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// Copyright (C) 2016 The Qt Company Ltd.
// Copyright (C) 2016 Intel Corporation.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
#include "qplatformdefs.h"
#include "qwaitcondition.h"
#include "qmutex.h"
#include "qreadwritelock.h"
#include "qatomic.h"
#include "qstring.h"
#include "qdeadlinetimer.h"
#include "private/qdeadlinetimer_p.h"
#include "qelapsedtimer.h"
#include "private/qcore_unix_p.h"
#include "qmutex_p.h"
#include "qreadwritelock_p.h"
#include <errno.h>
#include <sys/time.h>
#include <time.h>
QT_BEGIN_NAMESPACE
#ifdef Q_OS_ANDROID
// pthread_condattr_setclock is available only since Android 5.0. On older versions, there's
// a private function for relative waits (hidden in 5.0).
// Use weakref so we can determine at runtime whether each of them is present.
static int local_condattr_setclock(pthread_condattr_t*, clockid_t)
__attribute__((weakref("pthread_condattr_setclock")));
static int local_cond_timedwait_relative(pthread_cond_t*, pthread_mutex_t *, const timespec *)
__attribute__((weakref("__pthread_cond_timedwait_relative")));
#endif
static void report_error(int code, const char *where, const char *what)
{
if (code != 0)
qErrnoWarning(code, "%s: %s failure", where, what);
}
void qt_initialize_pthread_cond(pthread_cond_t *cond, const char *where)
{
pthread_condattr_t condattr;
pthread_condattr_init(&condattr);
#if (_POSIX_MONOTONIC_CLOCK-0 >= 0)
#if defined(Q_OS_ANDROID)
if (local_condattr_setclock && QElapsedTimer::clockType() == QElapsedTimer::MonotonicClock)
local_condattr_setclock(&condattr, CLOCK_MONOTONIC);
#elif !defined(Q_OS_MAC)
if (QElapsedTimer::clockType() == QElapsedTimer::MonotonicClock)
pthread_condattr_setclock(&condattr, CLOCK_MONOTONIC);
#endif
#endif
report_error(pthread_cond_init(cond, &condattr), where, "cv init");
pthread_condattr_destroy(&condattr);
}
void qt_abstime_for_timeout(timespec *ts, QDeadlineTimer deadline)
{
#ifdef Q_OS_MAC
// on Mac, qt_gettime() (on qelapsedtimer_mac.cpp) returns ticks related to the Mach absolute time
// that doesn't work with pthread
// Mac also doesn't have clock_gettime
struct timeval tv;
qint64 nsec = deadline.remainingTimeNSecs();
gettimeofday(&tv, 0);
ts->tv_sec = tv.tv_sec + nsec / (1000 * 1000 * 1000);
ts->tv_nsec = tv.tv_usec * 1000 + nsec % (1000 * 1000 * 1000);
normalizedTimespec(*ts);
#else
// depends on QDeadlineTimer's internals!!
