To clarify, you might never process a low item if a high is always available - but I believe that is what the OP is requesting.
It is also fairly trivial to add fairness to this ti always process a low if available every N cycles. > On Apr 29, 2021, at 9:31 AM, robert engels <reng...@ix.netcom.com> wrote: > > It is not. > > Because the low items will be read if there are no highs available. If the > low isn’t read, the producer on the low will block. > > Or you run out of memory if you cannot process the events fast enough - which > is also easily handled by bounding the queue - but then you may need to drop > items. > > There are no free lunches. > > But no deadlock. > > > >> On Apr 29, 2021, at 9:26 AM, Ian Davis <m...@iandavis.com >> <mailto:m...@iandavis.com>> wrote: >> >> On Thu, 29 Apr 2021, at 3:09 PM, robert engels wrote: >>> I will give you the pseudo code: >>> >>> { // step #1 do select on both >>> select high >>> select low >>> } >>> >>> if high read: >>> return high >>> else: >>> // we read a low so do a high poll >>> { >>> select high: >>> default: >>> } >>> >>> if high read: >>> enqueue low and return high >>> else: >>> if queue empty: >>> return low >>> else: >>> use queue and enqueue low from step #1 // FIFO order on low >>> reads >>> >>> The above code will always return high values over low values (if high >>> available), and return low values in order of events >> >> This seems likely deadlock if the low channel is being filled continually by >> another goroutine. In addition I usually aim to give ownership of the >> channel to the writer so it can close cleanly, but mixing reads and writes >> in a single function greatly complicates that. >> >> 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 >> <mailto:golang-nuts+unsubscr...@googlegroups.com>. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/golang-nuts/f26ee7f2-a518-433f-89d4-d55aa0a9b07d%40www.fastmail.com >> >> <https://groups.google.com/d/msgid/golang-nuts/f26ee7f2-a518-433f-89d4-d55aa0a9b07d%40www.fastmail.com?utm_medium=email&utm_source=footer>. > > > -- > 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 > <mailto:golang-nuts+unsubscr...@googlegroups.com>. > To view this discussion on the web visit > https://groups.google.com/d/msgid/golang-nuts/00218548-6E27-4E16-A75F-88B6E30195E5%40ix.netcom.com > > <https://groups.google.com/d/msgid/golang-nuts/00218548-6E27-4E16-A75F-88B6E30195E5%40ix.netcom.com?utm_medium=email&utm_source=footer>. -- 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. To view this discussion on the web visit https://groups.google.com/d/msgid/golang-nuts/10A8C321-E56E-43D2-8E00-C95AF52AD1E8%40ix.netcom.com.
