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qthread_unix.cpp

/****************************************************************************
**
** Copyright (C) 1992-2007 Trolltech ASA. All rights reserved.
**
** This file is part of the QtCore module of the Qt Toolkit.
**
** This file may be used under the terms of the GNU General Public
** License version 2.0 as published by the Free Software Foundation
** and appearing in the file LICENSE.GPL included in the packaging of
** this file.  Please review the following information to ensure GNU
** General Public Licensing requirements will be met:
** http://www.trolltech.com/products/qt/opensource.html
**
** If you are unsure which license is appropriate for your use, please
** review the following information:
** http://www.trolltech.com/products/qt/licensing.html or contact the
** sales department at sales@trolltech.com.
**
** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
**
****************************************************************************/

#include "qthread.h"

#include "qplatformdefs.h"

#include <private/qcoreapplication_p.h>
#if !defined(QT_NO_GLIB)
#  include "../kernel/qeventdispatcher_glib_p.h"
#endif
#include <private/qeventdispatcher_unix_p.h>

#include "qthreadstorage.h"

#include "qthread_p.h"

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

#ifndef QT_NO_THREAD

static pthread_once_t current_thread_data_once = PTHREAD_ONCE_INIT;
static pthread_key_t current_thread_data_key;

static void destroy_current_thread_data(void *p)
{
    // POSIX says the value in our key is set to zero before calling
    // this destructor function, so we need to set it back to the
    // right value...
    pthread_setspecific(current_thread_data_key, p);
    reinterpret_cast<QThreadData *>(p)->deref();
    // ... but we must reset it to zero before returning so we aren't
    // called again (POSIX allows implementations to call destructor
    // functions repeatedly until all values are zero)
    pthread_setspecific(current_thread_data_key, 0);
}

static void create_current_thread_data_key()
{
    pthread_key_create(&current_thread_data_key, destroy_current_thread_data);
}

QThreadData *QThreadData::current()
{
    pthread_once(&current_thread_data_once, create_current_thread_data_key);

    QThreadData *data = 0;
    QThread *adopted = 0;
    if (QInternal::activateCallbacks(QInternal::AdoptCurrentThread, (void **) &adopted)) {
        Q_ASSERT(adopted);
        data = QThreadData::get2(adopted);
        pthread_setspecific(current_thread_data_key, data);
        adopted->d_func()->running = true;
        adopted->d_func()->finished = false;
        static_cast<QAdoptedThread *>(adopted)->init();
    } else {
        data = reinterpret_cast<QThreadData *>(pthread_getspecific(current_thread_data_key));
        if (!data) {
            data = new QThreadData;
            pthread_setspecific(current_thread_data_key, data);
            data->thread = new QAdoptedThread(data);
            data->deref();
            (void) q_atomic_test_and_set_ptr(&QCoreApplicationPrivate::theMainThread, 0, data->thread);
        }
    }
    return data;
}


void QAdoptedThread::init()
{
    d_func()->thread_id = pthread_self();
}

/*
   QThreadPrivate
*/

#if defined(Q_C_CALLBACKS)
extern "C" {
#endif

typedef void*(*QtThreadCallback)(void*);

#if defined(Q_C_CALLBACKS)
}
#endif

#endif // QT_NO_THREAD

void QThreadPrivate::createEventDispatcher(QThreadData *data)
{
#if !defined(QT_NO_GLIB)
    if (qgetenv("QT_NO_GLIB").isEmpty())
        data->eventDispatcher = new QEventDispatcherGlib;
    else
#endif
        data->eventDispatcher = new QEventDispatcherUNIX;
    data->eventDispatcher->startingUp();
}

#ifndef QT_NO_THREAD

void *QThreadPrivate::start(void *arg)
{
    pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, NULL);
    pthread_cleanup_push(QThreadPrivate::finish, arg);

    QThread *thr = reinterpret_cast<QThread *>(arg);
    QThreadData *data = QThreadData::get2(thr);

    pthread_once(&current_thread_data_once, create_current_thread_data_key);
    pthread_setspecific(current_thread_data_key, data);

    data->ref();
    data->quitNow = false;

