#At file:///export/home/thek/bzr/mysql-6.0-bug38551/
2742 Kristofer Pettersson 2008-10-28
Bug#38551 query cache can still consume [very little] cpu time even when it is off.
When the query cache is disabled, the server shouldn't attempt to take the
query cache mutex.
By using the command line option --query_cache_type=0, the user can disable
the query cache permanently and avoid taking the query cache mutex.
added:
mysql-test/r/query_cache_disabled.result
mysql-test/t/query_cache_disabled-master.opt
mysql-test/t/query_cache_disabled.test
modified:
mysql-test/r/query_cache.result
mysql-test/r/query_cache_type_basic.result
mysql-test/r/query_cache_type_func.result
mysql-test/t/query_cache.test
mysql-test/t/query_cache_type_basic.test
mysql-test/t/query_cache_type_func.test
sql/set_var.cc
sql/set_var.h
sql/share/errmsg.txt
sql/sql_cache.cc
sql/sql_cache.h
per-file messages:
mysql-test/r/query_cache.result
* Modified test case to reflect changes in query_cache_type behavior.
mysql-test/r/query_cache_disabled.result
* Added test case to demonstrate changes in query_cache_type behavior.
mysql-test/r/query_cache_type_basic.result
* Modified test case to reflect changes in query_cache_type behavior.
mysql-test/r/query_cache_type_func.result
* Modified test case to reflect changes in query_cache_type behavior.
mysql-test/t/query_cache.test
* Modified test case to reflect changes in query_cache_type behavior.
mysql-test/t/query_cache_disabled-master.opt
* Added test case to demonstrate changes in query_cache_type behavior.
mysql-test/t/query_cache_disabled.test
* Added test case to demonstrate changes in query_cache_type behavior.
mysql-test/t/query_cache_type_basic.test
* Modified test case to reflect changes in query_cache_type behavior.
mysql-test/t/query_cache_type_func.test
* Modified test case to reflect changes in query_cache_type behavior.
sql/set_var.cc
* Added before trigger to verify that query_cache_type wasn't turned off or on during
runtime.
sql/set_var.h
* Changed order on how the enumeration is processed. By first projecting the
character representation of the variable to a temporary integer we can have one
function instead of two to check if the value is valid.
sql/share/errmsg.txt
* Added error message
sql/sql_cache.cc
* If the query cache is disabled at start up, shorten the execution path and avoid
grabbing the query cache mutex each time the invalidate interface methods are called.
sql/sql_cache.h
* Added new methods to set the query cache into a disabled state.
=== modified file 'mysql-test/r/query_cache.result'
--- a/mysql-test/r/query_cache.result 2008-07-17 19:55:18 +0000
+++ b/mysql-test/r/query_cache.result 2008-10-28 12:13:25 +0000
@@ -1600,6 +1600,7 @@ drop table t1,t2;
set global query_cache_size=100000;
set global query_cache_size=0;
set global query_cache_type=0;
+ERROR HY000: Incorrect arguments to SET
show status like 'Qcache_free_blocks';
Variable_name Value
Qcache_free_blocks 0
=== added file 'mysql-test/r/query_cache_disabled.result'
--- a/mysql-test/r/query_cache_disabled.result 1970-01-01 00:00:00 +0000
+++ b/mysql-test/r/query_cache_disabled.result 2008-10-28 12:13:25 +0000
@@ -0,0 +1,13 @@
+SHOW GLOBAL VARIABLES LIKE 'query_cache_type';
+Variable_name Value
+query_cache_type OFF
+SET GLOBAL query_cache_type=ON;
+ERROR HY000: Query cache is disabled from the command line
+SET GLOBAL query_cache_type=DEMAND;
+ERROR HY000: Query cache is disabled from the command line
+SET GLOBAL query_cache_type=OFF;
+ERROR HY000: Query cache is disabled from the command line
+SET GLOBAL query_cache_size=1024*1024;
+SHOW GLOBAL VARIABLES LIKE 'query_cache_size';
+Variable_name Value
+query_cache_size 1048576
=== modified file 'mysql-test/r/query_cache_type_basic.result'
--- a/mysql-test/r/query_cache_type_basic.result 2008-04-10 13:14:28 +0000
