qthread_win.cpp

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/****************************************************************************
**
** Copyright (C) 2016 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the QtCore module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
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** General Public License version 3 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL3 included in the
** packaging of this file. Please review the following information to
** ensure the GNU Lesser General Public License version 3 requirements
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** Alternatively, this file may be used under the terms of the GNU
** General Public License version 2.0 or (at your option) the GNU General
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** included in the packaging of this file. Please review the following
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** $QT_END_LICENSE$
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****************************************************************************/
 
#include "qthread.h"
#include "qthread_p.h"
#include "qthreadstorage.h"
#include "qmutex.h"
 
#include <qcoreapplication.h>
#include <qpointer.h>
 
#include <private/qcoreapplication_p.h>
#include <private/qeventdispatcher_win_p.h>
 
#include <qt_windows.h>
 
#ifndef _MT
#  define _MT
#endif // _MT
#include <process.h>
 
QT_BEGIN_NAMESPACE
 
#if QT_CONFIG(thread)
 
void qt_watch_adopted_thread(const HANDLE adoptedThreadHandle, QThread *qthread);
DWORD WINAPI qt_adopted_thread_watcher_function(LPVOID);
 
static DWORD qt_current_thread_data_tls_index = TLS_OUT_OF_INDEXES;
void qt_create_tls()
{
    if (qt_current_thread_data_tls_index != TLS_OUT_OF_INDEXES)
        return;
    static QBasicMutex mutex;
    QMutexLocker locker(&mutex);
    if (qt_current_thread_data_tls_index != TLS_OUT_OF_INDEXES)
        return;
    qt_current_thread_data_tls_index = TlsAlloc();
}
 
static void qt_free_tls()
{
    if (qt_current_thread_data_tls_index != TLS_OUT_OF_INDEXES) {
        TlsFree(qt_current_thread_data_tls_index);
        qt_current_thread_data_tls_index = TLS_OUT_OF_INDEXES;
    }
}
Q_DESTRUCTOR_FUNCTION(qt_free_tls)
 
/*
    QThreadData
*/
void QThreadData::clearCurrentThreadData()
{
    TlsSetValue(qt_current_thread_data_tls_index, 0);
}
 
QThreadData *QThreadData::current(bool createIfNecessary)
{
    qt_create_tls();
    QThreadData *threadData = reinterpret_cast<QThreadData *>(TlsGetValue(qt_current_thread_data_tls_index));
    if (!threadData && createIfNecessary) {
        threadData = new QThreadData;
        // This needs to be called prior to new AdoptedThread() to
        // avoid recursion.
        TlsSetValue(qt_current_thread_data_tls_index, threadData);
        QT_TRY {
            threadData->thread = new QAdoptedThread(threadData);
        } QT_CATCH(...) {
            TlsSetValue(qt_current_thread_data_tls_index, 0);
            threadData->deref();
            threadData = 0;
            QT_RETHROW;
        }
        threadData->deref();
        threadData->isAdopted = true;
        threadData->threadId.storeRelaxed(reinterpret_cast<Qt::HANDLE>(quintptr(GetCurrentThreadId())));
 
        if (!QCoreApplicationPrivate::theMainThread) {
            QCoreApplicationPrivate::theMainThread = threadData->thread.loadRelaxed();
        } else {
            HANDLE realHandle = INVALID_HANDLE_VALUE;
            DuplicateHandle(GetCurrentProcess(),
                    GetCurrentThread(),
                    GetCurrentProcess(),
                    &realHandle,
                    0,
                    FALSE,
                    DUPLICATE_SAME_ACCESS);
            qt_watch_adopted_thread(realHandle, threadData->thread);
        }
    }
    return threadData;
}
 
void QAdoptedThread::init()
{
    d_func()->handle = GetCurrentThread();
    d_func()->id = GetCurrentThreadId();
}
 
