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Use Bionic's __pthread_cond_timedwait_relative

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The Linux futex interface uses relative timeouts anyway, so this avoids
a double round-trip through clock_gettime: once in Qt code to calculate
absolute from relative and once in libc for reversing.

Glibc does not offer such a function because its pthread_cond objects
use a kernel interface that works on absolute times.

Change-Id: I8fbcd3f73d4364a16716b0eea17e8f5f9ab5cd05
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@digia.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
This commit is contained in:
Thiago Macieira 2013-03-30 10:52:52 -07:00 committed by The Qt Project
parent 2fbe972a65
commit dcf9c403ba
1 changed files with 15 additions and 0 deletions
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15
src/corelib/thread/qwaitcondition_unix.cpp
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@ -59,6 +59,14 @@
QT_BEGIN_NAMESPACE
#ifdef Q_OS_ANDROID
// Android lacks pthread_condattr_setclock, but it does have a nice function
// for relative waits. Use weakref so we can determine at runtime whether it is
// present.
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)
@ -107,6 +115,13 @@ public:
int wait_relative(unsigned long time)
{
timespec ti;
#ifdef Q_OS_ANDROID
if (Q_LIKELY(local_cond_timedwait_relative)) {
ti.tv_sec = time / 1000;
ti.tv_nsec = time % 1000 * Q_UINT64_C(1000) * 1000;
return local_cond_timedwait_relative(&cond, &mutex, &ti);
}
#endif
qt_abstime_for_timeout(&ti, time);
return pthread_cond_timedwait(&cond, &mutex, &ti);
}