[racket] tcp-read handlers

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Nops Matthias, I' afraid this did not work, since this function
returns immediatly.



On 01/18/2014 08:11 PM, Matthias Felleisen wrote:
> 
> If you can modify url.rkt for now, try something like this
> [untested]
> 
> ;; url.rkt (define (purify-http-port in-port) (define-values
> (in-pipe out-pipe) (make-pipe)) (define exn-raised #f) (thread (λ
> () (with-handlers ((exn? (lambda (e) (set! exn-raised e)))) ;; do
> choose the exn you really wish to catch (define status
> (http-read-status in-port)) (define chunked? (http-read-headers
> in-port)) (http-pipe-data chunked? in-port out-pipe) 
> (close-input-port in-port)))) (or exn-raised in-pipe))
> 
> 
> 
> 
> 
> On Jan 18, 2014, at 5:08 PM, Eduardo Bellani wrote:
> 
> Btw, forgot to ask, any alternatives that could solve my problem
> in the short term?
> 
> Again, thanks for the attention.
> 
> On 01/18/2014 02:18 PM, Matthias Felleisen wrote:
>>>> 
>>>> To supplement Matthew's response, see exn style:
>>>> 
>>>> http://plt.eecs.northwestern.edu/snapshots/current/doc/style/Choosing_the_Right_Construct.html#%28part._.Exceptions%29
>>>>
>>>>
>>>> 
This does not address the problem part.
>>>> 
>>>> On Jan 18, 2014, at 11:04 AM, Matthew Flatt wrote:
>>>> 
>>>>> The `exn?` predicate would catch all exceptions from the
>>>>> base libraries.[*]
>>>>> 
>>>>> I think the problem may be that the underlying TCP port is
>>>>> read in a separate decoding thread, and so the exception
>>>>> and printing happens in that thread. If I'm right, then
>>>>> that seems like a flaw in our implementation of decoding.
>>>>> 
>>>>> [*] To avoid interfering with the `exn:break?` exceptions 
>>>>> triggered by Ctl-C, you almost always want `exn:fail?`
>>>>> instead of just `exn?`.
>>>>> 
>>>>> At Sat, 18 Jan 2014 09:50:15 -0200, Eduardo Bellani wrote:
>>>> Is there a way to install a handler for the tcp-error
>>>> exception? I have a function like this
>>>> 
>>>> (define (get-page link-url (max-tries 5)) (let loop
>>>> ([current-try 0]) (with-handlers ([exn? (? (e) (if (>
>>>> current-try max-tries) (error 'get-page "failed because it
>>>> exceeded ~a tries" max-tries) (begin (sleep 2) (loop (add1
>>>> current-try)))))]) (get-pure-port link-url))))
>>>> 
>>>> that I'm using to crawl some data, but sometimes it's
>>>> printing:
>>>> 
>>>> tcp-read: error reading system error: Connection reset by
>>>> peer; errno=104 context...:
>>>> /usr/racket/collects/net/url.rkt:392:3
>>>> 
>>>> Thanks for the attention.
>>>> 
>>>>>> ____________________ Racket Users list: 
>>>>>> http://lists.racket-lang.org/users
>>>>> ____________________ Racket Users list: 
>>>>> http://lists.racket-lang.org/users
>>>> 
> 
> 

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