From: Michael Paquier <michael@paquier.xyz>
To: pgsql-committers@lists.postgresql.org
Subject: pgsql: Add backend support for injection points
Date: Mon, 22 Jan 2024 01:18:12 +0000
Message-ID: <E1rRix2-002Vp9-7J@gemulon.postgresql.org> (raw)
Add backend support for injection points
Injection points are a new facility that makes possible for developers
to run custom code in pre-defined code paths. Its goal is to provide
ways to design and run advanced tests, for cases like:
- Race conditions, where processes need to do actions in a controlled
ordered manner.
- Forcing a state, like an ERROR, FATAL or even PANIC for OOM, to force
recovery, etc.
- Arbitrary sleeps.
This implements some basics, and there are plans to extend it more in
the future depending on what's required. Hence, this commit adds a set
of routines in the backend that allows developers to attach, detach and
run injection points:
- A code path calling an injection point can be declared with the macro
INJECTION_POINT(name).
- InjectionPointAttach() and InjectionPointDetach() to respectively
attach and detach a callback to/from an injection point. An injection
point name is registered in a shmem hash table with a library name and a
function name, which will be used to load the callback attached to an
injection point when its code path is run.
Injection point names are just strings, so as an injection point can be
declared and run by out-of-core extensions and modules, with callbacks
defined in external libraries.
This facility is hidden behind a dedicated switch for ./configure and
meson, disabled by default.
Note that backends use a local cache to store callbacks already loaded,
cleaning up their cache if a callback has found to be removed on a
best-effort basis. This could be refined further but any tests but what
we have here was fine with the tests I've written while implementing
these backend APIs.
Author: Michael Paquier, with doc suggestions from Ashutosh Bapat.
Reviewed-by: Ashutosh Bapat, Nathan Bossart, Álvaro Herrera, Dilip
Kumar, Amul Sul, Nazir Bilal Yavuz
Discussion: https://postgr.es/m/ZTiV8tn_MIb_H2rE@paquier.xyz
Branch
------
master
Details
-------
https://git.postgresql.org/pg/commitdiff/d86d20f0ba79451f19782dbb5fbf206746aaffd1
Modified Files
--------------
configure | 34 +++
configure.ac | 7 +
doc/src/sgml/installation.sgml | 30 +++
doc/src/sgml/xfunc.sgml | 69 ++++++
meson.build | 1 +
meson_options.txt | 3 +
src/Makefile.global.in | 1 +
src/backend/storage/ipc/ipci.c | 3 +
src/backend/storage/lmgr/lwlocknames.txt | 1 +
src/backend/utils/activity/wait_event_names.txt | 1 +
src/backend/utils/misc/Makefile | 1 +
src/backend/utils/misc/injection_point.c | 317 ++++++++++++++++++++++++
src/backend/utils/misc/meson.build | 1 +
src/include/pg_config.h.in | 3 +
src/include/utils/injection_point.h | 37 +++
src/makefiles/meson.build | 1 +
src/tools/pgindent/typedefs.list | 2 +
17 files changed, 512 insertions(+)
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-committers@postgresql.org
Cc: michael@paquier.xyz, pgsql-committers@lists.postgresql.org
Subject: Re: pgsql: Add backend support for injection points
In-Reply-To: <E1rRix2-002Vp9-7J@gemulon.postgresql.org>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox