On Sun, Oct 11, 2009 at 5:28 PM, Raoul Duke <rao...@gmail.com> wrote:
> >> will actors actually do the queued function w/in a reasonable > >> timeframe? i don't think there are any guarantees of it so if one is > >> hoping to get really nicely periodic behaviour... just curious because > >> i'd thought of using agents for periodic stuff, too. > > > > In practice, they seem to. > > it seems like a common thing people try to do in Clojure e.g. random > link > http://github.com/fffej/ClojureProjects/blob/33ef9f0d1c67821658122273321e0a403486374b/misc/uk/co/fatvat/flock.clj > > so, can anybody "official" say if this use case is / will be > explicitly kept in mind for agent implementation? > > thanks :) Agents are for asynchronous, sequential state changes. Which means there is a guarantee that a change to an actor will be processed before its next action (but after its current one). There's no guarantee of promptness of getting to any particular message, but the evidence is that it's on a best-effort basis. The system's semantics won't change, then, but it may get slow if the system is heavily loaded (CPU, I/O contention, RAM/pagefile, whatever is relevant) or the actor tasks are long-running. If you want one with the ability to interrupt/abort the current task you'll need to roll your own using threads and interrupt (I wouldn't recommend interrupting an agent thread, even if the agent task catches InterruptedException and returns; if the interrupt hits at the wrong moment between one job's catch and the next's try, you'll get at best agent errors (an InterruptedException in the error queue) and at worst a crashed agent thread. (Finding the thread an agent is using is possible but nontrivial; the same agent may be using a different thread on successive sends, so it's really the agent task and not the agent that has a thread. A long-running task could start with a reset! of an atom to (Thread/currentThread) to give the code that launched it a reference to the Thread object via which to interrupt it. Interrupting it after the task is complete may interrupt some OTHER agent's task, never mind some other task given to the same agent.) --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
