<HTML><BODY>Ready. Package `finalizer' on pkgs.racket-lang.org Sat, 02 Aug 2014 21:12:50 +0400 от Roman Klochkov <kalimehtar@mail.ru>: <blockquote style="border-left:1px solid #0857A6; margin:10px; padding:0 0 0 10px;"> <div id=""> <div class="js-helper js-readmsg-msg"> <style type="text/css"></style> <div> <base target="_self" href="https://e.mail.ru/"> <div id="style_14070000930000000911_BODY"> Here we have a thread per every module, that use such approach. It is better,than a thread per object, but ... How many such threads can Racket run without performance degrading? Maybe better make common module for such purpose? Hmm..., I think I should make one... Sat, 2 Aug 2014 07:38:08 -0500 от Robby Findler <robby@eecs.northwestern.edu>: <blockquote style="border-left:1px solid #0857A6;margin:10px;padding:0 0 0 10px;"> <div> <div> <div> <div>Probably you want to do something like this, I guess. It creates a single thread that just waits until anything registered with an-executor is garbage and then runs the executors. They will run asynchronously, but perhaps that's okay for your usecase. Robby #lang racket (define an-executor (make-will-executor)) (void (thread (λ () (let loop () (will-execute an-executor) (loop))))) (define a-box (box #f)) (will-register an-executor a-box (λ (x) (printf "a-box is now garbage\n"))) (collect-garbage) (collect-garbage) (collect-garbage) (printf "breaking the link\n") (set! a-box #f) (collect-garbage) (collect-garbage) (collect-garbage) On Sat, Aug 2, 2014 at 7:31 AM, Roman Klochkov <<a target="_blank">kalimehtar@mail.ru</a>> wrote: > So I can write > > (define (make-obj stream) > (define res (obj (open-output-file "out.dat"))) > (define will (make-will-executor)) > (will-register will res (lambda (x) (close-output-port (obj-file x)))) > (thread (lambda () (let loop () (will-try-execute will) (sleep 1) > (loop))))) > > to make my objects? Additional threads don't hinder performance, do they? > > Or should I somehow figure out if the thread is already running, don't run > it and use common `will' for all objects? > > Sat, 2 Aug 2014 07:00:04 -0500 от Robby Findler > <<a target="_blank">robby@eecs.northwestern.edu</a>>: > > One way is to set up a separate thread to do that. > > The reason they are not called automatically is sometimes running the > procedure passed to will-register needs to access some shared state > and so your program must be allowed to be in control of the timing of > the executor. > > In this case, it sounds like you can run the executor at any time, so > just creating a thread to close the port inside my-obj should work > fine. > > Robby > > > On Sat, Aug 2, 2014 at 6:15 AM, Roman Klochkov <<a target="_blank">kalimehtar@mail.ru</a>> wrote: >> Then how? >> >> Suppose I have >> (struct obj (file)) >> (define my-obj (obj (open-output-file "out.dat"))) >> >> What I have to write to close the file, when my-obj will be GC'ed? >> >> I can write >> (define will (make-will-executor)) >> (will-register will my-obj (lambda (x) (close-output-port (obj-file x)))) >> >> But as far as I understand, it will not be called until `will-execute' or >> `will-try-execute' will be manually called? >> >> Then how to call will-try-execute when GC is collecting my-obj? >> >> >> Sat, 2 Aug 2014 11:57:32 +0100 от Matthew Flatt <<a target="_blank">mflatt@cs.utah.edu</a>>: >> >> No, use the safe "will executors" API, instead. >> >> The unsafe finalizer API is for low-level, atomic finalization. Closing a >> port can flush buffers and more, and it's not a good idea to do that in an >> unsafe atomic context. >> >>> On Aug 2, 2014, at 11:12 AM, Roman Klochkov <<a target="_blank">kalimehtar@mail.ru</a>> wrote: >>> >>> I have a structure, that has a filestream inside it. File have to be >>> cosed, when the structure is not used anymore (so gargbage collected). >>> >>> Is the best way to do >>> (require ffi/unsafe) >>> (register-finalizer my-obj >>> (lambda (x) (close-output-port (obj-file x)))) >>> >>> ? >>> >>> It seems doing right thing, but why `ffi/unsafe'? Is it OK, when my >>> program actually doesn't use FFI? >>> >>> >>> -- >>> Roman Klochkov >>> ____________________ >>> Racket Users list: >>> <a href="http://lists.racket-lang.org/users" target="_blank">http://lists.racket-lang.org/users</a> >> >> >> >> -- >> Roman Klochkov >> >> ____________________ >> Racket Users list: >> <a href="http://lists.racket-lang.org/users" target="_blank">http://lists.racket-lang.org/users</a> >> > > > > -- > Roman Klochkov </div> </div> </div> </div> </blockquote> -- Roman Klochkov </div> <div>____________________ Racket Users list: <a href="http://lists.racket-lang.org/users" target="_blank">http://lists.racket-lang.org/users</a> </div> <base target="_self" href="https://e.mail.ru/"> </div> </div> </div> </blockquote> -- Roman Klochkov </BODY></HTML>