path: root/src/corelib/thread/qthread_unix.cpp

/****************************************************************************
**
** Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the QtCore module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** No Commercial Usage
** This file contains pre-release code and may not be distributed.
** You may use this file in accordance with the terms and conditions
** contained in the Technology Preview License Agreement accompanying
** this package.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain additional
** rights.  These rights are described in the Nokia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** If you have questions regarding the use of this file, please contact
** Nokia at qt-info@nokia.com.
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** $QT_END_LICENSE$
**
****************************************************************************/

#include "qthread.h"

#include "qplatformdefs.h"

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

#ifdef Q_OS_SYMBIAN
#include <private/qeventdispatcher_symbian_p.h>
#else
#include <private/qeventdispatcher_unix_p.h>
#endif

#include "qthreadstorage.h"

#include "qthread_p.h"

#include "qdebug.h"

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

#ifdef Q_OS_BSD4
#include <sys/sysctl.h>
#endif
#ifdef Q_OS_VXWORKS
#  if (_WRS_VXWORKS_MAJOR > 6) || ((_WRS_VXWORKS_MAJOR == 6) && (_WRS_VXWORKS_MINOR >= 6))
#    include <vxCpuLib.h>
#    include <cpuset.h>
#    define QT_VXWORKS_HAS_CPUSET
#  endif
#endif

#ifdef Q_OS_HPUX
#include <sys/pstat.h>
#endif

#if defined(Q_OS_MAC)
# ifdef qDebug
#   define old_qDebug qDebug
#   undef qDebug
# endif
#ifndef QT_NO_CORESERVICES
# include <CoreServices/CoreServices.h>
#endif //QT_NO_CORESERVICES

# ifdef old_qDebug
#   undef qDebug
#   define qDebug QT_NO_QDEBUG_MACRO
#   undef old_qDebug
# endif
#endif

#if defined(Q_OS_LINUX) && !defined(SCHED_IDLE)
// from linux/sched.h
# define SCHED_IDLE    5
#endif

#if defined(Q_OS_DARWIN) || !defined(Q_OS_OPENBSD) && defined(_POSIX_THREAD_PRIORITY_SCHEDULING) && (_POSIX_THREAD_PRIORITY_SCHEDULING-0 >= 0)
#define QT_HAS_THREAD_PRIORITY_SCHEDULING
#endif


QT_BEGIN_NAMESPACE

#ifndef QT_NO_THREAD

enum { ThreadPriorityResetFlag = 0x80000000 };

#if defined(Q_OS_LINUX) && defined(__GLIBC__) && (defined(Q_CC_GNU) || defined(Q_CC_INTEL))
#define HAVE_TLS
#endif
#if defined(Q_CC_XLC) || defined (Q_CC_SUN)
#define HAVE_TLS
#endif

#ifdef HAVE_TLS
static __thread QThreadData *currentThreadData = 0;
#endif

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)
{
#if defined(Q_OS_VXWORKS)
    // Calling setspecific(..., 0) sets the value to 0 for ALL threads.
    // The 'set to 1' workaround adds a bit of an overhead though,
    // since this function is called twice now.
    if (p == (void *)1)
        return;
#endif
    // 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,
#if defined(Q_OS_VXWORKS)
                                                 (void *)1);
#else
                                                 0);
#endif
}

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

static void destroy_current_thread_data_key()
{
    pthread_once(&current_thread_data_once, create_current_thread_data_key);
    pthread_key_delete(current_thread_data_key);
}
Q_DESTRUCTOR_FUNCTION(destroy_current_thread_data_key)


