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Thomas Munro 0da096d78e Fix recovery conflict SIGUSR1 handling.
We shouldn't be doing non-trivial work in signal handlers in general,
and in this case the handler could reach unsafe code and corrupt state.
It also clobbered its own "reason" code.

Move all recovery conflict decision logic into the next
CHECK_FOR_INTERRUPTS(), and have the signal handler just set flags and
the latch, following the standard pattern.  Since there are several
different "reasons", use a separate flag for each.

With this refactoring, the recovery conflict system no longer
piggy-backs on top of the regular query cancelation mechanism, but
instead raises an error directly if it decides that is necessary.  It
still needs to respect QueryCancelHoldoffCount, because otherwise the
FEBE protocol might get out of sync (see commit 2b3a8b20c2).

This fixes one class of intermittent failure in the new
031_recovery_conflict.pl test added by commit 9f8a050f, though the buggy
coding is much older.  Failures outside contrived testing seem to be
very rare (or perhaps incorrectly attributed) in the field, based on
lack of reports.

No back-patch for now due to complexity and release schedule.  We have
the option to back-patch into 16 later, as 16 has prerequisite commit
bea3d7e.

Reviewed-by: Andres Freund <andres@anarazel.de> (earlier version)
Reviewed-by: Michael Paquier <michael@paquier.xyz> (earlier version)
Reviewed-by: Robert Haas <robertmhaas@gmail.com> (earlier version)
Tested-by: Christoph Berg <myon@debian.org>
Discussion: https://postgr.es/m/CA%2BhUKGK3PGKwcKqzoosamn36YW-fsuTdOPPF1i_rtEO%3DnEYKSg%40mail.gmail.com
Discussion: https://postgr.es/m/CALj2ACVr8au2J_9D88UfRCi0JdWhyQDDxAcSVav0B0irx9nXEg%40mail.gmail.com
2023-09-07 12:39:24 +12:00
config Use native CRC instructions on 64-bit LoongArch 2023-08-10 11:36:15 +07:00
contrib Remove the "snapshot too old" feature. 2023-09-05 19:53:43 +12:00
doc Allow using syncfs() in frontend utilities. 2023-09-06 16:27:16 -07:00
src Fix recovery conflict SIGUSR1 handling. 2023-09-07 12:39:24 +12:00
.cirrus.star ci: Prepare to make compute resources for CI configurable 2023-08-23 15:15:28 -07:00
.cirrus.tasks.yml Use "template" data directory in tests 2023-08-24 14:38:02 -07:00
.cirrus.yml ci: Make compute resources for CI configurable 2023-08-23 15:15:28 -07:00
.dir-locals.el Make Emacs perl-mode indent more like perltidy. 2019-01-13 11:32:31 -08:00
.editorconfig Add .editorconfig 2019-12-18 09:13:13 +01:00
.git-blame-ignore-revs Add bc6041b61f to .git-blame-ignore-revs. 2023-08-30 16:06:12 +09:00
.gitattributes gitattributes: Ignore imported pg_bsd_indent code for whitespace checks 2023-02-22 09:00:28 +01:00
.gitignore Update top-level .gitignore. 2022-12-04 15:23:00 -05:00
aclocal.m4 autoconf: Move export_dynamic determination to configure 2022-12-06 18:55:28 -08:00
configure Remove traces of Sun -lposix4. 2023-08-17 16:16:43 +12:00
configure.ac Remove traces of Sun -lposix4. 2023-08-17 16:16:43 +12:00
COPYRIGHT Update copyright for 2023 2023-01-02 15:00:37 -05:00
GNUmakefile.in Integrate pg_bsd_indent into our build/test infrastructure. 2023-02-12 12:22:21 -05:00
HISTORY Canonicalize some URLs 2020-02-10 20:47:50 +01:00
Makefile Dynamically find correct installation docs in Makefile. 2022-01-19 14:48:25 +01:00
meson_options.txt meson: Attach colon to keyword argument 2023-06-29 12:53:41 +02:00
meson.build Generate a locale-agnostic initdb template 2023-08-29 18:06:55 +02:00
README Canonicalize some URLs 2020-02-10 20:47:50 +01:00
README.git Canonicalize some URLs 2020-02-10 20:47:50 +01:00

PostgreSQL Database Management System
=====================================

This directory contains the source code distribution of the PostgreSQL
database management system.

PostgreSQL is an advanced object-relational database management system
that supports an extended subset of the SQL standard, including
transactions, foreign keys, subqueries, triggers, user-defined types
and functions.  This distribution also contains C language bindings.

PostgreSQL has many language interfaces, many of which are listed here:

	https://www.postgresql.org/download/

See the file INSTALL for instructions on how to build and install
PostgreSQL.  That file also lists supported operating systems and
hardware platforms and contains information regarding any other
software packages that are required to build or run the PostgreSQL
system.  Copyright and license information can be found in the
file COPYRIGHT.  A comprehensive documentation set is included in this
distribution; it can be read as described in the installation
instructions.

The latest version of this software may be obtained at
https://www.postgresql.org/download/.  For more information look at our
web site located at https://www.postgresql.org/.