Add InjectionPointList() to retrieve list of injection points

This routine has come as a useful piece to be able to know the list of
injection points currently attached in a system.  One area would be to
use it in a set-returning function, or just let out-of-core code play
with it.

This hides the internals of the shared memory array lookup holding the
information about the injection points (point name, library and function
name), allocating the result in a palloc'd List consumable by the
caller.

Reviewed-by: Jeff Davis <[email protected]>
Reviewed-by: Hayato Kuroda <[email protected]>
Reviewed-by: Rahila Syed <[email protected]>
Discussion: https://postgr.es/m/[email protected]
Discussion: https://postgr.es/m/[email protected]

3 files changed, 63 insertions, 0 deletions

diff --git a/src/backend/utils/misc/injection_point.c b/src/backend/utils/misc/injection_point.c
index f58ebc8ee52..83b887b6978 100644
--- a/src/backend/utils/misc/injection_point.c
+++ b/src/backend/utils/misc/injection_point.c
@@ -584,3 +584,49 @@ IsInjectionPointAttached(const char *name)
 	return false;				/* silence compiler */
 #endif
 }
+
+/*
+ * Retrieve a list of all the injection points currently attached.
+ *
+ * This list is palloc'd in the current memory context.
+ */
+List *
+InjectionPointList(void)
+{
+#ifdef USE_INJECTION_POINTS
+	List	   *inj_points = NIL;
+	uint32		max_inuse;
+
+	LWLockAcquire(InjectionPointLock, LW_SHARED);
+
+	max_inuse = pg_atomic_read_u32(&ActiveInjectionPoints->max_inuse);
+
+	for (uint32 idx = 0; idx < max_inuse; idx++)
+	{
+		InjectionPointEntry *entry;
+		InjectionPointData *inj_point;
+		uint64		generation;
+
+		entry = &ActiveInjectionPoints->entries[idx];
+		generation = pg_atomic_read_u64(&entry->generation);
+
+		/* skip free slots */
+		if (generation % 2 == 0)
+			continue;
+
+		inj_point = (InjectionPointData *) palloc0(sizeof(InjectionPointData));
+		inj_point->name = pstrdup(entry->name);
+		inj_point->library = pstrdup(entry->library);
+		inj_point->function = pstrdup(entry->function);
+		inj_points = lappend(inj_points, inj_point);
+	}
+
+	LWLockRelease(InjectionPointLock);
+
+	return inj_points;
+
+#else
+	elog(ERROR, "Injection points are not supported by this build");
+	return NIL;					/* keep compiler quiet */
+#endif
+}
diff --git a/src/include/utils/injection_point.h b/src/include/utils/injection_point.h
index a37958e1835..fd5bc061b7b 100644
--- a/src/include/utils/injection_point.h
+++ b/src/include/utils/injection_point.h
@@ -11,6 +11,19 @@
 #ifndef INJECTION_POINT_H
 #define INJECTION_POINT_H
 
+#include "nodes/pg_list.h"
+
+/*
+ * Injection point data, used when retrieving a list of all the attached
+ * injection points.
+ */
+typedef struct InjectionPointData
+{
+	const char *name;
+	const char *library;
+	const char *function;
+} InjectionPointData;
+
 /*
  * Injection points require --enable-injection-points.
  */
@@ -47,6 +60,9 @@ extern void InjectionPointCached(const char *name, void *arg);
 extern bool IsInjectionPointAttached(const char *name);
 extern bool InjectionPointDetach(const char *name);
 
+/* Get the current set of injection points attached */
+extern List *InjectionPointList(void);
+
 #ifdef EXEC_BACKEND
 extern PGDLLIMPORT struct InjectionPointsCtl *ActiveInjectionPoints;
 #endif
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index baf636a7643..66c5782688a 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -1291,6 +1291,7 @@ InjectionPointCacheEntry
 InjectionPointCallback
 InjectionPointCondition
 InjectionPointConditionType
+InjectionPointData
 InjectionPointEntry
 InjectionPointSharedState
 InjectionPointsCtl