Debasish, The problem with groupBy was that it was too easy to create leaks and silently broken solutions with it, but I sympathize with your situation, I also felt the original as being more ergonomic. I think there is room for improvement in the current solution.
-- Cheers, √ On Apr 26, 2016 7:20 PM, "Debasish Ghosh" <ghosh.debas...@gmail.com> wrote: Roland - The problem is I cannot access the substreams separately within the fold. In the earlier solution the fold was on individual substreams (not on the whole stream). Here the fold gets *all* the elements from all substreams and I lose the ability to process substreams separately. Hence I lose the ability to compose with a Monoid. Possibly I need to create a separate Map and then do the aggregation. It will be clunky .. I am already starting to feel the loss of the 1.0 API, which I thought was very idiomatic from groupBy point of view. Let me see if I can at all get a solution for this .. regards. On Tue, Apr 26, 2016 at 10:33 PM, Roland Kuhn <goo...@rkuhn.info> wrote: > Instead of using a fold sink which materializes to a Future you’ll need to > use a fold combinator which produces the result as its only value after the > substream has completed, i.e. you keep the computation results within the > streaming domain a bit longer instead of going to the Future domain > immediately. Your 1.0 solution must have done something very similar, only > with a different API (i.e. you folded the substreams and then probably used > mapAsync to flatten the resulting stream of Futures). > > Regards, > > Roland > > 26 apr 2016 kl. 18:05 skrev Debasish Ghosh <ghosh.debas...@gmail.com>: > > Roland - > > I need to merge into a fold sink w/ a Monoid. Consider the following > example .. > > case class Transaction(id: String, accountNo: String, debitCredit: > TransactionType, amount: Amount, date: Date = today) > > and I have the following list of Transactions .. > > val txns = > Seq( > Transaction("t-1", "a-1", Debit, 1000), > Transaction("t-2", "a-2", Debit, 1000), > Transaction("t-3", "a-3", Credit, 1000), > Transaction("t-4", "a-1", Credit, 1000), > Transaction("t-5", "a-1", Debit, 1000), > Transaction("t-6", "a-2", Debit, 1000), > Transaction("t-7", "a-3", Credit, 1000), > Transaction("t-8", "a-3", Debit, 1000), > Transaction("t-9", "a-2", Credit, 1000), > Transaction("t-10", "a-2", Debit, 1000), > Transaction("t-11", "a-1", Credit, 1000), > Transaction("t-12", "a-3", Debit, 1000) > ) > > I do a group by accountNo, which gives me 3 substreams. Each substream > needs to go into a fold sink where I fold using a Monoid. The Monoid has > the logic of merging transactions belonging to the same accountNo. The > logic that u suggest will not do this. I need to access the substreams > separately. That's why I did a groupBy (similar to SQL groupBy). And I > could do this in the 1.0 version. > > Any workaround that u suggest ? > > Thanks. > > On Tue, Apr 26, 2016 at 9:18 PM, Roland Kuhn <goo...@rkuhn.info> wrote: > >> If you need the results from the substreams you’ll have to merge them >> back into the mainstream and aggregate them there: >> >> transactions.groupBy(100, >> ...).fold(...).mergeSubstreams.grouped(100).to(Sink.head) >> >> Regards, >> >> Roland >> >> 26 apr 2016 kl. 17:36 skrev debasish <ghosh.debas...@gmail.com>: >> >> Viktor - >> >> Here's the same stuff that works for akka-streams version >> akka-stream-experimental 1.0 RC4. .. >> https://gist.github.com/debasishg/4d596c1f26d4759ed65e281bb2e6fd2c .. >> >> The upgrade that I am having trouble with is defining netTxn (pls see >> the gist). The groupBy works like a charm in the older version. But in the >> newer version it returns a Subflow and I was stumped how to get hold of >> each of the substreams and fold them using a Monoid on a fold sink. >> Konrad's solution was to use the to method of subflow. But somehow it's >> not giving the desired result .. help ? >> >> Thanks. >> >> >> On Tuesday, April 26, 2016 at 8:46:11 PM UTC+5:30, √ wrote: >>> >>> What are you expecting to be returned? >>> >>> -- >>> Cheers, >>> √ >>> On Apr 26, 2016 3:49 PM, "Debasish Ghosh" <ghosh.d...