0001-Introduce-runtime-conditions-in-module-injection_poi.patch

From 5f00092a0bd193f70d9daff77caacfc2ba83ca52 Mon Sep 17 00:00:00 2001
From: Michael Paquier <michael@paquier.xyz>
Date: Fri, 15 Mar 2024 16:03:05 +0900
Subject: [PATCH 1/2] Introduce runtime conditions in module injection_points

This adds a new SQL function injection_points_condition() that can be
used to register a runtime condition to an injection point, declared or
not.  For now, it is possible to register a database name to make an
injection point run only on a defined database.
---
 .../expected/injection_points.out             |  54 ++++++++
 .../injection_points--1.0.sql                 |  13 ++
 .../injection_points/injection_points.c       | 131 ++++++++++++++++++
 .../injection_points/sql/injection_points.sql |  14 ++
 4 files changed, 212 insertions(+)

diff --git a/src/test/modules/injection_points/expected/injection_points.out b/src/test/modules/injection_points/expected/injection_points.out
index 827456ccc5..ccb83b291f 100644
--- a/src/test/modules/injection_points/expected/injection_points.out
+++ b/src/test/modules/injection_points/expected/injection_points.out
@@ -115,4 +115,58 @@ NOTICE:  notice triggered for injection point TestInjectionLog2
  
 (1 row)
 
+SELECT injection_points_detach('TestInjectionLog2');
+ injection_points_detach 
+-------------------------
+ 
+(1 row)
+
+-- Conditions
+SELECT current_database() AS datname \gset
+-- Register injection point to run on database 'postgres'.
+SELECT injection_points_attach('TestConditionError', 'error');
+ injection_points_attach 
+-------------------------
+ 
+(1 row)
+
+SELECT injection_points_condition('TestConditionError', 'postgres');
+ injection_points_condition 
+----------------------------
+ 
+(1 row)
+
+SELECT injection_points_run('TestConditionError'); -- nothing
+ injection_points_run 
+----------------------
+ 
+(1 row)
+
+SELECT injection_points_detach('TestConditionError');
+ injection_points_detach 
+-------------------------
+ 
+(1 row)
+
+-- Register injection point to run on current database
+SELECT injection_points_attach('TestConditionError', 'error');
+ injection_points_attach 
+-------------------------
+ 
+(1 row)
+
+SELECT injection_points_condition('TestConditionError', :'datname');
+ injection_points_condition 
+----------------------------
+ 
+(1 row)
+
+SELECT injection_points_run('TestConditionError'); -- error
+ERROR:  error triggered for injection point TestConditionError
+SELECT injection_points_detach('TestConditionError');
+ injection_points_detach 
+-------------------------
+ 
+(1 row)
+
 DROP EXTENSION injection_points;
diff --git a/src/test/modules/injection_points/injection_points--1.0.sql b/src/test/modules/injection_points/injection_points--1.0.sql
index 0a2e59aba7..b707f23dad 100644
--- a/src/test/modules/injection_points/injection_points--1.0.sql
+++ b/src/test/modules/injection_points/injection_points--1.0.sql
@@ -34,6 +34,19 @@ RETURNS void
 AS 'MODULE_PATHNAME', 'injection_points_wakeup'
 LANGUAGE C STRICT PARALLEL UNSAFE;
 
+--
+-- injection_points_condition()
+--
+-- Register a runtime condition associated to an injection point.
+--
+-- dbname can be specified to restrict an injection point to run on a
+-- wanted database.
+--
+CREATE FUNCTION injection_points_condition(IN point_name TEXT, IN dbname text)
+RETURNS void
+AS 'MODULE_PATHNAME', 'injection_points_condition'
+LANGUAGE C STRICT PARALLEL UNSAFE;
+
 --
 -- injection_points_detach()
 --
diff --git a/src/test/modules/injection_points/injection_points.c b/src/test/modules/injection_points/injection_points.c
index 0730254d54..ce9317f0ee 100644
--- a/src/test/modules/injection_points/injection_points.c
+++ b/src/test/modules/injection_points/injection_points.c
@@ -17,7 +17,9 @@
 