+++ b/mysql-test/r/query_cache_type_basic.result 2008-10-28 12:13:25 +0000
@@ -8,11 +8,13 @@ SELECT @session_start_value;
ON
'#--------------------FN_DYNVARS_134_01------------------------#'
SET @@global.query_cache_type = 0;
+ERROR HY000: Incorrect arguments to SET
SET @@global.query_cache_type = DEFAULT;
SELECT @@global.query_cache_type;
@@global.query_cache_type
ON
SET @@session.query_cache_type = 0;
+ERROR HY000: Incorrect arguments to SET
SET @@session.query_cache_type = DEFAULT;
SELECT @@session.query_cache_type;
@@session.query_cache_type
@@ -28,9 +30,10 @@ SET @@session.query_cache_type = '';
ERROR 42000: Variable 'query_cache_type' can't be set to the value of ''
'#--------------------FN_DYNVARS_134_03------------------------#'
SET @@global.query_cache_type = OFF;
+ERROR HY000: Incorrect arguments to SET
SELECT @@global.query_cache_type;
@@global.query_cache_type
-OFF
+ON
SET @@global.query_cache_type = ON;
SELECT @@global.query_cache_type;
@@global.query_cache_type
@@ -40,9 +43,10 @@ SELECT @@global.query_cache_type;
@@global.query_cache_type
DEMAND
SET @@session.query_cache_type = OFF;
+ERROR HY000: Incorrect arguments to SET
SELECT @@session.query_cache_type;
@@session.query_cache_type
-OFF
+ON
SET @@session.query_cache_type = ON;
SELECT @@session.query_cache_type;
@@session.query_cache_type
@@ -59,9 +63,10 @@ ERROR 42000: Variable 'query_cache_type'
SET @@global.query_cache_type = 'ON,OFF';
ERROR 42000: Variable 'query_cache_type' can't be set to the value of 'ON,OFF'
SET @@global.query_cache_type = 'OF';
+ERROR HY000: Incorrect arguments to SET
SELECT @@global.query_cache_type;
@@global.query_cache_type
-OFF
+DEMAND
'Bug# 34828: OF is taken as OFF.'
SET @@global.query_cache_type = YES;
ERROR 42000: Variable 'query_cache_type' can't be set to the value of 'YES'
@@ -81,9 +86,10 @@ WHERE VARIABLE_NAME='query_cache_type';
1
'#---------------------FN_DYNVARS_134_07-------------------------#'
SET @@global.query_cache_type = 0;
+ERROR HY000: Incorrect arguments to SET
SELECT @@global.query_cache_type;
@@global.query_cache_type
-OFF
+DEMAND
SET @@global.query_cache_type = 1;
SELECT @@global.query_cache_type;
@@global.query_cache_type
@@ -93,9 +99,10 @@ SELECT @@global.query_cache_type;
@@global.query_cache_type
DEMAND
SET @@global.query_cache_type = 0.4;
+ERROR HY000: Incorrect arguments to SET
SELECT @@global.query_cache_type;
@@global.query_cache_type
-OFF
+DEMAND
SET @@global.query_cache_type = 1.0;
SELECT @@global.query_cache_type;
@@global.query_cache_type
@@ -130,9 +137,10 @@ SELECT @@global.query_cache_type;
@@global.query_cache_type
ON
SET @@global.query_cache_type = FALSE;
+ERROR HY000: Incorrect arguments to SET
SELECT @@global.query_cache_type;
@@global.query_cache_type
-OFF
+ON
'#---------------------FN_DYNVARS_134_09----------------------#'
SET query_cache_type = 'ON';
SET session.query_cache_type = 'OFF';
@@ -144,9 +152,10 @@ SELECT @@query_cache_type;
@@query_cache_type
ON
SET global query_cache_type = 0;
+ERROR HY000: Incorrect arguments to SET
SELECT @@global.query_cache_type;
@@global.query_cache_type
-OFF
+ON
SET @@global.query_cache_type = @global_start_value;
SELECT @@global.query_cache_type;
@@global.query_cache_type
=== modified file 'mysql-test/r/query_cache_type_func.result'
--- a/mysql-test/r/query_cache_type_func.result 2008-04-10 13:14:28 +0000
+++ b/mysql-test/r/query_cache_type_func.result 2008-10-28 12:13:25 +0000
@@ -29,9 +29,10 @@ SELECT @@query_cache_type;
ON
ON Expected
SET @@query_cache_type = OFF;
+ERROR HY000: Incorrect arguments to SET
SELECT @@query_cache_type;
@@query_cache_type
-OFF
+ON
OFF Expected
SET @@query_cache_type = DEMAND;
SELECT @@query_cache_type;
@@ -119,24 +120,6 @@ Qcache_queries_in_cache 5
Expected value : 3
==================
Bug#35388: Stored procedure execution causes improper behavior of query cache.
