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fix: lock adding to tailnet waitgroup to avoid race (and fix flake)#14195

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ethanndickson merged 1 commit intomainfrom08-07-fix_lock_adding_to_tailnet_waitgroup_to_avoid_race_and_fix_flake_

Aug 7, 2024

Merged

fix: lock adding to tailnet waitgroup to avoid race (and fix flake)#14195

ethanndickson merged 1 commit intomainfrom08-07-fix_lock_adding_to_tailnet_waitgroup_to_avoid_race_and_fix_flake_

Aug 7, 2024

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ethanndickson commentedAug 7, 2024•
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Fixes#14143.
Fixes a race condition that can occur when atailnet connection is closed just before a network telemetry event is about to be sent off. Specifically, wherewaitgroup.Add(n) is called on a waitgroup wherewaitgroup.Wait() is currently blocking another goroutine.

This works as we only callWait() on thetelemetryWg waitgroup when theConn mutex is held, and only after the closed channel has been closed. We then require that the goroutine sending the telemetry event acquire said mutex, and that the channel is not closed, before adding to the waitgroup and sending the event.