include/ptlib/mutex.h

   1 /*
   2  * mutex.h
   3  *
   4  * Mutual exclusion thread synchonisation class.
   5  *
   6  * Portable Windows Library
   7  *
   8  * Copyright (c) 1993-1998 Equivalence Pty. Ltd.
   9  *
  10  * The contents of this file are subject to the Mozilla Public License
  11  * Version 1.0 (the "License"); you may not use this file except in
  12  * compliance with the License. You may obtain a copy of the License at
  13  * http://www.mozilla.org/MPL/
  14  *
  15  * Software distributed under the License is distributed on an "AS IS"
  16  * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
  17  * the License for the specific language governing rights and limitations
  18  * under the License.
  19  *
  20  * The Original Code is Portable Windows Library.
  21  *
  22  * The Initial Developer of the Original Code is Equivalence Pty. Ltd.
  23  *
  24  * Portions are Copyright (C) 1993 Free Software Foundation, Inc.
  25  * All Rights Reserved.
  26  *
  27  * Contributor(s): ______________________________________.
  28  *
  29  * $Log$
  30  * Revision 1.10  2003/09/17 05:41:58  csoutheren
  31  * Removed recursive includes
  32  *
  33  * Revision 1.9  2003/09/17 01:18:02  csoutheren
  34  * Removed recursive include file system and removed all references
  35  * to deprecated coooperative threading support
  36  *
  37  * Revision 1.8  2002/09/16 01:08:59  robertj
  38  * Added #define so can select if #pragma interface/implementation is used on
  39  *   platform basis (eg MacOS) rather than compiler, thanks Robert Monaghan.
  40  *
  41  * Revision 1.7  2002/01/23 04:26:36  craigs
  42  * Added copy constructors for PSemaphore, PMutex and PSyncPoint to allow
  43  * use of default copy constructors for objects containing instances of
  44  * these classes
  45  *
  46  * Revision 1.6  2001/05/22 12:49:32  robertj
  47  * Did some seriously wierd rewrite of platform headers to eliminate the
  48  *   stupid GNU compiler warning about braces not matching.
  49  *
  50  * Revision 1.5  1999/03/09 02:59:50  robertj
  51  * Changed comments to doc++ compatible documentation.
  52  *
  53  * Revision 1.4  1999/02/16 08:12:22  robertj
  54  * MSVC 6.0 compatibility changes.
  55  *
  56  * Revision 1.3  1998/11/30 02:50:59  robertj
  57  * New directory structure
  58  *
  59  * Revision 1.2  1998/09/23 06:20:55  robertj
  60  * Added open source copyright license.
  61  *
  62  * Revision 1.1  1998/03/23 02:41:31  robertj
  63  * Initial revision
  64  *
  65  */
  66
  67 #ifndef _PMUTEX
  68 #define _PMUTEX
  69
  70 #ifdef P_USE_PRAGMA
  71 #pragma interface
  72 #endif
  73
  74 #include <ptlib/semaphor.h>
  75
  76
  77 /**This class defines a thread mutual exclusion object. A mutex is where a
  78    piece of code or data cannot be accessed by more than one thread at a time.
  79    To prevent this the PMutex is used in the following manner:
  80 \begin{verbatim}
  81       PMutex mutex;
  82
  83       ...
  84
  85       mutex.Wait();
  86
  87       ... critical section - only one thread at a time here.
  88
  89       mutex.Signal();
  90
  91       ...
  92 \end{verbatim}
  93     The first thread will pass through the #Wait()# function, a second
  94     thread will block on that function until the first calls the
  95     #Signal()# function, releasing the second thread.
  96  */
  97 class PMutex : public PSemaphore
  98 {
  99   PCLASSINFO(PMutex, PSemaphore);
 100
 101   public:
 102     /* Create a new mutex.
 103        Initially the mutex will not be "set", so the first call to Wait() will
 104        never wait.
 105      */
 106     PMutex();
 107     PMutex(const PMutex & mutex);
 108
 109 // Include platform dependent part of class
 110 #ifdef _WIN32
 111 #include "msos/ptlib/mutex.h"
 112 #else
 113 #include "unix/ptlib/mutex.h"
 114 #endif
 115 };
 116
 117 #endif
 118
 119 // End Of File ///////////////////////////////////////////////////////////////