget)
: mQueue(Move(aQueue))
, mEventTarget(aEventTarget)
{}
};
nsTArray<NestedQueueItem> mNestedQueues;
Mutex mLock;
CondVar mEventsAvailable;
bool mEventsAreDoomed = false;
nsCOMPtr<nsIThreadObserver> mObserver;
};
extern template class ThreadEventQueue<EventQueue>;
extern template class ThreadEventQueue<PrioritizedEventQueue<EventQueue>>;
extern template class ThreadEventQueue<PrioritizedEventQueue<LabeledEventQueue>>;
}; // namespace mozilla
#endif // mozilla_ThreadEventQueue_h