postgresql/src
Michael Paquier d86d20f0ba 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
2024-01-22 10:15:50 +09:00
..
backend Add backend support for injection points 2024-01-22 10:15:50 +09:00
bin Rename COPY option from SAVE_ERROR_TO to ON_ERROR 2024-01-19 15:15:51 +02:00
common Cleanup for unicode-update build target and test. 2024-01-11 12:35:29 -08:00
fe_utils Update copyright for 2024 2024-01-03 20:49:05 -05:00
include Add backend support for injection points 2024-01-22 10:15:50 +09:00
interfaces Remove some comments related to pqPipelineSync() and PQsendPipelineSync() 2024-01-17 15:53:59 +09:00
makefiles Add backend support for injection points 2024-01-22 10:15:50 +09:00
pl Fix plpgsql to allow new-style SQL CREATE FUNCTION as a SQL command. 2024-01-18 16:11:16 -05:00
port Update copyright for 2024 2024-01-03 20:49:05 -05:00
template
test Fix table name collision in tests in 0452b461bc 2024-01-21 23:27:29 +02:00
timezone Update copyright for 2024 2024-01-03 20:49:05 -05:00
tools Add backend support for injection points 2024-01-22 10:15:50 +09:00
tutorial Update copyright for 2024 2024-01-03 20:49:05 -05:00
.gitignore
DEVELOPERS
Makefile Remove distprep 2023-11-06 15:18:04 +01:00
Makefile.global.in Add backend support for injection points 2024-01-22 10:15:50 +09:00
Makefile.shlib Stop using "-multiply_defined suppress" on macOS. 2023-09-26 21:06:21 -04:00
meson.build Update copyright for 2024 2024-01-03 20:49:05 -05:00
nls-global.mk Remove distprep 2023-11-06 15:18:04 +01:00