    // ### TODO: allow the user to create a custom event dispatcher
    createEventDispatcher(data);

    emit thr->started();
    pthread_setcancelstate(PTHREAD_CANCEL_ENABLE, NULL);
    pthread_testcancel();
    thr->run();

    pthread_cleanup_pop(1);
    return 0;
}

void QThreadPrivate::finish(void *arg)
{
    QThread *thr = reinterpret_cast<QThread *>(arg);
    QThreadPrivate *d = thr->d_func();
    QMutexLocker locker(&d->mutex);

    d->priority = QThread::InheritPriority;
    d->running = false;
    d->finished = true;
    if (d->terminated)
        emit thr->terminated();
    d->terminated = false;
    emit thr->finished();

    if (d->data->eventDispatcher) {
        d->data->eventDispatcher->closingDown();
        QAbstractEventDispatcher *eventDispatcher = d->data->eventDispatcher;
        d->data->eventDispatcher = 0;
        delete eventDispatcher;
    }

    QThreadStorageData::finish(d->data->tls);
    d->data->tls = 0;

    d->thread_id = 0;
    d->thread_done.wakeAll();
}




/**************************************************************************
 ** QThread
 *************************************************************************/

/*!
    Returns the thread handle of the currently executing thread.

    \warning The handle returned by this function is used for internal
    purposes and should not be used in any application code. On
    Windows, the returned value is a pseudo-handle for the current
    thread that cannot be used for numerical comparison.
*/
00195 Qt::HANDLE QThread::currentThreadId()
{
    // requires a C cast here otherwise we run into trouble on AIX
    return (Qt::HANDLE)pthread_self();
}

/*  \internal
    helper function to do thread sleeps, since usleep()/nanosleep()
    aren't reliable enough (in terms of behavior and availability)
*/
static void thread_sleep(struct timespec *ti)
{
    pthread_mutex_t mtx;
    pthread_cond_t cnd;

    pthread_mutex_init(&mtx, 0);
    pthread_cond_init(&cnd, 0);

    pthread_mutex_lock(&mtx);
    (void) pthread_cond_timedwait(&cnd, &mtx, ti);
    pthread_mutex_unlock(&mtx);

    pthread_cond_destroy(&cnd);
    pthread_mutex_destroy(&mtx);
}

/*!
    Forces the current thread to sleep for \a secs seconds.

    \sa msleep(), usleep()
*/
00226 void QThread::sleep(unsigned long secs)
{
    struct timeval tv;
    gettimeofday(&tv, 0);
    struct timespec ti;
    ti.tv_sec = tv.tv_sec + secs;
    ti.tv_nsec = (tv.tv_usec * 1000);
    thread_sleep(&ti);
}

/*!
    Causes the current thread to sleep for \a msecs milliseconds.

    \sa sleep(), usleep()
*/
00241 void QThread::msleep(unsigned long msecs)
{
    struct timeval tv;
    gettimeofday(&tv, 0);
    struct timespec ti;

    ti.tv_nsec = (tv.tv_usec + (msecs % 1000) * 1000) * 1000;
    ti.tv_sec = tv.tv_sec + (msecs / 1000) + (ti.tv_nsec / 1000000000);
    ti.tv_nsec %= 1000000000;
    thread_sleep(&ti);
}

/*!
    Causes the current thread to sleep for \a usecs microseconds.

    \sa sleep(), msleep()
*/
00258 void QThread::usleep(unsigned long usecs)
{
    struct timeval tv;
    gettimeofday(&tv, 0);
    struct timespec ti;

    ti.tv_nsec = (tv.tv_usec + (usecs % 1000000)) * 1000;
    ti.tv_sec = tv.tv_sec + (usecs / 1000000) + (ti.tv_nsec / 1000000000);
    ti.tv_nsec %= 1000000000;
    thread_sleep(&ti);
}

/*!
    Begins execution of the thread by calling run(), which should be
    reimplemented in a QThread subclass to contain your code. The
    operating system will schedule the thread according to the \a
    priority parameter. If the thread is already running, this
    function does nothing.

