qmutex_unix.cpp

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/****************************************************************************
** $Id: qmutex_unix.cpp,v 1.2 2003/07/10 02:40:12 llornkcor Exp $
**
** QMutex class for Unix
**
** Created : 20010725
**
** Copyright (C) 1992-2002 Trolltech AS.  All rights reserved.
**
** This file is part of the tools module of the Qt GUI Toolkit.
**
** This file may be distributed under the terms of the Q Public License
** as defined by Trolltech AS of Norway and appearing in the file
** LICENSE.QPL included in the packaging of this file.
**
** This file may be distributed and/or modified under the terms of the
** GNU General Public License version 2 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file.
**
** Licensees holding valid Qt Enterprise Edition or Qt Professional Edition
** licenses may use this file in accordance with the Qt Commercial License
** Agreement provided with the Software.
**
** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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**   information about Qt Commercial License Agreements.
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**********************************************************************/

#if defined(QT_THREAD_SUPPORT)

#include "qplatformdefs.h"

typedef pthread_mutex_t     Q_MUTEX_T;

// POSIX threads mutex types
#if ((defined(PTHREAD_MUTEX_RECURSIVE) && defined(PTHREAD_MUTEX_DEFAULT)) || \
     defined(Q_OS_FREEBSD)) && !defined(Q_OS_UNIXWARE) && !defined(Q_OS_SOLARIS) && \
    !defined(Q_OS_MAC)
// POSIX 1003.1c-1995 - We love this OS
#  define Q_MUTEX_SET_TYPE(a, b) pthread_mutexattr_settype((a), (b))
#  if defined(QT_CHECK_RANGE)
#    define Q_NORMAL_MUTEX_TYPE PTHREAD_MUTEX_ERRORCHECK
#  else
#    define Q_NORMAL_MUTEX_TYPE PTHREAD_MUTEX_DEFAULT
#  endif
#  define Q_RECURSIVE_MUTEX_TYPE PTHREAD_MUTEX_RECURSIVE
#elif defined(MUTEX_NONRECURSIVE_NP) && defined(MUTEX_RECURSIVE_NP)
// POSIX 1003.4a pthreads draft extensions
#  define Q_MUTEX_SET_TYPE(a, b) pthread_mutexattr_setkind_np((a), (b));
#  define Q_NORMAL_MUTEX_TYPE MUTEX_NONRECURSIVE_NP
#  define Q_RECURSIVE_MUTEX_TYPE MUTEX_RECURSIVE_NP
#else
// Unknown mutex types - skip them
#  define Q_MUTEX_SET_TYPE(a, b)
#  undef  Q_NORMAL_MUTEX_TYPE
#  undef  Q_RECURSIVE_MUTEX_TYPE
#endif

#include "qmutex.h"
#include "qmutex_p.h"

#include <errno.h>
#include <string.h>


// Private class declarations

class QRealMutexPrivate : public QMutexPrivate {
public:
    QRealMutexPrivate(bool = FALSE);

    void lock();
    void unlock();
    bool locked();
    bool trylock();
    int type() const;

    bool recursive;
};

#ifndef    Q_RECURSIVE_MUTEX_TYPE
class QRecursiveMutexPrivate : public QMutexPrivate
{
public:
    QRecursiveMutexPrivate();
    ~QRecursiveMutexPrivate();

    void lock();
    void unlock();
    bool locked();
    bool trylock();
    int type() const;

    int count;
    unsigned long owner;
    pthread_mutex_t handle2;
};
#endif // !Q_RECURSIVE_MUTEX_TYPE


// Private class implementation

// base destructor
QMutexPrivate::~QMutexPrivate()
{
    int ret = pthread_mutex_destroy(&handle);

#ifdef QT_CHECK_RANGE
    if ( ret )
        qWarning( "Mutex destroy failure: %s", strerror( ret ) );
#endif
}

// real mutex class
QRealMutexPrivate::QRealMutexPrivate(bool recurs)
    : recursive(recurs)
{
    pthread_mutexattr_t attr;
    pthread_mutexattr_init(&attr);
    Q_MUTEX_SET_TYPE(&attr, recursive ? Q_RECURSIVE_MUTEX_TYPE : Q_NORMAL_MUTEX_TYPE);
    Q_UNUSED(recursive);
    int ret = pthread_mutex_init(&handle, &attr);
    pthread_mutexattr_destroy(&attr);

#ifdef QT_CHECK_RANGE
    if( ret )
        qWarning( "Mutex init failure: %s", strerror( ret ) );
#endif // QT_CHECK_RANGE
}

void QRealMutexPrivate::lock()
{
    int ret = pthread_mutex_lock(&handle);

#ifdef QT_CHECK_RANGE
    if (ret)
        qWarning("Mutex lock failure: %s", strerror(ret));
#endif
}

void QRealMutexPrivate::unlock()
{
    int ret = pthread_mutex_unlock(&handle);

