Hi, Several questions / thoughts:
2010/9/6 K. <kotot...@gmail.com>: > Hello, > > I've got a concurrency problem and it's not really clear to me how to > solve it. I have a Swing GUI doing a search in background with agents > and the results are displayed one after the other, also in background. > > Here is, largely simplified, how I do it: > > (defvar- *end-search* (atom false)) > > ;; this will be called from a Swing listener, when the user clicks on > the 'Search' button > ;; so this is called from the swing thread > (defn on-search-begins [] > ;; > (reset! *end-search* false) > (send *search-agent* do-search)) Mmm, an agent without state always rings a bell in my head. There's a smell of "abuse" of the agent concept here. Aren't you just using it for its commodity to "start a new thread". If so, you could as well just use a future, for example, and then you'll have simpler semantics. Or you could just (Thread/start) your fn (but then you introduce java clearly in the code, so maybe just using a future is "the right balance"). Agents carry with them a lot of semantics, so readers of you code may have unsatisfied expectations on your usage ... until they "get it" and think: "ok it's just an 'agent abuse'". > (defn do-search [state] > ;; while (deref *end-search*) is false and while there are results > for the search, do > (do-swing > ;; we are not in a swing thread within the agent, so we need to > call do-swing > (display-result swingview result) As said by others, I suppose result is computed outside the do-swing form so that the Swing thread is blocked as few as possible > > ;; search ends? yes, then > (do-swing > (display-search-is-ended swingview))) > > > When the user clicks on the 'Stop' button, the following function will > be called from the Swing thread: > > (defn search-stops [] > (reset! *end-search* true) > ;; NOW we need to wait for the agents to stop > (await *search-agent*)) It would be interested to know in the first place why you have to add this call to await at all ? Anyway, to just answer your question, maybe your (display-search-is-ended swingview) call could be placed right after the (await) call, but in another thread ? As in (defn search-stops [] (reset! *end-search* true) (future (await *search-agent*) (display-search-is-ended swingview))) But all in all, I'm not sure the overall smells indicate that there must be another way, probably radically differently structured, to do all this. I'm thinking about something with watchers on refs / atoms... -- 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