    \sa run(), terminate()
*/
00279 void QThread::start(Priority priority)
{
    Q_D(QThread);
    QMutexLocker locker(&d->mutex);
    if (d->running)
        return;

    d->running = true;
    d->finished = false;
    d->terminated = false;

    pthread_attr_t attr;
    pthread_attr_init(&attr);
    pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);

    d->priority = priority;

#if defined(Q_OS_DARWIN) || !defined(Q_OS_OPENBSD) && defined(_POSIX_THREAD_PRIORITY_SCHEDULING) && (_POSIX_THREAD_PRIORITY_SCHEDULING-0 >= 0)
    switch (priority) {
    case InheritPriority:
        {
            pthread_attr_setinheritsched(&attr, PTHREAD_INHERIT_SCHED);
            break;
        }

    default:
        {
            int sched_policy;
            if (pthread_attr_getschedpolicy(&attr, &sched_policy) != 0) {
                // failed to get the scheduling policy, don't bother
                // setting the priority
                qWarning("QThread::start: Cannot determine default scheduler policy");
                break;
            }

            int prio_min = sched_get_priority_min(sched_policy);
            int prio_max = sched_get_priority_max(sched_policy);
            if (prio_min == -1 || prio_max == -1) {
                // failed to get the scheduling parameters, don't
                // bother setting the priority
                qWarning("QThread::start: Cannot determine scheduler priority range");
                break;
            }

            int prio;
            switch (priority) {
            case IdlePriority:
                prio = prio_min;
                break;

            case TimeCriticalPriority:
                prio = prio_max;
                break;

            default:
                // crudely scale our priority enum values to the prio_min/prio_max
                prio = (((prio_max - prio_min) / TimeCriticalPriority) * priority) + prio_min;
                prio = qMax(prio_min, qMin(prio_max, prio));
                break;
            }

            sched_param sp;
            sp.sched_priority = prio;

            pthread_attr_setinheritsched(&attr, PTHREAD_EXPLICIT_SCHED);
            pthread_attr_setschedparam(&attr, &sp);
            break;
        }
    }
#endif // _POSIX_THREAD_PRIORITY_SCHEDULING

    if (d->stackSize > 0) {
#if defined(_POSIX_THREAD_ATTR_STACKSIZE) && (_POSIX_THREAD_ATTR_STACKSIZE-0 > 0)
        int code = pthread_attr_setstacksize(&attr, d->stackSize);
#else
        int code = ENOSYS; // stack size not supported, automatically fail
#endif // _POSIX_THREAD_ATTR_STACKSIZE

        if (code) {
            qWarning("QThread::start: Thread stack size error: %s",
                     qPrintable(qt_error_string(code)));

            // we failed to set the stacksize, and as the documentation states,
            // the thread will fail to run...
            d->running = false;
            d->finished = false;
            return;
        }
    }

    int code =
        pthread_create(&d->thread_id, &attr, QThreadPrivate::start, this);
    if (code == EPERM) {
        // caller does not have permission to set the scheduling
        // parameters/policy
        pthread_attr_setinheritsched(&attr, PTHREAD_INHERIT_SCHED);
        code =
            pthread_create(&d->thread_id, &attr, QThreadPrivate::start, this);
    }

    pthread_attr_destroy(&attr);

    if (code) {
        qWarning("QThread::start: Thread creation error: %s", qPrintable(qt_error_string(code)));

        d->running = false;
        d->finished = false;
        d->thread_id = 0;
    }
}

/*!
    Terminates the execution of the thread. The thread may or may not
    be terminated immediately, depending on the operating systems
    scheduling policies. Use QThread::wait() after terminate() for
    synchronous termination.

    When the thread is terminated, all threads waiting for the thread
    to finish will be woken up.

    \warning This function is dangerous and its use is discouraged.
    The thread can be terminate at any point in its code path.
    Threads can be terminated while modifying data. There is no
    chance for the thread to cleanup after itself, unlock any held
    mutexes, etc. In short, use this function only if absolutely
    necessary.

    Termination can be explicitly enabled or disabled by calling
    QThread::setTerminationEnabled(). Calling this function while
    termination is disabled results in the termination being
    deferred, until termination is re-enabled. See the documentation
    of QThread::setTerminationEnabled() for more information.

