Funny that exactly on this day that the proposal was opened I said in two groups the lack that I was doing something similar to "Promise.any" in Elixir.
I needed it and found it complicated to do now, I had a job because I'm starting in Elixir. I would love to have another solution for what I did, when researching several APIs to return the CEP query to me and get the first valid result. I'm starting in Elixir and in love, and I made my first package with exactly this need: https://github.com/ciareis/cep-promise-elixir/blob/master/lib/cep_promise.ex#L52 I could probably write everything in a better way, but I still get there. Please implement something to facilitate this;) Elixir S2! Em sexta-feira, 2 de abril de 2021 às 04:51:53 UTC-3, José Valim escreveu: > I have been thinking more about this problem and there is still one issue > for us to solve: when you say you are waiting for "n" tasks, does it mean > you are waiting for "n" successes or "n" results (regardless if they are > success or failure)? > > So I thought perhaps a better solution is to introduce something called > Task.yield_stream/2. "yield_stream" receives an enumerable of tasks and > emits them as they complete. To get the first successful task you would do: > > tasks > |> Task.yield_stream(ordered: false, timeout: 5000) > |> Stream.filter(&match?({:ok, _})) > |> Enum.at(0) > > And this made me wonder: is there any reason why you can't use > Task.async_stream? > > > On Thu, Apr 1, 2021 at 3:59 PM José Valim <jose....@dashbit.co> wrote: > >> I don't see a reason why we wouldn't return the same order. You can >> easily get the ones you want by `for {task, {:ok, value}} <- result do`. >> Plus forcing people to iterate will remind them that they most likely need >> to shutdown the other tasks. >> >> On Thu, Apr 1, 2021 at 3:57 PM thia.md...@gmail.com <thia.md...@gmail.com> >> wrote: >> >>> > In this sense, yield_many becomes a special case of yield_first where >>> you want to yield on all given tasks. >>> >>> I'm not sure if we would want that, because in yield_many the returned >>> list will be in the same order as the tasks supplied in the tasks input >>> argument. >>> However yield_first to preserve the semantics of "returning as soon it >>> finishes", maybe we should return the tasks in the order of finish (the >>> first to complete first in the list). >>> That makes sense? >>> >>> Em quarta-feira, 31 de março de 2021 às 19:35:47 UTC-3, >>> thia.md...@gmail.com escreveu: >>> >>>> +1 for yield_first(tasks, n, timeout) >>>> >>>> It seems to better convey the meaning "yield the first n tasks". >>>> >>>> Em qua., 31 de mar. de 2021 às 19:26, Felipe Stival <v0i...@gmail.com> >>>> escreveu: >>>> >>>>> +1 for yield_first(tasks, n, timeout) >>>>> >>>>> >>>>> On Thu, Apr 1, 2021, 01:11 José Valim <jose....@dashbit.co> wrote: >>>>> >>>>>> It was not possible to implement yield_first in Elixir but now that >>>>>> we have map_get in guards, we can easily do so by putting all refs in a >>>>>> map >>>>>> and only getting messages from the inbox where the ref is in the map. >>>>>> The >>>>>> number of tasks to wait and the maximum timeout should be configurable >>>>>> too. >>>>>> For example: >>>>>> >>>>>> yield_first(task, 3, 1000) >>>>>> >>>>>> The above will yield the first 3 tasks within 1000ms. It should have >>>>>> the same result type as yield_many. In this sense, yield_many becomes a >>>>>> special case of yield_first where you want to yield on all given tasks. >>>>>> >>>>>> Another option is to not introduce a new function but instead >>>>>> introduce a new argument to yield_many with the limit to yield: >>>>>> >>>>>> yield_many(task, 1000, 3) >>>>>> >>>>>> >>>>>> >>>>>> On Wed, Mar 31, 2021 at 11:52 PM thia.md...