From 46503d161ecc5756f0dd7130969e9ae9df303b31 Mon Sep 17 00:00:00 2001
From: unknown <cmiller@zippy.cornsilk.net>
Date: Tue, 3 Apr 2007 19:50:55 -0400
Subject: [PATCH] Backport:

B-g#27501: 5.0 significantly more sys ("kernel") time than 4.1 \
      due to getrusage() calls

Even if profiling is turned off, the parser makes calls to reset
the state at the beginning of each query.  That would eventually
instantiate a PROFILE_ENTRY, which does indeed capture resource
usage.

Instead, now check that profiling is active before progressing
far into the storage/expiration of old entries in the history.
This has the pleasant side-effect that queries to toggle profiling
are not recorded in the history.


mysql-test/r/profiling.result:
  Now after we turn off profiling, the beginning of the next query
  refuses to enter the profiling code and it discards the info.
sql/sql_profile.cc:
  Add the same condition twice:  Once to abort storing previous
  query information and the other to abort initialization for this
  query that is starting.

  We do this symmetrically, before and after expiring old history
  entries, so that the counts are correct.
---
 mysql-test/r/profiling.result |  2 +-
 sql/sql_profile.cc            | 11 +++++++++++
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/mysql-test/r/profiling.result b/mysql-test/r/profiling.result
index a1e994220b9..75977f7f2e8 100644
--- a/mysql-test/r/profiling.result
+++ b/mysql-test/r/profiling.result
@@ -248,6 +248,7 @@ sum(id)
 12
 show profiles;
 Query_ID	Duration	Query
+15	#	select count(*) from t1
 16	#	insert into t1 select * from t1
 17	#	insert into t1 select * from t1
 18	#	insert into t1 select * from t1
@@ -277,7 +278,6 @@ Query_ID	Duration	Query
 42	#	insert into t1 values (1), (2), (3)
 43	#	insert into t1 values (1), (2), (3)
 44	#	select * from t1
-45	#	set session profiling = OFF
 set session profiling = ON;
 select @@profiling;
 @@profiling
diff --git a/sql/sql_profile.cc b/sql/sql_profile.cc
index 4ee8d1ba9c8..b17bb6daa0d 100644
--- a/sql/sql_profile.cc
+++ b/sql/sql_profile.cc
@@ -493,6 +493,9 @@ void PROFILING::store()
   while (history.elements > thd->variables.profiling_history_size)
     delete history.pop();
 
+  if (likely(((thd)->options & OPTION_PROFILING) == 0))
+    DBUG_VOID_RETURN;
+
   if (current != NULL)
   {
     if (keeping && 
@@ -519,12 +522,20 @@ void PROFILING::store()
   DBUG_VOID_RETURN;
 }
 
+/**
+  Store and clean up the old information and get ready to hold info about this
+  new query.  This is called very often so it must be very lightweight if
+  profiling is not active.
+*/
 void PROFILING::reset()
 {
   DBUG_ENTER("PROFILING::reset");
 
   store();
 
+  if (likely(((thd)->options & OPTION_PROFILING) == 0))
+    DBUG_VOID_RETURN;
+
   if (current != NULL)
     current->reset();
   keep();