injection_points: Add stats for point caching and loading

This adds two counters to the fixed-numbered stats of injection points
to track the number of times injection points have been cached and
loaded from the cache, as of the additions coming from a0a5869a8598 and
4b211003ecc2.

These should have been part of f68cd847fa40, but I have lacked time and
energy back then, and it did not prevent the code to be a useful
template.

While on it, this commit simplifies the description of a few tests while
adding coverage for the new stats data.

Author: Yogesh Sharma
Discussion: https://postgr.es/m/3a6977f7-54ab-43ce-8806-11d5e15526a2@catprosystems.com

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

@@ -91,7 +91,9 @@ LANGUAGE C STRICT;
 -- Reports fixed-numbered statistics for injection points.
 CREATE FUNCTION injection_points_stats_fixed(OUT numattach int8,
    OUT numdetach int8,
-   OUT numrun int8)
+   OUT numrun int8,
+   OUT numcached int8,
+   OUT numloaded int8)
 RETURNS record
 AS 'MODULE_PATHNAME', 'injection_points_stats_fixed'
 LANGUAGE C STRICT;

src/test/modules/injection_points/injection_points.c

@@ -297,7 +297,7 @@ injection_points_attach(PG_FUNCTION_ARGS)
 		condition.pid = MyProcPid;
 	}
 
-	pgstat_report_inj_fixed(1, 0, 0);
+	pgstat_report_inj_fixed(1, 0, 0, 0, 0);
 	InjectionPointAttach(name, "injection_points", function, &condition,
 						 sizeof(InjectionPointCondition));
 
@@ -329,6 +329,7 @@ injection_points_load(PG_FUNCTION_ARGS)
 	if (inj_state == NULL)
 		injection_init_shmem();
 
+	pgstat_report_inj_fixed(0, 0, 0, 0, 1);
 	INJECTION_POINT_LOAD(name);
 
 	PG_RETURN_VOID();
@@ -343,7 +344,7 @@ injection_points_run(PG_FUNCTION_ARGS)
 {
 	char	   *name = text_to_cstring(PG_GETARG_TEXT_PP(0));
 
-	pgstat_report_inj_fixed(0, 0, 1);
+	pgstat_report_inj_fixed(0, 0, 1, 0, 0);
 	INJECTION_POINT(name);
 
 	PG_RETURN_VOID();
@@ -358,6 +359,7 @@ injection_points_cached(PG_FUNCTION_ARGS)
 {
 	char	   *name = text_to_cstring(PG_GETARG_TEXT_PP(0));
 
+	pgstat_report_inj_fixed(0, 0, 0, 1, 0);
 	INJECTION_POINT_CACHED(name);
 
 	PG_RETURN_VOID();
@@ -434,7 +436,7 @@ injection_points_detach(PG_FUNCTION_ARGS)
 {
 	char	   *name = text_to_cstring(PG_GETARG_TEXT_PP(0));
 
-	pgstat_report_inj_fixed(0, 1, 0);
+	pgstat_report_inj_fixed(0, 1, 0, 0, 0);
 	if (!InjectionPointDetach(name))
 		elog(ERROR, "could not detach injection point \"%s\"", name);
 

src/test/modules/injection_points/injection_stats.h

@@ -25,6 +25,8 @@ extern void pgstat_report_inj(const char *name);
 extern void pgstat_register_inj_fixed(void);
 extern void pgstat_report_inj_fixed(uint32 numattach,
 									uint32 numdetach,
-									uint32 numrun);
+									uint32 numrun,
+									uint32 numcached,
+									uint32 numloaded);
 
 #endif

src/test/modules/injection_points/injection_stats_fixed.c

@@ -29,6 +29,8 @@ typedef struct PgStat_StatInjFixedEntry
 	PgStat_Counter numattach;	/* number of points attached */
 	PgStat_Counter numdetach;	/* number of points detached */
 	PgStat_Counter numrun;		/* number of points run */
+	PgStat_Counter numcached;	/* number of points cached */
+	PgStat_Counter numloaded;	/* number of points loaded */
 	TimestampTz stat_reset_timestamp;
 } PgStat_StatInjFixedEntry;
 
@@ -114,6 +116,8 @@ injection_stats_fixed_snapshot_cb(void)
 	FIXED_COMP(numattach);
 	FIXED_COMP(numdetach);
 	FIXED_COMP(numrun);
+	FIXED_COMP(numcached);
+	FIXED_COMP(numloaded);
 #undef FIXED_COMP
 }
 
