Support loading of injection points

This can be used to load an injection point and prewarm the
backend-level cache before running it, to avoid issues if the point
cannot be loaded due to restrictions in the code path where it would be
run, like a critical section where no memory allocation can happen
(load_external_function() can do allocations when expanding a library
name).

Tests can use a macro called INJECTION_POINT_LOAD() to load an injection
point.  The test module injection_points gains some tests, and a SQL
function able to load an injection point.

Based on a request from Andrey Borodin, who has implemented a test for
multixacts requiring this facility.

Reviewed-by: Andrey Borodin
Discussion: https://postgr.es/m/ZkrBE1e2q2wGvsoN@paquier.xyz

1 files changed, 7 insertions, 0 deletions

diff --git a/src/test/modules/injection_points/sql/injection_points.sql b/src/test/modules/injection_points/sql/injection_points.sql
index 71e2972a7e4..fabf0a8823b 100644
--- a/src/test/modules/injection_points/sql/injection_points.sql
+++ b/src/test/modules/injection_points/sql/injection_points.sql
@@ -41,6 +41,13 @@ SELECT injection_points_detach('TestInjectionLog'); -- fails
 SELECT injection_points_run('TestInjectionLog2'); -- notice
 SELECT injection_points_detach('TestInjectionLog2');
 
+-- Loading
+SELECT injection_points_load('TestInjectionLogLoad'); -- nothing
+SELECT injection_points_attach('TestInjectionLogLoad', 'notice');
+SELECT injection_points_load('TestInjectionLogLoad'); -- nothing happens
+SELECT injection_points_run('TestInjectionLogLoad'); -- runs from cache
+SELECT injection_points_detach('TestInjectionLogLoad');
+
 -- Runtime conditions
 SELECT injection_points_attach('TestConditionError', 'error');
 -- Any follow-up injection point attached will be local to this process.