Add test module injection_points

This provides basic coverage for injection points within a single
process, while providing some callbacks that can be used for other
tests.  There are plans to extend this module later with more
advanced capabilities for tests.

Author: Michael Paquier, with comment fixes 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

src/test/modules/Makefile

@@ -38,6 +38,13 @@ SUBDIRS = \
 		  worker_spi \
 		  xid_wraparound
 
+
+ifeq ($(enable_injection_points),yes)
+SUBDIRS += injection_points
+else
+ALWAYS_SUBDIRS += injection_points
+endif
+
 ifeq ($(with_ssl),openssl)
 SUBDIRS += ssl_passphrase_callback
 else

src/test/modules/injection_points/.gitignore

@@ -0,0 +1,4 @@
+# Generated subdirectories
+/log/
+/results/
+/tmp_check/

src/test/modules/injection_points/Makefile

@@ -0,0 +1,20 @@
+# src/test/modules/injection_points/Makefile
+
+MODULES = injection_points
+
+EXTENSION = injection_points
+DATA = injection_points--1.0.sql
+PGFILEDESC = "injection_points - facility for injection points"
+
+REGRESS = injection_points
+
+ifdef USE_PGXS
+PG_CONFIG = pg_config
+PGXS := $(shell $(PG_CONFIG) --pgxs)
+include $(PGXS)
+else
+subdir = src/test/modules/injection_points
+top_builddir = ../../../..
+include $(top_builddir)/src/Makefile.global
+include $(top_srcdir)/contrib/contrib-global.mk
+endif

src/test/modules/injection_points/expected/injection_points.out

@@ -0,0 +1,118 @@
+CREATE EXTENSION injection_points;
+SELECT injection_points_attach('TestInjectionBooh', 'booh');
+ERROR:  incorrect action "booh" for injection point creation
+SELECT injection_points_attach('TestInjectionError', 'error');
+ injection_points_attach 
+-------------------------
+ 
+(1 row)
+
+SELECT injection_points_attach('TestInjectionLog', 'notice');
+ injection_points_attach 
+-------------------------
+ 
+(1 row)
+
+SELECT injection_points_attach('TestInjectionLog2', 'notice');
+ injection_points_attach 
+-------------------------
+ 
+(1 row)
+
+SELECT injection_points_run('TestInjectionBooh'); -- nothing
+ injection_points_run 
+----------------------
+ 
+(1 row)
+
+SELECT injection_points_run('TestInjectionLog2'); -- notice
+NOTICE:  notice triggered for injection point TestInjectionLog2
+ injection_points_run 
+----------------------
+ 
+(1 row)
+
+SELECT injection_points_run('TestInjectionLog'); -- notice
+NOTICE:  notice triggered for injection point TestInjectionLog
+ injection_points_run 
+----------------------
+ 
+(1 row)
+
+SELECT injection_points_run('TestInjectionError'); -- error
+ERROR:  error triggered for injection point TestInjectionError
+-- Re-load cache and run again.
+\c
+SELECT injection_points_run('TestInjectionLog2'); -- notice
+NOTICE:  notice triggered for injection point TestInjectionLog2
+ injection_points_run 
+----------------------
+ 
+(1 row)
+
+SELECT injection_points_run('TestInjectionLog'); -- notice
+NOTICE:  notice triggered for injection point TestInjectionLog
+ injection_points_run 
+----------------------
+ 
+(1 row)
+
+SELECT injection_points_run('TestInjectionError'); -- error
+ERROR:  error triggered for injection point TestInjectionError
+-- Remove one entry and check the remaining entries.
+SELECT injection_points_detach('TestInjectionError'); -- ok
+ injection_points_detach 
+-------------------------
+ 
+(1 row)
+
+SELECT injection_points_run('TestInjectionLog'); -- notice
+NOTICE:  notice triggered for injection point TestInjectionLog
+ injection_points_run 
+----------------------
+ 
+(1 row)
+
+SELECT injection_points_run('TestInjectionError'); -- nothing
+ injection_points_run 
+----------------------
+ 
+(1 row)
+
+-- More entries removed, letting TestInjectionLog2 to check the same
+-- callback used in more than one point.
+SELECT injection_points_detach('TestInjectionLog'); -- ok
+ injection_points_detach 
+-------------------------
+ 
+(1 row)
+
+SELECT injection_points_run('TestInjectionLog'); -- nothing
+ injection_points_run 
+----------------------
+ 
+(1 row)
+
+SELECT injection_points_run('TestInjectionError'); -- nothing
+ injection_points_run 
+----------------------
+ 
+(1 row)
+
+SELECT injection_points_run('TestInjectionLog2'); -- notice
+NOTICE:  notice triggered for injection point TestInjectionLog2
+ injection_points_run 
+----------------------
+ 
+(1 row)
+
+SELECT injection_points_detach('TestInjectionLog'); -- fails
+ERROR:  injection point "TestInjectionLog" not found
+SELECT injection_points_run('TestInjectionLog2'); -- notice
+NOTICE:  notice triggered for injection point TestInjectionLog2
+ injection_points_run 
+----------------------
+ 
+(1 row)
+
+DROP EXTENSION injection_points;

