Make Condition use CLOCK_MONOTONIC
Changes to the REALTIME clock can cause Condition::waitRelative() to
timeout early or delayed. This behavior is undesired and new since
https://android-review.googlesource.com/#/c/181058/ moved the
underlying pthread_cond_timedwait() implementation to use absolute
timeouts rather than relative ones. Having Condition use
CLOCK_MONOTONIC prevents these timeout issues.
Bug: 34592766
Bug: 35678943
Test: Boot bullhead
Test: Ensure time changes do not cause Condition::waitRelative() to
timeout early or delayed
Change-Id: I3a8d7a48f9b42fe990c3c7331313b6d85aa546f9
diff --git a/libutils/include/utils/Condition.h b/libutils/include/utils/Condition.h
index 25a53aa..2c80acd 100644
--- a/libutils/include/utils/Condition.h
+++ b/libutils/include/utils/Condition.h
@@ -86,19 +86,22 @@
#if !defined(_WIN32)
-inline Condition::Condition() {
- pthread_cond_init(&mCond, NULL);
+inline Condition::Condition() : Condition(PRIVATE) {
}
inline Condition::Condition(int type) {
+ pthread_condattr_t attr;
+ pthread_condattr_init(&attr);
+#if defined(__linux__)
+ pthread_condattr_setclock(&attr, CLOCK_MONOTONIC);
+#endif
+
if (type == SHARED) {
- pthread_condattr_t attr;
- pthread_condattr_init(&attr);
pthread_condattr_setpshared(&attr, PTHREAD_PROCESS_SHARED);
- pthread_cond_init(&mCond, &attr);
- pthread_condattr_destroy(&attr);
- } else {
- pthread_cond_init(&mCond, NULL);
}
+
+ pthread_cond_init(&mCond, &attr);
+ pthread_condattr_destroy(&attr);
+
}
inline Condition::~Condition() {
pthread_cond_destroy(&mCond);
@@ -109,7 +112,7 @@
inline status_t Condition::waitRelative(Mutex& mutex, nsecs_t reltime) {
struct timespec ts;
#if defined(__linux__)
- clock_gettime(CLOCK_REALTIME, &ts);
+ clock_gettime(CLOCK_MONOTONIC, &ts);
#else // __APPLE__
// Apple doesn't support POSIX clocks.
struct timeval t;