-'#--------------------FN_DYNVARS_135_06-------------------------#'
-FLUSHING CACHE
-SET @@GLOBAL.query_cache_size = 0;
-SET @@GLOBAL.query_cache_size = 65536;
-** Turning cache to OFF **
-SET @@query_cache_type = OFF;
-SELECT @@query_cache_type;
-@@query_cache_type
-OFF
-SELECT id FROM t1;
-id
-1
-2
-3
-SHOW STATUS LIKE 'Qcache_queries_in_cache';
-Variable_name Value
-Qcache_queries_in_cache 0
-0 Expected
'#--------------------FN_DYNVARS_135_07-------------------------#'
SELECT SQL_CACHE id FROM t1;
id
@@ -145,8 +128,8 @@ id
3
SHOW STATUS LIKE 'Qcache_queries_in_cache';
Variable_name Value
-Qcache_queries_in_cache 0
-0 Expected
+Qcache_queries_in_cache 6
+6 Expected
SELECT SQL_CACHE * FROM t1;
id value
1 val1
@@ -154,8 +137,8 @@ id value
3 val3
SHOW STATUS LIKE 'Qcache_queries_in_cache';
Variable_name Value
-Qcache_queries_in_cache 0
-0 Expected
+Qcache_queries_in_cache 7
+7 Expected
'#--------------------FN_DYNVARS_135_08-------------------------#'
FLUSHING CACHE
SET @@GLOBAL.query_cache_size = 0;
@@ -185,15 +168,9 @@ Variable_name Value
Qcache_queries_in_cache 1
0 Expected
** TESTING GLOBAL SCOPE **
-'#--------------------FN_DYNVARS_135_10-------------------------#'
-SET @@GLOBAL.query_cache_type = OFF;
+'#--------------------FN_DYNVARS_135_11-------------------------#'
** Connecting con1 using root **
** Connection con1 **
-SELECT @@query_cache_type;
-@@query_cache_type
-OFF
-OFF Expected
-'#--------------------FN_DYNVARS_135_11-------------------------#'
SET @@GLOBAL.query_cache_type = DEMAND;
** Connecting con2 using root **
** Connection con2 **
=== modified file 'mysql-test/t/query_cache.test'
--- a/mysql-test/t/query_cache.test 2008-10-09 10:58:51 +0000
+++ b/mysql-test/t/query_cache.test 2008-10-28 12:13:25 +0000
@@ -1249,6 +1249,7 @@ disconnect user3;
--echo #
set global query_cache_size=100000;
set global query_cache_size=0;
+--error ER_WRONG_ARGUMENTS
set global query_cache_type=0;
show status like 'Qcache_free_blocks';
=== added file 'mysql-test/t/query_cache_disabled-master.opt'
--- a/mysql-test/t/query_cache_disabled-master.opt 1970-01-01 00:00:00 +0000
+++ b/mysql-test/t/query_cache_disabled-master.opt 2008-10-28 12:13:25 +0000
@@ -0,0 +1 @@
+--query_cache_type=0
=== added file 'mysql-test/t/query_cache_disabled.test'
--- a/mysql-test/t/query_cache_disabled.test 1970-01-01 00:00:00 +0000
+++ b/mysql-test/t/query_cache_disabled.test 2008-10-28 12:13:25 +0000
@@ -0,0 +1,13 @@
+#
+# Bug#38551 query cache can still consume [very little] cpu time even when it is off.
