To: Igor Shevchenko <igor@carcass.ath.cx>
Cc: pgsql-interfaces@postgresql.org
Subject: Re: libpq/async notifications 
In-reply-to: <200310141946.07374.igor@carcass.ath.cx> 
References: <200310111220.25923.igor@carcass.ath.cx>
	<9884.1066147821@sss.pgh.pa.us>
	<200310141946.07374.igor@carcass.ath.cx>
Comments: In-reply-to Igor Shevchenko <igor@carcass.ath.cx>
	message dated "Tue, 14 Oct 2003 19:46:07 +0300"
Date: Tue, 14 Oct 2003 13:18:29 -0400
Message-ID: <10861.1066151909@sss.pgh.pa.us>
From: Tom Lane <tgl@sss.pgh.pa.us>

Igor Shevchenko <igor@carcass.ath.cx> writes:
> The idea behind this checking function is to separate the *checking* if 
> there's any notifications and actually *processing* them. I want to check 
> right after any transaction or any PQ* function which calls PQconsumeInput 
> and process notifications only once, after my app had returned to it's main 
> loop (I'm talking about GUI apps here). In Qt, for example, this is done by 
> creating a new QEvent and dispatching it via QApplication::postEvent(...), 
> which is quite an overhead; with just PQnotifies I have to do this all the 
> time.

How so?  Seems to me the check operation could read

	notify = PQnotifies(...);
	if (notify)
	{
		make QEvent, put notify pointer in it, dispatch
	}

The event handler then fetches the notify pointer from the QEvent
(and eventually frees it).

			regards, tom lane