From: Tom Lane <tgl@sss.pgh.pa.us>
To: Justin Pryzby <pryzby@telsasoft.com>
cc: pgsql-hackers@postgresql.org, Fabien COELHO <coelho@cri.ensmp.fr>,
        Alvaro Herrera <alvherre@2ndquadrant.com>,
        David Steele <david@pgmasters.net>,
        "Bossart,
    Nathan" <bossartn@amazon.com>,
        Thomas Munro <thomas.munro@gmail.com>
Subject: Re: pg11+: pg_ls_*dir LIMIT 1: temporary files .. not closed at
 end-of-transaction
In-reply-to: <5679.1583696409@sss.pgh.pa.us>
References: <20200308173103.GC1357@telsasoft.com>
 <27334.1583692669@sss.pgh.pa.us> <20200308191456.GD1357@telsasoft.com>
 <5679.1583696409@sss.pgh.pa.us>
Comments: In-reply-to Tom Lane <tgl@sss.pgh.pa.us>
	message dated "Sun, 08 Mar 2020 15:40:09 -0400"
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Date: Sun, 08 Mar 2020 16:30:44 -0400
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I wrote:
> I've just finished scanning the source code and concluding that all
> of these functions are similarly broken:
> pg_ls_dir
> pg_ls_dir_files
> pg_tablespace_databases
> pg_logdir_ls_internal
> pg_timezone_names
> pgrowlocks

BTW, another thing I noticed while looking around is that some of
the functions using SRF_RETURN_DONE() think they should clean up
memory beforehand.  This is a waste of code/cycles, as long as the
memory was properly allocated in funcctx->multi_call_memory_ctx,
because funcapi.c takes care of deleting that context.

We should probably document that *any* manual cleanup before
SRF_RETURN_DONE() is an antipattern.  If you have to have cleanup,
it needs to be done via RegisterExprContextCallback instead.

			regards, tom lane