Re: LISTEN/NOTIFY enhancement: Portable signal handling?

From: Sean Chittenden <sean(at)chittenden(dot)org>
To: "Merlin Moncure" <merlin(dot)moncure(at)rcsonline(dot)com>
Cc: "PostgreSQL-development" <pgsql-hackers(at)postgresql(dot)org>, "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Subject: Re: LISTEN/NOTIFY enhancement: Portable signal handling?
Date: 2004-12-27 19:07:23
Message-ID: 8A7EF364-583A-11D9-A9FF-000A95C705DC@chittenden.org
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>> NOTIFY 'relname' a_expr;
> This would be great to have...at least I think this is what you are
> driving at: (adding a noiseword for readability)
>
> LISTEN system_messages;
> NOTIFY system_messages MESSAGE logoff;
> NOTIFY request_unlock MESSAGE 12345; <-- for use with user locks!

Hrm... the userlock module may work for what I'm after, but the module
is GPL'ed, which is something I don't want to rely on. I wanted to
have a backend process essentially act as a long running client that
would act on notify messages to dispatch work. I was hoping to
accomplish something like, "LISTEN REGISTER event_name; LISTEN * BLOCK
WITH TIMEOUT = 30;" which would only listen to events that you've
registered to listen to, but would only deliver messages when you
explicitly were going to block waiting for message delivery (ie, LISTEN
BLOCK). I'll settle for getting just message passing via NOTIFY/LISTEN
to work and will revisit extending things further once I have this bit
done. -sc

--
Sean Chittenden

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