Re: Multiplexing SUGUSR1

From: Markus Wanner <markus(at)bluegap(dot)ch>
To: Alvaro Herrera <alvherre(at)commandprompt(dot)com>
Cc: Dimitri Fontaine <dfontaine(at)hi-media(dot)com>, pgsql-hackers(at)postgresql(dot)org, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>, Fujii Masao <masao(dot)fujii(at)gmail(dot)com>
Subject: Re: Multiplexing SUGUSR1
Date: 2008-12-12 17:40:03
Message-ID: 4942A1F3.1040809@bluegap.ch
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Hi,

Alvaro Herrera wrote:
> No, the signalling needed here is far simpler than Markus' IMessage
> stuff.

Yup, see also Tom's comment [1].

For Postgres-R I'm currently multiplexing by embedding a message type in
the imessage data itself. So this part is certainly overlapping, yes.

Some of the messages I'm using do have additional payload data, others
don't. Moving this message type out of the "body" part of the message
itself and instead use the upcoming signal multiplexing could save a few
imessage types in favor of using these multiplexed signals. Most message
types require some additional data to be transferred, though.

From my point of view it's hard to understand why one should want to
move out exactly 32 or 64 bits (sig_atomic_t) of a message. From the
point of view of Postgres, it's certainly better than being bound to the
existing Unix signals.

Regards

Markus Wanner

[1]:
http://archives.postgresql.org/message-id/28487.1221147665@sss.pgh.pa.us

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