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#include "qwaitcondition.h"

#include "qmutex.h"

#include <pthread.h>

#define MIN(a,b) ((a)<(b)?(a):(b))

static void report_error(int code, const char *where, const char *what)

{

    if (code != 0)

        qWarning("%s: %s failure: %d", where, what, code);

}

class QWaitConditionPrivate

{

  public:

    pthread_mutex_t mutex;

    pthread_cond_t cond;

    int waiters;

    int wakeups;

    void wait()

    {

        int code;

        for (;;)

        {

            code = pthread_cond_wait(&cond, &mutex);

            if (code == 0 && wakeups == 0) 

            {

                // many vendors warn of spurious wakeups from

                // pthread_cond_wait(), especially after signal delivery,

                // even though POSIX doesn't allow for it... sigh

                continue;

            }

            break;

        }

        --waiters;

        if (code == 0)

        {

            --wakeups;

        }

        else

        {

            report_error(code, "QWaitCondition::wait()", "cv wait");

        }

        report_error(pthread_mutex_unlock(&mutex), "QWaitCondition::wait()", "mutex unlock");

    }

};

QWaitCondition::QWaitCondition()

{

    d = new QWaitConditionPrivate;

    report_error(pthread_mutex_init(&d->mutex, NULL), "QWaitCondition", "mutex init");

    report_error(pthread_cond_init(&d->cond, NULL), "QWaitCondition", "cv init");

    d->waiters = d->wakeups = 0;

}

QWaitCondition::~QWaitCondition()

{

    report_error(pthread_cond_destroy(&d->cond), "QWaitCondition", "cv destroy");

    report_error(pthread_mutex_destroy(&d->mutex), "QWaitCondition", "mutex destroy");

    delete d;

}

void QWaitCondition::wakeOne()

{

    report_error(pthread_mutex_lock(&d->mutex), "QWaitCondition::wakeOne()", "mutex lock");

    d->wakeups = MIN(d->wakeups + 1, d->waiters);

    report_error(pthread_cond_signal(&d->cond), "QWaitCondition::wakeOne()", "cv signal");

    report_error(pthread_mutex_unlock(&d->mutex), "QWaitCondition::wakeOne()", "mutex unlock");

}

void QWaitCondition::wakeAll()

{

    report_error(pthread_mutex_lock(&d->mutex), "QWaitCondition::wakeAll()", "mutex lock");

    d->wakeups = d->waiters;

    report_error(pthread_cond_broadcast(&d->cond), "QWaitCondition::wakeAll()", "cv broadcast");

    report_error(pthread_mutex_unlock(&d->mutex), "QWaitCondition::wakeAll()", "mutex unlock");

}

void QWaitCondition::wait(QMutex *mutex)

{

    if (!mutex) return;

    report_error(pthread_mutex_lock(&d->mutex), "QWaitCondition::wait()", "mutex lock");

    ++d->waiters;

    mutex->unlock();

    d->wait();

    mutex->lock();

}