src/test/modules/injection_points/injection_points--1.0.sql

@@ -0,0 +1,35 @@
+/* src/test/modules/injection_points/injection_points--1.0.sql */
+
+-- complain if script is sourced in psql, rather than via CREATE EXTENSION
+\echo Use "CREATE EXTENSION injection_points" to load this file. \quit
+
+--
+-- injection_points_attach()
+--
+-- Attaches the action to the given injection point.
+--
+CREATE FUNCTION injection_points_attach(IN point_name TEXT,
+    IN action text)
+RETURNS void
+AS 'MODULE_PATHNAME', 'injection_points_attach'
+LANGUAGE C STRICT PARALLEL UNSAFE;
+
+--
+-- injection_points_run()
+--
+-- Executes the action attached to the injection point.
+--
+CREATE FUNCTION injection_points_run(IN point_name TEXT)
+RETURNS void
+AS 'MODULE_PATHNAME', 'injection_points_run'
+LANGUAGE C STRICT PARALLEL UNSAFE;
+
+--
+-- injection_points_detach()
+--
+-- Detaches the current action, if any, from the given injection point.
+--
+CREATE FUNCTION injection_points_detach(IN point_name TEXT)
+RETURNS void
+AS 'MODULE_PATHNAME', 'injection_points_detach'
+LANGUAGE C STRICT PARALLEL UNSAFE;

src/test/modules/injection_points/injection_points.c

@@ -0,0 +1,95 @@
+/*--------------------------------------------------------------------------
+ *
+ * injection_points.c
+ *		Code for testing injection points.
+ *
+ * Injection points are able to trigger user-defined callbacks in pre-defined
+ * code paths.
+ *
+ * Portions Copyright (c) 1996-2024, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * IDENTIFICATION
+ *		src/test/modules/injection_points/injection_points.c
+ *
+ * -------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include "fmgr.h"
+#include "storage/lwlock.h"
+#include "storage/shmem.h"
+#include "utils/builtins.h"
+#include "utils/injection_point.h"
+#include "utils/wait_event.h"
+
+PG_MODULE_MAGIC;
+
+extern PGDLLEXPORT void injection_error(const char *name);
+extern PGDLLEXPORT void injection_notice(const char *name);
+
+
+/* Set of callbacks available to be attached to an injection point. */
+void
+injection_error(const char *name)
+{
+	elog(ERROR, "error triggered for injection point %s", name);
+}
+
+void
+injection_notice(const char *name)
+{
+	elog(NOTICE, "notice triggered for injection point %s", name);
+}
+
+/*
+ * SQL function for creating an injection point.
+ */
+PG_FUNCTION_INFO_V1(injection_points_attach);
+Datum
+injection_points_attach(PG_FUNCTION_ARGS)
+{
+	char	   *name = text_to_cstring(PG_GETARG_TEXT_PP(0));
+	char	   *action = text_to_cstring(PG_GETARG_TEXT_PP(1));
+	char	   *function;
+
+	if (strcmp(action, "error") == 0)
+		function = "injection_error";
+	else if (strcmp(action, "notice") == 0)
+		function = "injection_notice";
+	else
+		elog(ERROR, "incorrect action \"%s\" for injection point creation", action);
+
+	InjectionPointAttach(name, "injection_points", function);
+
+	PG_RETURN_VOID();
+}
+
+/*
+ * SQL function for triggering an injection point.
+ */
+PG_FUNCTION_INFO_V1(injection_points_run);
+Datum
+injection_points_run(PG_FUNCTION_ARGS)
+{
+	char	   *name = text_to_cstring(PG_GETARG_TEXT_PP(0));
+
+	INJECTION_POINT(name);
+
+	PG_RETURN_VOID();
+}
+
+/*
+ * SQL function for dropping an injection point.
+ */
+PG_FUNCTION_INFO_V1(injection_points_detach);
+Datum
+injection_points_detach(PG_FUNCTION_ARGS)
+{
+	char	   *name = text_to_cstring(PG_GETARG_TEXT_PP(0));
+
+	InjectionPointDetach(name);
+
+	PG_RETURN_VOID();
+}

