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****************************************************************************/

#include "qwaitcondition.h"

#include "qnamespace.h"

#include "qmutex.h"

#include "qreadwritelock.h"

#include "qlist.h"

#include "qalgorithms.h"

#include "qt_windows.h"

#ifndef QT_NO_THREAD

#define Q_MUTEX_T void*

#include <private/qmutex_p.h>

#include <private/qreadwritelock_p.h>

QT_BEGIN_NAMESPACE

//***********************************************************************

// QWaitConditionPrivate

// **********************************************************************

class QWaitConditionEvent

{

public:

    inline QWaitConditionEvent() : priority(0), wokenUp(false)

    {

        event = CreateEvent(NULL, TRUE, FALSE, NULL);

    }

    inline ~QWaitConditionEvent() { CloseHandle(event); }

    int priority;

    bool wokenUp;

    HANDLE event;

};

typedef QList<QWaitConditionEvent *> EventQueue;

class QWaitConditionPrivate

{

public:

    QMutex mtx;

    EventQueue queue;

    EventQueue freeQueue;

    QWaitConditionEvent *pre();

    bool wait(QWaitConditionEvent *wce, unsigned long time);

    void post(QWaitConditionEvent *wce, bool ret);

};

QWaitConditionEvent *QWaitConditionPrivate::pre()

{

    mtx.lock();

    QWaitConditionEvent *wce =

        freeQueue.isEmpty() ? new QWaitConditionEvent : freeQueue.takeFirst();

    wce->priority = GetThreadPriority(GetCurrentThread());

    wce->wokenUp = false;

    // insert 'wce' into the queue (sorted by priority)

    int index = 0;

    for (; index < queue.size(); ++index) {

        QWaitConditionEvent *current = queue.at(index);

        if (current->priority < wce->priority)

            break;

    }

    queue.insert(index, wce);

    mtx.unlock();

    return wce;

}

bool QWaitConditionPrivate::wait(QWaitConditionEvent *wce, unsigned long time)

{

    // wait for the event

    bool ret = false;

    switch (WaitForSingleObject(wce->event, time)) {

    default: break;

    case WAIT_OBJECT_0:

        ret = true;

        break;

    }

    return ret;

}

void QWaitConditionPrivate::post(QWaitConditionEvent *wce, bool ret)

{

    mtx.lock();

    // remove 'wce' from the queue

    queue.removeAll(wce);

    ResetEvent(wce->event);

    freeQueue.append(wce);

    // wakeups delivered after the timeout should be forwarded to the next waiter

    if (!ret && wce->wokenUp && !queue.isEmpty()) {

        QWaitConditionEvent *other = queue.first();

        SetEvent(other->event);

        other->wokenUp = true;

    }

    mtx.unlock();

}

//***********************************************************************

// QWaitCondition implementation

//***********************************************************************

QWaitCondition::QWaitCondition()

{

    d = new QWaitConditionPrivate;

}

QWaitCondition::~QWaitCondition()

{

    if (!d->queue.isEmpty()) {

        qWarning("QWaitCondition: Destroyed while threads are still waiting");

        qDeleteAll(d->queue);

    }

    qDeleteAll(d->freeQueue);

    delete d;

}

bool QWaitCondition::wait(QMutex *mutex, unsigned long time)

{

    if (!mutex)

        return false;

    if (mutex->d->recursive) {

        qWarning("QWaitCondition::wait: Cannot wait on recursive mutexes");

        return false;

    }

    QWaitConditionEvent *wce = d->pre();

    mutex->unlock();

    bool returnValue = d->wait(wce, time);

    mutex->lock();

    d->post(wce, returnValue);

    return returnValue;

}

bool QWaitCondition::wait(QReadWriteLock *readWriteLock, unsigned long time)

{

    if (!readWriteLock || readWriteLock->d->accessCount == 0)

        return false;

    if (readWriteLock->d->accessCount < -1) {

        qWarning("QWaitCondition: cannot wait on QReadWriteLocks with recursive lockForWrite()");

        return false;

    }

    QWaitConditionEvent *wce = d->pre();

    int previousAccessCount = readWriteLock->d->accessCount;

    readWriteLock->unlock();

    bool returnValue = d->wait(wce, time);

    if (previousAccessCount < 0)

        readWriteLock->lockForWrite();

    else

        readWriteLock->lockForRead();

    d->post(wce, returnValue);

    return returnValue;

}

void QWaitCondition::wakeOne()

{

    // wake up the first waiting thread in the queue

    QMutexLocker locker(&d->mtx);

    for (int i = 0; i < d->queue.size(); ++i) {

        QWaitConditionEvent *current = d->queue.at(i);

        if (current->wokenUp)

            continue;

        SetEvent(current->event);

        current->wokenUp = true;

        break;

    }

}

void QWaitCondition::wakeAll()

{

    // wake up the all threads in the queue

    QMutexLocker locker(&d->mtx);

    for (int i = 0; i < d->queue.size(); ++i) {

        QWaitConditionEvent *current = d->queue.at(i);

        SetEvent(current->event);

        current->wokenUp = true;

    }

}

QT_END_NAMESPACE

#endif // QT_NO_THREAD