@gmail.com < >>>>>> thia.md...@gmail.com> wrote: >>>>>> >>>>>>> I think the proposal would work differently from yield_many. >>>>>>> yield_many "receives a list of tasks and waits for their replies in the >>>>>>> given time interval". >>>>>>> The proposal of the new function is to return as soon as the first >>>>>>> task finishes. >>>>>>> >>>>>>> For example, if we start tasks to make call to 3 different remote >>>>>>> APIs, with different response times. >>>>>>> >>>>>>> API A - 50ms >>>>>>> API B - 500ms >>>>>>> API C - 1500ms >>>>>>> >>>>>>> tasks = [ >>>>>>> Task.async(&api_a/0), >>>>>>> Task.async(&api_b/0), >>>>>>> Task.async(&api_c/0) >>>>>>> ] >>>>>>> >>>>>>> # returns result of API A and API B waiting for 1000ms >>>>>>> Task.yield_many(tasks, 1000) >>>>>>> >>>>>>> With run using `yield_many` we would wait for the 1000ms and get the >>>>>>> responses of API A and API B. >>>>>>> >>>>>>> The proposal of the new function is to return as soon as we get a >>>>>>> response. >>>>>>> Using the same example of the 3 calls, we would wait only for 50ms >>>>>>> (as soon as the first task finishes) and return the result of the first >>>>>>> task finishing, without waiting for the other call. >>>>>>> >>>>>>> tasks = [ >>>>>>> Task.async(&api_a/0), >>>>>>> Task.async(&api_b/0), >>>>>>> Task.async(&api_c/0) >>>>>>> ] >>>>>>> >>>>>>> # returns only result of API A waiting for 50ms >>>>>>> Task.proposed_function(tasks) >>>>>>> >>>>>>> Em quarta-feira, 31 de março de 2021 às 18:06:47 UTC-3, >>>>>>> woj...@wojtekmach.pl escreveu: >>>>>>> >>>>>>>> Check out Task.yield_many/2 ( >>>>>>>> https://hexdocs.pm/elixir/Task.html#yield_many/2) :-) >>>>>>>> >>>>>>>> On 31 Mar 2021, at 22:54, thia.md...@gmail.com < >>>>>>>> thia.md...@gmail.com> wrote: >>>>>>>> >>>>>>>> *Proposal* >>>>>>>> >>>>>>>> Add a function to the Task module that takes a list of tasks, and >>>>>>>> returns as soon as one of the tasks finishes, shuting down the other >>>>>>>> tasks. >>>>>>>> The behaviour would pretty similar to what Javascript have with >>>>>>>> Promise.any >>>>>>>> https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise/any >>>>>>>> >>>>>>>> *Motivation* >>>>>>>> >>>>>>>> One scenario that it could be useful is when we are integrating >>>>>>>> with multiple APIs (providers) of the same data, and we want only the >>>>>>>> fastest result without needing to wait for the other requests to >>>>>>>> complete. >>>>>>>> >>>>>>>> Today I think this could be implemented with something similar to >>>>>>>> the following code: >>>>>>>> >>>>>>>> tasks = [ >>>>>>>> Task.async(&heavy_fun_1/0), >>>>>>>> Task.async(&heavy_fun_2/0), >>>>>>>> Task.async(&heavy_fun_3/0) >>>>>>>> ] >>>>>>>> >>>>>>>> receive do >>>>>>>> {ref, result} -> >>>>>>>> tasks >>>>>>>> |> Enum.reject(fn task -> task.ref == ref end) >>>>>>>> |> Enum.each(&Task.shutdown/1) >>>>>>>> >>>>>>>> result >>>>>>>> after >>>>>>>> 5000 -> >>>>>>>> {:error, :timeout} >>>>>>>> end >>>>>>>> >>>>>>>> However that seems to be a common enough pattern to add to the >>>>>>>> standard library. >>>>>>>> >>>>>>>> *Questions* >>>>>>>> >>>>>>>> - Am I missing something here and this could already be easily >>>>>>>> accomplished with the existing API? >>>>>>>> - What should be the behaviour when the first task to complete >>>>>>>> exits? >>>>>>>> >>>>>>>> -- >>>>>>>> You received this message because you are subscribed to the Google >>>>>>>> Groups "elixir-lang-core" group. >>>>>>>> To unsubscribe from this group and stop receiving emails from it, >>>>>>>> send an email to elixir-lang-co...