Mutex.h

// Mutex.h -- Interface to a mutual exclusion object.

/*
 * Copyright (C) 2003 Tudor Hulubei <tudor@hulubei.net>.
 *
 * This library is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2, or (at
 * your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA,
 * 02111-1307, USA.
 */

/*
 * NOTE: This is an interal header file.
 * You should not attempt to use it directly.
 */

// $Id: Mutex_8h-source.html,v 1.1 2005/05/25 12:37:18 tudor Exp $

#ifndef _CSP_KERNEL_Mutex_H
#define _CSP_KERNEL_Mutex_H


#ifdef _WIN32
#include <windows.h>
#else
#include <pthread.h>
#endif


CSP_NAMESPACE_BEGIN(csp);


class CSP_API Mutex
{
  public:
    class GlobalData;

    Mutex(GlobalData* globalData) :
        m_globalData(globalData)
    {
        m_depth = 0;
        m_thread = -1;
    }

    virtual ~Mutex() { while (m_depth) release(); }

    bool iHoldIt() const
    {
        return ((m_thread == currentThread()) && (m_depth > 0));
    }

    void acquire()
    {
        if (m_thread != currentThread())
        {
            m_globalData->lock();
            m_thread = currentThread();

            assert(m_depth == 0);
        }
        m_depth++;
    }

    void release()
    {
        assert(iHoldIt());
        m_depth--;

        if (m_depth == 0)
        {
            m_thread = -1;
            m_globalData->unlock();
        }
    }

    class CSP_API GlobalData
    {
      private:
#ifndef _WIN32
        pthread_mutex_t m_mutex;
#else
        HANDLE m_mutex;
#endif

      public:
        friend class Mutex;

        GlobalData()
        {
#ifdef _WIN32
            m_mutex = CreateMutex(0, FALSE, 0);
#else
            pthread_mutex_init(&m_mutex, 0);
#endif
        }

        ~GlobalData()
        {
#ifdef _WIN32
            CloseHandle(m_mutex);
#else
            pthread_mutex_destroy(&m_mutex);
#endif
        }

        void lock()
        {
#ifdef _WIN32
            WaitForSingleObject(m_mutex, INFINITE);
#else
            pthread_mutex_lock(&m_mutex);
#endif
        }

        void unlock()
        {
#ifdef _WIN32
            ReleaseMutex(m_mutex);
#else
            pthread_mutex_unlock(&m_mutex);
#endif
        }

      private:
        // Copy constructor, disallowed.
        GlobalData(const GlobalData&);
    };

  private:
    int currentThread() const
    {
#ifdef _WIN32
        return GetCurrentThreadId();
#else
        return pthread_self();
#endif
    }

    Mutex::GlobalData* m_globalData;

    int m_thread;

    int m_depth;
};


CSP_NAMESPACE_END(csp);


#endif // _CSP_KERNEL_Mutex_H

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