LCOV - code coverage report
Current view: directory - xpcom/threads - nsEventQueue.h (source / functions) Found Hit Coverage
Test: app.info Lines: 13 11 84.6 %
Date: 2012-06-02 Functions: 6 5 83.3 %

       1                 : /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
       2                 : /* vim:set ts=2 sw=2 sts=2 et cindent: */
       3                 : /* ***** BEGIN LICENSE BLOCK *****
       4                 :  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
       5                 :  *
       6                 :  * The contents of this file are subject to the Mozilla Public License Version
       7                 :  * 1.1 (the "License"); you may not use this file except in compliance with
       8                 :  * the License. You may obtain a copy of the License at
       9                 :  * http://www.mozilla.org/MPL/
      10                 :  *
      11                 :  * Software distributed under the License is distributed on an "AS IS" basis,
      12                 :  * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
      13                 :  * for the specific language governing rights and limitations under the
      14                 :  * License.
      15                 :  *
      16                 :  * The Original Code is Mozilla code.
      17                 :  *
      18                 :  * The Initial Developer of the Original Code is Google Inc.
      19                 :  * Portions created by the Initial Developer are Copyright (C) 2006
      20                 :  * the Initial Developer. All Rights Reserved.
      21                 :  *
      22                 :  * Contributor(s):
      23                 :  *  Darin Fisher <darin@meer.net>
      24                 :  *
      25                 :  * Alternatively, the contents of this file may be used under the terms of
      26                 :  * either the GNU General Public License Version 2 or later (the "GPL"), or
      27                 :  * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
      28                 :  * in which case the provisions of the GPL or the LGPL are applicable instead
      29                 :  * of those above. If you wish to allow use of your version of this file only
      30                 :  * under the terms of either the GPL or the LGPL, and not to allow others to
      31                 :  * use your version of this file under the terms of the MPL, indicate your
      32                 :  * decision by deleting the provisions above and replace them with the notice
      33                 :  * and other provisions required by the GPL or the LGPL. If you do not delete
      34                 :  * the provisions above, a recipient may use your version of this file under
      35                 :  * the terms of any one of the MPL, the GPL or the LGPL.
      36                 :  *
      37                 :  * ***** END LICENSE BLOCK ***** */
      38                 : 
      39                 : #ifndef nsEventQueue_h__
      40                 : #define nsEventQueue_h__
      41                 : 
      42                 : #include <stdlib.h>
      43                 : #include "mozilla/ReentrantMonitor.h"
      44                 : #include "nsIRunnable.h"
      45                 : 
      46                 : // A threadsafe FIFO event queue...
      47                 : class nsEventQueue
      48                 : {
      49                 :   typedef mozilla::ReentrantMonitor ReentrantMonitor;
      50                 : 
      51                 : public:
      52                 :   nsEventQueue();
      53                 :   ~nsEventQueue();
      54                 : 
      55                 :   // This method adds a new event to the pending event queue.  The event object
      56                 :   // is AddRef'd if this method succeeds.  This method returns true if the
      57                 :   // event was stored in the event queue, and it returns false if it could
      58                 :   // not allocate sufficient memory.
      59                 :   bool PutEvent(nsIRunnable *event);
      60                 : 
      61                 :   // This method gets an event from the event queue.  If mayWait is true, then
      62                 :   // the method will block the calling thread until an event is available.  If
      63                 :   // the event is null, then the method returns immediately indicating whether
      64                 :   // or not an event is pending.  When the resulting event is non-null, the
      65                 :   // caller is responsible for releasing the event object.  This method does
      66                 :   // not alter the reference count of the resulting event.
      67                 :   bool GetEvent(bool mayWait, nsIRunnable **event);
      68                 : 
      69                 :   // This method returns true if there is a pending event.
      70            6106 :   bool HasPendingEvent() {
      71            6106 :     return GetEvent(false, nsnull);
      72                 :   }
      73                 : 
      74                 :   // This method returns the next pending event or null.
      75               0 :   bool GetPendingEvent(nsIRunnable **runnable) {
      76               0 :     return GetEvent(false, runnable);
      77                 :   }
      78                 : 
      79                 :   // This method waits for and returns the next pending event.
      80                 :   bool WaitPendingEvent(nsIRunnable **runnable) {
      81                 :     return GetEvent(true, runnable);
      82                 :   }
      83                 : 
      84                 :   // Expose the event queue's monitor for "power users"
      85           12450 :   ReentrantMonitor& GetReentrantMonitor() {
      86           12450 :     return mReentrantMonitor;
      87                 :   }
      88                 : 
      89                 : private:
      90                 : 
      91          885089 :   bool IsEmpty() {
      92          885089 :     return !mHead || (mHead == mTail && mOffsetHead == mOffsetTail);
      93                 :   }
      94                 : 
      95                 :   enum { EVENTS_PER_PAGE = 250 };
      96                 : 
      97                 :   // Page objects are linked together to form a simple deque.
      98                 : 
      99                 :   struct Page {
     100                 :     struct Page *mNext;
     101                 :     nsIRunnable *mEvents[EVENTS_PER_PAGE];
     102                 :   };
     103                 : 
     104            8284 :   static Page *NewPage() {
     105            8284 :     return static_cast<Page *>(calloc(1, sizeof(Page)));
     106                 :   }
     107                 : 
     108            8273 :   static void FreePage(Page *p) {
     109            8273 :     free(p);
     110            8273 :   }
     111                 : 
     112                 :   ReentrantMonitor mReentrantMonitor;
     113                 : 
     114                 :   Page *mHead;
     115                 :   Page *mTail;
     116                 : 
     117                 :   PRUint16 mOffsetHead;  // offset into mHead where next item is removed
     118                 :   PRUint16 mOffsetTail;  // offset into mTail where next item is added
     119                 : };
     120                 : 
     121                 : #endif  // nsEventQueue_h__

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