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From: "Ludovic Courtès" <ludo@gnu.org>
To: Christopher Baines <mail@cbaines.net>
Cc: Josselin Poiret <dev@jpoiret.xyz>,
	Simon Tournier <zimon.toutoune@gmail.com>,
	Mathieu Othacehe <othacehe@gnu.org>,
	Tobias Geerinckx-Rice <me@tobias.gr>,
	Ricardo Wurmus <rekado@elephly.net>,
	67245@debbugs.gnu.org, Christopher Baines <guix@cbaines.net>
Subject: [bug#67245] [PATCH v2] store: Add with-store/non-blocking.
Date: Mon, 13 May 2024 14:44:18 +0200	[thread overview]
Message-ID: <87seylankt.fsf@gnu.org> (raw)
In-Reply-To: <e692ef2de80732b3ed87e95a489f053616f4130a.1715446400.git.mail@cbaines.net> (Christopher Baines's message of "Sat, 11 May 2024 17:53:20 +0100")

Hi,

Christopher Baines <mail@cbaines.net> skribis:

> For some applications, it's important to establish a non-blocking connection
> rather than just making the socket non-blocking after the connection is
> established. This is because there is I/O on the socket that will block during
> the handshake.
>
> I've noticed this blocking during the handshake causing issues in the build
> coordinator for example.
>
> This commit adds a new with-store variant to avoid changing the behaviour of
> with-store/open-connection to ensure that this change can't break anything
> that depends on the blocking nature of the socket.
>
> * guix/store.scm (open-unix-domain-socket, open-inet-socket): Take
>  #:non-blocking? and use SOCK_NONBLOCK when calling socket if appropriate.
> (connect-to-daemon, open-connection, call-with-store): Take #:non-blocking?
> and pass it on.
> (with-store/non-blocking): New syntax rule.
>
> Change-Id: I8225762b78448bc1f7b698c8de5d736e13f577bf

[...]

> +(define* (open-unix-domain-socket file #:key non-blocking?)
>    "Connect to the Unix-domain socket at FILE and return it.  Raise a
> -'&store-connection-error' upon error."
> +'&store-connection-error' upon error.  If NON-BLOCKING?, make the socket
> +non-blocking."
>    (let ((s (with-fluids ((%default-port-encoding #f))
>               ;; This trick allows use of the `scm_c_read' optimization.
> -             (socket PF_UNIX (logior SOCK_STREAM SOCK_CLOEXEC) 0)))
> +             (socket PF_UNIX
> +                     (logior SOCK_STREAM SOCK_CLOEXEC SOCK_NONBLOCK)
> +                     0)))

Make sure SOCK_NONBLOCK is added only when ‘non-blocking?’ is true.

> +(define-syntax-rule (with-store/non-blocking store exp ...)
> +  "Bind STORE to an non-blocking open connection to the store and evaluate
> +EXPs; automatically close the store when the dynamic extent of EXP is left."
> +  (call-with-store (lambda (store) exp ...) #:non-blocking? #t))

I think we’ll need an entry in ‘.dir-locals.el’ and one in (guix
read-print) for proper formatting.

OK for me with these changes!

Thanks,
Ludo’.




  reply	other threads:[~2024-05-13 13:20 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-11-17 18:05 [bug#67245] [PATCH] store: Use a non-blocking socket for store connections Christopher Baines
2023-11-26 22:16 ` Ludovic Courtès
2023-11-27  9:48   ` Christopher Baines
2023-11-30 21:11     ` Ludovic Courtès
2024-05-12 17:38       ` Christopher Baines
2024-05-11 16:53 ` [bug#67245] [PATCH v2] store: Add with-store/non-blocking Christopher Baines
2024-05-13 12:44   ` Ludovic Courtès [this message]
2024-05-13 19:32     ` bug#67245: " Christopher Baines

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