MySQL Lists are EOL. Please join:

List:Commits« Previous MessageNext Message »
From:Kristofer Pettersson Date:October 29 2008 4:19pm
Subject:bzr commit into mysql-6.0 branch (kristofer.pettersson:2742) Bug#38551
View as plain text  
#At file:///export/home/thek/bzr/mysql-6.0-bug38551/

 2742 Kristofer Pettersson	2008-10-29
      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/t/query_cache_limit_func.test
  mysql-test/t/query_cache_type_basic.test
  mysql-test/t/query_cache_type_func.test
  mysql-test/t/query_cache_wlock_invalidate_basic.test
  mysql-test/t/query_cache_wlock_invalidate_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_disabled.result
    * Added test case to reflect changes in query_cache_type behavior.
  mysql-test/t/query_cache_disabled-master.opt
    * Added test case to reflect changes in query_cache_type behavior.
  mysql-test/t/query_cache_disabled.test
    * Added test case to reflect changes in query_cache_type behavior.
  mysql-test/t/query_cache_limit_func.test
    * modified test case to require query cache.
  mysql-test/t/query_cache_type_basic.test
    * modified test case to require query cache.
  mysql-test/t/query_cache_type_func.test
    * modified test case to require query cache.
  mysql-test/t/query_cache_wlock_invalidate_basic.test
    * modified test case to require query cache.
  mysql-test/t/query_cache_wlock_invalidate_func.test
    * modified test case to require query cache.
  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/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.
=== 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	2008-10-29 16:18:44 +0000
@@ -0,0 +1,14 @@
+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; restart the server with query_cache_type=1 to enable it
+SET GLOBAL query_cache_type=DEMAND;
+ERROR HY000: Query cache is disabled; restart the server with query_cache_type=1 to enable it
+SET GLOBAL query_cache_type=OFF;
+ERROR HY000: Query cache is disabled; restart the server with query_cache_type=1 to enable it
+SET GLOBAL query_cache_size=1024*1024;
+SHOW GLOBAL VARIABLES LIKE 'query_cache_size';
+Variable_name	Value
+query_cache_size	1048576
+SET GLOBAL query_cache_size=0;

=== 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	2008-10-29 16:18:44 +0000
@@ -0,0 +1 @@
+--loose-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	2008-10-29 16:18:44 +0000
@@ -0,0 +1,14 @@
+-- source include/have_query_cache.inc
+#
+# 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';
+SET GLOBAL query_cache_size=0;

=== modified file 'mysql-test/t/query_cache_limit_func.test'
--- a/mysql-test/t/query_cache_limit_func.test	2008-04-10 13:14:28 +0000
+++ b/mysql-test/t/query_cache_limit_func.test	2008-10-29 16:18:44 +0000
@@ -20,6 +20,7 @@
 #                                                                             #
 ###############################################################################
 
+--souce include/have_query_cache.inc
 
 --echo ** Setup **
 --echo

=== 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	2008-10-29 16:18:44 +0000
@@ -23,6 +23,7 @@
 #                                                                             #
 ###############################################################################
 
+--source include/have_query_cache.inc
 --source include/load_sysvars.inc
 
 ######################################################################## 

=== 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	2008-10-29 16:18:44 +0000
@@ -18,7 +18,7 @@
 #            server-system-variables.html#option_mysqld_query_cache_type      #
 #                                                                             #
 ###############################################################################
-
+--source include/have_query_cache.inc
 --echo ** Setup **
 --echo
 

=== modified file 'mysql-test/t/query_cache_wlock_invalidate_basic.test'
--- a/mysql-test/t/query_cache_wlock_invalidate_basic.test	2008-04-10 13:14:28 +0000
+++ b/mysql-test/t/query_cache_wlock_invalidate_basic.test	2008-10-29 16:18:44 +0000
@@ -24,6 +24,8 @@
 #                                                                             #
 ###############################################################################
 
+--source include/have_query_cache.inc
+
 --source include/load_sysvars.inc
 
 ######################################################################## 

=== modified file 'mysql-test/t/query_cache_wlock_invalidate_func.test'
--- a/mysql-test/t/query_cache_wlock_invalidate_func.test	2008-05-06 14:17:23 +0000
+++ b/mysql-test/t/query_cache_wlock_invalidate_func.test	2008-10-29 16:18:44 +0000
@@ -23,6 +23,8 @@
 #                                                                                    #
 ######################################################################################
 