+#
+SHOW GLOBAL VARIABLES LIKE 'query_cache_type';
+--error ER_QUERY_CACHE_DISABLED
+SET GLOBAL query_cache_type=ON;
+--error ER_QUERY_CACHE_DISABLED
+SET GLOBAL query_cache_type=DEMAND;
+--error ER_QUERY_CACHE_DISABLED
+SET GLOBAL query_cache_type=OFF;
+SET GLOBAL query_cache_size=1024*1024;
+SHOW GLOBAL VARIABLES LIKE 'query_cache_size';
+
=== modified file 'mysql-test/t/query_cache_type_basic.test'
--- a/mysql-test/t/query_cache_type_basic.test 2008-04-10 13:14:28 +0000
+++ b/mysql-test/t/query_cache_type_basic.test 2008-10-28 12:13:25 +0000
@@ -45,10 +45,12 @@ SELECT @session_start_value;
# Display the DEFAULT value of query_cache_type #
########################################################################
+--error ER_WRONG_ARGUMENTS
SET @@global.query_cache_type = 0;
SET @@global.query_cache_type = DEFAULT;
SELECT @@global.query_cache_type;
+--error ER_WRONG_ARGUMENTS
SET @@session.query_cache_type = 0;
SET @@session.query_cache_type = DEFAULT;
SELECT @@session.query_cache_type;
@@ -76,6 +78,7 @@ SET @@session.query_cache_type = '';
# Change the value of query_cache_type to a valid value #
########################################################################
+--error ER_WRONG_ARGUMENTS
SET @@global.query_cache_type = OFF;
SELECT @@global.query_cache_type;
@@ -85,6 +88,7 @@ SELECT @@global.query_cache_type;
SET @@global.query_cache_type = DEMAND;
SELECT @@global.query_cache_type;
+--error ER_WRONG_ARGUMENTS
SET @@session.query_cache_type = OFF;
SELECT @@session.query_cache_type;
@@ -108,6 +112,7 @@ SET @@global.query_cache_type = ONDEMAND
--Error ER_WRONG_VALUE_FOR_VAR
SET @@global.query_cache_type = 'ON,OFF';
+--error ER_WRONG_ARGUMENTS
SET @@global.query_cache_type = 'OF';
SELECT @@global.query_cache_type;
@@ -145,6 +150,7 @@ WHERE VARIABLE_NAME='query_cache_type';
###################################################################
# test if variable accepts 0,1,2
+--error ER_WRONG_ARGUMENTS
SET @@global.query_cache_type = 0;
SELECT @@global.query_cache_type;
@@ -156,6 +162,7 @@ SELECT @@global.query_cache_type;
# use of decimal values
+--error ER_WRONG_ARGUMENTS
SET @@global.query_cache_type = 0.4;
SELECT @@global.query_cache_type;
@@ -192,6 +199,7 @@ SET @@global.query_cache_type = 3;
SET @@global.query_cache_type = TRUE;
SELECT @@global.query_cache_type;
+--error ER_WRONG_ARGUMENTS
SET @@global.query_cache_type = FALSE;
SELECT @@global.query_cache_type;
@@ -210,6 +218,7 @@ SET global.query_cache_type = 'DEMAND';
SET session query_cache_type = 1;
SELECT @@query_cache_type;
+--error ER_WRONG_ARGUMENTS
SET global query_cache_type = 0;
SELECT @@global.query_cache_type;
=== modified file 'mysql-test/t/query_cache_type_func.test'
--- a/mysql-test/t/query_cache_type_func.test 2008-04-10 13:14:28 +0000
+++ b/mysql-test/t/query_cache_type_func.test 2008-10-28 12:13:25 +0000
@@ -85,6 +85,7 @@ SET @@query_cache_type = ON;
SELECT @@query_cache_type;
--echo ON Expected
+--error ER_WRONG_ARGUMENTS
SET @@query_cache_type = OFF;
SELECT @@query_cache_type;
--echo OFF Expected
@@ -173,26 +174,6 @@ SHOW STATUS LIKE 'Qcache_queries_in_cach
--echo ==================
--echo Bug#35388: Stored procedure execution causes improper behavior of query cache.