    \sa setTerminationEnabled()
*/
00414 void QThread::terminate()
{
    Q_D(QThread);
    QMutexLocker locker(&d->mutex);

    if (!d->thread_id)
        return;

    int code = pthread_cancel(d->thread_id);
    if (code) {
        qWarning("QThread::start: Thread termination error: %s",
                 qPrintable(qt_error_string((code))));
    } else {
        d->terminated = true;
    }
}

/*!
    Blocks the thread until either of these conditions is met:

    \list
    \o The thread associated with this QThread object has finished
       execution (i.e. when it returns from \l{run()}). This function
       will return true if the thread has finished. It also returns
       true if the thread has not been started yet.
    \o \a time milliseconds has elapsed. If \a time is ULONG_MAX (the
        default), then the wait will never timeout (the thread must
        return from \l{run()}). This function will return false if the
        wait timed out.
    \endlist

    This provides similar functionality to the POSIX \c
    pthread_join() function.

    \sa sleep(), terminate()
*/
00450 bool QThread::wait(unsigned long time)
{
    Q_D(QThread);
    QMutexLocker locker(&d->mutex);

    if (d->thread_id == pthread_self()) {
        qWarning("QThread::wait: Thread tried to wait on itself");
        return false;
    }

    if (d->finished || !d->running)
        return true;

    while (d->running) {
        if (!d->thread_done.wait(locker.mutex(), time))
            return false;
    }
    return true;
}

/*!
    Enables or disables termination of the current thread based on the
    \a enabled parameter. The thread must have been started by
    QThread.

    When \a enabled is false, termination is disabled.  Future calls
    to QThread::terminate() will return immediately without effect.
    Instead, the termination is deferred until termination is enabled.

    When \a enabled is true, termination is enabled.  Future calls to
    QThread::terminate() will terminate the thread normally.  If
    termination has been deferred (i.e. QThread::terminate() was
    called with termination disabled), this function will terminate
    the calling thread \e immediately.  Note that this function will
    not return in this case.

    \sa terminate()
*/
00488 void QThread::setTerminationEnabled(bool enabled)
{
    Q_ASSERT_X(currentThread() != 0, "QThread::setTerminationEnabled()",
               "Current thread was not started with QThread.");
    pthread_setcancelstate(enabled ? PTHREAD_CANCEL_ENABLE : PTHREAD_CANCEL_DISABLE, NULL);
    if (enabled)
        pthread_testcancel();
}

00497 void QThread::setPriority(Priority priority)
{
    Q_D(QThread);
    QMutexLocker locker(&d->mutex);
    if (!d->running) {
        qWarning("QThread::setPriority: Cannot set priority, thread is not running");
        return;
    }

    d->priority = priority;

    // copied from start() with a few modifications:

#if defined(Q_OS_DARWIN) || !defined(Q_OS_OPENBSD) && defined(_POSIX_THREAD_PRIORITY_SCHEDULING) && (_POSIX_THREAD_PRIORITY_SCHEDULING-0 >= 0)
    int sched_policy;
    sched_param param;

    if (pthread_getschedparam(d->thread_id, &sched_policy, &param) != 0) {
        // failed to get the scheduling policy, don't bother setting
        // the priority
        qWarning("QThread::setPriority: Cannot get scheduler parameters");
        return;
    }

    int prio_min = sched_get_priority_min(sched_policy);
    int prio_max = sched_get_priority_max(sched_policy);
    if (prio_min == -1 || prio_max == -1) {
        // failed to get the scheduling parameters, don't
        // bother setting the priority
        qWarning("QThread::setPriority: Cannot determine scheduler priority range");
        return;
    }

    int prio;
    switch (priority) {
    case InheritPriority:
        qWarning("QThread::setPriority: Argument cannot be InheritPriority");
        return;

    case IdlePriority:
        prio = prio_min;
        break;

    case TimeCriticalPriority:
        prio = prio_max;
        break;

    default:
        // crudely scale our priority enum values to the prio_min/prio_max
        prio = (((prio_max - prio_min) / TimeCriticalPriority) * priority) + prio_min;
        prio = qMax(prio_min, qMin(prio_max, prio));
        break;
    }

    param.sched_priority = prio;
    pthread_setschedparam(d->thread_id, sched_policy, &param);
#endif
}

#endif // QT_NO_THREAD

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