+--source include/have_query_cache.inc
+
 --echo ** Setup **
 --echo
 #

=== modified file 'sql/set_var.cc'
--- a/sql/set_var.cc	2008-10-08 15:37:32 +0000
+++ b/sql/set_var.cc	2008-10-29 16:18:44 +0000
@@ -126,8 +126,10 @@ static void fix_net_read_timeout(THD *th
 static void fix_net_write_timeout(THD *thd, enum_var_type type);
 static void fix_net_retry_count(THD *thd, enum_var_type type);
 static void fix_max_join_size(THD *thd, enum_var_type type);
+#ifdef HAVE_QUERY_CACHE
 static void fix_query_cache_size(THD *thd, enum_var_type type);
 static void fix_query_cache_min_res_unit(THD *thd, enum_var_type type);
+#endif
 static void fix_myisam_max_sort_file_size(THD *thd, enum_var_type type);
 static void fix_max_binlog_size(THD *thd, enum_var_type type);
 static void fix_max_relay_log_size(THD *thd, enum_var_type type);
@@ -420,10 +422,6 @@ static sys_var_thd_ulong	sys_div_precinc
                                               &SV::div_precincrement);
 static sys_var_long_ptr	sys_rpl_recovery_rank(&vars, "rpl_recovery_rank",
 					      &rpl_recovery_rank);
-static sys_var_long_ptr	sys_query_cache_size(&vars, "query_cache_size",
-					     &query_cache_size,
-					     fix_query_cache_size);
-
 static sys_var_thd_ulong	sys_range_alloc_block_size(&vars, "range_alloc_block_size",
 						   &SV::range_alloc_block_size);
 static sys_var_thd_ulong	sys_query_alloc_block_size(&vars, "query_alloc_block_size",
@@ -445,14 +443,18 @@ sys_var_enum_const        sys_thread_han
                                               NULL);
 
 #ifdef HAVE_QUERY_CACHE
+static sys_var_long_ptr	sys_query_cache_size(&vars, "query_cache_size",
+					     &query_cache_size,
+					     fix_query_cache_size);
 static sys_var_long_ptr	sys_query_cache_limit(&vars, "query_cache_limit",
 					      &query_cache.query_cache_limit);
 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 +1105,9 @@ 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 +1121,34 @@ 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));
+    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 +3799,16 @@ 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	2008-10-29 16:18:44 +0000
@@ -485,10 +485,16 @@ public:
   { chain_sys_var(chain); }
   bool check(THD *thd, set_var *var)
   {
-    int ret= 0;
-    if (check_func)
-      ret= (*check_func)(thd, var);
-    return ret ? ret : check_enum(thd, var, enum_names);
+    /*
+      check_enum fails if the character representation supplied was wrong
+      or that the integer value was wrong or missing.
+    */
+    if (check_enum(thd, var, enum_names))
+      return TRUE;
+    else if ((check_func && (*check_func)(thd, var)))
+      return TRUE;
+    else
+      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	2008-10-29 16:18:44 +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; restart the server with query_cache_type=1 to enable it"
 

=== modified file 'sql/sql_cache.cc'
--- a/sql/sql_cache.cc	2008-10-17 17:47:16 +0000
+++ b/sql/sql_cache.cc	2008-10-29 16:18:44 +0000
@@ -286,6 +286,7 @@ functions:
          if (and only if) this query has a registered result set writer
          (thd->net.query_cache_query).
  4. Query_cache::invalidate
+    Query_cache::invalidate_locked_for_write
        - Called from various places to invalidate query cache based on data-
          base, table and myisam file name. During an on going invalidation
          the query cache is temporarily disabled.
@@ -686,7 +687,7 @@ 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 +754,7 @@ 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 +907,7 @@ 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 +994,7 @@ 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 +1504,9 @@ 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 +1533,9 @@ 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)
   {
@@ -1556,6 +1563,8 @@ void Query_cache::invalidate_locked_for_
 {
   THD *thd= current_thd;
   DBUG_ENTER("Query_cache::invalidate_locked_for_write");
+  if (is_disabled())
+    DBUG_VOID_RETURN;
   for (; tables_used; tables_used= tables_used->next_local)
   {
     thd_proc_info(thd, "invalidating query cache entries (table)");
@@ -1576,7 +1585,10 @@ 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 +1605,8 @@ 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));
@@ -1654,14 +1668,15 @@ 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);
   if (interrupt)
   {
     STRUCT_UNLOCK(&structure_guard_mutex);
-    return;
+    DBUG_VOID_RETURN;
   }
 
   THD *thd= current_thd;
@@ -1742,6 +1757,9 @@ 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 +1787,8 @@ 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 +1848,15 @@ 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	2008-10-29 16:18:44 +0000
@@ -280,9 +280,10 @@ 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);
+  void disable_query_cache(void) { m_query_cache_is_disabled= TRUE; }
 
 protected:
   /*
@@ -428,6 +429,8 @@ 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; }
+
   /* initialize cache (mutex) */
   void init();
   /* resize query cache (return real query size, 0 if disabled) */

Thread
bzr commit into mysql-6.0 branch (kristofer.pettersson:2742) Bug#38551Kristofer Pettersson29 Oct