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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
This commit is contained in:
Tom Cherry 2017-02-22 17:38:00 -08:00
parent 4bd3facbb1
commit 1fb04ff4e5
1 changed files with 12 additions and 9 deletions
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21
libutils/include/utils/Condition.h
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@ -86,19 +86,22 @@ private:
#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::wait(Mutex& mutex) {
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;