From 112e53fdc4e46a5e94cb2d575d132e2015694407 Mon Sep 17 00:00:00 2001 From: Thiago Macieira Date: Thu, 28 Apr 2016 17:47:57 -0700 Subject: Don't store the pthread_t thread ID twice in QThread MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit It was being stored once in QThreadPrivate and once in QThreadData, with the latter being hidden as a Qt::HANDLE. Besides saving a little bit of memory, this also solves a small data race condition that arises from trying to connect a signal to an object moved to that thread and then emit that signal shortly after the thread starts. Before this patch, QThreadData::threadId was initialized only by QThreadPrivate::start(), which meant that we were racing that initialization with this check in QMetaObject::activate: const bool receiverInSameThread = currentThreadId == receiver->d_func()->threadData->threadId; Task-number: QTBUG-52337 Change-Id: Ifea6e497f11a461db432ffff1449ae01f1099aae Reviewed-by: Olivier Goffart (Woboq GmbH) Reviewed-by: JÄ™drzej Nowacki --- src/corelib/thread/qthread.cpp | 6 +----- src/corelib/thread/qthread_p.h | 1 - src/corelib/thread/qthread_unix.cpp | 33 +++++++++++++++++---------------- 3 files changed, 18 insertions(+), 22 deletions(-) (limited to 'src/corelib') diff --git a/src/corelib/thread/qthread.cpp b/src/corelib/thread/qthread.cpp index a0a2e76bda..8ea487e330 100644 --- a/src/corelib/thread/qthread.cpp +++ b/src/corelib/thread/qthread.cpp @@ -142,16 +142,12 @@ QThreadPrivate::QThreadPrivate(QThreadData *d) exited(false), returnCode(-1), stackSize(0), priority(QThread::InheritPriority), data(d) { -#if defined (Q_OS_UNIX) - thread_id = 0; -#elif defined (Q_OS_WIN) +#if defined (Q_OS_WIN) handle = 0; # ifndef Q_OS_WINRT id = 0; # endif waiters = 0; -#endif -#if defined (Q_OS_WIN) terminationEnabled = true; terminatePending = false; #endif diff --git a/src/corelib/thread/qthread_p.h b/src/corelib/thread/qthread_p.h index a0d354acdc..a56b879462 100644 --- a/src/corelib/thread/qthread_p.h +++ b/src/corelib/thread/qthread_p.h @@ -169,7 +169,6 @@ public: static QThread *threadForId(int id); #ifdef Q_OS_UNIX - pthread_t thread_id; QWaitCondition thread_done; static void *start(void *arg); diff --git a/src/corelib/thread/qthread_unix.cpp b/src/corelib/thread/qthread_unix.cpp index af4ce7c59e..3fc0ebfbb6 100644 --- a/src/corelib/thread/qthread_unix.cpp +++ b/src/corelib/thread/qthread_unix.cpp @@ -105,6 +105,8 @@ QT_BEGIN_NAMESPACE #ifndef QT_NO_THREAD +Q_STATIC_ASSERT(sizeof(pthread_t) == sizeof(Qt::HANDLE)); + enum { ThreadPriorityResetFlag = 0x80000000 }; #if defined(Q_OS_LINUX) && defined(__GLIBC__) && (defined(Q_CC_GNU) || defined(Q_CC_INTEL)) && !defined(QT_LINUXBASE) @@ -234,8 +236,6 @@ QThreadData *QThreadData::current(bool createIfNecessary) void QAdoptedThread::init() { - Q_D(QThread); - d->thread_id = pthread_self(); } /* @@ -325,10 +325,11 @@ void *QThreadPrivate::start(void *arg) // sets the name of the current thread. QString objectName = thr->objectName(); + pthread_t thread_id = reinterpret_cast(data->threadId); if (Q_LIKELY(objectName.isEmpty())) - setCurrentThreadName(thr->d_func()->thread_id, thr->metaObject()->className()); + setCurrentThreadName(thread_id, thr->metaObject()->className()); else - setCurrentThreadName(thr->d_func()->thread_id, objectName.toLocal8Bit()); + setCurrentThreadName(thread_id, objectName.toLocal8Bit()); } #endif @@ -369,7 +370,6 @@ void QThreadPrivate::finish(void *arg) locker.relock(); } - d->thread_id = 0; d->running = false; d->finished = true; d->interruptionRequested = false; @@ -615,15 +615,16 @@ void QThread::start(Priority priority) } int code = - pthread_create(&d->thread_id, &attr, QThreadPrivate::start, this); + pthread_create(reinterpret_cast(&d->data->threadId), &attr, + QThreadPrivate::start, this); if (code == EPERM) { // caller does not have permission to set the scheduling // parameters/policy #if defined(QT_HAS_THREAD_PRIORITY_SCHEDULING) pthread_attr_setinheritsched(&attr, PTHREAD_INHERIT_SCHED); #endif - code = - pthread_create(&d->thread_id, &attr, QThreadPrivate::start, this); + code = pthread_create(reinterpret_cast(&d->data->threadId), &attr, + QThreadPrivate::start, this); } pthread_attr_destroy(&attr); @@ -633,7 +634,7 @@ void QThread::start(Priority priority) d->running = false; d->finished = false; - d->thread_id = 0; + d->data->threadId = 0; } } @@ -643,10 +644,10 @@ void QThread::terminate() Q_D(QThread); QMutexLocker locker(&d->mutex); - if (!d->thread_id) + if (!d->data->threadId) return; - int code = pthread_cancel(d->thread_id); + int code = pthread_cancel(reinterpret_cast(d->data->threadId)); if (code) { qWarning("QThread::start: Thread termination error: %s", qPrintable(qt_error_string((code)))); @@ -659,7 +660,7 @@ bool QThread::wait(unsigned long time) Q_D(QThread); QMutexLocker locker(&d->mutex); - if (d->thread_id == pthread_self()) { + if (reinterpret_cast(d->data->threadId) == pthread_self()) { qWarning("QThread::wait: Thread tried to wait on itself"); return false; } @@ -701,7 +702,7 @@ void QThreadPrivate::setPriority(QThread::Priority threadPriority) int sched_policy; sched_param param; - if (pthread_getschedparam(thread_id, &sched_policy, ¶m) != 0) { + if (pthread_getschedparam(reinterpret_cast(data->threadId), &sched_policy, ¶m) != 0) { // failed to get the scheduling policy, don't bother setting // the priority qWarning("QThread::setPriority: Cannot get scheduler parameters"); @@ -717,15 +718,15 @@ void QThreadPrivate::setPriority(QThread::Priority threadPriority) } param.sched_priority = prio; - int status = pthread_setschedparam(thread_id, sched_policy, ¶m); + int status = pthread_setschedparam(reinterpret_cast(data->threadId), sched_policy, ¶m); # 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(thread_id, &sched_policy, ¶m); + pthread_getschedparam(reinterpret_cast(data->threadId), &sched_policy, ¶m); param.sched_priority = sched_get_priority_min(sched_policy); - pthread_setschedparam(thread_id, sched_policy, ¶m); + pthread_setschedparam(reinterpret_cast(data->threadId), sched_policy, ¶m); } # else Q_UNUSED(status); -- cgit v1.2.3