If you want to simply keep some messages in order, then a cat transducer will do the trick just fine:
;; need a buffer or buffer size to get to the transducer param (def c (chan 20 cat)) (async/onto-chan c [1]) (async/>!! c [2 3 4]) (async/close! c) (<!! (async/into [] c)) ;; returns [1 2 3 4] In this case, 2 3 4 will always be adjacent due to the way transducers are processed in the channel. A single value will come in, and the results of running that value through the transducer will be spooled into the channel's internals. On Wed, Oct 11, 2017 at 6:09 AM, Gary Trakhman <gary.trakh...@gmail.com> wrote: > If you don't want to split at the consumer I would recommend adding > another channel, and piping it with a cat xform as mentioned above. > > On Oct 11, 2017 3:28 AM, "JokkeB" <jahve...@gmail.com> wrote: > >> Thanks. I'm not interested in reading the messages as pairs, I just need >> to make sure nothing gets in between them. I think I'll choose some way to >> merge the messages, for example just a vector like you suggested, and then >> have the end consumer recognise and split the vector. I guess splitting the >> vector into two messages somewhere before the end consumer can't be made >> deterministic. >> >> keskiviikko 11. lokakuuta 2017 8.02.40 UTC+3 Rangel Spasov kirjoitti: >>> >>> I think simply wrapping the two values in a vector is the only thing >>> that's needed in this case. Simply do a put like (>!! ch [my-val-1 >>> my-val-2]) and take from the channel from another place. If my-val-1 and >>> my-val-2 are not immediately available, you can have a separate mechanism >>> (atoms, (loop [...] (recur ...)) or another set of core.async channels >>> perhaps) that "collects" them until they are ready to be sent together as >>> one value. >>> >>> partition-all on its own does not really help with the ordering here. >>> For example: >>> >>> (let [ch (chan 42 (partition-all 2))] >>> (>!! ch :x') >>> (thread ;in another >>> thread far, far away >>> (<!! (timeout (rand-int 1000))) ;simulate busy >>> for random 0-99ms >>> ;put value on ch >>> (>!! ch :y')) >>> >>> (<!! (timeout (rand-int 1000))) ;simulate busy >>> for random 0-99ms >>> (>!! ch :x'') >>> >>> ;take from ch >>> (<!! ch)) >>> >>> >>> This will non-deterministically output either >>> => [:x' :x''] >>> >>> or >>> >>> => [:x' :y'] >>> >>> But again as I said, you can employ partition-all separately as a >>> "collecting" mechanism before doing the (>!! ch [my-val-1 my-val-2]). >>> Didn't write an example for that but let me know if that's not clear and >>> I can put together a few lines. >>> >>> On Tuesday, October 10, 2017 at 7:50:20 AM UTC-7, Gary Trakhman wrote: >>>> >>>> So, at the point where you need 2 things to be consecutive, wrap them >>>> up in a vector so they're one thing. `(partition-all 2)` will return a >>>> transducer xform that chunks up your message stream by 2 >>>> https://clojuredocs.org/clojure.core/partition-all, and if you need to >>>> undo it you can do so with the `cat` transducer >>>> https://clojuredocs.org/clojure.core/cat . >>>> >>>> On Tue, Oct 10, 2017 at 10:42 AM JokkeB <jahv...@gmail.com> wrote: >>>> >>>>> Thanks for the response. That's what I suspected. >>>>> >>>>> How does partition help me in this case? I can't see any way of using >>>>> it. >>>>> >>>>> How about onto-chan, would that be deterministic? Or any other >>>>> function? >>>>> >>>>> >>>>> tiistai 10. lokakuuta 2017 17.33.22 UTC+3 Gary Trakhman kirjoitti: >>>>> >>>>>> I think a core assumption is that all writes can yield control at any >>>>>> time to other worker go processes. I wouldn't rely on the consecutive >>>>>> behavior even if it were true, nondeterminism is a good assumption with >>>>>> core.async. If you need that particular guarantee, consider a call to >>>>>> partition? >>>>>> >>>>>> On Tue, Oct 10, 2017 at 10:30 AM JokkeB <jahv...@gmail.com> wrote: >>>>>> >>>>> I'm wondering about a case when using async: >>>>>>> >>>>>>> I have a channel where I write from multiple threads. One of the >>>>>>> sources is a go-loop with a timeout, so each second I write something to >>>>>>> the channel. If I do two consecutive writes inside the go block, can >>>>>>> another thread write between the two writes? Or can I rely on the two >>>>>>> messages being consecutive in the channel? >>>>>>> >>>>>>> -- >>>>>>> You received this message because you are subscribed to the Google >>>>>>> Groups "Clojure" group. >>>>>>> >>>>>> To post to this group, send email to clo...@googlegroups.com >>>>>> >>>>>> >>>>>>> Note that posts from new members are moderated - please be patient >>>>>>> with your first post. >>>>>>> To unsubscribe from this group, send email to >>>>>>> >>>>>> clojure+u...@googlegroups.com >>>>>> >>>>>> >>>>>>> For more options, visit this group at >>>>>>> http://groups.google.com/group/clojure?hl=en >>>>>>> --- >>>>>>> You received this message because you are subscribed to the Google >>>>>>> Groups "Clojure" group. >>>>>>> >>>>>> To unsubscribe from this group and stop receiving emails from it, >>>>>>> send an email to clojure+u...@googlegroups.com. >>>>>> >>>>>> >>>>>>> For more options, visit https://groups.google.com/d/optout. >>>>>>> >>>>>> -- >>>>> You received this message because you are subscribed to the Google >>>>> Groups "Clojure" group. >>>>> To post to this group, send email to clo...@googlegroups.com >>>>> Note that posts from new members are moderated - please be patient >>>>> with your first post. >>>>> To unsubscribe from this group, send email to >>>>> clojure+u...@googlegroups.com >>>>> For more options, visit this group at >>>>> http://groups.google.com/group/clojure?hl=en >>>>> --- >>>>> You received this message because you are subscribed to the Google >>>>> Groups "Clojure" group. >>>>> To unsubscribe from this group and stop receiving emails from it, send >>>>> an email to clojure+u...@googlegroups.com. >>>>> For more options, visit https://groups.google.com/d/optout. >>>>> >>>> -- >> You received this message because you are subscribed to the Google >> Groups "Clojure" group. >> To post to this group, send email to clojure@googlegroups.com >> Note that posts from new members are moderated - please be patient with >> your first post. >> To unsubscribe from this group, send email to >> clojure+unsubscr...@googlegroups.com >> For more options, visit this group at >> http://groups.google.com/group/clojure?hl=en >> --- >> You received this message because you are subscribed to the Google Groups >> "Clojure" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to clojure+unsubscr...@googlegroups.com. >> For more options, visit https://groups.google.com/d/optout. >> > -- > You received this message because you are subscribed to the Google > Groups "Clojure" group. > To post to this group, send email to clojure@googlegroups.com > Note that posts from new members are moderated - please be patient with > your first post. > To unsubscribe from this group, send email to > clojure+unsubscr...@googlegroups.com > For more options, visit this group at > http://groups.google.com/group/clojure?hl=en > --- > You received this message because you are subscribed to the Google Groups > "Clojure" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to clojure+unsubscr...@googlegroups.com. > For more options, visit https://groups.google.com/d/optout. > -- “One of the main causes of the fall of the Roman Empire was that–lacking zero–they had no way to indicate successful termination of their C programs.” (Robert Firth) -- You received this message because you are subscribed to the Google Groups "Clojure" group. 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