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[bug#47160] [PATCH] scripts: substitute: Add back some error handling.
From: |
Ludovic Courtès |
Subject: |
[bug#47160] [PATCH] scripts: substitute: Add back some error handling. |
Date: |
Tue, 16 Mar 2021 22:30:19 +0100 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/27.1 (gnu/linux) |
Christopher Baines <mail@cbaines.net> skribis:
> In f50f5751fff4cfc6d5abba9681054569694b7a5c, the way fetch was called within
> process-substitution was changed. As with-cached-connection actually includes
> important error handling for the opening of a HTTP request (when using a
> cached connection), this change removed some error handling.
>
> This commit adds that error handling back,
> (call-)with-cached-connection is back, rebranded as
> call-with-cached-connection-and-error-handling.
>
> * guix/scripts/substitute.scm (process-substitution): Retry once for some
> errors when making HTTP requests to fetch substitutes.
Please mention also the new procedure, and a
“Fixes <https://bugs.gnu.org/47157>.” line
> +(define (call-with-cached-connection-and-error-handling uri proc)
> + (define (get-port)
> + (open-connection-for-uri/cached uri
> + #:verify-certificate? #f))
> +
> + (let ((port (get-port)))
> + (catch #t
> + (lambda ()
> + (proc port))
> + (lambda (key . args)
> + ;; If PORT was cached and the server closed the connection in the
> + ;; meantime, we get EPIPE. In that case, open a fresh connection
> + ;; and retry. We might also get 'bad-response or a similar
> + ;; exception from (web response) later on, once we've sent the
> + ;; request, or a ERROR/INVALID-SESSION from GnuTLS.
> + (if (or (and (eq? key 'system-error)
> + (= EPIPE (system-error-errno `(,key ,@args))))
> + (and (eq? key 'gnutls-error)
> + (eq? (first args) error/invalid-session))
> + (memq key '(bad-response bad-header bad-header-component)))
> + (begin
> + (close-port port) ; close the port to get a fresh one
> + (proc (get-port)))
I find it marginally clearer to pass #:fresh? #t (as was done in
the code removed in 7c85877fdf964694061e3192eac35723ebc047bf) than to
rely on the closed-port side effect.
I think it’s OK to remove ‘-and-error-handling’ because that doesn’t
really tell much and because too many words obscure the message IMO, but
that’s a detail. I also like the helper macro as was removed in
7c85877fdf964694061e3192eac35723ebc047bf.
Apart from that LGTM.
My limited testing suggests it’s working as intended.
Thank you!
Ludo’.
[bug#47160] [PATCH v2 1/2] scripts: substitute: Add back some error handling., Christopher Baines, 2021/03/15
[bug#47160] [PATCH 1/2] scripts: substitute: Add back some error handling., Christopher Baines, 2021/03/16