Aurelien DARRAGON d514ca45c6 BUG/MINOR: event_hdl: make event_hdl_subscribe thread-safe ... List insertion in event_hdl_subscribe() was not thread-safe when dealing with unique identifiers. Indeed, in this case the list insertion is conditional (we check for a duplicate, then we insert). And while we're using mt lists for this, the whole operation is not atomic: there is a race between the check and the insertion. This could lead to the same ID being registered multiple times with concurrent calls to event_hdl_subscribe() on the same ID. To fix this, we add 'insert_lock' dedicated lock in the subscription list struct. The lock's cost is nearly 0 since it is only used when registering identified subscriptions and the lock window is very short: we only guard the duplicate check and the list insertion to make the conditional insertion "atomic" within a given subscription list. This is the only place where we need the lock: as soon as the item is properly inserted we're out of trouble because all other operations on the list are already thread-safe thanks to mt lists. A new lock hint is introduced: LOCK_EHDL which is dedicated to event_hdl The patch may seem quite large since we had to rework the logic around the subscribe function and switch from simple mt_list to a dedicated struct wrapping both the mt_list and the insert_lock for the event_hdl_sub_list type. (sizeof(event_hdl_sub_list) is now 24 instead of 16) However, all the changes are internal: we don't break the API. If 68e692da0 ("MINOR: event_hdl: add event handler base api") is being backported, then this commit should be backported with it.		2023-04-05 08:58:17 +02:00
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haproxy	BUG/MINOR: event_hdl: make event_hdl_subscribe thread-safe	2023-04-05 08:58:17 +02:00
import	CLEANUP: assorted typo fixes in the code and comments	2022-11-30 14:02:36 +01:00
make	BUILD: makefile: only consider settings from enabled options	2022-12-23 17:01:55 +01:00