@gmail.com> wrote: >>> >>>> Thanks Konrad for the pointer .. when I run the graph I get a NotUsed .. >>>> That's not hwat I get with the earlier implementation. Please have a look >>>> at the gist .. >>>> https://gist.github.com/debasishg/a42e867bb2bc8ad18243597178bbce93 .. >>>> what am I doing wrong. >>>> >>>> Thanks. >>>> >>>> On Tue, Apr 26, 2016 at 6:22 PM, Konrad Malawski < >>>> konrad....@typesafe.com> wrote: >>>> >>>>> (I did a quick mock Transaction type, your Monoid should work fine >>>>> there ofc). >>>>> >>>>> -- Konrad >>>>> >>>>> On Sunday, 24 April 2016 21:42:43 UTC+2, debasish wrote: >>>>> >>>>>> Hi - >>>>>> >>>>>> I am trying to migrate some akka-streams code from an earlier version >>>>>> (akka-stream-experimental 1.0.RC4) .. please have a look at the >>>>>> following .. >>>>>> >>>>>> /** >>>>>> * Create multiple streams out of a single stream. The stream >>>>>> "transactions" is being >>>>>> * demultiplexed into many streams split by account number. Each of >>>>>> the sub-streams are >>>>>> * then materialized to the fold sink "txnSink", which folds each of >>>>>> the transaction >>>>>> * substreams to compute the net value of the transaction for that >>>>>> account >>>>>> */ >>>>>> val netTxn: Source[RunnableGraph[Future[Transaction]], Unit] = >>>>>> transactions.map(validate).groupBy(_.accountNo).map { case (a, s) >>>>>> => s.toMat(txnSink)(Keep.right) } >>>>>> >>>>>> I am trying to create substreams based on a field accountNo within a >>>>>> Transaction. Then I pass each substream to toMat with a Sink which >>>>>> is a fold Sink defined as below .. >>>>>> >>>>>> /** >>>>>> * Would like to fold transactions through monoid append >>>>>> */ >>>>>> val txnSink: Sink[Transaction, Future[Transaction]] = >>>>>> Sink.fold[Transaction, Transaction](TransactionMonoid.zero)(_ |+| >>>>>> _) >>>>>> >>>>>> The idea is to apply a monoid over each substream and do some netting >>>>>> on transactions belonging to the same accountNo. >>>>>> >>>>>> How can I migrate this to 2.4.4 ? Now groupBy returns a Subflow and >>>>>> I am not sure how to apply each of the substreams to the materializer. >>>>>> One >>>>>> option that works will be to create a Map[String, Transaction] upfront >>>>>> and then directly apply the monoid to the Map in the main stream and >>>>>> not create any substream. But I would like to have the substreams fro >>>>>> some >>>>>> other purpose as well. >>>>>> >>>>>> Any help will be appreciated .. >>>>>> >>>>>> Regards. >>>>>> - Debasish >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> >>>>> -- >>>>> >>>>>>>>>> Read the docs: http://akka.io/docs/ >>>>> >>>>>>>>>> Check the FAQ: >>>>> http://doc.akka.io/docs/akka/current/additional/faq.html >>>>> >>>>>>>>>> Search the archives: >>>>> https://groups.google.com/group/akka-user >>>>> --- >>>>> You received this message because you are subscribed to a topic in the >>>>> Google Groups "Akka User List" group. >>>>> To unsubscribe from this topic, visit >>>>> https://groups.google.com/d/topic/akka-user/YhJfghLqnhw/unsubscribe. >>>>> To unsubscribe from this group and all its topics, send an email to >>>>> akka-user+...@googlegroups.com. >>>>> To post to this group, send email to akka...@googlegroups.com. >>>>> Visit this group at https://groups.google.com/group/akka-user. >>>>> For more options, visit https://groups.google.com/d/optout. >>>>> >>>> >>>> >>>> >>>> -- >>>> Debasish Ghosh >>>> http://manning.com/ghosh2 >>>> http://manning.com/ghosh >>>> >>>> Twttr: @debasishg >>>> Blog: http://debasishg.blogspot.com >>>> Code: http://github.com/debasishg >>>> >>>> -- >>>> >>>>>>>>>> Read the docs: http://akka.io/docs/ >>>> >>>>>>>>>> Check the FAQ: >>>> http://doc.akka.io/docs/akka/current/additional/faq.html >>>> >>>>>>>>>> Search the archives: >>>> https://groups.google.com/group/akka-user >>>> --- >>>> You received this message because you are subscribed to the Google >>>> Groups "Akka User List" group. >>>> To unsubscribe from this group and stop receiving emails from it, send >>>> an email to akka-user+...