static QList<HANDLE> qt_adopted_thread_handles;
static QList<QThread *> qt_adopted_qthreads;
static QBasicMutex qt_adopted_thread_watcher_mutex;
static DWORD qt_adopted_thread_watcher_id = 0;
static HANDLE qt_adopted_thread_wakeup = 0;
 
void qt_watch_adopted_thread(const HANDLE adoptedThreadHandle, QThread *qthread)
{
    QMutexLocker lock(&qt_adopted_thread_watcher_mutex);
 
    if (GetCurrentThreadId() == qt_adopted_thread_watcher_id) {
        CloseHandle(adoptedThreadHandle);
        return;
    }
 
    qt_adopted_thread_handles.append(adoptedThreadHandle);
    qt_adopted_qthreads.append(qthread);
 
    // Start watcher thread if it is not already running.
    if (qt_adopted_thread_watcher_id == 0) {
        if (qt_adopted_thread_wakeup == 0) {
            qt_adopted_thread_wakeup = CreateEvent(0, false, false, 0);
            qt_adopted_thread_handles.prepend(qt_adopted_thread_wakeup);
        }
 
        CloseHandle(CreateThread(0, 0, qt_adopted_thread_watcher_function, 0, 0, &qt_adopted_thread_watcher_id));
    } else {
        SetEvent(qt_adopted_thread_wakeup);
    }
}
 
/*
    This function loops and waits for native adopted threads to finish.
    When this happens it derefs the QThreadData for the adopted thread
    to make sure it gets cleaned up properly.
*/
DWORD WINAPI qt_adopted_thread_watcher_function(LPVOID)
{
    forever {
        qt_adopted_thread_watcher_mutex.lock();
 
        if (qt_adopted_thread_handles.count() == 1) {
            qt_adopted_thread_watcher_id = 0;
            qt_adopted_thread_watcher_mutex.unlock();
            break;
        }
 
        QList<HANDLE> handlesCopy = qt_adopted_thread_handles;
        qt_adopted_thread_watcher_mutex.unlock();
 
        DWORD ret = WAIT_TIMEOUT;
        int count;
        int offset;
        int loops = handlesCopy.size() / MAXIMUM_WAIT_OBJECTS;
        if (handlesCopy.size() % MAXIMUM_WAIT_OBJECTS)
            ++loops;
        if (loops == 1) {
            // no need to loop, no timeout
            offset = 0;
            count = handlesCopy.count();
            ret = WaitForMultipleObjects(handlesCopy.count(), handlesCopy.constData(), false, INFINITE);
        } else {
            int loop = 0;
            do {
                offset = loop * MAXIMUM_WAIT_OBJECTS;
                count = qMin(handlesCopy.count() - offset, MAXIMUM_WAIT_OBJECTS);
                ret = WaitForMultipleObjects(count, handlesCopy.constData() + offset, false, 100);
                loop = (loop + 1) % loops;
            } while (ret == WAIT_TIMEOUT);
        }
 
        if (ret == WAIT_FAILED || ret >= WAIT_OBJECT_0 + uint(count)) {
            qWarning("QThread internal error while waiting for adopted threads: %d", int(GetLastError()));
            continue;
        }
 
        const int handleIndex = offset + ret - WAIT_OBJECT_0;
        if (handleIndex == 0) // New handle to watch was added.
            continue;
        const int qthreadIndex = handleIndex - 1;
 
        qt_adopted_thread_watcher_mutex.lock();
        QThreadData *data = QThreadData::get2(qt_adopted_qthreads.at(qthreadIndex));
        qt_adopted_thread_watcher_mutex.unlock();
        if (data->isAdopted) {
            QThread *thread = data->thread;
            Q_ASSERT(thread);
            auto thread_p = static_cast<QThreadPrivate *>(QObjectPrivate::get(thread));
            Q_UNUSED(thread_p);
            Q_ASSERT(!thread_p->finished);
            QThreadPrivate::finish(thread);
        }
        data->deref();
 
