Bug#16501: IS_USED_LOCK does not appear to work

Update User_level_lock::thread_id on acquiring an existing lock,
and reset it on lock release.


mysql-test/r/func_misc.result:
  Add result for bug#16501.
mysql-test/t/func_misc.test:
  Add test case for bug#16501.
sql/item_func.cc:
  Update User_level_lock::thread_id on acquiring an existing lock,
  and reset it on lock release (for safety).

3 files changed, 76 insertions, 0 deletions

diff --git a/mysql-test/r/func_misc.result b/mysql-test/r/func_misc.result
index 181ecf7b65b..a5beef859f0 100644
--- a/mysql-test/r/func_misc.result
+++ b/mysql-test/r/func_misc.result
@@ -57,3 +57,39 @@ t1	CREATE TABLE `t1` (
   `length(uuid())` int(10) NOT NULL default '0'
 ) ENGINE=MyISAM DEFAULT CHARSET=latin1
 drop table t1;
+DROP TABLE IF EXISTS t1;
+CREATE TABLE t1 (conn CHAR(7), connection_id INT);
+INSERT INTO t1 VALUES ('default', CONNECTION_ID());
+SELECT GET_LOCK('bug16501',600);
+GET_LOCK('bug16501',600)
+1
+INSERT INTO t1 VALUES ('con1', CONNECTION_ID());
+SELECT IS_USED_LOCK('bug16501') = connection_id
+FROM t1
+WHERE conn = 'default';
+IS_USED_LOCK('bug16501') = connection_id
+1
+ SELECT GET_LOCK('bug16501',600);
+SELECT IS_USED_LOCK('bug16501') = CONNECTION_ID();
+IS_USED_LOCK('bug16501') = CONNECTION_ID()
+1
+SELECT RELEASE_LOCK('bug16501');
+RELEASE_LOCK('bug16501')
+1
+SELECT IS_USED_LOCK('bug16501') = connection_id
+FROM t1
+WHERE conn = 'con1';
+IS_USED_LOCK('bug16501') = connection_id
+1
+GET_LOCK('bug16501',600)
+1
+SELECT IS_USED_LOCK('bug16501') = CONNECTION_ID();
+IS_USED_LOCK('bug16501') = CONNECTION_ID()
+1
+SELECT RELEASE_LOCK('bug16501');
+RELEASE_LOCK('bug16501')
+1
+SELECT IS_USED_LOCK('bug16501');
+IS_USED_LOCK('bug16501')
+NULL
+DROP TABLE t1;
diff --git a/mysql-test/t/func_misc.test b/mysql-test/t/func_misc.test
index 87d9d601c87..9c706161ba9 100644
--- a/mysql-test/t/func_misc.test
+++ b/mysql-test/t/func_misc.test
@@ -43,4 +43,42 @@ create table t1 as select uuid(), length(uuid());
 show create table t1;
 drop table t1;
 
+
+#
+# Bug#16501: IS_USED_LOCK does not appear to work
+#
+--disable_warnings
+DROP TABLE IF EXISTS t1;
+--enable_warnings
+
+CREATE TABLE t1 (conn CHAR(7), connection_id INT);
+INSERT INTO t1 VALUES ('default', CONNECTION_ID());
+
+SELECT GET_LOCK('bug16501',600);
+
+connect (con1,localhost,root,,);
+INSERT INTO t1 VALUES ('con1', CONNECTION_ID());
+SELECT IS_USED_LOCK('bug16501') = connection_id
+FROM t1
+WHERE conn = 'default';
+send SELECT GET_LOCK('bug16501',600);
+
+connection default;
+SELECT IS_USED_LOCK('bug16501') = CONNECTION_ID();
+SELECT RELEASE_LOCK('bug16501');
+SELECT IS_USED_LOCK('bug16501') = connection_id
+FROM t1
+WHERE conn = 'con1';
+
+connection con1;
+reap;
+SELECT IS_USED_LOCK('bug16501') = CONNECTION_ID();
+SELECT RELEASE_LOCK('bug16501');
+SELECT IS_USED_LOCK('bug16501');
+
+disconnect con1;
+connection default;
+
+DROP TABLE t1;
+
 # End of 4.1 tests
diff --git a/sql/item_func.cc b/sql/item_func.cc
index 174a8c55d01..1f170242113 100644
--- a/sql/item_func.cc
+++ b/sql/item_func.cc
@@ -1972,6 +1972,7 @@ void item_user_lock_free(void)
 void item_user_lock_release(User_level_lock *ull)
 {
   ull->locked=0;
+  ull->thread_id= 0;
   if (mysql_bin_log.is_open())
   {
     char buf[256];
@@ -2170,6 +2171,7 @@ longlong Item_func_get_lock::val_int()
   {
     ull->locked=1;
     ull->thread=thd->real_id;
+    ull->thread_id= thd->thread_id;
     thd->ull=ull;
     error=0;
   }