Use monotonic clock for rtc::Event::Wait on linux and android.
Unfortunately, pthread_condattr_setclock is lacking in the
versions of MacOS and iOS we support, and we have to stay
with gettimeofday on those platforms.
Bug: webrtc:9269
Change-Id: I8554e56496cc7b6948cb9b8a4c0bcf886c3544be
Reviewed-on: https://webrtc-review.googlesource.com/77122
Commit-Queue: Niels Moller <nisse@webrtc.org>
Reviewed-by: Sami Kalliomäki <sakal@webrtc.org>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#23349}diff --git a/rtc_base/event.cc b/rtc_base/event.cc
index ff4faad..9e38159 100644
--- a/rtc_base/event.cc
+++ b/rtc_base/event.cc
@@ -52,11 +52,34 @@
#elif defined(WEBRTC_POSIX)
+// On MacOS, clock_gettime is available from version 10.12, and on
+// iOS, from version 10.0. So we can't use it yet.
+#if defined(WEBRTC_MAC) || defined(WEBRTC_IOS)
+#define USE_CLOCK_GETTIME 0
+#define USE_PTHREAD_COND_TIMEDWAIT_MONOTONIC_NP 0
+// On Android, pthread_condattr_setclock is available from version 21. By
+// default, we target a new enough version for 64-bit platforms but not for
+// 32-bit platforms. For older versions, use
+// pthread_cond_timedwait_monotonic_np.
+#elif defined(WEBRTC_ANDROID) && (__ANDROID_API__ < 21)
+#define USE_CLOCK_GETTIME 1
+#define USE_PTHREAD_COND_TIMEDWAIT_MONOTONIC_NP 1
+#else
+#define USE_CLOCK_GETTIME 1
+#define USE_PTHREAD_COND_TIMEDWAIT_MONOTONIC_NP 0
+#endif
+
Event::Event(bool manual_reset, bool initially_signaled)
: is_manual_reset_(manual_reset),
event_status_(initially_signaled) {
RTC_CHECK(pthread_mutex_init(&event_mutex_, nullptr) == 0);
- RTC_CHECK(pthread_cond_init(&event_cond_, nullptr) == 0);
+ pthread_condattr_t cond_attr;
+ RTC_CHECK(pthread_condattr_init(&cond_attr) == 0);
+#if USE_CLOCK_GETTIME && !USE_PTHREAD_COND_TIMEDWAIT_MONOTONIC_NP
+ RTC_CHECK(pthread_condattr_setclock(&cond_attr, CLOCK_MONOTONIC) == 0);
+#endif
+ RTC_CHECK(pthread_cond_init(&event_cond_, &cond_attr) == 0);
+ pthread_condattr_destroy(&cond_attr);
}
Event::~Event() {
@@ -82,14 +105,17 @@
struct timespec ts;
if (milliseconds != kForever) {
- // Converting from seconds and microseconds (1e-6) plus
- // milliseconds (1e-3) to seconds and nanoseconds (1e-9).
-
+#if USE_CLOCK_GETTIME
+ clock_gettime(CLOCK_MONOTONIC, &ts);
+#else
struct timeval tv;
gettimeofday(&tv, nullptr);
+ ts.tv_sec = tv.tv_sec;
+ ts.tv_nsec = tv.tv_usec * 1000;
+#endif
- ts.tv_sec = tv.tv_sec + (milliseconds / 1000);
- ts.tv_nsec = tv.tv_usec * 1000 + (milliseconds % 1000) * 1000000;
+ ts.tv_sec += (milliseconds / 1000);
+ ts.tv_nsec += (milliseconds % 1000) * 1000000;
// Handle overflow.
if (ts.tv_nsec >= 1000000000) {
@@ -101,7 +127,12 @@
pthread_mutex_lock(&event_mutex_);
if (milliseconds != kForever) {
while (!event_status_ && error == 0) {
+#if USE_PTHREAD_COND_TIMEDWAIT_MONOTONIC_NP
+ error =
+ pthread_cond_timedwait_monotonic_np(&event_cond_, &event_mutex_, &ts);
+#else
error = pthread_cond_timedwait(&event_cond_, &event_mutex_, &ts);
+#endif
}
} else {
while (!event_status_ && error == 0)
