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| author | Matt A. Tobin <mattatobin@localhost.localdomain> | 2018-02-02 04:16:08 -0500 |
|---|---|---|
| committer | Matt A. Tobin <mattatobin@localhost.localdomain> | 2018-02-02 04:16:08 -0500 |
| commit | 5f8de423f190bbb79a62f804151bc24824fa32d8 (patch) | |
| tree | 10027f336435511475e392454359edea8e25895d /xpcom/threads/nsEventQueue.h | |
| parent | 49ee0794b5d912db1f95dce6eb52d781dc210db5 (diff) | |
| download | UXP-5f8de423f190bbb79a62f804151bc24824fa32d8.tar UXP-5f8de423f190bbb79a62f804151bc24824fa32d8.tar.gz UXP-5f8de423f190bbb79a62f804151bc24824fa32d8.tar.lz UXP-5f8de423f190bbb79a62f804151bc24824fa32d8.tar.xz UXP-5f8de423f190bbb79a62f804151bc24824fa32d8.zip | |
Add m-esr52 at 52.6.0
Diffstat (limited to 'xpcom/threads/nsEventQueue.h')
| -rw-r--r-- | xpcom/threads/nsEventQueue.h | 123 |
1 files changed, 123 insertions, 0 deletions
diff --git a/xpcom/threads/nsEventQueue.h b/xpcom/threads/nsEventQueue.h new file mode 100644 index 000000000..23b55e63d --- /dev/null +++ b/xpcom/threads/nsEventQueue.h @@ -0,0 +1,123 @@ +/* -*- 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 nsEventQueue_h__ +#define nsEventQueue_h__ + +#include <stdlib.h> +#include "mozilla/CondVar.h" +#include "mozilla/Mutex.h" +#include "nsIRunnable.h" +#include "nsCOMPtr.h" +#include "mozilla/AlreadyAddRefed.h" +#include "mozilla/UniquePtr.h" + +class nsThreadPool; + +// A threadsafe FIFO event queue... +class nsEventQueue +{ +public: + typedef mozilla::MutexAutoLock MutexAutoLock; + + enum EventQueueType + { + eNormalQueue, + eSharedCondVarQueue + }; + + nsEventQueue(mozilla::CondVar& aCondVar, EventQueueType aType); + ~nsEventQueue(); + + // This method adds a new event to the pending event queue. The queue holds + // a strong reference to the event after this method returns. This method + // cannot fail. + void PutEvent(nsIRunnable* aEvent, MutexAutoLock& aProofOfLock); + void PutEvent(already_AddRefed<nsIRunnable>&& aEvent, + MutexAutoLock& aProofOfLock); + + // This method gets an event from the event queue. If mayWait is true, then + // the method will block the calling thread until an event is available. If + // the event is null, then the method returns immediately indicating whether + // or not an event is pending. When the resulting event is non-null, the + // caller is responsible for releasing the event object. This method does + // not alter the reference count of the resulting event. + bool GetEvent(bool aMayWait, nsIRunnable** aEvent, + MutexAutoLock& aProofOfLock); + + // This method returns true if there is a pending event. + bool HasPendingEvent(MutexAutoLock& aProofOfLock) + { + return GetEvent(false, nullptr, aProofOfLock); + } + + // This method returns the next pending event or null. + bool GetPendingEvent(nsIRunnable** aRunnable, MutexAutoLock& aProofOfLock) + { + return GetEvent(false, aRunnable, aProofOfLock); + } + + size_t Count(MutexAutoLock&) const; + +private: + bool IsEmpty() + { + return !mHead || (mHead == mTail && mOffsetHead == mOffsetTail); + } + + enum + { + EVENTS_PER_PAGE = 255 + }; + + // Page objects are linked together to form a simple deque. + + struct Page + { + struct Page* mNext; + nsIRunnable* mEvents[EVENTS_PER_PAGE]; + }; + + static_assert((sizeof(Page) & (sizeof(Page) - 1)) == 0, + "sizeof(Page) should be a power of two to avoid heap slop."); + + static Page* NewPage() + { + return static_cast<Page*>(moz_xcalloc(1, sizeof(Page))); + } + + static void FreePage(Page* aPage) + { + free(aPage); + } + + Page* mHead; + Page* mTail; + + uint16_t mOffsetHead; // offset into mHead where next item is removed + uint16_t mOffsetTail; // offset into mTail where next item is added + mozilla::CondVar& mEventsAvailable; + + EventQueueType mType; + + // These methods are made available to nsThreadPool as a hack, since + // nsThreadPool needs to have its threads sleep for fixed amounts of + // time as well as being able to wake up all threads when thread + // limits change. + friend class nsThreadPool; + void Wait(PRIntervalTime aInterval) + { + MOZ_ASSERT(mType == eNormalQueue); + mEventsAvailable.Wait(aInterval); + } + void NotifyAll() + { + MOZ_ASSERT(mType == eNormalQueue); + mEventsAvailable.NotifyAll(); + } +}; + +#endif // nsEventQueue_h__ |