@@ -135,7 +139,9 @@ pgstat_register_inj_fixed(void)
 void
 pgstat_report_inj_fixed(uint32 numattach,
 						uint32 numdetach,
-						uint32 numrun)
+						uint32 numrun,
+						uint32 numcached,
+						uint32 numloaded)
 {
 	PgStatShared_InjectionPointFixed *stats_shmem;
 
@@ -149,6 +155,8 @@ pgstat_report_inj_fixed(uint32 numattach,
 	stats_shmem->stats.numattach += numattach;
 	stats_shmem->stats.numdetach += numdetach;
 	stats_shmem->stats.numrun += numrun;
+	stats_shmem->stats.numcached += numcached;
+	stats_shmem->stats.numloaded += numloaded;
 	pgstat_end_changecount_write(&stats_shmem->changecount);
 }
 
@@ -160,8 +168,8 @@ Datum
 injection_points_stats_fixed(PG_FUNCTION_ARGS)
 {
 	TupleDesc	tupdesc;
-	Datum		values[3] = {0};
-	bool		nulls[3] = {0};
+	Datum		values[5] = {0};
+	bool		nulls[5] = {0};
 	PgStat_StatInjFixedEntry *stats;
 
 	if (!inj_fixed_loaded)
@@ -171,21 +179,29 @@ injection_points_stats_fixed(PG_FUNCTION_ARGS)
 	stats = pgstat_get_custom_snapshot_data(PGSTAT_KIND_INJECTION_FIXED);
 
 	/* Initialise attributes information in the tuple descriptor */
-	tupdesc = CreateTemplateTupleDesc(3);
+	tupdesc = CreateTemplateTupleDesc(5);
 	TupleDescInitEntry(tupdesc, (AttrNumber) 1, "numattach",
 					   INT8OID, -1, 0);
 	TupleDescInitEntry(tupdesc, (AttrNumber) 2, "numdetach",
 					   INT8OID, -1, 0);
 	TupleDescInitEntry(tupdesc, (AttrNumber) 3, "numrun",
 					   INT8OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 4, "numcached",
+					   INT8OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 5, "numloaded",
+					   INT8OID, -1, 0);
 	BlessTupleDesc(tupdesc);
 
 	values[0] = Int64GetDatum(stats->numattach);
 	values[1] = Int64GetDatum(stats->numdetach);
 	values[2] = Int64GetDatum(stats->numrun);
+	values[3] = Int64GetDatum(stats->numcached);
+	values[4] = Int64GetDatum(stats->numloaded);
 	nulls[0] = false;
 	nulls[1] = false;
 	nulls[2] = false;
+	nulls[3] = false;
+	nulls[4] = false;
 
 	/* Returns the record as Datum */
 	PG_RETURN_DATUM(HeapTupleGetDatum(heap_form_tuple(tupdesc, values, nulls)));

src/test/modules/injection_points/t/001_stats.pl

@@ -35,16 +35,26 @@ my $numcalls = $node->safe_psql('postgres',
 is($numcalls, '2', 'number of stats calls');
 my $fixedstats = $node->safe_psql('postgres',
 	"SELECT * FROM injection_points_stats_fixed();");
-is($fixedstats, '1|0|2', 'number of fixed stats');
+is($fixedstats, '1|0|2|0|0', 'fixed stats after some calls');
+
+# Loading and caching.
+$node->safe_psql(
+	'postgres', "
+SELECT injection_points_load('stats-notice');
+SELECT injection_points_cached('stats-notice');
+");
+$fixedstats = $node->safe_psql('postgres',
+	"SELECT * FROM injection_points_stats_fixed();");
+is($fixedstats, '1|0|2|1|1', 'fixed stats after loading and caching');
 
 # Restart the node cleanly, stats should still be around.
 $node->restart;
 $numcalls = $node->safe_psql('postgres',
 	"SELECT injection_points_stats_numcalls('stats-notice');");
-is($numcalls, '2', 'number of stats after clean restart');
+is($numcalls, '3', 'number of stats after clean restart');
 $fixedstats = $node->safe_psql('postgres',
 	"SELECT * FROM injection_points_stats_fixed();");
-is($fixedstats, '1|0|2', 'number of fixed stats after clean restart');
+is($fixedstats, '1|0|2|1|1', 'fixed stats after clean restart');
 
 # On crash the stats are gone.
 $node->stop('immediate');
@@ -54,6 +64,6 @@ $numcalls = $node->safe_psql('postgres',
 is($numcalls, '', 'number of stats after crash');
 $fixedstats = $node->safe_psql('postgres',
 	"SELECT * FROM injection_points_stats_fixed();");
-is($fixedstats, '0|0|0', 'number of fixed stats after crash');
+is($fixedstats, '0|0|0|0|0', 'fixed stats after crash');
 
 done_testing();