зеркало из https://github.com/mozilla/gecko-dev.git
90 строки
2.6 KiB
C++
90 строки
2.6 KiB
C++
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim:set ts=2 sw=2 sts=2 et cindent: */
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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 nsEventQueue_h__
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#define nsEventQueue_h__
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#include <stdlib.h>
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#include "mozilla/ReentrantMonitor.h"
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#include "nsIRunnable.h"
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// A threadsafe FIFO event queue...
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class nsEventQueue
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{
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typedef mozilla::ReentrantMonitor ReentrantMonitor;
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public:
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nsEventQueue();
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~nsEventQueue();
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// This method adds a new event to the pending event queue. The event object
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// is AddRef'd if this method succeeds. This method returns true if the
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// event was stored in the event queue, and it returns false if it could
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// not allocate sufficient memory.
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bool PutEvent(nsIRunnable *event);
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// This method gets an event from the event queue. If mayWait is true, then
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// the method will block the calling thread until an event is available. If
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// the event is null, then the method returns immediately indicating whether
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// or not an event is pending. When the resulting event is non-null, the
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// caller is responsible for releasing the event object. This method does
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// not alter the reference count of the resulting event.
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bool GetEvent(bool mayWait, nsIRunnable **event);
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// This method returns true if there is a pending event.
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bool HasPendingEvent() {
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return GetEvent(false, nullptr);
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}
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// This method returns the next pending event or null.
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bool GetPendingEvent(nsIRunnable **runnable) {
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return GetEvent(false, runnable);
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}
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// This method waits for and returns the next pending event.
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bool WaitPendingEvent(nsIRunnable **runnable) {
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return GetEvent(true, runnable);
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}
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// Expose the event queue's monitor for "power users"
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ReentrantMonitor& GetReentrantMonitor() {
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return mReentrantMonitor;
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}
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private:
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bool IsEmpty() {
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return !mHead || (mHead == mTail && mOffsetHead == mOffsetTail);
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}
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enum { EVENTS_PER_PAGE = 250 };
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// Page objects are linked together to form a simple deque.
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struct Page {
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struct Page *mNext;
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nsIRunnable *mEvents[EVENTS_PER_PAGE];
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};
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static Page *NewPage() {
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return static_cast<Page *>(calloc(1, sizeof(Page)));
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}
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static void FreePage(Page *p) {
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free(p);
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}
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ReentrantMonitor mReentrantMonitor;
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Page *mHead;
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Page *mTail;
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uint16_t mOffsetHead; // offset into mHead where next item is removed
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uint16_t mOffsetTail; // offset into mTail where next item is added
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};
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#endif // nsEventQueue_h__
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