Willy Tarreau 9a1f57351d MEDIUM: threads: add thread_sync_release() to synchronize steps ... This function provides an alternate way to leave a critical section run under thread_isolate(). Currently, a thread may remain in thread_release() without having the time to notice that the rdv mask was released and taken again by another thread entering thread_isolate() (often the same that just released it). This is because threads wait in harmless mode in the loop, which is compatible with the conditions to enter thread_isolate(). It's not possible to make them wait with the harmless bit off or we cannot know when the job is finished for the next thread to start in thread_isolate(), and if we don't clear the rdv bit when going there, we create another race on the start point of thread_isolate(). This new synchronous variant of thread_release() makes use of an extra mask to indicate the threads that want to be synchronously released. In this case, they will be marked harmless before releasing their sync bit, and will wait for others to release their bit as well, guaranteeing that thread_isolate() cannot be started by any of them before they all left thread_sync_release(). This allows to construct synchronized blocks like this : thread_isolate() /* optionally do something alone here */ thread_sync_release() /* do something together here */ thread_isolate() /* optionally do something alone here */ thread_sync_release() And so on. This is particularly useful during initialization where several steps have to be respected and no thread must start a step before the previous one is completed by other threads. This one must not be placed after any call to thread_release() or it would risk to block an earlier call to thread_isolate() which the current thread managed to leave without waiting for others to complete, and end up here with the thread's harmless bit cleared, blocking others. This might be improved in the future.		2019-06-10 09:42:43 +02:00
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common	MEDIUM: threads: add thread_sync_release() to synchronize steps	2019-06-10 09:42:43 +02:00
import	BUILD: threads/plock: fix a build issue on Clang without optimization	2017-11-20 21:06:35 +01:00
proto	BUILD: stream-int: avoid a build warning in dev mode in si_state_bit()	2019-06-06 16:42:08 +02:00
types	MINOR: peers: Optimization for dictionary cache lookup.	2019-06-07 15:47:54 +02:00