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Fix the timeout calculation for futexes in QMutex.

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Recalculate how much time is remaining.

This commit needs to be backported to 4.8.

Change-Id: Ib587335bb90306e65969bb26256fb388f8f6bd24
Merge-request: 20
Reviewed-by: Olivier Goffart <olivier.goffart@nokia.com>
Reviewed-on: http://codereview.qt.nokia.com/1666
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
This commit is contained in:
Thiago Macieira 2011-07-14 14:43:44 +02:00 committed by Qt by Nokia
parent 2c8e030a3f
commit 412ef92162
1 changed files with 22 additions and 6 deletions
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28
src/corelib/thread/qmutex_unix.cpp
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@ -60,6 +60,7 @@
# include <linux/futex.h>
# include <sys/syscall.h>
# include <unistd.h>
# include <QtCore/qelapsedtimer.h>
#endif
QT_BEGIN_NAMESPACE
@ -138,16 +139,31 @@ static inline int _q_futex(volatile int *addr, int op, int val, const struct tim
bool QMutexPrivate::wait(int timeout)
{
struct timespec ts, *pts = 0;
QElapsedTimer timer;
if (timeout >= 0) {
ts.tv_nsec = ((timeout % 1000) * 1000) * 1000;
ts.tv_sec = (timeout / 1000);
pts = &ts;
timer.start();
}
while (contenders.fetchAndStoreAcquire(2) > 0) {
struct timespec ts, *pts = 0;
if (timeout >= 0) {
ts.tv_nsec = ((timeout % 1000) * 1000) * 1000;
ts.tv_sec = (timeout / 1000);
pts = &ts;
}
int r = _q_futex(&contenders._q_value, FUTEX_WAIT, 2, pts, 0, 0);
if (r != 0 && errno == ETIMEDOUT)
return false;
if (pts) {
// recalculate the timeout
qint64 xtimeout = timeout * 1000 * 1000;
xtimeout -= timer.nsecsElapsed();
if (xtimeout < 0) {
// timer expired after we returned
return false;
}
ts.tv_sec = timeout / Q_INT64_C(1000) / 1000 / 1000;
ts.tv_nsec = timeout % (Q_INT64_C(1000) * 1000 * 1000);
}
}
return true;
}