-
---echo '#--------------------FN_DYNVARS_135_06-------------------------#'
-#
-# TESTING FOR VALUE OFF or 0
-#
-
---echo FLUSHING CACHE
-SET @@GLOBAL.query_cache_size = 0;
-SET @@GLOBAL.query_cache_size = 65536;
-
---echo ** Turning cache to OFF **
-
-SET @@query_cache_type = OFF;
-SELECT @@query_cache_type;
-
-SELECT id FROM t1;
-
-SHOW STATUS LIKE 'Qcache_queries_in_cache';
---echo 0 Expected
-
--echo '#--------------------FN_DYNVARS_135_07-------------------------#'
#
# TESTING QUERY WITH SQL_CACHE
@@ -201,12 +182,12 @@ SHOW STATUS LIKE 'Qcache_queries_in_cach
SELECT SQL_CACHE id FROM t1;
SHOW STATUS LIKE 'Qcache_queries_in_cache';
---echo 0 Expected
+--echo 6 Expected
SELECT SQL_CACHE * FROM t1;
SHOW STATUS LIKE 'Qcache_queries_in_cache';
---echo 0 Expected
+--echo 7 Expected
--echo '#--------------------FN_DYNVARS_135_08-------------------------#'
#
@@ -243,26 +224,15 @@ SHOW STATUS LIKE 'Qcache_queries_in_cach
--echo ** TESTING GLOBAL SCOPE **
---echo '#--------------------FN_DYNVARS_135_10-------------------------#'
+--echo '#--------------------FN_DYNVARS_135_11-------------------------#'
#
-# Turning global cache to OFF
+# Turning global cache to DEMAND
#
-
-SET @@GLOBAL.query_cache_type = OFF;
-
--echo ** Connecting con1 using root **
connect (con1,localhost,root,,);
--echo ** Connection con1 **
connection con1;
-
-SELECT @@query_cache_type;
---echo OFF Expected
-
---echo '#--------------------FN_DYNVARS_135_11-------------------------#'
-#
-# Turning global cache to DEMAND
-#
SET @@GLOBAL.query_cache_type = DEMAND;
--echo ** Connecting con2 using root **
=== modified file 'sql/set_var.cc'
--- a/sql/set_var.cc 2008-10-08 15:37:32 +0000
+++ b/sql/set_var.cc 2008-10-28 12:13:25 +0000
@@ -450,9 +450,10 @@ static sys_var_long_ptr sys_query_cache_
static sys_var_long_ptr sys_query_cache_min_res_unit(&vars, "query_cache_min_res_unit",
&query_cache_min_res_unit,
fix_query_cache_min_res_unit);
+static int check_query_cache_type(THD *thd, set_var *var);
static sys_var_thd_enum sys_query_cache_type(&vars, "query_cache_type",
&SV::query_cache_type,
- &query_cache_type_typelib);
+ &query_cache_type_typelib, NULL, check_query_cache_type);
static sys_var_thd_bool
sys_query_cache_wlock_invalidate(&vars, "query_cache_wlock_invalidate",
&SV::query_cache_wlock_invalidate);
@@ -1103,10 +1104,9 @@ static void fix_net_retry_count(THD *thd
{}
#endif /* HAVE_REPLICATION */
-
+#ifdef HAVE_QUERY_CACHE
static void fix_query_cache_size(THD *thd, enum_var_type type)
{
-#ifdef HAVE_QUERY_CACHE
ulong new_cache_size= query_cache.resize(query_cache_size);
/*
@@ -1120,11 +1120,43 @@ static void fix_query_cache_size(THD *th
query_cache_size, new_cache_size);
query_cache_size= new_cache_size;
-#endif
}
-#ifdef HAVE_QUERY_CACHE
+/**
+ Trigger before query_cache_type variable is updated.
+ @param thd Thread handler
+ @param var Pointer to the new variable status
+
+ @return Status code
+ @retval 1 Failure
+ @retval 0 Success
+*/
+
+static int check_query_cache_type(THD *thd, set_var *var)
+{
+ /*
+ Don't allow changes of the query_cache_type if the query cache
+ is disabled.
+ */
+ if (query_cache.is_disabled())
+ {
+ my_error(ER_QUERY_CACHE_DISABLED,MYF(0),ER_QUERY_CACHE_DISABLED);
+ return 1;
+ }
+
+ /*
+ Deny any attempt to modify query cache type to OFF in a multi-thread
+ environment.
+ Note: When this function is called the new value is stored in
+ var->save_result.