        QMutexLocker lock(&qt_adopted_thread_watcher_mutex);
        CloseHandle(qt_adopted_thread_handles.at(handleIndex));
        qt_adopted_thread_handles.remove(handleIndex);
        qt_adopted_qthreads.remove(qthreadIndex);
    }
 
    QThreadData *threadData = reinterpret_cast<QThreadData *>(TlsGetValue(qt_current_thread_data_tls_index));
    if (threadData)
        threadData->deref();
 
    return 0;
}
 
#if !defined(QT_NO_DEBUG) && defined(Q_CC_MSVC)
 
#ifndef Q_OS_WIN64
#  define ULONG_PTR DWORD
#endif
 
typedef struct tagTHREADNAME_INFO
{
    DWORD dwType;      // must be 0x1000
    LPCSTR szName;     // pointer to name (in user addr space)
    HANDLE dwThreadID; // thread ID (-1=caller thread)
    DWORD dwFlags;     // reserved for future use, must be zero
} THREADNAME_INFO;
 
void qt_set_thread_name(HANDLE threadId, LPCSTR threadName)
{
    THREADNAME_INFO info;
    info.dwType = 0x1000;
    info.szName = threadName;
    info.dwThreadID = threadId;
    info.dwFlags = 0;
 
    __try
    {
        RaiseException(0x406D1388, 0, sizeof(info)/sizeof(DWORD),
                       reinterpret_cast<const ULONG_PTR*>(&info));
    }
    __except (EXCEPTION_CONTINUE_EXECUTION)
    {
    }
}
#endif // !QT_NO_DEBUG && Q_CC_MSVC
 
/**************************************************************************
 ** QThreadPrivate
 *************************************************************************/
 
#endif // QT_CONFIG(thread)
 
QAbstractEventDispatcher *QThreadPrivate::createEventDispatcher(QThreadData *data)
{
    Q_UNUSED(data);
    return new QEventDispatcherWin32;
}
 
#if QT_CONFIG(thread)
 
unsigned int __stdcall QT_ENSURE_STACK_ALIGNED_FOR_SSE QThreadPrivate::start(void *arg) noexcept
{
    QThread *thr = reinterpret_cast<QThread *>(arg);
    QThreadData *data = QThreadData::get2(thr);
 
    qt_create_tls();
    TlsSetValue(qt_current_thread_data_tls_index, data);
    data->threadId.storeRelaxed(reinterpret_cast<Qt::HANDLE>(quintptr(GetCurrentThreadId())));
 
    QThread::setTerminationEnabled(false);
 
    {
        QMutexLocker locker(&thr->d_func()->mutex);
        data->quitNow = thr->d_func()->exited;
    }
 
    data->ensureEventDispatcher();
    data->eventDispatcher.loadRelaxed()->startingUp();
 
#if !defined(QT_NO_DEBUG) && defined(Q_CC_MSVC)
    // sets the name of the current thread.
    qt_set_thread_name(HANDLE(-1), thr->d_func()->objectName.isEmpty()
                        ? thr->metaObject()->className()
                        : std::exchange(thr->d_func()->objectName, {}).toLocal8Bit().constData());
#endif
 
    emit thr->started(QThread::QPrivateSignal());
    QThread::setTerminationEnabled(true);
    thr->run();
 
    finish(arg);
    return 0;
}
 
void QThreadPrivate::finish(void *arg, bool lockAnyway) noexcept
{
    QThread *thr = reinterpret_cast<QThread *>(arg);
    QThreadPrivate *d = thr->d_func();
 
    QMutexLocker locker(lockAnyway ? &d->mutex : 0);
    d->isInFinish = true;
    d->priority = QThread::InheritPriority;
    void **tls_data = reinterpret_cast<void **>(&d->data->tls);
    locker.unlock();
    emit thr->finished(QThread::QPrivateSignal());
    QCoreApplication::sendPostedEvents(0, QEvent::DeferredDelete);
    QThreadStorageData::finish(tls_data);
    locker.relock();
 
