Ready. Package `finalizer' on pkgs.racket-lang.org
Sat, 02 Aug 2014 21:12:50 +0400 от Roman Klochkov <[email protected]>: >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 <[email protected]>: >>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 < [email protected] > 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 >>> < [email protected] >: >>> >>> 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 < [email protected] > 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 < [email protected] >: >>>> >>>> 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 < [email protected] > 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: >>>>> http://lists.racket-lang.org/users >>>> >>>> >>>> >>>> -- >>>> Roman Klochkov >>>> >>>> ____________________ >>>> Racket Users list: >>>> http://lists.racket-lang.org/users >>>> >>> >>> >>> >>> -- >>> Roman Klochkov > > >-- >Roman Klochkov >____________________ > Racket Users list: > http://lists.racket-lang.org/users > -- Roman Klochkov
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