From: Corinna Vinschen <corinna-cygwin@cygwin.com>
To: cygwin-developers@cygwin.com
Subject: Re: The unreliability of AF_UNIX datagram sockets
Date: Mon, 3 May 2021 20:40:03 +0200 [thread overview]
Message-ID: <YJBDg7uwWi0abDJh@calimero.vinschen.de> (raw)
In-Reply-To: <5564e10e-9099-fc5a-3a8d-c2ffb8ca4cff@cornell.edu>
On May 3 12:56, Ken Brown wrote:
> On 5/3/2021 11:45 AM, Corinna Vinschen wrote:
> > 7. The idea of _mq_recv partial reads is entirely broken. Given that
> > the information in the queue consists of header info plus payload,
> > the entire block has to be read, and then a new block with fixed
> > header and shortened payload has to be rewritten with bumped priority.
> > This in turn can only be performed by the AF_UNIX code, unless we
> > expect knowledge of the AF_UNIX packet layout in the mqueue code.
>
> The partial read is actually OK as is, since it's comparable to what happens
> on a partial read from a pipe. I already have AF_UNIX code (on the
> topic/af_unix branch) that deals with that. A boolean variable _unread
> keeps track of whether there's unread data from a previous partial read. If
> so, the next read just reads data without expecting a header.
Ok, never mind.
One advantage of the mqueue when utilized as above would be that this
kind of state info is not required. The content of a packet would
always be self-contained and bumping the priority would automagically
move the packet content to the top of the queue. But that's just
idle musing at this point.
Corinna
next prev parent reply other threads:[~2021-05-03 18:40 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-27 15:47 Ken Brown
2021-04-29 11:05 ` Corinna Vinschen
2021-04-29 11:16 ` Corinna Vinschen
2021-04-29 14:38 ` Ken Brown
2021-04-29 15:05 ` Corinna Vinschen
2021-04-29 15:18 ` Corinna Vinschen
2021-04-29 16:44 ` Ken Brown
2021-04-29 17:39 ` Corinna Vinschen
2021-05-01 21:41 ` Ken Brown
2021-05-03 10:30 ` Corinna Vinschen
2021-05-03 15:45 ` Corinna Vinschen
2021-05-03 16:56 ` Ken Brown
2021-05-03 18:40 ` Corinna Vinschen [this message]
2021-05-03 19:48 ` Ken Brown
2021-05-03 20:50 ` Ken Brown
2021-05-04 11:06 ` Corinna Vinschen
2021-05-13 14:30 ` Ken Brown
2021-05-17 10:26 ` Corinna Vinschen
2021-05-17 13:02 ` Ken Brown
2021-05-17 13:02 ` Ken Brown
2021-05-20 13:46 ` Ken Brown
2021-05-20 19:25 ` Corinna Vinschen
2021-05-21 21:54 ` Ken Brown
2021-05-22 15:49 ` Corinna Vinschen
2021-05-22 16:50 ` Ken Brown
2021-05-22 18:21 ` Ken Brown
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