    QAbstractEventDispatcher *eventDispatcher = d->data->eventDispatcher.loadRelaxed();
    if (eventDispatcher) {
        d->data->eventDispatcher = 0;
        locker.unlock();
        eventDispatcher->closingDown();
        delete eventDispatcher;
        locker.relock();
    }
 
    d->running = false;
    d->finished = true;
    d->isInFinish = false;
    d->interruptionRequested = false;
 
    if (!d->waiters) {
        CloseHandle(d->handle);
        d->handle = 0;
    }
 
    d->id = 0;
}
 
/**************************************************************************
 ** QThread
 *************************************************************************/
 
Qt::HANDLE QThread::currentThreadIdImpl() noexcept
{
    return reinterpret_cast<Qt::HANDLE>(quintptr(GetCurrentThreadId()));
}
 
int QThread::idealThreadCount() noexcept
{
    SYSTEM_INFO sysinfo;
    GetSystemInfo(&sysinfo);
    return sysinfo.dwNumberOfProcessors;
}
 
void QThread::yieldCurrentThread()
{
    SwitchToThread();
}
 
#endif // QT_CONFIG(thread)
 
void QThread::sleep(unsigned long secs)
{
    ::Sleep(secs * 1000);
}
 
void QThread::msleep(unsigned long msecs)
{
    ::Sleep(msecs);
}
 
void QThread::usleep(unsigned long usecs)
{
    ::Sleep((usecs / 1000) + 1);
}
 
#if QT_CONFIG(thread)
 
void QThread::start(Priority priority)
{
    Q_D(QThread);
    QMutexLocker locker(&d->mutex);
 
    if (d->isInFinish) {
        locker.unlock();
        wait();
        locker.relock();
    }
 
    if (d->running)
        return;
 
    // avoid interacting with the binding system
    d->objectName = d->extraData ? d->extraData->objectName.valueBypassingBindings()
                                 : QString();
    d->running = true;
    d->finished = false;
    d->exited = false;
    d->returnCode = 0;
    d->interruptionRequested = false;
 
    /*
      NOTE: we create the thread in the suspended state, set the
      priority and then resume the thread.
 
      since threads are created with normal priority by default, we
      could get into a case where a thread (with priority less than
      NormalPriority) tries to create a new thread (also with priority
      less than NormalPriority), but the newly created thread preempts
      its 'parent' and runs at normal priority.
    */
#if defined(Q_CC_MSVC) && !defined(_DLL)
    // MSVC -MT or -MTd build
    d->handle = (Qt::HANDLE) _beginthreadex(NULL, d->stackSize, QThreadPrivate::start,
                                            this, CREATE_SUSPENDED, &(d->id));
#else
    // MSVC -MD or -MDd or MinGW build
    d->handle = CreateThread(nullptr, d->stackSize,
                             reinterpret_cast<LPTHREAD_START_ROUTINE>(QThreadPrivate::start),
                             this, CREATE_SUSPENDED, reinterpret_cast<LPDWORD>(&d->id));
#endif
 
    if (!d->handle) {
        qErrnoWarning("QThread::start: Failed to create thread");
        d->running = false;
        d->finished = true;
        return;
    }
 
    int prio;
    d->priority = priority;
    switch (priority) {
    case IdlePriority:
        prio = THREAD_PRIORITY_IDLE;
        break;
 
    case LowestPriority:
        prio = THREAD_PRIORITY_LOWEST;
        break;
 
    case LowPriority:
        prio = THREAD_PRIORITY_BELOW_NORMAL;
        break;
 
    case NormalPriority:
        prio = THREAD_PRIORITY_NORMAL;
        break;
 
    case HighPriority:
        prio = THREAD_PRIORITY_ABOVE_NORMAL;
        break;
 