// Utility functions for getting, setting and clearing thread specific data.
// In Symbian, TLS access is significantly faster than pthread_getspecific.
// However Symbian does not have the thread destruction cleanup functionality
// that pthread has, so pthread_setspecific is also used.
static QThreadData *get_thread_data()
{
#ifdef HAVE_TLS
    return currentThreadData;
#elif defined Q_OS_SYMBIAN
    return reinterpret_cast<QThreadData *>(Dll::Tls());
#else
    pthread_once(&current_thread_data_once, create_current_thread_data_key);
    return reinterpret_cast<QThreadData *>(pthread_getspecific(current_thread_data_key));
#endif
}

static void set_thread_data(QThreadData *data)
{
#ifdef HAVE_TLS
    currentThreadData = data;
#elif defined Q_OS_SYMBIAN
    qt_symbian_throwIfError(Dll::SetTls(data));
#endif
    pthread_once(&current_thread_data_once, create_current_thread_data_key);
    pthread_setspecific(current_thread_data_key, data);
}

static void clear_thread_data()
{
#ifdef HAVE_TLS
    currentThreadData = 0;
#elif defined Q_OS_SYMBIAN
    Dll::FreeTls();
#endif
    pthread_setspecific(current_thread_data_key, 0);
}


#ifdef Q_OS_SYMBIAN
static void init_symbian_thread_handle(RThread &thread)
{
    thread = RThread();
    TThreadId threadId = thread.Id();
    thread.Open(threadId);

    // Make thread handle accessible process wide
    RThread originalCloser = thread;
    thread.Duplicate(thread, EOwnerProcess);
    originalCloser.Close();
}
#endif

QThreadData *QThreadData::current()
{
    QThreadData *data = get_thread_data();
    if (!data) {
        void *a;
        if (QInternal::activateCallbacks(QInternal::AdoptCurrentThread, &a)) {
            QThread *adopted = static_cast<QThread*>(a);
            Q_ASSERT(adopted);
            data = QThreadData::get2(adopted);
            set_thread_data(data);
            adopted->d_func()->running = true;
            adopted->d_func()->finished = false;
            static_cast<QAdoptedThread *>(adopted)->init();
        } else {
            data = new QThreadData;
            QT_TRY {
                set_thread_data(data);
                data->thread = new QAdoptedThread(data);
            } QT_CATCH(...) {
                clear_thread_data();
                data->deref();
                data = 0;
                QT_RETHROW;
            }
            data->deref();
        }
        if (!QCoreApplicationPrivate::theMainThread)
            QCoreApplicationPrivate::theMainThread = data->thread;
    }
    return data;
}


void QAdoptedThread::init()
{
    Q_D(QThread);
    d->thread_id = pthread_self();
#ifdef Q_OS_SYMBIAN
    init_symbian_thread_handle(d->data->symbian_thread_handle);
#endif
}

/*
   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()
        && qgetenv("QT_NO_THREADED_GLIB").isEmpty()
        && QEventDispatcherGlib::versionSupported())
        data->eventDispatcher = new QEventDispatcherGlib;
    else
#endif
#ifdef Q_OS_SYMBIAN
        data->eventDispatcher = new QEventDispatcherSymbian;
#else
        data->eventDispatcher = new QEventDispatcherUNIX;
#endif
    data->eventDispatcher->startingUp();
}

#ifndef QT_NO_THREAD

void *QThreadPrivate::start(void *arg)
{
    // Symbian Open C supports neither thread cancellation nor cleanup_push.
#ifndef Q_OS_SYMBIAN
    pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, NULL);
    pthread_cleanup_push(QThreadPrivate::finish, arg);
#endif

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

    // do we need to reset the thread priority?
    if (int(thr->d_func()->priority) & ThreadPriorityResetFlag) {
        thr->setPriority(QThread::Priority(thr->d_func()->priority & ~ThreadPriorityResetFlag));
    }

#ifdef Q_OS_SYMBIAN
    // Because Symbian Open C does not provide a way to convert between
    // RThread and pthread_t, we must delay initialization of the RThread
    // handle when creating a thread, until we are running in the new thread.
    // Here, we pick up the current thread and assign that to the handle.
    init_symbian_thread_handle(data->symbian_thread_handle);

