injection_points: Fix incrementation of variable-numbered stats

michaelpq · michaelpq · commit 6e8286f9a153 · 2025-09-17T10:16:10.000+09:00
The pending entry was not used when incrementing its data, directly manipulating the shared memory pointer, without even locking it. This could mean losing statistics under concurrent activity. The flush callback was a no-op. This code serves as a base template for extensions for the custom cumulative statistics, so let's be clean and use a pending entry for the incrementations, whose data is then flushed to the corresponding entry in the shared hashtable when all the stats are reported, in its own flush callback. Author: Sami Imseih <samimseih@gmail.com> Discussion: https://postgr.es/m/CAA5RZ0v0U0yhPbY+bqChomkPbyUrRQ3rQXnZf_SB-svDiQOpgQ@mail.gmail.com Backpatch-through: 18
diff --git a/src/test/modules/injection_points/injection_stats.c b/src/test/modules/injection_points/injection_stats.c
@@ -164,8 +164,7 @@ void
 pgstat_report_inj(const char *name)
 {
 	PgStat_EntryRef *entry_ref;
-	PgStatShared_InjectionPoint *shstatent;
-	PgStat_StatInjEntry *statent;
+	PgStat_StatInjEntry *pending;
 
 	/* leave if disabled */
 	if (!inj_stats_loaded || !inj_stats_enabled)
@@ -174,11 +173,10 @@ pgstat_report_inj(const char *name)
 	entry_ref = pgstat_prep_pending_entry(PGSTAT_KIND_INJECTION, InvalidOid,
 										  PGSTAT_INJ_IDX(name), NULL);
 
-	shstatent = (PgStatShared_InjectionPoint *) entry_ref->shared_stats;
-	statent = &shstatent->stats;
+	pending = (PgStat_StatInjEntry *) entry_ref->pending;
 
-	/* Update the injection point statistics */
-	statent->numcalls++;
+	/* Update the injection point pending statistics */
+	pending->numcalls++;
 }
 
 /*
