syncthrd.h

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/*
 * syncthrd.h
 *
 * Various thread synchronisation classes.
 *
 * Portable Windows Library
 *
 * Copyright (c) 1993-1998 Equivalence Pty. Ltd.
 *
 * The contents of this file are subject to the Mozilla Public License
 * Version 1.0 (the "License"); you may not use this file except in
 * compliance with the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS"
 * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
 * the License for the specific language governing rights and limitations
 * under the License.
 *
 * The Original Code is Portable Windows Library.
 *
 * The Initial Developer of the Original Code is Equivalence Pty. Ltd.
 *
 * Portions are Copyright (C) 1993 Free Software Foundation, Inc.
 * All Rights Reserved.
 *
 * Contributor(s): ______________________________________.
 *
 * $Log: syncthrd.h,v $
 * Revision 1.14  2005/11/25 03:43:47  csoutheren
 * Fixed function argument comments to be compatible with Doxygen
 *
 * Revision 1.13  2004/03/22 10:15:27  rjongbloed
 * Added classes similar to PWaitAndSignal to automatically unlock a PReadWriteMutex
 *   when goes out of scope.
 *
 * Revision 1.12  2002/12/11 03:21:28  robertj
 * Updated documentation for read/write mutex.
 *
 * Revision 1.11  2002/10/04 08:20:44  robertj
 * Changed read/write mutex so can be called by same thread without deadlock.
 *
 * Revision 1.10  2002/09/16 01:08:59  robertj
 * Added #define so can select if #pragma interface/implementation is used on
 *   platform basis (eg MacOS) rather than compiler, thanks Robert Monaghan.
 *
 * Revision 1.9  2002/05/01 03:45:31  robertj
 * Added initialisation of PreadWriteMutex and changed slightly to agree
 *   with the text book definition of a semaphore for one of the mutexes.
 *
 * Revision 1.8  2002/04/30 06:21:54  robertj
 * Fixed PReadWriteMutex class to implement text book algorithm!
 *
 * Revision 1.7  2001/05/22 12:49:32  robertj
 * Did some seriously wierd rewrite of platform headers to eliminate the
 *   stupid GNU compiler warning about braces not matching.
 *
 * Revision 1.6  1999/03/09 02:59:51  robertj
 * Changed comments to doc++ compatible documentation.
 *
 * Revision 1.5  1999/02/16 08:11:17  robertj
 * MSVC 6.0 compatibility changes.
 *
 * Revision 1.4  1998/11/30 02:52:01  robertj
 * New directory structure
 *
 * Revision 1.3  1998/10/31 12:46:45  robertj
 * Renamed file for having general thread synchronisation objects.
 * Added conditional mutex and read/write mutex thread synchronisation objects.
 *
 * Revision 1.2  1998/09/23 06:21:35  robertj
 * Added open source copyright license.
 *
 * Revision 1.1  1998/05/30 13:26:15  robertj
 * Initial revision
 *
 */


#define _PSYNCPOINTACK

#ifdef P_USE_PRAGMA
#pragma interface
#endif

#include <ptlib/mutex.h>
#include <ptlib/syncpoint.h>

class PSyncPointAck : public PSyncPoint
{
  PCLASSINFO(PSyncPointAck, PSyncPoint);

  public:
    virtual void Signal();
    void Signal(const PTimeInterval & waitTime);

    void Acknowledge();

  protected:
    PSyncPoint ack;
};


class PCondMutex : public PMutex
{
  PCLASSINFO(PCondMutex, PMutex);

  public:
    virtual void WaitCondition();

    virtual void Signal();

    virtual BOOL Condition() = 0;

    virtual void OnWait();

  protected:
    PSyncPoint syncPoint;
};


class PIntCondMutex : public PCondMutex
{
  PCLASSINFO(PIntCondMutex, PCondMutex);

  public:

    enum Operation {
      LT,
      LE,
      EQ,
      GE,
      GT
    };

    PIntCondMutex(
      int value = 0,            
      int target = 0,           
      Operation operation = LE  
    );

    void PrintOn(ostream & strm) const;

    virtual BOOL Condition();

    operator int() const { return value; }

    PIntCondMutex & operator=(int newval);

    PIntCondMutex & operator++();

    PIntCondMutex & operator+=(int inc);

    PIntCondMutex & operator--();

    PIntCondMutex & operator-=(int dec);


  protected:
    int value, target;
    Operation operation;
};


class PReadWriteMutex : public PObject
{
  PCLASSINFO(PReadWriteMutex, PObject);
  public:
    PReadWriteMutex();

    void StartRead();

    void EndRead();

    void StartWrite();

    void EndWrite();

  protected:
    PSemaphore readerSemaphore;
    PMutex     readerMutex;
    unsigned   readerCount;
    PMutex     starvationPreventer;

    PSemaphore writerSemaphore;
    PMutex     writerMutex;
    unsigned   writerCount;

    class Nest : public PObject
    {
      PCLASSINFO(Nest, PObject);
      Nest() { readerCount = writerCount = 0; }
      unsigned readerCount;
      unsigned writerCount;
    };
    PDictionary<POrdinalKey, Nest> nestedThreads;
    PMutex                         nestingMutex;

    Nest * GetNest() const;
    Nest & StartNest();
    void EndNest();
    void InternalStartRead();
    void InternalEndRead();
};


class PReadWaitAndSignal {
  public:
    PReadWaitAndSignal(
      const PReadWriteMutex & rw,   
      BOOL start = TRUE    
    );
    ~PReadWaitAndSignal();

  protected:
    PReadWriteMutex & mutex;
};


class PWriteWaitAndSignal {
  public:
    PWriteWaitAndSignal(
      const PReadWriteMutex & rw,   
      BOOL start = TRUE    
    );
    ~PWriteWaitAndSignal();

  protected:
    PReadWriteMutex & mutex;
};


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