CriticalSection.h

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/*
 * $Revision: 2299 $
 * 
 * last checkin:
 *   $Author: gutwenger $ 
 *   $Date: 2012-05-07 15:57:08 +0200 (Mon, 07 May 2012) $ 
 ***************************************************************/
 
#ifdef _MSC_VER
#pragma once
#endif


#ifndef OGDF_CRITICAL_SECTION_H
#define OGDF_CRITICAL_SECTION_H

#if !defined(OGDF_SYSTEM_WINDOWS)
#include <pthread.h>
#include <errno.h>
#endif

#include <ogdf/basic/System.h>


namespace ogdf {

#if defined(OGDF_SYSTEM_WINDOWS)


class OGDF_EXPORT CriticalSection
{
public:
    CriticalSection() {
        InitializeCriticalSection(&m_cs);
    }


    explicit CriticalSection(int spinCount) {
        InitializeCriticalSectionAndSpinCount(&m_cs, spinCount);
    }

    ~CriticalSection() {
        DeleteCriticalSection(&m_cs);
    }

    void enter() {
        EnterCriticalSection(&m_cs);
    }

    bool tryEnter() {
        return (TryEnterCriticalSection(&m_cs) != 0);
    }

    void leave() {
        LeaveCriticalSection(&m_cs);
    }

private:
    CRITICAL_SECTION m_cs; 
};


#else

class OGDF_EXPORT CriticalSection
{
public:
    CriticalSection() : m_spinCount(0) {
        pthread_mutex_init(&m_mutex, NULL);
    }

    explicit CriticalSection(int spinCount) {
        m_spinCount = (System::numberOfProcessors() >= 2) ? spinCount : 0;
        int ret = pthread_mutex_init(&m_mutex, NULL);
        if(ret != 0)
            cout << "initialization of mutex failed: " << ret << endl;
    }

    ~CriticalSection() {
        pthread_mutex_destroy(&m_mutex);
    }

    void enter() {
        if(m_spinCount > 0) {
            for(int i = m_spinCount; i > 0; --i)
                if(pthread_mutex_trylock(&m_mutex) != EBUSY)
                    return;
        }
        pthread_mutex_lock(&m_mutex);
    }

    bool tryEnter() {
        return (pthread_mutex_trylock(&m_mutex) != EBUSY);
    }

    void leave() {
        pthread_mutex_unlock(&m_mutex);
    }

private:
    pthread_mutex_t m_mutex;
    int             m_spinCount;
};

#endif


} // end namespace ogdf


#endif