Date: Mon, 6 May 2019 14:21:34 -0400
From: Alvaro Herrera <alvherre@2ndquadrant.com>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Antonin Houska <ah@cybertec.at>,
	"pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Subject: Re: Attempt to consolidate reading of XLOG page
Message-ID: <20190506182134.GA592@alvherre.pgsql>
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On 2019-May-06, Robert Haas wrote:

> On Thu, May 2, 2019 at 12:18 PM Antonin Houska <ah@cybertec.at> wrote:
> > The next version of the patch is attached.
> 
> I don't think any of this looks acceptable:

I agree.  I inteded to suggest upthread to pass an additional argument
to XLogRead, which is a function that takes a message string and
SQLSTATE; in backend, the function does errstart / errstate / errmsg /
errfinish, and in frontend programs it does pg_log_fatal (and ignores
sqlstate).  The message must be sprintf'ed and translated by XLogRead.
(xlogreader.c could itself provide a default error reporting callback,
at least for frontend, to avoid repeating the code).  That way, if a
different frontend program wants to do something different, it's fairly
easy to pass a different function pointer.

BTW, having frontend's XLogFileNameCommon use a totally unrelated
variable for its printing is naughty.

-- 
Álvaro Herrera                https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services