syncthrd.h

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/*
 * syncthrd.h
 *
 * Various thread synchronisation classes.
 *
 * Portable Tools 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): ______________________________________.
 *
 * $Revision: 28062 $
 * $Author: rjongbloed $
 * $Date: 2012-07-19 19:45:52 +1000 (Thu, 19 Jul 2012) $
 */

#ifndef PTLIB_SYNCTHRD_H
#define PTLIB_SYNCTHRD_H

#ifdef P_USE_PRAGMA
#pragma interface
#endif

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


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 PBoolean 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 PBoolean 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();
    ~PReadWriteMutex();

    void StartRead();

    void EndRead();

    void StartWrite();

    void EndWrite();

  protected:
    PSemaphore  m_readerSemaphore;
    PTimedMutex m_readerMutex;
    unsigned    m_readerCount;
    PTimedMutex m_starvationPreventer;

    PSemaphore  m_writerSemaphore;
    PTimedMutex m_writerMutex;
    unsigned    m_writerCount;

    struct Nest
    {
      unsigned m_readerCount;
      unsigned m_writerCount;
      bool     m_waiting;

      Nest()
        : m_readerCount(0)
        , m_writerCount(0)
        , m_waiting(false)
      { }
    };
    typedef std::map<PThreadIdentifier, Nest> NestMap;
    NestMap m_nestedThreads;
    PMutex  m_nestingMutex;

    Nest * GetNest();
    Nest & StartNest();
    void EndNest();
    void InternalStartRead(Nest & nest);
    void InternalEndRead(Nest & nest);
    void InternalWait(Nest & nest, PSync & sync) const;
};


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

  protected:
    PReadWriteMutex & mutex;
};


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

  protected:
    PReadWriteMutex & mutex;
};


#endif // PTLIB_SYNCTHRD_H


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