Backport of:

----------------------------------------------------------
revno: 2630.10.1
committer: Konstantin Osipov <konstantin@mysql.com>
branch nick: mysql-6.0-lock-tables-tidyup
timestamp: Wed 2008-06-11 15:49:58 +0400
message:
  WL#3726, review fixes.
  Now that we have metadata locks, we don't need to keep a crippled
  TABLE instance in the table cache to indicate that a table is locked.
  Remove all code that used this technique. Instead, rely on metadata
  locks and use the standard open_table() and close_thread_table()
  to manipulate with the table cache tables.
  Removes a list of functions that have become unused (see the comment
  for sql_base.cc for details).
  Under LOCK TABLES, keep a TABLE_LIST instance for each table
  that may be temporarily closed. For that, implement an own class for
  LOCK TABLES mode, Locked_tables_list.

This is a pre-requisite patch for WL#4144.
This is not exactly a backport: there is no new 
online ALTER table in Celosia, so the old alter table
code was changed to work with the new table cache API.


mysql-test/r/lock.result:
  Update results (WL#3726 post-review patch).
mysql-test/r/trigger-compat.result:
  We take the table from the table cache now, thus no warning.
mysql-test/suite/rpl/r/rpl_trigger.result:
  We take the table from the table cache now, thus no warning.
mysql-test/t/lock.test:
  Additional tests for LOCK TABLES mode (previously not covered by
  the test suite (WL#3726).
sql/field.h:
  Remove reopen_table().
sql/lock.cc:
  Remove an obsolete parameter of mysql_lock_remove().
  It's not used anywhere now either.
sql/mysql_priv.h:
  Add 4 new open_table() flags.
  Remove declarations of removed functions.
sql/sp_head.cc:
  Rename thd->mdl_el_root to thd->locked_tables_root.
sql/sql_acl.cc:
  Use the new implementation of unlock_locked_tables().
sql/sql_base.cc:
  Implement class Locked_tables_list.
  Implement close_all_tables_for_name().
  Rewrite close_cached_tables() to use the new reopen_tables().
  Remove reopen_table(), reopen_tables(), reopen_table_entry() 
  (ex. open_unireg_entry()), close_data_files_and_leave_as_placeholders(),
  close_handle_and_leave_table_as_placeholder(), close_cached_table(),
  table_def_change_share(), reattach_merge(), reopen_name_locked_table(),
  unlink_open_table().
  
  Move acquisition of a metadata lock into an own function
  - open_table_get_mdl_lock().
sql/sql_class.cc:
  Deploy class Locked_tables_list.
sql/sql_class.h:
  Declare class Locked_tables_list.
  Keep one instance of this class in class THD.
  Rename mdl_el_root to locked_tables_root.
sql/sql_db.cc:
  Update a comment.
sql/sql_insert.cc:
  Use the plain open_table() to open a just created table in
  CREATE TABLE .. SELECT.
sql/sql_parse.cc:
  Use thd->locked_tables_list to enter and leave LTM_LOCK_TABLES mode.
sql/sql_partition.cc:
  Deploy the new method of working with partitioned table locks.
sql/sql_servers.cc:
  Update to the new signature of unlock_locked_tables().
sql/sql_table.cc:
  In mysql_rm_table_part2(), the branch that removes a table under
  LOCK TABLES, make sure that the table being dropped
  is also removed from THD::locked_tables_list.
  Update ALTER TABLE and CREATE TABLE LIKE implementation to use
  open_table() and close_all_tables_for_name() instead of 
  reopen_tables().
sql/sql_trigger.cc:
  Use the new locking way.
sql/table.h:
  Add TABLE::pos_in_locked_tables, which is used only under
  LOCK TABLES.

sql/sql_trigger.cc

@@ -328,6 +328,7 @@ bool mysql_create_or_drop_trigger(THD *thd, TABLE_LIST *tables, bool create)
   bool result= TRUE;
   String stmt_query;
   bool need_start_waiting= FALSE;
+  bool lock_upgrade_done= FALSE;
 
   DBUG_ENTER("mysql_create_or_drop_trigger");
 