    // On symbian, threads other than the main thread are non critical by default
    // This means a worker thread can crash without crashing the application - to
    // use this feature, we would need to use RThread::Logon in the main thread
    // to catch abnormal thread exit and emit the finished signal.
    // For the sake of cross platform consistency, we set the thread as process critical
    // - advanced users who want the symbian behaviour can change the critical
    // attribute of the thread again once the app gains control in run()
    User::SetCritical(User::EProcessCritical);
#endif

    set_thread_data(data);

    data->ref();
    {
        QMutexLocker locker(&thr->d_func()->mutex);
        data->quitNow = thr->d_func()->exited;
    }

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

    emit thr->started();
#ifndef Q_OS_SYMBIAN
    pthread_setcancelstate(PTHREAD_CANCEL_ENABLE, NULL);
    pthread_testcancel();
#endif
    thr->run();

#ifdef Q_OS_SYMBIAN
    QThreadPrivate::finish(arg);
#else
    pthread_cleanup_pop(1);
#endif

    return 0;
}

#ifdef Q_OS_SYMBIAN
void QThreadPrivate::finish(void *arg, bool lockAnyway, bool closeNativeHandle)
#else
void QThreadPrivate::finish(void *arg)
#endif
{
    QThread *thr = reinterpret_cast<QThread *>(arg);
    QThreadPrivate *d = thr->d_func();

#ifdef Q_OS_SYMBIAN
    QMutexLocker locker(lockAnyway ? &d->mutex : 0);
#else
    QMutexLocker locker(&d->mutex);
#endif

    d->isInFinish = true;
    d->priority = QThread::InheritPriority;
    bool terminated = d->terminated;
    void *data = &d->data->tls;
    locker.unlock();
    if (terminated)
        emit thr->terminated();
    emit thr->finished();
    QCoreApplication::sendPostedEvents(0, QEvent::DeferredDelete);
    QThreadStorageData::finish((void **)data);
    locker.relock();
    d->terminated = false;

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

    d->thread_id = 0;
#ifdef Q_OS_SYMBIAN
    if (closeNativeHandle)
        d->data->symbian_thread_handle.Close();
#endif
    d->running = false;
    d->finished = true;

    d->isInFinish = false;
    d->thread_done.wakeAll();
}




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

Qt::HANDLE QThread::currentThreadId()
{
    // requires a C cast here otherwise we run into trouble on AIX
    return (Qt::HANDLE)pthread_self();
}

#if defined(QT_LINUXBASE) && !defined(_SC_NPROCESSORS_ONLN)
// LSB doesn't define _SC_NPROCESSORS_ONLN.
#  define _SC_NPROCESSORS_ONLN 84
#endif

int QThread::idealThreadCount()
{
    int cores = -1;

#if defined(Q_OS_MAC) && !defined(Q_WS_QPA)
    // Mac OS X
    cores = MPProcessorsScheduled();
#elif defined(Q_OS_HPUX)
    // HP-UX
    struct pst_dynamic psd;
    if (pstat_getdynamic(&psd, sizeof(psd), 1, 0) == -1) {
        perror("pstat_getdynamic");
        cores = -1;
    } else {
        cores = (int)psd.psd_proc_cnt;
    }
#elif defined(Q_OS_BSD4)
    // FreeBSD, OpenBSD, NetBSD, BSD/OS
    size_t len = sizeof(cores);
    int mib[2];
    mib[0] = CTL_HW;
    mib[1] = HW_NCPU;
    if (sysctl(mib, 2, &cores, &len, NULL, 0) != 0) {
        perror("sysctl");
        cores = -1;
    }
#elif defined(Q_OS_IRIX)
    // IRIX
    cores = (int)sysconf(_SC_NPROC_ONLN);
#elif defined(Q_OS_INTEGRITY)
    // as of aug 2008 Integrity only supports one single core CPU
    cores = 1;
#elif defined(Q_OS_SYMBIAN)
	 // ### TODO - Get the number of cores from HAL? when multicore architectures (SMP) are supported
    cores = 1;
#elif defined(Q_OS_VXWORKS)
    // VxWorks
#  if defined(QT_VXWORKS_HAS_CPUSET)
    cpuset_t cpus = vxCpuEnabledGet();
    cores = 0;