+ */
+ if (var->save_result.ulong_value == 0)
+ return 1;
+
+ return 0;
+}
+
static void fix_query_cache_min_res_unit(THD *thd, enum_var_type type)
{
query_cache_min_res_unit=
@@ -3775,6 +3807,16 @@ bool not_all_support_one_shot(List<set_v
Functions to handle SET mysql_internal_variable=const_expr
*****************************************************************************/
+/**
+ Verify that the supplied value is correct.
+
+ @param thd Thread handler
+
+ @return status code
+ @retval -1 Failure
+ @retval 0 Success
+ */
+
int set_var::check(THD *thd)
{
if (var->is_readonly())
=== modified file 'sql/set_var.h'
--- a/sql/set_var.h 2008-10-08 15:37:32 +0000
+++ b/sql/set_var.h 2008-10-28 12:13:25 +0000
@@ -486,9 +486,22 @@ public:
bool check(THD *thd, set_var *var)
{
int ret= 0;
+ ret= check_enum(thd, var, enum_names);
+
+ /*
+ TRUE means that the character representation supplied was wrong
+ or that the integer value was wrong or missing.
+ */
+ if (ret == TRUE)
+ return TRUE;
+
if (check_func)
ret= (*check_func)(thd, var);
- return ret ? ret : check_enum(thd, var, enum_names);
+
+ if (ret == 1)
+ return TRUE;
+
+ return FALSE;
}
bool update(THD *thd, set_var *var);
void set_default(THD *thd, enum_var_type type);
=== modified file 'sql/share/errmsg.txt'
--- a/sql/share/errmsg.txt 2008-10-24 14:17:49 +0000
+++ b/sql/share/errmsg.txt 2008-10-28 12:13:25 +0000
@@ -6409,4 +6409,6 @@ WARN_PLUGIN_DELETE_BUILTIN
WARN_PLUGIN_BUSY
eng "Plugin is busy and will be uninstalled on shutdown"
+ER_QUERY_CACHE_DISABLED
+ eng "Query cache is disabled from the command line"
=== modified file 'sql/sql_cache.cc'
--- a/sql/sql_cache.cc 2008-10-17 17:47:16 +0000
+++ b/sql/sql_cache.cc 2008-10-28 12:13:25 +0000
@@ -686,7 +686,7 @@ Query_cache::insert(Query_cache_tls *que
DBUG_ENTER("Query_cache::insert");
/* See the comment on double-check locking usage above. */
- if (query_cache_tls->first_query_block == NULL)
+ if (is_disabled() || query_cache_tls->first_query_block == NULL)
DBUG_VOID_RETURN;
DBUG_EXECUTE_IF("wait_in_query_cache_insert",
@@ -753,7 +753,7 @@ Query_cache::abort(Query_cache_tls *quer
THD *thd= current_thd;
/* See the comment on double-check locking usage above. */
- if (query_cache_tls->first_query_block == NULL)
+ if (is_disabled() || query_cache_tls->first_query_block == NULL)
DBUG_VOID_RETURN;
STRUCT_LOCK(&structure_guard_mutex);
@@ -906,7 +906,7 @@ Query_cache::Query_cache(ulong query_cac
min_result_data_size(ALIGN_SIZE(min_result_data_size_arg)),
def_query_hash_size(ALIGN_SIZE(def_query_hash_size_arg)),
def_table_hash_size(ALIGN_SIZE(def_table_hash_size_arg)),
- initialized(0)
+ initialized(0),m_query_cache_is_disabled(FALSE)
{
ulong min_needed= (ALIGN_SIZE(sizeof(Query_cache_block)) +
ALIGN_SIZE(sizeof(Query_cache_block_table)) +
@@ -993,7 +993,7 @@ void Query_cache::store_query(THD *thd,
See also a note on double-check locking usage above.