 #include "postgres.h"
 
+#include "commands/dbcommands.h"
 #include "fmgr.h"
+#include "miscadmin.h"
 #include "storage/condition_variable.h"
 #include "storage/dsm_registry.h"
 #include "storage/lwlock.h"
@@ -31,6 +33,23 @@ PG_MODULE_MAGIC;
 /* Maximum number of waits usable in injection points at once */
 #define INJ_MAX_WAIT	8
 #define INJ_NAME_MAXLEN	64
+#define	INJ_MAX_CONDITION	8
+
+/*
+ * Conditions related to injection points.  This tracks in shared memory the
+ * some runtime conditions under which an injection point is allowed to run.
+ *
+ * If more types of runtime conditions need to be tracked, this structure
+ * should be expanded.
+ */
+typedef struct InjectionPointCondition
+{
+	/* Name of the injection point related to its  */
+	char	name[INJ_NAME_MAXLEN];
+
+	/* Oid of the database where the injection point is allowed to run */
+	Oid		dboid;
+} InjectionPointCondition;
 
 /* Shared state information for injection points. */
 typedef struct InjectionPointSharedState
@@ -44,6 +63,9 @@ typedef struct InjectionPointSharedState
 	/* Names of injection points attached to wait counters */
 	char		name[INJ_MAX_WAIT][INJ_NAME_MAXLEN];
 
+	/* Condition to run an injection point */
+	InjectionPointCondition	condition[INJ_MAX_CONDITION];
+
 	/* Condition variable used for waits and wakeups */
 	ConditionVariable wait_point;
 } InjectionPointSharedState;
@@ -67,6 +89,7 @@ injection_point_init_state(void *ptr)
 	SpinLockInit(&state->lock);
 	memset(state->wait_counts, 0, sizeof(state->wait_counts));
 	memset(state->name, 0, sizeof(state->name));
+	memset(state->condition, 0, sizeof(state->condition));
 	ConditionVariableInit(&state->wait_point);
 }
 
@@ -87,16 +110,62 @@ injection_init_shmem(void)
 								   &found);
 }
 
+/*
+ * Check runtime conditions associated to an injection point.
+ *
+ * Returns true if the named injection point is allowed to run, and false
+ * otherwise.  Multiple conditions can be associated to a single injection
+ * point, so check them all.
+ */
+static bool
+injection_point_allowed(const char *name)
+{
+	bool	result = true;
+
+	if (inj_state == NULL)
+		injection_init_shmem();
+
+	SpinLockAcquire(&inj_state->lock);
+
+	for (int i = 0; i < INJ_MAX_CONDITION; i++)
+	{
+		InjectionPointCondition	*condition = &inj_state->condition[i];
+
+		if (strcmp(condition->name, name) == 0)
+		{
+			/*
+			 * Check that if the database matches with what's used in this
+			 * backend.
+			 */
+			if (MyDatabaseId != condition->dboid)
+			{
+				result = false;
+				break;
+			}
+		}
+	}
+
+	SpinLockRelease(&inj_state->lock);
+
+	return result;
+}
+
 /* Set of callbacks available to be attached to an injection point. */
 void
 injection_error(const char *name)
 {
+	if (!injection_point_allowed(name))
+		return;
+
 	elog(ERROR, "error triggered for injection point %s", name);
 }
 
 void
 injection_notice(const char *name)
 {
+	if (!injection_point_allowed(name))
+		return;
+
 	elog(NOTICE, "notice triggered for injection point %s", name);
 }
 
@@ -111,6 +180,9 @@ injection_wait(const char *name)
 	if (inj_state == NULL)
 		injection_init_shmem();
 
