From 2d99d49872b90210eb0158d8c1a18fda2937fb53 Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Thu, 2 Aug 2012 14:28:51 +0000
Subject: [PATCH] Wonky hack to print stats on every backend exit.

---
 contrib/hashtest/hashtest--1.0.sql |  5 ---
 contrib/hashtest/hashtest.c        | 71 +++++++++++++++++-------------
 2 files changed, 41 insertions(+), 35 deletions(-)

diff --git a/contrib/hashtest/hashtest--1.0.sql b/contrib/hashtest/hashtest--1.0.sql
index c787532e73..e271baff0f 100644
--- a/contrib/hashtest/hashtest--1.0.sql
+++ b/contrib/hashtest/hashtest--1.0.sql
@@ -26,11 +26,6 @@ RETURNS void
 AS 'MODULE_PATHNAME', 'chash_collision_test'
 LANGUAGE C;
 
-CREATE FUNCTION chash_write_stats_to_log()
-RETURNS void
-AS 'MODULE_PATHNAME', 'chash_write_stats_to_log'
-LANGUAGE C;
-
 CREATE FUNCTION dynahash_insert_test()
 RETURNS void
 AS 'MODULE_PATHNAME', 'dynahash_insert_test'
diff --git a/contrib/hashtest/hashtest.c b/contrib/hashtest/hashtest.c
index 554457df0e..9288708ea4 100644
--- a/contrib/hashtest/hashtest.c
+++ b/contrib/hashtest/hashtest.c
@@ -6,6 +6,7 @@
 #include "postgres.h"
 
 #include "funcapi.h"
+#include "libpq/auth.h"
 #include "miscadmin.h"
 #include "portability/instr_time.h"
 #include "storage/ipc.h"
@@ -19,7 +20,6 @@ Datum		chash_search_test(PG_FUNCTION_ARGS);
 Datum		chash_delete_test(PG_FUNCTION_ARGS);
 Datum		chash_concurrent_test(PG_FUNCTION_ARGS);
 Datum		chash_collision_test(PG_FUNCTION_ARGS);
-Datum		chash_write_stats_to_log(PG_FUNCTION_ARGS);
 Datum		dynahash_insert_test(PG_FUNCTION_ARGS);
 Datum		dynahash_search_test(PG_FUNCTION_ARGS);
 Datum		dynahash_delete_test(PG_FUNCTION_ARGS);
@@ -57,6 +57,10 @@ static shmem_startup_hook_type prev_shmem_startup_hook = NULL;
 static CHashTable chash;
 static HTAB *dynahash;
 static LWLockId dynahash_lock[DYNAHASH_PARTITIONS];
+static ClientAuthentication_hook_type original_client_auth_hook = NULL;
+
+static void hashtest_client_auth_hook(Port *port, int status);
+static void chash_write_stats_to_log(int code, Datum dummy);
 
 #define dynahash_get_lock(hashcode) \
 	(dynahash_lock[(hashcode) % DYNAHASH_PARTITIONS])
@@ -79,6 +83,42 @@ _PG_init(void)
 	elog(LOG, "chash: %u bytes; dynahash: %u bytes", (unsigned) cs,
 		 (unsigned) ds);
 	RequestAddinLWLocks(DYNAHASH_PARTITIONS);
+	original_client_auth_hook = ClientAuthentication_hook;
+	ClientAuthentication_hook = hashtest_client_auth_hook;
+	
+}
+
+static void
+hashtest_client_auth_hook(Port *port, int status)
+{
+	if (original_client_auth_hook)
+		original_client_auth_hook(port, status);
+	on_proc_exit(chash_write_stats_to_log, (Datum) 0);
+}
+
+static void
+chash_write_stats_to_log(int code, Datum dummy)
+{
+	uint64	stats[CHS_NumberOfStatistics];
+	CHashStatisticsType i;
+	StringInfoData	buf;
+
+	CHashStatistics(chash, stats);
+	initStringInfo(&buf);
+
+	for (i = 0; i < CHS_NumberOfStatistics; ++i)
+	{
+		if (stats[i] == 0)
+			continue;
+		appendStringInfo(&buf, UINT64_FORMAT " %s; ", stats[i],
+						 CHashStatisticsNames[i]);
+	}
+
+	if (buf.len > 1)
+	{
+		buf.data[buf.len-2] = '\0';
+		elog(LOG, "chash statistics: %s", buf.data);
+	}
 }
 
 static void
@@ -275,35 +315,6 @@ chash_collision_test(PG_FUNCTION_ARGS)
 	PG_RETURN_VOID();
 }
 
-Datum
-chash_write_stats_to_log(PG_FUNCTION_ARGS)
-{
-	uint64	stats[CHS_NumberOfStatistics];
-	CHashStatisticsType i;
-	StringInfoData	buf;
-
-	CHashStatistics(chash, stats);
-	initStringInfo(&buf);
-
-	for (i = 0; i < CHS_NumberOfStatistics; ++i)
-	{
-		if (stats[i] == 0)
-			continue;
-		appendStringInfo(&buf, UINT64_FORMAT " %s; ", stats[i],
-						 CHashStatisticsNames[i]);
-	}
-
-	if (buf.len > 1)
-	{
-		buf.data[buf.len-2] = '\0';
-		elog(LOG, "chash statistics: %s", buf.data);
-	}
-	else
-		elog(LOG, "chash statistics: nothing to report");
-
-	PG_RETURN_VOID();
-}
-
 static bool
 dynahash_insert(uint32 key, uint32 val)
 {
-- 
2.39.5