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Diffstat (limited to 'src/tools/qwaitcondition_unix.cpp')
| -rw-r--r-- | src/tools/qwaitcondition_unix.cpp | 316 |
1 files changed, 316 insertions, 0 deletions
diff --git a/src/tools/qwaitcondition_unix.cpp b/src/tools/qwaitcondition_unix.cpp new file mode 100644 index 000000000..e3becc54e --- /dev/null +++ b/src/tools/qwaitcondition_unix.cpp @@ -0,0 +1,316 @@ +/**************************************************************************** +** +** TQWaitCondition class for Unix +** +** Created : 20010725 +** +** Copyright (C) 1992-2008 Trolltech ASA. All rights reserved. +** +** This file is part of the tools module of the TQt GUI Toolkit. +** +** This file may be used under the terms of the GNU General +** Public License versions 2.0 or 3.0 as published by the Free +** Software Foundation and appearing in the files LICENSE.GPL2 +** and LICENSE.GPL3 included in the packaging of this file. +** Alternatively you may (at your option) use any later version +** of the GNU General Public License if such license has been +** publicly approved by Trolltech ASA (or its successors, if any) +** and the KDE Free TQt Foundation. +** +** Please review the following information to ensure GNU General +** Public Licensing retquirements will be met: +** http://trolltech.com/products/qt/licenses/licensing/opensource/. +** If you are unsure which license is appropriate for your use, please +** review the following information: +** http://trolltech.com/products/qt/licenses/licensing/licensingoverview +** or contact the sales department at sales@trolltech.com. +** +** This file may be used under the terms of the Q Public License as +** defined by Trolltech ASA and appearing in the file LICENSE.TQPL +** included in the packaging of this file. Licensees holding valid TQt +** Commercial licenses may use this file in accordance with the TQt +** Commercial License Agreement provided with the Software. +** +** This file is provided "AS IS" with NO WARRANTY OF ANY KIND, +** INCLUDING THE WARRANTIES OF DESIGN, MERCHANTABILITY AND FITNESS FOR +** A PARTICULAR PURPOSE. Trolltech reserves all rights not granted +** herein. +** +**********************************************************************/ + +#if defined(QT_THREAD_SUPPORT) + +#include "qplatformdefs.h" + +typedef pthread_mutex_t Q_MUTEX_T; + +#include "qwaitcondition.h" +#include "qmutex.h" +#include "qmutex_p.h" + +#include <errno.h> +#include <string.h> + + +struct TQWaitConditionPrivate { + pthread_cond_t cond; +}; + + +/*! + \class TQWaitCondition qwaitcondition.h + \threadsafe + \brief The TQWaitCondition class allows waiting/waking for conditions between threads. + + \ingroup thread + \ingroup environment + + TQWaitConditions allow a thread to tell other threads that some + sort of condition has been met; one or many threads can block + waiting for a TQWaitCondition to set a condition with wakeOne() or + wakeAll(). Use wakeOne() to wake one randomly selected event or + wakeAll() to wake them all. For example, say we have three tasks + that should be performed every time the user presses a key; each + task could be split into a thread, each of which would have a + run() body like this: + + \code + TQWaitCondition key_pressed; + + for (;;) { + key_pressed.wait(); // This is a TQWaitCondition global variable + // Key was pressed, do something interesting + do_something(); + } + \endcode + + A fourth thread would read key presses and wake the other three + threads up every time it receives one, like this: + + \code + TQWaitCondition key_pressed; + + for (;;) { + getchar(); + // Causes any thread in key_pressed.wait() to return from + // that method and continue processing + key_pressed.wakeAll(); + } + \endcode + + Note that the order the three threads are woken up in is + undefined, and that if some or all of the threads are still in + do_something() when the key is pressed, they won't be woken up + (since they're not waiting on the condition variable) and so the + task will not be performed for that key press. This can be + avoided by, for example, doing something like this: + + \code + TQMutex mymutex; + TQWaitCondition key_pressed; + int mycount=0; + + // Worker thread code + for (;;) { + key_pressed.wait(); // This is a TQWaitCondition global variable + mymutex.lock(); + mycount++; + mymutex.unlock(); + do_something(); + mymutex.lock(); + mycount--; + mymutex.unlock(); + } + + // Key reading thread code + for (;;) { + getchar(); + mymutex.lock(); + // Sleep until there are no busy worker threads + while( mycount > 0 ) { + mymutex.unlock(); + sleep( 1 ); + mymutex.lock(); + } + mymutex.unlock(); + key_pressed.wakeAll(); + } + \endcode + + The mutexes are necessary because the results of two threads + attempting to change the value of the same variable simultaneously + are unpredictable. +*/ + +/*! + Constructs a new event signalling, i.e. wait condition, object. +*/ +TQWaitCondition::TQWaitCondition() +{ + d = new TQWaitConditionPrivate; + + int ret = pthread_cond_init(&d->cond, NULL); + +#ifdef QT_CHECK_RANGE + if (ret) + qWarning( "Wait condition init failure: %s", strerror( ret ) ); +#endif +} + + +/*! + Deletes the event signalling, i.e. wait condition, object. +*/ +TQWaitCondition::~TQWaitCondition() +{ + int ret = pthread_cond_destroy(&d->cond); + + if (ret) { +#ifdef QT_CHECK_RANGE + qWarning( "Wait condition destroy failure: %s", strerror( ret ) ); +#endif + + // seems we have threads waiting on us, lets wake them up + pthread_cond_broadcast(&d->cond); + } + + delete d; +} + +/*! + This wakes one thread waiting on the TQWaitCondition. The thread + that is woken up depends on the operating system's scheduling + policies, and cannot be controlled or predicted. + + \sa wakeAll() +*/ +void TQWaitCondition::wakeOne() +{ + int ret = pthread_cond_signal(&d->cond); + +#ifdef QT_CHECK_RANGE + if (ret) + qWarning("Wait condition wakeOne failure: %s", strerror(ret)); +#endif +} + +/*! + This wakes all threads waiting on the TQWaitCondition. The order in + which the threads are woken up depends on the operating system's + scheduling policies, and cannot be controlled or predicted. + + \sa wakeOne() +*/ +void TQWaitCondition::wakeAll() +{ + int ret = pthread_cond_broadcast(&d->cond); + +#ifdef QT_CHECK_RANGE + if (ret) + qWarning("Wait condition wakeAll failure: %s", strerror(ret)); +#endif +} + +/*! + Wait on the thread event object. The thread calling this will + block until either of these conditions is met: + \list + \i Another thread signals it using wakeOne() or wakeAll(). This + function will return TRUE in this case. + \i \a time milliseconds has elapsed. If \a time is ULONG_MAX (the + default), then the wait will never timeout (the event must be + signalled). This function will return FALSE if the wait timed + out. + \endlist + + \sa wakeOne(), wakeAll() +*/ +bool TQWaitCondition::wait(unsigned long time) +{ + static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER; + pthread_mutex_lock( &mutex ); + + int ret; + if (time != ULONG_MAX) { + struct timeval tv; + gettimeofday(&tv, 0); + + timespec ti; + ti.tv_nsec = ( tv.tv_usec + ( time % 1000 ) * 1000 ) * 1000; + ti.tv_sec = tv.tv_sec + (time / 1000) + ( ti.tv_nsec / 1000000000 ); + ti.tv_nsec %= 1000000000; + + ret = pthread_cond_timedwait(&d->cond, &mutex, &ti); + } else + ret = pthread_cond_wait(&d->cond, &mutex); + +#ifdef QT_CHECK_RANGE + if (ret && ret != ETIMEDOUT) + qWarning("Wait condition wait failure: %s",strerror(ret)); +#endif + + pthread_mutex_unlock( &mutex ); + + return (ret == 0); +} + +/*! + \overload + + Release the locked \a mutex and wait on the thread event object. + The \a mutex must be initially locked by the calling thread. If \a + mutex is not in a locked state, this function returns immediately. + If \a mutex is a recursive mutex, this function returns + immediately. The \a mutex will be unlocked, and the calling thread + will block until either of these conditions is met: + \list + \i Another thread signals it using wakeOne() or wakeAll(). This + function will return TRUE in this case. + \i \a time milliseconds has elapsed. If \a time is ULONG_MAX (the + default), then the wait will never timeout (the event must be + signalled). This function will return FALSE if the wait timed + out. + \endlist + + The mutex will be returned to the same locked state. This function + is provided to allow the atomic transition from the locked state + to the wait state. + + \sa wakeOne(), wakeAll() +*/ +bool TQWaitCondition::wait(TQMutex *mutex, unsigned long time) +{ + if (! mutex) + return FALSE; + + if (mutex->d->type() == Q_MUTEX_RECURSIVE) { +#ifdef QT_CHECK_RANGE + qWarning("Wait condition warning: using recursive mutexes with\n" + " wait conditions is undefined!"); +#endif + return FALSE; + } + + int ret; + if (time != ULONG_MAX) { + struct timeval tv; + gettimeofday(&tv, 0); + + timespec ti; + ti.tv_nsec = ( tv.tv_usec + ( time % 1000 ) * 1000 ) * 1000; + ti.tv_sec = tv.tv_sec + (time / 1000) + ( ti.tv_nsec / 1000000000 ); + ti.tv_nsec %= 1000000000; + + ret = pthread_cond_timedwait(&d->cond, &mutex->d->handle, &ti); + } else + ret = pthread_cond_wait(&d->cond, &mutex->d->handle); + +#ifdef QT_CHECK_RANGE + if (ret && ret != ETIMEDOUT) + qWarning("Wait condition wait failure: %s",strerror(ret)); +#endif + + return (ret == 0); +} + +#endif // QT_THREAD_SUPPORT |