+	if (!injection_point_allowed(name))
+		return;
+
 	/*
 	 * Use the injection point name for this custom wait event.  Note that
 	 * this custom wait event name is not released, but we don't care much for
@@ -235,6 +307,48 @@ injection_points_wakeup(PG_FUNCTION_ARGS)
 	PG_RETURN_VOID();
 }
 
+/*
+ * injection_points_condition
+ *
+ * Register a runtime condition associated to an injection point.  Currently,
+ * it is possible to define a database name where an injection point can be
+ * restricted to run on.
+ */
+PG_FUNCTION_INFO_V1(injection_points_condition);
+Datum
+injection_points_condition(PG_FUNCTION_ARGS)
+{
+	char	   *name = text_to_cstring(PG_GETARG_TEXT_PP(0));
+	char	   *dbname = text_to_cstring(PG_GETARG_TEXT_PP(1));
+	Oid			dboid = get_database_oid(dbname, false);
+	int			index = -1;
+
+	if (inj_state == NULL)
+		injection_init_shmem();
+
+	SpinLockAcquire(&inj_state->lock);
+
+	for (int i = 0; i < INJ_MAX_CONDITION; i++)
+	{
+		InjectionPointCondition	*condition = &inj_state->condition[i];
+
+		if (condition->name[0] == '\0')
+		{
+			index = i;
+			strlcpy(condition->name, name, INJ_NAME_MAXLEN);
+			condition->dboid = dboid;
+			break;
+		}
+	}
+	SpinLockRelease(&inj_state->lock);
+
+	if (index < 0)
+		elog(ERROR, "could not find free slot for condition of injection point %s",
+			 name);
+
+	PG_RETURN_VOID();
+}
+
 /*
  * SQL function for dropping an injection point.
  */
@@ -246,5 +360,22 @@ injection_points_detach(PG_FUNCTION_ARGS)
 
 	InjectionPointDetach(name);
 
+	if (inj_state == NULL)
+		injection_init_shmem();
+
+	/* Clean up any conditions associated to this injection point */
+	SpinLockAcquire(&inj_state->lock);
+	for (int i = 0; i < INJ_MAX_CONDITION; i++)
+	{
+		InjectionPointCondition	*condition = &inj_state->condition[i];
+
+		if (strcmp(condition->name, name) == 0)
+		{
+			condition->dboid = InvalidOid;
+			condition->name[0] = '\0';
+		}
+	}
+	SpinLockRelease(&inj_state->lock);
+
 	PG_RETURN_VOID();
 }
diff --git a/src/test/modules/injection_points/sql/injection_points.sql b/src/test/modules/injection_points/sql/injection_points.sql
index 23c7e435ad..1b52e7e6d7 100644
--- a/src/test/modules/injection_points/sql/injection_points.sql
+++ b/src/test/modules/injection_points/sql/injection_points.sql
@@ -30,5 +30,19 @@ SELECT injection_points_run('TestInjectionLog2'); -- notice
 SELECT injection_points_detach('TestInjectionLog'); -- fails
 
 SELECT injection_points_run('TestInjectionLog2'); -- notice
+SELECT injection_points_detach('TestInjectionLog2');
+
+-- Conditions
+SELECT current_database() AS datname \gset
+-- Register injection point to run on database 'postgres'.
+SELECT injection_points_attach('TestConditionError', 'error');
+SELECT injection_points_condition('TestConditionError', 'postgres');
+SELECT injection_points_run('TestConditionError'); -- nothing
+SELECT injection_points_detach('TestConditionError');
+-- Register injection point to run on current database
+SELECT injection_points_attach('TestConditionError', 'error');
+SELECT injection_points_condition('TestConditionError', :'datname');
+SELECT injection_points_run('TestConditionError'); -- error
+SELECT injection_points_detach('TestConditionError');
 
 DROP EXTENSION injection_points;
-- 
2.43.0