@googlegroups.com. >>>>>>>> To view this discussion on the web visit >>>>>>>> https://groups.google.com/d/msgid/elixir-lang-core/59a5b5af-528b-4f1f-8e17-6dad9edfe9ccn%40googlegroups.com >>>>>>>> >>>>>>>> <https://groups.google.com/d/msgid/elixir-lang-core/59a5b5af-528b-4f1f-8e17-6dad9edfe9ccn%40googlegroups.com?utm_medium=email&utm_source=footer> >>>>>>>> . >>>>>>>> >>>>>>>> >>>>>>>> -- >>>>>>> You received this message because you are subscribed to the Google >>>>>>> Groups "elixir-lang-core" group. >>>>>>> To unsubscribe from this group and stop receiving emails from it, >>>>>>> send an email to elixir-lang-co...@googlegroups.com. >>>>>>> To view this discussion on the web visit >>>>>>> https://groups.google.com/d/msgid/elixir-lang-core/fe8d048f-605b-4b7a-ad2d-64fb11727d4dn%40googlegroups.com >>>>>>> >>>>>>> <https://groups.google.com/d/msgid/elixir-lang-core/fe8d048f-605b-4b7a-ad2d-64fb11727d4dn%40googlegroups.com?utm_medium=email&utm_source=footer> >>>>>>> . >>>>>>> >>>>>> -- >>>>>> You received this message because you are subscribed to the Google >>>>>> Groups "elixir-lang-core" group. >>>>>> To unsubscribe from this group and stop receiving emails from it, >>>>>> send an email to elixir-lang-co...@googlegroups.com. >>>>>> To view this discussion on the web visit >>>>>> https://groups.google.com/d/msgid/elixir-lang-core/CAGnRm4L%2BogpwDohNaRoZHkT0%3DkOdFROdT37BQJx3k%3D%3DzZqQzAA%40mail.gmail.com >>>>>> >>>>>> <https://groups.google.com/d/msgid/elixir-lang-core/CAGnRm4L%2BogpwDohNaRoZHkT0%3DkOdFROdT37BQJx3k%3D%3DzZqQzAA%40mail.gmail.com?utm_medium=email&utm_source=footer> >>>>>> . >>>>>> >>>>> -- >>>>> >>>> You received this message because you are subscribed to a topic in the >>>>> Google Groups "elixir-lang-core" group. >>>>> To unsubscribe from this topic, visit >>>>> https://groups.google.com/d/topic/elixir-lang-core/ZIFsisK12CM/unsubscribe >>>>> . >>>>> To unsubscribe from this group and all its topics, send an email to >>>>> elixir-lang-co...@googlegroups.com. >>>>> To view this discussion on the web visit >>>>> https://groups.google.com/d/msgid/elixir-lang-core/CAKC64%2BwFh20dRTVnJi5QC8Ekk5CNcSx8k8jW_xBP65rOYGukYw%40mail.gmail.com >>>>> >>>>> <https://groups.google.com/d/msgid/elixir-lang-core/CAKC64%2BwFh20dRTVnJi5QC8Ekk5CNcSx8k8jW_xBP65rOYGukYw%40mail.gmail.com?utm_medium=email&utm_source=footer> >>>>> . >>>>> >>>> -- >>> You received this message because you are subscribed to the Google >>> Groups "elixir-lang-core" group. >>> To unsubscribe from this group and stop receiving emails from it, send >>> an email to elixir-lang-co...@googlegroups.com. >>> To view this discussion on the web visit >>> https://groups.google.com/d/msgid/elixir-lang-core/c31c31f1-2de8-41a4-a3f3-f5b924c2ea1an%40googlegroups.com >>> >>> <https://groups.google.com/d/msgid/elixir-lang-core/c31c31f1-2de8-41a4-a3f3-f5b924c2ea1an%40googlegroups.com?utm_medium=email&utm_source=footer> >>> . >>> >> -- You received this message because you are subscribed to the Google Groups "elixir-lang-core" group. 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