From: Jeff King <peff@peff.net>
To: Junio C Hamano <gitster@pobox.com>
Cc: Eric Sunshine <ericsunshine@gmail.com>,
Stefan Beller <sbeller@google.com>,
Git List <git@vger.kernel.org>,
Jonathan Nieder <jrnieder@gmail.com>,
Johannes Schindelin <johannes.schindelin@gmail.com>,
Jens Lehmann <Jens.Lehmann@web.de>, Johannes Sixt <j6t@kdbg.org>
Subject: Re: [PATCH 3/8] xread_nonblock: add functionality to read from fds without blocking
Date: Mon, 14 Dec 2015 18:57:37 -0500 [thread overview]
Message-ID: <20151214235736.GA26133@sigill.intra.peff.net> (raw)
In-Reply-To: <xmqqio40hbam.fsf@gitster.mtv.corp.google.com>
On Mon, Dec 14, 2015 at 03:15:29PM -0800, Junio C Hamano wrote:
> -- >8 --
> From: Stefan Beller <sbeller@google.com>
> Date: Mon, 14 Dec 2015 11:37:13 -0800
> Subject: [PATCH] xread_nonblock: add functionality to read from fds without blocking
>
> Provide a wrapper to read(), similar to xread(), that restarts on
> EINTR but not EAGAIN (or EWOULDBLOCK). This enables the caller to
> handle polling itself, possibly polling multiple sockets or performing
> some other action.
This makes me wonder why we restart xread() on EAGAIN in the first
place.
On EINTR, sure; signals can come and we want to keep going. But if do
not have non-blocking descriptors, it should never happen, right?
Are we trying to protect ourselves against somebody _else_ giving us a
non-blocking descriptor? In that case we'll quietly spin and waste CPU.
Which isn't great, but perhaps better than returning an error.
-Peff
next prev parent reply other threads:[~2015-12-14 23:57 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-12-14 19:37 [PATCH 0/8] Rerolling sb/submodule-parallel-fetch for the time after 2.7 Stefan Beller
2015-12-14 19:37 ` [PATCH 1/8] submodule.c: write "Fetching submodule <foo>" to stderr Stefan Beller
2015-12-14 19:37 ` [PATCH 2/8] xread: poll on non blocking fds Stefan Beller
2015-12-14 22:58 ` Eric Sunshine
2015-12-14 23:07 ` Stefan Beller
2015-12-14 23:11 ` Junio C Hamano
2015-12-14 23:14 ` Stefan Beller
2015-12-14 19:37 ` [PATCH 3/8] xread_nonblock: add functionality to read from fds without blocking Stefan Beller
2015-12-14 20:59 ` Junio C Hamano
2015-12-14 23:03 ` Eric Sunshine
2015-12-14 23:05 ` Eric Sunshine
2015-12-14 23:15 ` Junio C Hamano
2015-12-14 23:57 ` Jeff King [this message]
2015-12-15 0:09 ` Stefan Beller
2015-12-15 0:16 ` Jeff King
2015-12-15 0:25 ` Stefan Beller
2015-12-15 1:44 ` Jeff King
2015-12-15 6:12 ` Johannes Sixt
2015-12-15 1:40 ` Junio C Hamano
2015-12-14 19:37 ` [PATCH 4/8] strbuf: add strbuf_read_once to read " Stefan Beller
2015-12-14 23:16 ` Eric Sunshine
2015-12-14 23:27 ` Stefan Beller
2015-12-14 19:37 ` [PATCH 5/8] sigchain: add command to pop all common signals Stefan Beller
2015-12-14 19:37 ` [PATCH 6/8] run-command: add an asynchronous parallel child processor Stefan Beller
2015-12-14 20:39 ` Johannes Sixt
2015-12-14 21:40 ` Stefan Beller
2015-12-14 19:37 ` [PATCH 7/8] fetch_populated_submodules: use new parallel job processing Stefan Beller
2015-12-14 19:37 ` [PATCH 8/8] submodules: allow parallel fetching, add tests and documentation Stefan Beller
2015-12-14 20:40 ` [PATCH 0/8] Rerolling sb/submodule-parallel-fetch for the time after 2.7 Johannes Sixt
2015-12-14 21:00 ` Junio C Hamano
-- strict thread matches above, loose matches on Subject: below --
2015-09-28 23:13 [PATCH 0/8] fetch submodules in parallel Stefan Beller
2015-09-28 23:14 ` [PATCH 3/8] xread_nonblock: add functionality to read from fds without blocking Stefan Beller
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