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tqt3/src/tools/qwaitcondition_unix.cpp

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/****************************************************************************
**
** 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 requirements 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 "ntqwaitcondition.h"
#include "ntqmutex.h"
#include "qmutex_p.h"
#include <errno.h>
#include <string.h>
struct TQWaitConditionPrivate {
pthread_cond_t cond;
};
/*!
\class TQWaitCondition ntqwaitcondition.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)
tqWarning( "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
tqWarning( "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)
tqWarning("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)
tqWarning("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)
tqWarning("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
tqWarning("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)
tqWarning("Wait condition wait failure: %s",strerror(ret));
#endif
return (ret == 0);
}
#endif // QT_THREAD_SUPPORT