@@ -450,72 +451,54 @@ bool mysql_create_or_drop_trigger(THD *thd, TABLE_LIST *tables, bool create)
     if (!(tables->table= find_write_locked_table(thd->open_tables, tables->db,
                                                  tables->table_name)))
       goto end;
-    /*
-      Ensure that table is opened only by this thread and that no other
-      statement will open this table.
-    */
-    if (wait_while_table_is_used(thd, tables->table, HA_EXTRA_FORCE_REOPEN))
-      goto end;
-
-    pthread_mutex_lock(&LOCK_open);
+    /* Later on we will need it to downgrade the lock */
+    tables->mdl_lock_data= tables->table->mdl_lock_data;
   }
   else
   {
-    /*
-      Obtain exlusive meta-data lock on the table and remove TABLE
-      instances from cache.
-    */
-    if (lock_table_names(thd, tables))
+    tables->table= open_n_lock_single_table(thd, tables,
+                                            TL_WRITE_ALLOW_READ,
+                                            MYSQL_OPEN_TAKE_UPGRADABLE_MDL);
+    if (! tables->table)
       goto end;
-
-    pthread_mutex_lock(&LOCK_open);
-    tdc_remove_table(thd, TDC_RT_REMOVE_ALL, tables->db, tables->table_name);
-
-    if (reopen_name_locked_table(thd, tables))
-      goto end_unlock;
+    tables->table->use_all_columns();
   }
   table= tables->table;
 
+  if (wait_while_table_is_used(thd, table, HA_EXTRA_FORCE_REOPEN))
+    goto end;
+
+  lock_upgrade_done= TRUE;
+
   if (!table->triggers)
   {
     if (!create)
     {
       my_error(ER_TRG_DOES_NOT_EXIST, MYF(0));
-      goto end_unlock;
+      goto end;
     }
 
     if (!(table->triggers= new (&table->mem_root) Table_triggers_list(table)))
-      goto end_unlock;
+      goto end;
   }
 
+  pthread_mutex_lock(&LOCK_open);
   result= (create ?
            table->triggers->create_trigger(thd, tables, &stmt_query):
            table->triggers->drop_trigger(thd, tables, &stmt_query));
-
-  /* Under LOCK TABLES we must reopen the table to activate the trigger. */
-  if (!result && thd->locked_tables_mode)
-  {
-    /* Make table suitable for reopening */
-    close_data_files_and_leave_as_placeholders(thd, tables->db,
-                                               tables->table_name);
-    thd->in_lock_tables= 1;
-    if (reopen_tables(thd, 1))
-    {
-      /* To be safe remove this table from the set of LOCKED TABLES */
-      unlink_open_table(thd, tables->table, FALSE);
-
-      /*
-        Ignore reopen_tables errors for now. It's better not leave master/slave
-        in a inconsistent state.
-      */
-      thd->clear_error();
-    }
-    thd->in_lock_tables= 0;
-  }
-
-end_unlock:
   pthread_mutex_unlock(&LOCK_open);
 
+  if (result)
+    goto end;
+
+  close_all_tables_for_name(thd, table->s, FALSE);
+  /*
+    Reopen the table if we were under LOCK TABLES.
+    Ignore the return value for now. It's better to
+    keep master/slave in consistent state.
+  */
+  thd->locked_tables_list.reopen_tables(thd);
+
 end:
   if (!result)
   {
@@ -525,11 +508,11 @@ end:
   /*
     If we are under LOCK TABLES we should restore original state of meta-data
     locks. Otherwise call to close_thread_tables() will take care about both
-    TABLE instance created by reopen_name_locked_table() and metadata lock.
+    TABLE instance created by open_n_lock_single_table() and metadata lock.
   */
-  if (thd->locked_tables_mode && tables && tables->table)
+  if (thd->locked_tables_mode && tables && lock_upgrade_done)
     mdl_downgrade_exclusive_lock(&thd->mdl_context,
-                                 tables->table->mdl_lock_data);
+                                 tables->mdl_lock_data);
 
   if (need_start_waiting)
     start_waiting_global_read_lock(thd);