Index: base/task_scheduler/scheduler_lock_impl.cc |
diff --git a/base/task_scheduler/scheduler_lock_impl.cc b/base/task_scheduler/scheduler_lock_impl.cc |
index 7480e18da164edea00b7cafaed5d6e32ac86d835..a23df7d580e4061f435d3f15ff4acd7bbb7e3eed 100644 |
--- a/base/task_scheduler/scheduler_lock_impl.cc |
+++ b/base/task_scheduler/scheduler_lock_impl.cc |
@@ -67,19 +67,25 @@ class SafeAcquisitionTracker { |
// Otherwise, make sure that the previous lock acquired is an allowed |
// predecessor. |
AutoLock auto_lock(allowed_predecessor_map_lock_); |
+ // Using at() is exception-safe here as |lock| was registered already. |
const SchedulerLockImpl* allowed_predecessor = |
allowed_predecessor_map_.at(lock); |
DCHECK_EQ(acquired_locks->back(), allowed_predecessor); |
} |
+ // This asserts that |lock|'s registered predecessor is safe (and by |
robliao
2016/08/04 18:13:29
Iterating over chat.
gab
2016/08/04 18:15:06
Done.
|
+ // indicution that the predecessor chain is safe -- cycle free). Since |
+ // registration only happens at construction time, the predecessor is safe as |
+ // long as it is either null or already registered. |
void AssertSafePredecessor(const SchedulerLockImpl* lock) const { |
allowed_predecessor_map_lock_.AssertAcquired(); |
- for (const SchedulerLockImpl* predecessor = |
- allowed_predecessor_map_.at(lock); |
- predecessor != nullptr; |
- predecessor = allowed_predecessor_map_.at(predecessor)) { |
- DCHECK_NE(predecessor, lock) << |
- "Scheduler lock predecessor cycle detected."; |
+ // Using at() is exception-safe here as |lock| was registered already. |
+ const SchedulerLockImpl* predecessor = allowed_predecessor_map_.at(lock); |
+ if (predecessor) { |
+ DCHECK(allowed_predecessor_map_.find(predecessor) != |
+ allowed_predecessor_map_.end()) |
+ << "SchedulerLock was registered before its predecessor. " |
+ << "Potential cycle detected"; |
} |
} |