bzr commit into mysql-6.1-fk branch (dlenev:2724) WL#148

[Dmitry Lenev]

#At file:///home/dlenev/src/bzr/mysql-6.1-mil14/ based on
revid:dlenev@stripped

 2724 Dmitry Lenev	2009-05-13
      WL#148 "Foreign keys".
      
      Milestone 14 "DDL checks and changes: DROP, TRUNCATE, RENAME".
      
      Work in progress. "Solve" remaining problems with auto-discovery
      and LOCK_open handling.

    modified:
      sql/mysql_priv.h
      sql/sql_base.cc
      sql/sql_table.cc
=== modified file 'sql/mysql_priv.h'
--- a/sql/mysql_priv.h	2009-05-07 05:16:19 +0000
+++ b/sql/mysql_priv.h	2009-05-13 05:28:49 +0000
@@ -1311,6 +1311,9 @@ uint create_table_def_key(THD *thd, char
                           bool tmp_table);
 TABLE_SHARE *get_table_share(THD *thd, TABLE_LIST *table_list, char *key,
                              uint key_length, uint db_flags, int *error);
+TABLE_SHARE *get_table_share_with_create(THD *thd, TABLE_LIST *table_list,
+                                         char *key, uint key_length,
+                                         uint db_flags, int *error);
 void release_table_share(TABLE_SHARE *share);
 TABLE_SHARE *get_cached_table_share(const char *db, const char *table_name);
 TABLE *open_ltable(THD *thd, TABLE_LIST *table_list, thr_lock_type update,

=== modified file 'sql/sql_base.cc'
--- a/sql/sql_base.cc	2009-05-09 19:19:11 +0000
+++ b/sql/sql_base.cc	2009-05-13 05:28:49 +0000
@@ -536,7 +536,7 @@ found:
   For arguments and return values, see get_table_from_share()
 */
 
-static TABLE_SHARE
+TABLE_SHARE
 *get_table_share_with_create(THD *thd, TABLE_LIST *table_list,
                              char *key, uint key_length,
                              uint db_flags, int *error)

=== modified file 'sql/sql_table.cc'
--- a/sql/sql_table.cc	2009-05-09 19:19:11 +0000
+++ b/sql/sql_table.cc	2009-05-13 05:28:49 +0000
@@ -2340,13 +2340,11 @@ fk_check_tables_before_drop(THD *thd, TA
       data-dictionary as result. We accept this as a trade-off.
       ER_CANT_OPEN_FILE is transient so it makes sense to abort statement
       to allow it to be executed normally later.
-
-      TODO/QQ: Should we perform auto-discovery here ? Probably yes...
-               But what about opt_fk_all_engines = 0 mode ?
     */
     thd->push_internal_handler(&non_fatal_error_silencer);
     pthread_mutex_lock(&LOCK_open);
-    share= get_table_share(thd, table, key, key_length, OPEN_VIEW, &error);
+    share= get_table_share_with_create(thd, table, key, key_length, OPEN_VIEW,
+                                       &error);
     pthread_mutex_unlock(&LOCK_open);
     thd->pop_internal_handler();
 
@@ -2691,9 +2689,6 @@ retry_lock:
       parents_locked= parents_to_lock;
       fk_names_locked= fk_names_to_lock;
 
-      // TODO/FIXME: Move auto-discovery here?
-
-
       if (opt_fk_all_engines)
       {
         if (fk_check_tables_before_drop(thd, tables,
@@ -2849,11 +2844,22 @@ retry_lock:
     /*
       TODO: Investigate what should be done to remove this lock completely.
             Is exclusive meta-data lock enough ?
+
+      TODO: We can move auto-discovery of table in --foreign-key-all-engines=0
+            mode to the same place as it happens in --foreign-key-all-engines=1
+            once WL#3983 "LOCK_open: no longer necessary for disk I/O (to read/
+            write .frm files)" is done so there will be no chance that other
+            thread will ignore metadata lock and create or drop table between
+            the moment when we perform auto-discovery and when the table is
+            finally dropped. To be efficient after this change we also will
+            have to introduce per-table runtime context to be able to cache
+            information about table type, existence and etc.
     */
     pthread_mutex_lock(&LOCK_open);
     if (drop_temporary ||
         (table_type == NULL &&        
          (access(path, F_OK) &&
+          ! opt_fk_all_engines &&
           ha_create_table_from_engine(thd, db, alias)) ||
          (!drop_view &&
           mysql_frm_type(thd, path, &frm_db_type) != FRMTYPE_TABLE)))
@@ -2869,18 +2875,22 @@ retry_lock:
     else
     {
       char *end;
-      /*
-        FIXME: - Get rid of this ugly LOCK_open handling,
-               - Ensure that FK operation is atomic with .FRM deletion.
-      */
-      pthread_mutex_unlock(&LOCK_open);
-      if (opt_fk_all_engines &&
-          fk_ctx.install_new_frms())
+
+      if (opt_fk_all_engines)
       {
-        error= 1;
-        goto err_table;
+        /*
+          TODO: Once WL#3983 "LOCK_open: no longer necessary for disk I/O
+                (to read/write .frm files)" is done this ugly handling of
+                LOCK_open will go away.
+        */
+        pthread_mutex_unlock(&LOCK_open);
+        if (fk_ctx.install_new_frms())
+        {
+          error= 1;
+          goto err_table;
+        }
+        pthread_mutex_lock(&LOCK_open);
       }
-      pthread_mutex_lock(&LOCK_open);
 
 
       if (table_type == NULL)
@@ -2932,8 +2942,15 @@ retry_lock:
         }
       }
 
-      if (thd->locked_tables_mode)
+      if (opt_fk_all_engines && thd->locked_tables_mode)
       {
+        /*
+          Re-open tables related to table being dropped (tables which
+          participate in a foreign key relationship with this table)
+          after updating their .FRMs.
+
+          See comment about the fate of LOCK_open above.
+        */
         pthread_mutex_unlock(&LOCK_open);
         if (thd->locked_tables_list.reopen_tables(thd))
         {


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