#ifdef QT_CHECK_RANGE
    if (ret)
        qWarning("Mutex unlock failure: %s", strerror(ret));
#endif
}

bool QRealMutexPrivate::locked()
{
    int ret = pthread_mutex_trylock(&handle);

    if (ret == EBUSY) {
        return TRUE;
    } else if (ret) {
#ifdef QT_CHECK_RANGE
        qWarning("Mutex locktest failure: %s", strerror(ret));
#endif
    } else
        pthread_mutex_unlock(&handle);

    return FALSE;
}

bool QRealMutexPrivate::trylock()
{
    int ret = pthread_mutex_trylock(&handle);

    if (ret == EBUSY) {
        return FALSE;
    } else if (ret) {
#ifdef QT_CHECK_RANGE
        qWarning("Mutex trylock failure: %s", strerror(ret));
#endif
        return FALSE;
    }

    return TRUE;
}

int QRealMutexPrivate::type() const
{
    return recursive ? Q_MUTEX_RECURSIVE : Q_MUTEX_NORMAL;
}


#ifndef    Q_RECURSIVE_MUTEX_TYPE
QRecursiveMutexPrivate::QRecursiveMutexPrivate()
    : count(0), owner(0)
{
    pthread_mutexattr_t attr;
    pthread_mutexattr_init(&attr);
    Q_MUTEX_SET_TYPE(&attr, Q_NORMAL_MUTEX_TYPE);
    int ret = pthread_mutex_init(&handle, &attr);
    pthread_mutexattr_destroy(&attr);

#  ifdef QT_CHECK_RANGE
    if (ret)
        qWarning( "Mutex init failure: %s", strerror(ret) );
#  endif

    pthread_mutexattr_init(&attr);
    ret = pthread_mutex_init( &handle2, &attr );
    pthread_mutexattr_destroy(&attr);

#  ifdef QT_CHECK_RANGE
    if (ret)
        qWarning( "Mutex init failure: %s", strerror(ret) );
#  endif
}

QRecursiveMutexPrivate::~QRecursiveMutexPrivate()
{
    int ret = pthread_mutex_destroy(&handle2);

#  ifdef QT_CHECK_RANGE
    if (ret)
        qWarning( "Mutex destroy failure: %s", strerror(ret) );
#  endif
}

void QRecursiveMutexPrivate::lock()
{
    pthread_mutex_lock(&handle2);

    if (count > 0 && owner == (unsigned long) pthread_self()) {
        count++;
    } else {
        pthread_mutex_unlock(&handle2);
        pthread_mutex_lock(&handle);
        pthread_mutex_lock(&handle2);
        count = 1;
        owner = (unsigned long) pthread_self();
    }

    pthread_mutex_unlock(&handle2);
}

void QRecursiveMutexPrivate::unlock()
{
    pthread_mutex_lock(&handle2);

    if (owner == (unsigned long) pthread_self()) {
        // do nothing if the count is already 0... to reflect the behaviour described
        // in the docs
        if (count && (--count) < 1) {
            count = 0;
            pthread_mutex_unlock(&handle);
        }
    } else {
#ifdef QT_CHECK_RANGE
        qWarning("QMutex::unlock: unlock from different thread than locker");
        qWarning("                was locked by %d, unlock attempt from %d",
                 (int)owner, (int)pthread_self());
#endif
    }

    pthread_mutex_unlock(&handle2);
}

bool QRecursiveMutexPrivate::locked()
{
    pthread_mutex_lock(&handle2);

    bool ret;
    int code = pthread_mutex_trylock(&handle);

    if (code == EBUSY) {
        ret = TRUE;
    } else {
#ifdef QT_CHECK_RANGE
        if (code)
            qWarning("Mutex trylock failure: %s", strerror(code));
#endif

        pthread_mutex_unlock(&handle);
        ret = FALSE;
    }

    pthread_mutex_unlock(&handle2);

    return ret;
}

bool QRecursiveMutexPrivate::trylock()
{
    bool ret = TRUE;

    pthread_mutex_lock(&handle2);

    if ( count > 0 && owner == (unsigned long) pthread_self() ) {
        count++;
    } else {
        int code = pthread_mutex_trylock(&handle);

        if (code == EBUSY) {
            ret = FALSE;
        } else if (code) {
#ifdef QT_CHECK_RANGE
            qWarning("Mutex trylock failure: %s", strerror(code));
#endif
            ret = FALSE;
        } else {
            count = 1;
            owner = (unsigned long) pthread_self();
        }
    }

    pthread_mutex_unlock(&handle2);

    return ret;
}

int QRecursiveMutexPrivate::type() const
{
    return Q_MUTEX_RECURSIVE;
}

#endif // !Q_RECURSIVE_MUTEX_TYPE


QMutex::QMutex(bool recursive)
{
#ifndef    Q_RECURSIVE_MUTEX_TYPE
    if ( recursive )
        d = new QRecursiveMutexPrivate();
    else
#endif // !Q_RECURSIVE_MUTEX_TYPE
        d = new QRealMutexPrivate(recursive);
}

QMutex::~QMutex()
{
    delete d;
}

void QMutex::lock()
{
    d->lock();
}

void QMutex::unlock()
{
    d->unlock();
}

bool QMutex::locked()
{
    return d->locked();
}

bool QMutex::tryLock()
{
    return d->trylock();
}

#endif // QT_THREAD_SUPPORT

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