On Wed, Jan 25, 2017 at 9:34 AM, 'Tim Hockin' via golang-nuts <golang-nuts@googlegroups.com> wrote: > I'm not convinced that the docs quite cover the case I am looking, so > I am posting here. > > https://golang.org/pkg/time/#Timer.Reset says "This should not be done > concurrent to other receives from the Timer's channel" but it's not > clear what the repercussions are. > > In our case, I have a function to be run periodically, on a timer, but > it can be run manually too. When run manually, I want to push the > timer out (restart the period). > > I have a goroutine doing: > > ``` > for { > select { > case <-stop: > pr.stop() > return > case <-timer.C: > run() > } > } > ``` > > deep inside run(), we have: > > ``` > timer.Stop() > timer.Reset(period) > ``` > > I understand that I could lose the race and deliver on timer.C _just > before_ this runs, and that is fine. What I am seeking to know is > whether this is considered "safe"? The receive is running > concurrently to the Reset(). Will this cause problems inside Timer, > beyond the potential "extra" delivery? Do I need to break the loop > and stop receiving on it while the Reset() happens?
The sentence "This should not be done concurrent to other receives from the Timer's channel." is intended to apply to the description of how to use t.Stop safely. It's there because if you use the code fragment described there and there is a concurrent receive, you don't know which channel receive will succeed. In other words, the channel receive in the code fragment might hang. It is safe to use Reset as you describe, as long as you understand that the timer may expire, and send a value to the channel, as you call Stop and Reset. If you don't care about that--if an extra value sent to the channel doesn't matter--then your code is fine. Ian -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
