Horton

Re: Small memory fixes for pg_createsubcriber

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Dagfinn Ilmari Mannsåker <ilmari@ilmari.org>
Cc: Andres Freund <andres@anarazel.de>, Euler Taveira <euler@eulerto.com>, "ranier.vf@gmail.com" <ranier.vf@gmail.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2025-02-12T17:38:21Z
Lists: pgsql-hackers 
=?utf-8?Q?Dagfinn_Ilmari_Manns=C3=A5ker?= <ilmari@ilmari.org> writes:
> Tom Lane <tgl@sss.pgh.pa.us> writes:
>> libpq-fe.h has to be compilable by application code that has never
>> heard of pg_config.h let alone c.h, so we'd have to tread carefully
>> about not breaking that property.  But it seems like this would be
>> worth looking into.

> The fallback code isn't exactly complicated, so we could just duplicate
> it in libpq-fe.h:

> #ifndef __has_attribute
> #define __has_attribute(attribute) 0
> #endif

The problem with that approach is the likelihood of stomping on
symbols that a calling application will use later.  I think we
really need a controlling #ifdef check on some PG_FOO symbol
that we can be sure no outside application will have defined.
Roughly speaking,

#ifdef PG_USE_ALLOCATOR_CHECKS
#define pg_attribute_malloc __attribute__((malloc))
...
#else
#define pg_attribute_malloc
...
#endif

and then we could make definition of PG_USE_ALLOCATOR_CHECKS
be conditional on having the right compiler behavior, rather
than trusting that a nest of #ifdef checks is sufficient to
detect that.

			regards, tom lane

Commits

  1. pg_upgrade: Fix inconsistency in memory freeing

  2. pg_amcheck: Fix inconsistency in memory freeing

  3. Fix some inconsistencies with memory freeing in pg_createsubscriber

  4. Drop pre-existing subscriptions from the converted subscriber.