Hi Oleg, On Sun, May 17, 2015 at 6:48 AM, Oleg Dashevskii <olegdashevs...@gmail.com> wrote:
> Hi, > > I’m new to Clojure async operations (while have a good understanding of > other things) and want to get a bit of advice. Atoms & agents still confuse > me. > > What I’m implementing is a small REST webservice with custom in-memory > database. Database is indexed by unique key, basically it’s a map (I’ll > denote it as MAP). There are two basic operations: > > *PUT /api/…/<KEY>.* Initiate an update for given KEY. The HTTP response > should be returned immediately, and the processing should be done > asynchronously. The processing consists of downloading a data file from web > and doing some data crunching, the result should go into MAP. > > *GET /api/…/<KEY>.* Use (get MAP KEY) and request params to generate > response synchronously. > > The tricky part (well, for me :) is that parallel PUT requests should be > possible. The downloading and processing can and should go in parallel, > independently, whereas updating the MAP should come synchronized, > one-after-the-other. > > How would you implement this? > While this can be done with atoms & agents, perhaps you should check out core.async or Lamina first. Neither atoms nor agents can be updated in a parallel manner. Only one update runs on a single atom/agent at a given time. If you really need parallelism and the updates affect small parts of MAP, perhaps you can model it using refs, but then it's not one big map anymore. (Still you can't update a single ref in more than one thread at the same time.) You probably also want to control how the files are downloaded and processed, so that there's not duplication of effort. So an event driven solution seems to fit this problem. > > -- > Oleg. > > -- > 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. > -- Kind Regards, Atamert Ölçgen ◻◼◻ ◻◻◼ ◼◼◼ www.muhuk.com www.olcgen.com -- 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.
