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QWaitCondition/Unix: use QDeadlineTimer's <chrono> support 

We don't need to hand-roll our own conversions when QDeadlineTimer can
convert to the time points of any std::chrono clock. In particular, if
the clock we ask for is the clock its internal representation is already
storing, then it's more efficient too.

Change-Id: Ieec322d73c1e40ad95c8fffd174689a171cb6f18
Reviewed-by: Ahmad Samir <a.samirh78@gmail.com>
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
bb10
Thiago Macieira 2023-02-23 11:07:17 -08:00
parent 2a997942db
commit eac30fcb82
2 changed files with 32 additions and 21 deletions
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4
src/corelib/kernel/qdeadlinetimer.h
View File

@ -146,10 +146,6 @@ private:
unsigned type;
qint64 rawRemainingTimeNSecs() const noexcept;
public:
// This is not a public function, it's here only for Qt's internal convenience...
QPair<qint64, unsigned> _q_data() const { return qMakePair(t1, t2); }
};
#if defined(Q_OS_DARWIN) || defined(Q_OS_LINUX) || (defined(Q_CC_MSVC) && Q_CC_MSVC >= 1900)

49
src/corelib/thread/qwaitcondition_unix.cpp
View File

@ -22,6 +22,31 @@
QT_BEGIN_NAMESPACE
static constexpr clockid_t SteadyClockClockId =
#if !defined(CLOCK_MONOTONIC)
// we don't know how to set the monotonic clock
CLOCK_REALTIME
#elif defined(_LIBCPP_VERSION) && defined(_LIBCPP_HAS_NO_MONOTONIC_CLOCK)
// libc++ falling back to system_clock
CLOCK_REALTIME
#elif defined(__GLIBCXX__) && !defined(_GLIBCXX_USE_CLOCK_MONOTONIC)
// libstdc++ falling back to system_clock
CLOCK_REALTIME
#elif defined(Q_OS_DARWIN)
// Darwin lacks pthread_condattr_setclock()
CLOCK_REALTIME
#elif defined(Q_OS_QNX)
// unknown why
CLOCK_REALTIME
#elif defined(__GLIBCXX__) || defined(_LIBCPP_VERSION)
// both libstdc++ and libc++ do use CLOCK_MONOTONIC
CLOCK_MONOTONIC
#else
# warning "Unknown C++ Standard Library implementation - code may be sub-optimal"
CLOCK_REALTIME
#endif
;
static void report_error(int code, const char *where, const char *what)
{
if (code != 0)
@ -38,7 +63,8 @@ void qt_initialize_pthread_cond(pthread_cond_t *cond, const char *where)
pthread_condattr_init(&condattr);
auto destroy = qScopeGuard([&] { pthread_condattr_destroy(&condattr); });
pthread_condattr_setclock(&condattr, CLOCK_MONOTONIC);
if (SteadyClockClockId != CLOCK_REALTIME)
pthread_condattr_setclock(&condattr, SteadyClockClockId);
#endif
report_error(pthread_cond_init(cond, attrp), where, "cv init");
@ -46,22 +72,11 @@ void qt_initialize_pthread_cond(pthread_cond_t *cond, const char *where)
void qt_abstime_for_timeout(timespec *ts, QDeadlineTimer deadline)
{
#ifdef Q_OS_DARWIN
// on Mac, we don't have pthread_condattr_setclock(), so we need to
// calculate the CLOCK_REALTIME deadline
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
using namespace std::chrono;
using Clock =
std::conditional_t<SteadyClockClockId == CLOCK_REALTIME, system_clock, steady_clock>;
auto timePoint = deadline.deadline<Clock>();
*ts = durationToTimespec(timePoint.time_since_epoch());
}
class QWaitConditionPrivate