    // 128 cores should be enough for everyone ;)
    for (int i = 0; i < 128 && !CPUSET_ISZERO(cpus); ++i) {
        if (CPUSET_ISSET(cpus, i)) {
            CPUSET_CLR(cpus, i);
            cores++;
        }
    }
#  else
    // as of aug 2008 VxWorks < 6.6 only supports one single core CPU
    cores = 1;
#  endif
#else
    // the rest: Linux, Solaris, AIX, Tru64
    cores = (int)sysconf(_SC_NPROCESSORS_ONLN);
#endif

    return cores;
}

void QThread::yieldCurrentThread()
{
    sched_yield();
}

/*  \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);
}

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);
}

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);
}

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);
}

#ifdef QT_HAS_THREAD_PRIORITY_SCHEDULING
// Does some magic and calculate the Unix scheduler priorities
// sched_policy is IN/OUT: it must be set to a valid policy before calling this function
// sched_priority is OUT only
static bool calculateUnixPriority(int priority, int *sched_policy, int *sched_priority)
{
#ifdef SCHED_IDLE
    if (priority == QThread::IdlePriority) {
        *sched_policy = SCHED_IDLE;
        *sched_priority = 0;
        return true;
    }
    const int lowestPriority = QThread::LowestPriority;
#else
    const int lowestPriority = QThread::IdlePriority;
#endif
    const int highestPriority = QThread::TimeCriticalPriority;

    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)
        return false;

    int prio;
    // crudely scale our priority enum values to the prio_min/prio_max
    prio = ((priority - lowestPriority) * (prio_max - prio_min) / highestPriority) + prio_min;
    prio = qMax(prio_min, qMin(prio_max, prio));

    *sched_priority = prio;
    return true;
}
#endif

void QThread::start(Priority priority)
{
    Q_D(QThread);
    QMutexLocker locker(&d->mutex);

    if (d->isInFinish)
        d->thread_done.wait(locker.mutex());

    if (d->running)
        return;

    d->running = true;
    d->finished = false;
    d->terminated = false;
    d->returnCode = 0;
    d->exited = false;

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

    d->priority = priority;

#if defined(QT_HAS_THREAD_PRIORITY_SCHEDULING) && !defined(Q_OS_SYMBIAN)
// ### Need to implement thread sheduling and priorities for symbian os. Implementation removed for now
    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;
            if (!calculateUnixPriority(priority, &sched_policy, &prio)) {
                // failed to get the scheduling parameters, don't
                // bother setting the priority
                qWarning("QThread::start: Cannot determine scheduler priority range");
                break;
            }

            sched_param sp;
            sp.sched_priority = prio;

            if (pthread_attr_setinheritsched(&attr, PTHREAD_EXPLICIT_SCHED) != 0
                || pthread_attr_setschedpolicy(&attr, sched_policy) != 0
                || pthread_attr_setschedparam(&attr, &sp) != 0) {
                // could not set scheduling hints, fallback to inheriting them
                // we'll try again from inside the thread
                pthread_attr_setinheritsched(&attr, PTHREAD_INHERIT_SCHED);
                d->priority = Priority(priority | ThreadPriorityResetFlag);
            }
            break;
        }
    }
#endif // QT_HAS_THREAD_PRIORITY_SCHEDULING

#ifdef Q_OS_SYMBIAN
    if (d->stackSize == 0)
        // The default stack size on Symbian is very small, making even basic
        // operations like file I/O fail, so we increase it by default.
        d->stackSize = 0x14000; // Maximum stack size on Symbian.
#endif

