branches/zip: Fast index creation: Lock the data dictionary only after

acquiring the table lock.  The data dictionary should not be locked for
long periods.  Before this change, in the worst case, the dictionary
would be locked until the expiration of innodb_lock_wait_timeout.

Virtually, transaction-level locks (locks on database objects, such
as records and tables) have a latching order level of SYNC_USER_TRX_LOCK,
which is above any InnoDB rw-locks or mutexes.  However, the latching
order of SYNC_USER_TRX_LOCK is never checked, not even by UNIV_SYNC_DEBUG.

ha_innobase::add_index(), ha_innobase::final_drop_index(): Invoke
row_mysql_lock_data_dictionary(trx) only after row_merge_lock_table().

handler/handler0alter.cc

@@ -693,12 +693,6 @@ ha_innobase::add_index(
 	index = (dict_index_t**) mem_heap_alloc(
 		heap, num_of_idx * sizeof *index);
 
-	/* Latch the InnoDB data dictionary exclusively so that no deadlocks
-	or lock waits can happen in it during an index create operation. */
-
-	row_mysql_lock_data_dictionary(trx);
-	dict_locked = TRUE;
-
 	/* Flag this transaction as a dictionary operation, so that
 	the data dictionary will be locked in crash recovery.  Prevent
 	warnings if row_merge_lock_table() results in a lock wait,
@@ -717,6 +711,12 @@ ha_innobase::add_index(
 
 	trx_set_dict_operation(trx, TRX_DICT_OP_INDEX);
 
+	/* Latch the InnoDB data dictionary exclusively so that no deadlocks
+	or lock waits can happen in it during an index create operation. */
+
+	row_mysql_lock_data_dictionary(trx);
+	dict_locked = TRUE;
+
 	/* If a new primary key is defined for the table we need
 	to drop the original table and rebuild all indexes. */
 
@@ -1092,10 +1092,6 @@ ha_innobase::final_drop_index(
 	trx->mysql_thd = user_thd;
 	trx->mysql_query_str = thd_query(user_thd);
 
-	/* Drop indexes marked to be dropped */
-
-	row_mysql_lock_data_dictionary(trx);
-
 	/* Flag this transaction as a dictionary operation, so that
 	the data dictionary will be locked in crash recovery.  Prevent
 	warnings if row_merge_lock_table() results in a lock wait,
@@ -1116,6 +1112,10 @@ ha_innobase::final_drop_index(
 
 	trx_set_dict_operation(trx, TRX_DICT_OP_INDEX);
 
+	/* Drop indexes marked to be dropped */
+
+	row_mysql_lock_data_dictionary(trx);
+
 	index = dict_table_get_first_index(prebuilt->table);
 
 	while (index) {
@@ -1134,10 +1134,10 @@ ha_innobase::final_drop_index(
 #ifdef UNIV_DEBUG
 	dict_table_check_for_dup_indexes(prebuilt->table);
 #endif
+	row_mysql_unlock_data_dictionary(trx);
 
 func_exit:
 	trx_commit_for_mysql(trx);
-	row_mysql_unlock_data_dictionary(trx);
 
 	/* Flush the log to reduce probability that the .frm files and
 	the InnoDB data dictionary get out-of-sync if the user runs