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..e70a301cb2a733b62d0b6d2fb096bd11a9c212ff 100644
--- a/base/synchronization/condition_variable_posix.cc
+++ b/base/synchronization/condition_variable_posix.cc
@@ -20,7 +20,22 @@ ConditionVariable::ConditionVariable(Lock* user_lock)
     , user_lock_(user_lock)
 #endif
 {
-  int rv = pthread_cond_init(&condition_, NULL);
+  int rv = 0;
+  // http://crbug.com/293736
+  // NaCl doesn't support monotonic clock based absolute deadlines.
+  // Android supports it through the non-standard
+  // pthread_cond_timedwait_monotonic_np.
+  // Mac can use relative time deadlines.
+#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);
 }
 
@@ -44,23 +59,48 @@ void ConditionVariable::Wait() {
 void ConditionVariable::TimedWait(const TimeDelta& max_time) {
   base::ThreadRestrictions::AssertWaitAllowed();
   int64 usecs = max_time.InMicroseconds();
+  struct timespec relative_time;
+  relative_time.tv_sec = usecs / Time::kMicrosecondsPerSecond;
+  relative_time.tv_nsec =
+      (usecs % Time::kMicrosecondsPerSecond) * Time::kNanosecondsPerMicrosecond;
+
+#if !defined(NDEBUG)
+  user_lock_->CheckHeldAndUnmark();
+#endif
 
+#if defined(OS_MACOSX)
+  int rv = pthread_cond_timedwait_relative_np(
+      &condition_, user_mutex_, &relative_time);
+#else
   // The timeout argument to pthread_cond_timedwait is in absolute time.
+  struct timespec absolute_time;
+#if defined(OS_NACL)
+  // See comment in constructor for why this is different in NaCl.
   struct timeval now;
   gettimeofday(&now, NULL);
+  absolute_time.tv_sec = now.tv_sec;
+  absolute_time.tv_nsec = now.tv_usec * Time::kNanosecondsPerMicrosecond;
+#else
+  struct timespec now;
+  clock_gettime(CLOCK_MONOTONIC, &now);
+  absolute_time.tv_sec = now.tv_sec;
+  absolute_time.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 += abstime.tv_nsec / Time::kNanosecondsPerSecond;
-  abstime.tv_nsec %= Time::kNanosecondsPerSecond;
-  DCHECK_GE(abstime.tv_sec, now.tv_sec);  // Overflow paranoia
+  absolute_time.tv_sec += relative_time.tv_sec;
+  absolute_time.tv_nsec += relative_time.tv_nsec;
+  absolute_time.tv_sec += absolute_time.tv_nsec / Time::kNanosecondsPerSecond;
+  absolute_time.tv_nsec %= Time::kNanosecondsPerSecond;
+  DCHECK_GE(absolute_time.tv_sec, now.tv_sec);  // Overflow paranoia
+
+#if defined(OS_ANDROID)
+  int rv = pthread_cond_timedwait_monotonic_np(
+      &condition_, user_mutex_, &absolute_time);
+#else
+  int rv = pthread_cond_timedwait(&condition_, user_mutex_, &absolute_time);
+#endif  // OS_ANDROID
+#endif  // OS_MACOSX
 
-#if !defined(NDEBUG)
-  user_lock_->CheckHeldAndUnmark();
-#endif
-  int rv = pthread_cond_timedwait(&condition_, user_mutex_, &abstime);
   DCHECK(rv == 0 || rv == ETIMEDOUT);
 #if !defined(NDEBUG)
   user_lock_->CheckUnheldAndMark();