*/
- if (thd->locked_tables_mode || query_cache_size == 0)
+ if (is_disabled() || thd->locked_tables_mode || query_cache_size == 0)
DBUG_VOID_RETURN;
uint8 tables_type= 0;
@@ -1503,6 +1503,9 @@ void Query_cache::invalidate(THD *thd, T
{
DBUG_ENTER("Query_cache::invalidate (table list)");
+ if (is_disabled())
+ DBUG_VOID_RETURN;
+
using_transactions= using_transactions &&
(thd->options & (OPTION_NOT_AUTOCOMMIT | OPTION_BEGIN));
for (; tables_used; tables_used= tables_used->next_local)
@@ -1529,6 +1532,9 @@ void Query_cache::invalidate(THD *thd, T
void Query_cache::invalidate(CHANGED_TABLE_LIST *tables_used)
{
DBUG_ENTER("Query_cache::invalidate (changed table list)");
+ if (is_disabled())
+ DBUG_VOID_RETURN;
+
THD *thd= current_thd;
for (; tables_used; tables_used= tables_used->next)
{
@@ -1576,7 +1582,10 @@ void Query_cache::invalidate(THD *thd, T
my_bool using_transactions)
{
DBUG_ENTER("Query_cache::invalidate (table)");
-
+
+ if (is_disabled())
+ DBUG_VOID_RETURN;
+
using_transactions= using_transactions &&
(thd->options & (OPTION_NOT_AUTOCOMMIT | OPTION_BEGIN));
if (using_transactions &&
@@ -1593,6 +1602,8 @@ void Query_cache::invalidate(THD *thd, c
my_bool using_transactions)
{
DBUG_ENTER("Query_cache::invalidate (key)");
+ if (is_disabled())
+ DBUG_VOID_RETURN;
using_transactions= using_transactions &&
(thd->options & (OPTION_NOT_AUTOCOMMIT | OPTION_BEGIN));
@@ -1654,7 +1665,8 @@ void Query_cache::invalidate(char *db)
{
bool restart= FALSE;
DBUG_ENTER("Query_cache::invalidate (db)");
-
+ if (is_disabled())
+ DBUG_VOID_RETURN;
STRUCT_LOCK(&structure_guard_mutex);
bool interrupt;
wait_while_table_flush_is_in_progress(&interrupt);
@@ -1742,6 +1754,9 @@ void Query_cache::invalidate_by_MyISAM_f
void Query_cache::flush()
{
DBUG_ENTER("Query_cache::flush");
+ if (is_disabled())
+ DBUG_VOID_RETURN;
+
STRUCT_LOCK(&structure_guard_mutex);
if (query_cache_size > 0)
{
@@ -1769,7 +1784,8 @@ void Query_cache::flush()
void Query_cache::pack(ulong join_limit, uint iteration_limit)
{
DBUG_ENTER("Query_cache::pack");
-
+ if (is_disabled())
+ DBUG_VOID_RETURN;
bool interrupt;
STRUCT_LOCK(&structure_guard_mutex);
wait_while_table_flush_is_in_progress(&interrupt);
@@ -1829,6 +1845,15 @@ void Query_cache::init()
pthread_cond_init(&COND_cache_status_changed, NULL);
m_cache_status= Query_cache::NO_FLUSH_IN_PROGRESS;
initialized = 1;
+ /*
+ If we explicitly turn off query cache from the command line query cache will
+ be disabled for the reminder of the server life time. This is because we
+ want to avoid locking the QC specific mutex if query cache isn't going to
+ be used.
+ */
+ if (global_system_variables.query_cache_type == 0)
+ query_cache.disable_query_cache();
+
DBUG_VOID_RETURN;
}
=== modified file 'sql/sql_cache.h'
--- a/sql/sql_cache.h 2008-08-10 14:49:52 +0000
+++ b/sql/sql_cache.h 2008-10-28 12:13:25 +0000
@@ -280,7 +280,7 @@ private:
TABLE_FLUSH_IN_PROGRESS };
Cache_status m_cache_status;
-
+ bool m_query_cache_is_disabled;
void free_query_internal(Query_cache_block *point);
void invalidate_table_internal(THD *thd, uchar *key, uint32 key_length);
@@ -428,6 +428,9 @@ protected:
uint def_query_hash_size = QUERY_CACHE_DEF_QUERY_HASH_SIZE,
uint def_table_hash_size = QUERY_CACHE_DEF_TABLE_HASH_SIZE);
+ bool is_disabled(void) { return m_query_cache_is_disabled; }
+ void disable_query_cache(void) { m_query_cache_is_disabled= TRUE; }
+
/* initialize cache (mutex) */
void init();
/* resize query cache (return real query size, 0 if disabled) */
