Added startup option and settable session variable

innodb_table_locks_old_behavior: do not acquire an
InnoDB table lock for LOCK TABLES, as in mysql-4.0.18
and earlier.

sql/ha_innodb.cc

@@ -4693,7 +4693,8 @@ ha_innobase::external_lock(
 		}
 
 		if (prebuilt->select_lock_type != LOCK_NONE) {
-			if (thd->in_lock_tables) {
+			if (thd->in_lock_tables &&
+			    !thd->variables.innodb_table_locks_old_behavior) {
 				ulint	error;
 				error = row_lock_table_for_mysql(prebuilt);
 

sql/mysqld.cc

@@ -3526,6 +3526,7 @@ enum options_mysqld {
   OPT_INNODB_FORCE_RECOVERY,
   OPT_INNODB_STATUS_FILE,
   OPT_INNODB_MAX_DIRTY_PAGES_PCT,
+  OPT_INNODB_TABLE_LOCKS_OLD_BEHAVIOR,
   OPT_BDB_CACHE_SIZE,
   OPT_BDB_LOG_BUFFER_SIZE,
   OPT_BDB_MAX_LOCK,
@@ -3699,7 +3700,11 @@ struct my_option my_long_options[] =
   {"innodb_max_dirty_pages_pct", OPT_INNODB_MAX_DIRTY_PAGES_PCT,
    "Percentage of dirty pages allowed in bufferpool", (gptr*) &srv_max_buf_pool_modified_pct,
    (gptr*) &srv_max_buf_pool_modified_pct, 0, GET_ULONG, REQUIRED_ARG, 90, 0, 100, 0, 0, 0},
-   
+  {"innodb_table_locks_old_behavior", OPT_INNODB_TABLE_LOCKS_OLD_BEHAVIOR,
+   "Disable InnoDB locking in LOCK TABLES",
+   (gptr*) &global_system_variables.innodb_table_locks_old_behavior,
+   (gptr*) &global_system_variables.innodb_table_locks_old_behavior,
+   0, GET_BOOL, OPT_ARG, 0, 0, 0, 0, 0, 0},
 #endif /* End HAVE_INNOBASE_DB */
   {"help", '?', "Display this help and exit", 0, 0, 0, GET_NO_ARG, NO_ARG, 0,
    0, 0, 0, 0, 0},

sql/set_var.cc

@@ -263,6 +263,8 @@ sys_var_thd_ulong	sys_net_wait_timeout("wait_timeout",
 #ifdef HAVE_INNOBASE_DB
 sys_var_long_ptr        sys_innodb_max_dirty_pages_pct("innodb_max_dirty_pages_pct",
                                                         &srv_max_buf_pool_modified_pct);
+sys_var_thd_bool	sys_innodb_table_locks_old_behavior("innodb_table_locks_old_behavior",
+							&SV::innodb_table_locks_old_behavior);
 #endif 					     
 
 
@@ -449,6 +451,7 @@ sys_var *sys_variables[]=
   &sys_os,
 #ifdef HAVE_INNOBASE_DB
   &sys_innodb_max_dirty_pages_pct,
+  &sys_innodb_table_locks_old_behavior,
 #endif    
   &sys_unique_checks
 };
@@ -520,6 +523,7 @@ struct show_var_st init_vars[]= {
   {"innodb_log_group_home_dir", (char*) &innobase_log_group_home_dir, SHOW_CHAR_PTR},
   {"innodb_mirrored_log_groups", (char*) &innobase_mirrored_log_groups, SHOW_LONG},
   {sys_innodb_max_dirty_pages_pct.name, (char*) &sys_innodb_max_dirty_pages_pct, SHOW_SYS},
+  {sys_innodb_table_locks_old_behavior.name, (char*) &sys_innodb_table_locks_old_behavior, SHOW_SYS},
 #endif
   {sys_interactive_timeout.name,(char*) &sys_interactive_timeout,   SHOW_SYS},
   {sys_join_buffer_size.name,   (char*) &sys_join_buffer_size,	    SHOW_SYS},

sql/sql_class.h

@@ -338,6 +338,9 @@ struct system_variables
   my_bool low_priority_updates;
   my_bool new_mode;
   my_bool query_cache_wlock_invalidate;
+#ifdef HAVE_INNOBASE_DB
+  my_bool innodb_table_locks_old_behavior;
+#endif /* HAVE_INNOBASE_DB */
 
   CONVERT *convert_set;
 };