@googlegroups.com. >>>> To post to this group, send email to akka...@googlegroups.com. >>>> Visit this group at https://groups.google.com/group/akka-user. >>>> For more options, visit https://groups.google.com/d/optout. >>>> >>> >> -- >> >>>>>>>>>> Read the docs: http://akka.io/docs/ >> >>>>>>>>>> Check the FAQ: >> http://doc.akka.io/docs/akka/current/additional/faq.html >> >>>>>>>>>> Search the archives: https://groups.google.com/group/akka-user >> --- >> You received this message because you are subscribed to the Google Groups >> "Akka User List" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to akka-user+unsubscr...@googlegroups.com. >> To post to this group, send email to akka-user@googlegroups.com. >> Visit this group at https://groups.google.com/group/akka-user. >> For more options, visit https://groups.google.com/d/optout. >> >> >> >> -- >> >>>>>>>>>> Read the docs: http://akka.io/docs/ >> >>>>>>>>>> Check the FAQ: >> http://doc.akka.io/docs/akka/current/additional/faq.html >> >>>>>>>>>> Search the archives: https://groups.google.com/group/akka-user >> --- >> You received this message because you are subscribed to a topic in the >> Google Groups "Akka User List" group. >> To unsubscribe from this topic, visit >> https://groups.google.com/d/topic/akka-user/YhJfghLqnhw/unsubscribe. >> To unsubscribe from this group and all its topics, send an email to >> akka-user+unsubscr...@googlegroups.com. >> To post to this group, send email to akka-user@googlegroups.com. >> Visit this group at https://groups.google.com/group/akka-user. >> For more options, visit https://groups.google.com/d/optout. >> > > > > -- > Debasish Ghosh > http://manning.com/ghosh2 > http://manning.com/ghosh > > Twttr: @debasishg > Blog: http://debasishg.blogspot.com > Code: http://github.com/debasishg > > -- > >>>>>>>>>> Read the docs: http://akka.io/docs/ > >>>>>>>>>> Check the FAQ: > http://doc.akka.io/docs/akka/current/additional/faq.html > >>>>>>>>>> Search the archives: https://groups.google.com/group/akka-user > --- > You received this message because you are subscribed to the Google Groups > "Akka User List" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to akka-user+unsubscr...@googlegroups.com. > To post to this group, send email to akka-user@googlegroups.com. > Visit this group at https://groups.google.com/group/akka-user. > For more options, visit https://groups.google.com/d/optout. > > > -- > >>>>>>>>>> Read the docs: http://akka.io/docs/ > >>>>>>>>>> Check the FAQ: > http://doc.akka.io/docs/akka/current/additional/faq.html > >>>>>>>>>> Search the archives: https://groups.google.com/group/akka-user > --- > You received this message because you are subscribed to a topic in the > Google Groups "Akka User List" group. > To unsubscribe from this topic, visit > https://groups.google.com/d/topic/akka-user/YhJfghLqnhw/unsubscribe. > To unsubscribe from this group and all its topics, send an email to > akka-user+unsubscr...@googlegroups.com. > To post to this group, send email to akka-user@googlegroups.com. > Visit this group at https://groups.google.com/group/akka-user. > For more options, visit https://groups.google.com/d/optout. > -- Debasish Ghosh http://manning.com/ghosh2 http://manning.com/ghosh Twttr: @debasishg Blog: http://debasishg.blogspot.com Code: http://github.com/debasishg -- >>>>>>>>>> Read the docs: http://akka.io/docs/ >>>>>>>>>> Check the FAQ: http://doc.akka.io/docs/akka/current/additional/faq.html >>>>>>>>>> Search the archives: https://groups.google.com/group/akka-user --- You received this message because you are subscribed to the Google Groups "Akka User List" group. 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