That's clever! Just a bummer I have to feed everything to the chan in a collection for cat to work. Guess I could add a map transducer which converts non-collections into collections.
keskiviikko 11. lokakuuta 2017 15.25.24 UTC+3 tbc++ kirjoitti: > > 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.t...@gmail.com > <javascript:>> 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" <jahv...@gmail.com <javascript:>> >> 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 clo...@googlegroups.com >>> <javascript:> >>> 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 <javascript:> >>> 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 <javascript:>. >>> 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 >> <javascript:> >> 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 <javascript:> >> 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 <javascript:>. >> 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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