static_assert(QDeadlineTimerNanosecondsInT2);
ts->tv_sec = deadline._q_data().first;
ts->tv_nsec = deadline._q_data().second;
#endif
}
class QWaitConditionPrivate
{
public:
pthread_mutex_t mutex;
pthread_cond_t cond;
int waiters;
int wakeups;
int wait_relative(QDeadlineTimer deadline)
{
timespec ti;
#ifdef Q_OS_ANDROID
if (!local_condattr_setclock && local_cond_timedwait_relative) {
qint64 nsec = deadline.remainingTimeNSecs();
ti.tv_sec = nsec / (1000 * 1000 * 1000);
ti.tv_nsec = nsec - ti.tv_sec * 1000 * 1000 * 1000;
return local_cond_timedwait_relative(&cond, &mutex, &ti);
}
#endif
qt_abstime_for_timeout(&ti, deadline);
return pthread_cond_timedwait(&cond, &mutex, &ti);
}
bool wait(QDeadlineTimer deadline)
{
int code;
forever {
if (!deadline.isForever()) {
code = wait_relative(deadline);
} else {
code = pthread_cond_wait(&cond, &mutex);
}
if (code == 0 && wakeups == 0) {
// spurious wakeup
continue;
}
break;
}
Q_ASSERT_X(waiters > 0, "QWaitCondition::wait", "internal error (waiters)");
--waiters;
if (code == 0) {
Q_ASSERT_X(wakeups > 0, "QWaitCondition::wait", "internal error (wakeups)");
--wakeups;
}
report_error(pthread_mutex_unlock(&mutex), "QWaitCondition::wait()", "mutex unlock");
if (code && code != ETIMEDOUT)
report_error(code, "QWaitCondition::wait()", "cv wait");
return (code == 0);
}
};
QWaitCondition::QWaitCondition()
{
d = new QWaitConditionPrivate;
report_error(pthread_mutex_init(&d->mutex, nullptr), "QWaitCondition", "mutex init");
qt_initialize_pthread_cond(&d->cond, "QWaitCondition");
d->waiters = d->wakeups = 0;
}
QWaitCondition::~QWaitCondition()
{
report_error(pthread_cond_destroy(&d->cond), "QWaitCondition", "cv destroy");
report_error(pthread_mutex_destroy(&d->mutex), "QWaitCondition", "mutex destroy");
delete d;
}
void QWaitCondition::wakeOne()
{
report_error(pthread_mutex_lock(&d->mutex), "QWaitCondition::wakeOne()", "mutex lock");
d->wakeups = qMin(d->wakeups + 1, d->waiters);
report_error(pthread_cond_signal(&d->cond), "QWaitCondition::wakeOne()", "cv signal");
report_error(pthread_mutex_unlock(&d->mutex), "QWaitCondition::wakeOne()", "mutex unlock");
}
void QWaitCondition::wakeAll()
{
report_error(pthread_mutex_lock(&d->mutex), "QWaitCondition::wakeAll()", "mutex lock");
d->wakeups = d->waiters;
report_error(pthread_cond_broadcast(&d->cond), "QWaitCondition::wakeAll()", "cv broadcast");
report_error(pthread_mutex_unlock(&d->mutex), "QWaitCondition::wakeAll()", "mutex unlock");
}
bool QWaitCondition::wait(QMutex *mutex, unsigned long time)
{
if (time == std::numeric_limits<unsigned long>::max())
return wait(mutex, QDeadlineTimer(QDeadlineTimer::Forever));
return wait(mutex, QDeadlineTimer(time));
}
bool QWaitCondition::wait(QMutex *mutex, QDeadlineTimer deadline)
{
if (!mutex)
return false;
report_error(pthread_mutex_lock(&d->mutex), "QWaitCondition::wait()", "mutex lock");
++d->waiters;
mutex->unlock();
bool returnValue = d->wait(deadline);
mutex->lock();
return returnValue;
}
bool QWaitCondition::wait(QReadWriteLock *readWriteLock, unsigned long time)
{
if (time == std::numeric_limits<unsigned long>::max())
return wait(readWriteLock, QDeadlineTimer(QDeadlineTimer::Forever));
return wait(readWriteLock, QDeadlineTimer(time));
}
bool QWaitCondition::wait(QReadWriteLock *readWriteLock, QDeadlineTimer deadline)
{
if (!readWriteLock)
return false;
auto previousState = readWriteLock->stateForWaitCondition();
if (previousState == QReadWriteLock::Unlocked)
return false;
if (previousState == QReadWriteLock::RecursivelyLocked) {
qWarning("QWaitCondition: cannot wait on QReadWriteLocks with recursive lockForWrite()");
return false;
}
report_error(pthread_mutex_lock(&d->mutex), "QWaitCondition::wait()", "mutex lock");
++d->waiters;
readWriteLock->unlock();
bool returnValue = d->wait(deadline);
if (previousState == QReadWriteLock::LockedForWrite)
readWriteLock->lockForWrite();
else
readWriteLock->lockForRead();
return returnValue;
}
QT_END_NAMESPACE
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