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124 lines
4.2 KiB
C++
124 lines
4.2 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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/* ***** BEGIN LICENSE BLOCK *****
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* Version: MPL 1.1/GPL 2.0/LGPL 2.1
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*
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* The contents of this file are subject to the Mozilla Public License Version
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* 1.1 (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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* http://www.mozilla.org/MPL/
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*
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* Software distributed under the License is distributed on an "AS IS" basis,
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* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
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* for the specific language governing rights and limitations under the
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* License.
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*
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* The Original Code is Mozilla code.
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*
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* The Initial Developer of the Original Code is Google Inc.
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* Portions created by the Initial Developer are Copyright (C) 2006
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* the Initial Developer. All Rights Reserved.
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*
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* Contributor(s):
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* Darin Fisher <darin@meer.net>
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*
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* Alternatively, the contents of this file may be used under the terms of
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* either the GNU General Public License Version 2 or later (the "GPL"), or
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* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
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* in which case the provisions of the GPL or the LGPL are applicable instead
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* of those above. If you wish to allow use of your version of this file only
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* under the terms of either the GPL or the LGPL, and not to allow others to
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* use your version of this file under the terms of the MPL, indicate your
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* decision by deleting the provisions above and replace them with the notice
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* and other provisions required by the GPL or the LGPL. If you do not delete
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* the provisions above, a recipient may use your version of this file under
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* the terms of any one of the MPL, the GPL or the LGPL.
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*
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* ***** END LICENSE BLOCK ***** */
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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 "prmon.h"
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#include "nsIRunnable.h"
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// A threadsafe FIFO event queue...
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class NS_COM nsEventQueue
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{
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public:
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nsEventQueue();
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~nsEventQueue();
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// Returns "true" if the event queue has been completely constructed.
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PRBool IsInitialized() { return mMonitor != nsnull; }
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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 PR_TRUE if the
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// event was stored in the event queue, and it returns PR_FALSE if it could
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// not allocate sufficient memory.
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PRBool 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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PRBool GetEvent(PRBool mayWait, nsIRunnable **event);
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// This method returns true if there is a pending event.
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PRBool HasPendingEvent() {
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return GetEvent(PR_FALSE, nsnull);
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}
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// This method returns the next pending event or null.
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PRBool GetPendingEvent(nsIRunnable **runnable) {
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return GetEvent(PR_FALSE, runnable);
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}
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// This method waits for and returns the next pending event.
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PRBool WaitPendingEvent(nsIRunnable **runnable) {
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return GetEvent(PR_TRUE, runnable);
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}
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// Expose the event queue's monitor for "power users"
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PRMonitor *Monitor() {
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return mMonitor;
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}
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private:
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PRBool 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; friend struct Page; // VC6!
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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 NS_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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PRMonitor *mMonitor;
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Page *mHead;
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Page *mTail;
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PRUint16 mOffsetHead; // offset into mHead where next item is removed
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PRUint16 mOffsetTail; // offset into mTail where next item is added
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};
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#endif // nsEventQueue_h__
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