* runtime: fix ticker not stopping when Stop races with its callback
On the threads and cores schedulers, timer callbacks run concurrently
with user goroutines.
If Stop (or Reset) was called in the window after the node was popped
but before its callback re-added it, removeTimer would not find the
timer in the queue, so it would be re-added to timer anyway.
Track timers whose callback is currently running in a firing list, and
have removeTimer mark a firing timer as stopped so its callback does not
re-add it.
Also make the timers test drain robust: allow a possible in-flight tick
delivered concurrently with Stop to settle before draining the channel.
Signed-off-by: deadprogram <ron@hybridgroup.com>
* runtime: fix Stop/Reset semantics when racing a firing timer callback
Address review feedback on the ticker Stop-race fix. On the threads and
cores schedulers a timer callback runs concurrently with user goroutines,
which left several problems:
- removeTimer reported a firing timer as successfully removed, so
Stop/Reset could return true even though the callback had already
started (wrong semantics, notably for AfterFunc). firingTimerStop now
returns a bool and removeTimer no longer hands the still-firing node
back to resetTimer.
- The periodic advance (when += period) ran in timerCallback outside the
scheduler timer lock. Move it into each scheduler's reAddTimer, under
the lock and after the stopped check, so a concurrent Reset can't have
its freshly-queued deadline corrupted.
- resetTimer now sets when/period after removeTimer for the same reason.
Add testdata/timer_stop_reset_race.go and TestTimerStopResetRace, which
reproduce the stop-while-firing and reset-while-firing races via the
runtime timer linkname hooks.
Signed-off-by: deadprogram <ron@hybridgroup.com>
* runtime: fix timer Stop/Reset race with firing periodic timers
Signed-off-by: deadprogram <ron@hybridgroup.com>
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Signed-off-by: deadprogram <ron@hybridgroup.com>
Ron Evans