src/test/modules/injection_points/injection_points.control

@@ -0,0 +1,4 @@
+comment = 'Test code for injection points'
+default_version = '1.0'
+module_pathname = '$libdir/injection_points'
+relocatable = true

src/test/modules/injection_points/meson.build

@@ -0,0 +1,37 @@
+# Copyright (c) 2022-2024, PostgreSQL Global Development Group
+
+if not get_option('injection_points')
+  subdir_done()
+endif
+
+injection_points_sources = files(
+  'injection_points.c',
+)
+
+if host_system == 'windows'
+  injection_points_sources += rc_lib_gen.process(win32ver_rc, extra_args: [
+    '--NAME', 'injection_points',
+    '--FILEDESC', 'injection_points - facility for injection points',])
+endif
+
+injection_points = shared_module('injection_points',
+  injection_points_sources,
+  kwargs: pg_test_mod_args,
+)
+test_install_libs += injection_points
+
+test_install_data += files(
+  'injection_points.control',
+  'injection_points--1.0.sql',
+)
+
+tests += {
+  'name': 'injection_points',
+  'sd': meson.current_source_dir(),
+  'bd': meson.current_build_dir(),
+  'regress': {
+    'sql': [
+      'injection_points',
+    ],
+  },
+}

src/test/modules/injection_points/sql/injection_points.sql

@@ -0,0 +1,34 @@
+CREATE EXTENSION injection_points;
+
+SELECT injection_points_attach('TestInjectionBooh', 'booh');
+SELECT injection_points_attach('TestInjectionError', 'error');
+SELECT injection_points_attach('TestInjectionLog', 'notice');
+SELECT injection_points_attach('TestInjectionLog2', 'notice');
+
+SELECT injection_points_run('TestInjectionBooh'); -- nothing
+SELECT injection_points_run('TestInjectionLog2'); -- notice
+SELECT injection_points_run('TestInjectionLog'); -- notice
+SELECT injection_points_run('TestInjectionError'); -- error
+
+-- Re-load cache and run again.
+\c
+SELECT injection_points_run('TestInjectionLog2'); -- notice
+SELECT injection_points_run('TestInjectionLog'); -- notice
+SELECT injection_points_run('TestInjectionError'); -- error
+
+-- Remove one entry and check the remaining entries.
+SELECT injection_points_detach('TestInjectionError'); -- ok
+SELECT injection_points_run('TestInjectionLog'); -- notice
+SELECT injection_points_run('TestInjectionError'); -- nothing
+-- More entries removed, letting TestInjectionLog2 to check the same
+-- callback used in more than one point.
+SELECT injection_points_detach('TestInjectionLog'); -- ok
+SELECT injection_points_run('TestInjectionLog'); -- nothing
+SELECT injection_points_run('TestInjectionError'); -- nothing
+SELECT injection_points_run('TestInjectionLog2'); -- notice
+
+SELECT injection_points_detach('TestInjectionLog'); -- fails
+
+SELECT injection_points_run('TestInjectionLog2'); -- notice
+
+DROP EXTENSION injection_points;

src/test/modules/meson.build

@@ -5,6 +5,7 @@ subdir('commit_ts')
 subdir('delay_execution')
 subdir('dummy_index_am')
 subdir('dummy_seclabel')
+subdir('injection_points')
 subdir('ldap_password_func')
 subdir('libpq_pipeline')
 subdir('plsample')