Fix WaitableEvent and ConditionVariable::TimedWait to use monotonic time on non-mac posix

base/synchronization/condition_variable_posix.cc

Index: base/synchronization/condition_variable_posix.cc
diff --git a/base/synchronization/condition_variable_posix.cc b/base/synchronization/condition_variable_posix.cc
index 92b479ede470f0a6c80e26b6e5b1b67fa94b6230..1c7838a5fb6f6ab2c4328d4dca6e3f20274ad301 100644
--- a/base/synchronization/condition_variable_posix.cc
+++ b/base/synchronization/condition_variable_posix.cc
@@ -20,7 +20,21 @@ ConditionVariable::ConditionVariable(Lock* user_lock)
     , user_lock_(user_lock)
 #endif
 {
-  int rv = pthread_cond_init(&condition_, NULL);
+  int rv = 0;
+  // http://crbug.com/293736
+  // Mac and NaCl don't support monotonic clock based deadlines.
+  // Android supports it through the non-standard
+  // pthread_cond_timedwait_monotonic_np.
+#if !defined(OS_MACOSX) && !defined(OS_NACL) && !defined(OS_ANDROID)
+  pthread_condattr_t attrs;
+  rv = pthread_condattr_init(&attrs);
+  DCHECK_EQ(0, rv);
+  pthread_condattr_setclock(&attrs, CLOCK_MONOTONIC);
+  rv = pthread_cond_init(&condition_, &attrs);
+  pthread_condattr_destroy(&attrs);
+#else
+  rv = pthread_cond_init(&condition_, NULL);
+#endif
   DCHECK_EQ(0, rv);
 }
 
@@ -46,13 +60,22 @@ void ConditionVariable::TimedWait(const TimeDelta& max_time) {
   int64 usecs = max_time.InMicroseconds();
 
   // The timeout argument to pthread_cond_timedwait is in absolute time.
+  struct timespec abstime;
+#if defined(OS_MACOSX) || defined(OS_NACL)
   struct timeval now;
   gettimeofday(&now, NULL);
+  abstime.tv_sec = now.tv_sec;
+  abstime.tv_nsec = now.tv_usec * Time::kNanosecondsPerMicrosecond;
+#else
+  struct timespec now;
+  clock_gettime(CLOCK_MONOTONIC, &now);
+  abstime.tv_sec = now.tv_sec;
+  abstime.tv_nsec = now.tv_nsec;
+#endif
 
-  struct timespec abstime;
-  abstime.tv_sec = now.tv_sec + (usecs / Time::kMicrosecondsPerSecond);
-  abstime.tv_nsec = (now.tv_usec + (usecs % Time::kMicrosecondsPerSecond)) *
-                    Time::kNanosecondsPerMicrosecond;
+  abstime.tv_sec += usecs / Time::kMicrosecondsPerSecond;
+  abstime.tv_nsec +=
+      (usecs % Time::kMicrosecondsPerSecond) * Time::kNanosecondsPerMicrosecond;
   abstime.tv_sec += abstime.tv_nsec / Time::kNanosecondsPerSecond;
   abstime.tv_nsec %= Time::kNanosecondsPerSecond;
   DCHECK_GE(abstime.tv_sec, now.tv_sec);  // Overflow paranoia
@@ -60,7 +83,12 @@ void ConditionVariable::TimedWait(const TimeDelta& max_time) {
 #if !defined(NDEBUG)
   user_lock_->CheckHeldAndUnmark();
 #endif
+#if defined(OS_ANDROID)
+  int rv = pthread_cond_timedwait_monotonic_np(
+      &condition_, user_mutex_, &abstime);

[Nico, 2013/10/01 21:20:42]

I haven't used it before, but from some googling around it seems that os x has
pthread_cond_timedwait_relative_np():

/* Like pthread_cond_timedwait, but use a relative timeout */
int		pthread_cond_timedwait_relative_np(pthread_cond_t *,
				 pthread_mutex_t *,
				 const struct timespec *);

+#else
   int rv = pthread_cond_timedwait(&condition_, user_mutex_, &abstime);
+#endif
   DCHECK(rv == 0 || rv == ETIMEDOUT);
 #if !defined(NDEBUG)
   user_lock_->CheckUnheldAndMark();