    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
#ifndef Q_OS_SYMBIAN
        pthread_attr_setinheritsched(&attr, PTHREAD_INHERIT_SCHED);
#endif
        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;
#ifdef Q_OS_SYMBIAN
        d->data->symbian_thread_handle.Close();
#endif
    }
}

void QThread::terminate()
{
    Q_D(QThread);
    QMutexLocker locker(&d->mutex);

    if (!d->thread_id)
        return;

#ifndef Q_OS_SYMBIAN
    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;
    }
#else
    if (!d->running)
        return;
    if (!d->terminationEnabled) {
        d->terminatePending = true;
        return;
    }

    d->terminated = true;
    // "false, false" meaning:
    // 1. lockAnyway = false. Don't lock the mutex because it's already locked
    //    (see above).
    // 2. closeNativeSymbianHandle = false. We don't want to close the thread handle,
    //    because we need it here to terminate the thread.
    QThreadPrivate::finish(this, false, false);
    d->data->symbian_thread_handle.Terminate(KErrNone);
    d->data->symbian_thread_handle.Close();
#endif


}

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) {
#ifdef Q_OS_SYMBIAN
        // Check if thread still exists. Needed because kernel will kill it without notification
        // before global statics are deleted at application exit.
        if (d->data->symbian_thread_handle.Handle()
            && d->data->symbian_thread_handle.ExitType() != EExitPending) {
            // Cannot call finish here as wait is typically called from another thread.
            // It won't be necessary anyway, as we should never get here under normal operations;
            // all QThreads are EProcessCritical and therefore cannot normally exit
            // undetected (i.e. panic) as long as all thread control is via QThread.
            return true;
        }
#endif
        if (!d->thread_done.wait(locker.mutex(), time))
            return false;
    }
    return true;
}

void QThread::setTerminationEnabled(bool enabled)
{
    QThread *thr = currentThread();
    Q_ASSERT_X(thr != 0, "QThread::setTerminationEnabled()",
               "Current thread was not started with QThread.");
#ifndef Q_OS_SYMBIAN
    Q_UNUSED(thr)
    pthread_setcancelstate(enabled ? PTHREAD_CANCEL_ENABLE : PTHREAD_CANCEL_DISABLE, NULL);
    if (enabled)
        pthread_testcancel();
#else
    QThreadPrivate *d = thr->d_func();
    QMutexLocker locker(&d->mutex);
    d->terminationEnabled = enabled;
    if (enabled && d->terminatePending) {
        d->terminated = true;
        // "false" meaning:
        // -  lockAnyway = false. Don't lock the mutex because it's already locked
        //    (see above).
        QThreadPrivate::finish(thr, false);
        locker.unlock(); // don't leave the mutex locked!
        pthread_exit(NULL);
    }
#endif
}

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:

#ifdef QT_HAS_THREAD_PRIORITY_SCHEDULING
    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;
    if (!calculateUnixPriority(priority, &sched_policy, &prio)) {
        // failed to get the scheduling parameters, don't
        // bother setting the priority
        qWarning("QThread::setPriority: Cannot determine scheduler priority range");
        return;
    }

    param.sched_priority = prio;
    int status = pthread_setschedparam(d->thread_id, sched_policy, &param);

# ifdef SCHED_IDLE
    // were we trying to set to idle priority and failed?
    if (status == -1 && sched_policy == SCHED_IDLE && errno == EINVAL) {
        // reset to lowest priority possible
        pthread_getschedparam(d->thread_id, &sched_policy, &param);
        param.sched_priority = sched_get_priority_min(sched_policy);
        pthread_setschedparam(d->thread_id, sched_policy, &param);
    }
# else
    Q_UNUSED(status);
# endif // SCHED_IDLE
#endif
}

#endif // QT_NO_THREAD

QT_END_NAMESPACE