    case HighestPriority:
        prio = THREAD_PRIORITY_HIGHEST;
        break;
 
    case TimeCriticalPriority:
        prio = THREAD_PRIORITY_TIME_CRITICAL;
        break;
 
    case InheritPriority:
    default:
        prio = GetThreadPriority(GetCurrentThread());
        break;
    }
 
    if (!SetThreadPriority(d->handle, prio)) {
        qErrnoWarning("QThread::start: Failed to set thread priority");
    }
 
    if (ResumeThread(d->handle) == (DWORD) -1) {
        qErrnoWarning("QThread::start: Failed to resume new thread");
    }
}
 
void QThread::terminate()
{
    Q_D(QThread);
    QMutexLocker locker(&d->mutex);
    if (!d->running)
        return;
    if (!d->terminationEnabled) {
        d->terminatePending = true;
        return;
    }
 
    TerminateThread(d->handle, 0);
    QThreadPrivate::finish(this, false);
}
 
bool QThread::wait(QDeadlineTimer deadline)
{
    Q_D(QThread);
    QMutexLocker locker(&d->mutex);
 
    if (d->id == GetCurrentThreadId()) {
        qWarning("QThread::wait: Thread tried to wait on itself");
        return false;
    }
    if (d->finished || !d->running)
        return true;
 
    ++d->waiters;
    locker.mutex()->unlock();
 
    bool ret = false;
    switch (WaitForSingleObject(d->handle, deadline.remainingTime())) {
    case WAIT_OBJECT_0:
        ret = true;
        break;
    case WAIT_FAILED:
        qErrnoWarning("QThread::wait: Thread wait failure");
        break;
    case WAIT_ABANDONED:
    case WAIT_TIMEOUT:
    default:
        break;
    }
 
    locker.mutex()->lock();
    --d->waiters;
 
    if (ret && !d->finished) {
        // thread was terminated by someone else
 
        QThreadPrivate::finish(this, false);
    }
 
    if (d->finished && !d->waiters) {
        CloseHandle(d->handle);
        d->handle = 0;
    }
 
    return ret;
}
 
void QThread::setTerminationEnabled(bool enabled)
{
    QThread *thr = currentThread();
    Q_ASSERT_X(thr != 0, "QThread::setTerminationEnabled()",
               "Current thread was not started with QThread.");
    QThreadPrivate *d = thr->d_func();
    QMutexLocker locker(&d->mutex);
    d->terminationEnabled = enabled;
    if (enabled && d->terminatePending) {
        QThreadPrivate::finish(thr, false);
        locker.unlock(); // don't leave the mutex locked!
        _endthreadex(0);
    }
}
 
// Caller must hold the mutex
void QThreadPrivate::setPriority(QThread::Priority threadPriority)
{
    // copied from start() with a few modifications:
 
    int prio;
    priority = threadPriority;
    switch (threadPriority) {
    case QThread::IdlePriority:
        prio = THREAD_PRIORITY_IDLE;
        break;
 
    case QThread::LowestPriority:
        prio = THREAD_PRIORITY_LOWEST;
        break;
 
    case QThread::LowPriority:
        prio = THREAD_PRIORITY_BELOW_NORMAL;
        break;
 
    case QThread::NormalPriority:
        prio = THREAD_PRIORITY_NORMAL;
        break;
 
    case QThread::HighPriority:
        prio = THREAD_PRIORITY_ABOVE_NORMAL;
        break;
 
    case QThread::HighestPriority:
        prio = THREAD_PRIORITY_HIGHEST;
        break;
 
    case QThread::TimeCriticalPriority:
        prio = THREAD_PRIORITY_TIME_CRITICAL;
        break;
 
    default:
        return;
    }
 
    if (!SetThreadPriority(handle, prio)) {
        qErrnoWarning("QThread::setPriority: Failed to set thread priority");
    }
}
 
#endif // QT_CONFIG(thread)
 
QT_END_NAMESPACE