Yep. Thanks! cheers, - J
On Tue, Oct 10, 2017 at 11:01 PM, Ian Lance Taylor <i...@golang.org> wrote: > On Tue, Oct 10, 2017 at 7:56 AM, Jay Guo <guojiannan1...@gmail.com> wrote: > > > > In my use case, both cases you presented are valid and I don't really > need > > to disambiguate them. So I guess calling `Wait` before `Add` here should > be > > fine? I couldn't tell if there would be any unexpected crash from reading > > `WaitGroup` source code. > > It's fine to call Wait before Add, the Wait simply won't wait. > Presumably you are then going to call Wait again on the same > sync.WaitGroup, possibly after some Add calls have occurred. > > Ian > > > > On Tue, Oct 10, 2017 at 9:42 PM, Ian Lance Taylor <i...@golang.org> > wrote: > >> > >> On Tue, Oct 10, 2017 at 5:34 AM, Jay Guo <guojiannan1...@gmail.com> > wrote: > >> > > >> > It is suggested in https://golang.org/pkg/sync/#WaitGroup that: > >> > > >> > // Note that calls with a positive delta that occur when the counter > is > >> > zero > >> > // must happen before a Wait. > >> > > >> > I wonder what's the reason in terms of `sync` implementation. > >> > > >> > Essentially I'm trying to implement following logic: > >> > > >> > for { > >> > waitForAllTaskToComplete() > >> > ... > >> > } > >> > > >> > where we may have no task in flight initially. > >> > >> That rule clarifies that if all the Done calls happen before the > >> program gets around to calling Wait, the Wait will not block. > >> Basically, a Wait with a count of zero might mean that nobody has > >> called Add, or it might mean that all calls to Add have already called > >> Done. Clearly in the latter case we should not block, and the effect > >> is that we can not block in the former case as well. > >> > >> 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.
