branches/zip: Simplify the locking of the data dictionary.

row_upd_index_is_referenced(), row_upd_check_references_constraints(),
row_purge_parse_undo_rec(): Remove duplicated code that calls
row_mysql_unfreeze_data_dictionary().

row_undo_ins_remove_clust_rec():
Assert that the data dictionary is X-latched.  Do not attempt to re-latch
the data dictionary, because doing so introduces race conditions.  This
re-latching was probably made unnecessary already in r1676, which keeps
the data dictionary X-latched in ha_innobase::add_index() for the complete
duration of the data dictionary operations.

row_undo_ins_parse_undo_rec(): Do not attempt to acquire the data dictionary
latch.  The data dictionary should be already X-latched when a transaction
that modifies system tables is rolled back.  This also holds in the rollback
during crash recovery: trx_rollback_active() will X-latch the data dictionary
when needed.

row/row0purge.c

@@ -526,9 +526,8 @@ row_purge_parse_undo_rec(
 
 	if (node->table == NULL) {
 		/* The table has been dropped: no need to do purge */
-
+err_exit:
 		row_mysql_unfreeze_data_dictionary(trx);
-
 		return(FALSE);
 	}
 
@@ -537,9 +536,7 @@ row_purge_parse_undo_rec(
 
 		node->table = NULL;
 
-		row_mysql_unfreeze_data_dictionary(trx);
-
-		return(FALSE);
+		goto err_exit;
 	}
 
 	clust_index = dict_table_get_first_index(node->table);
@@ -547,9 +544,7 @@ row_purge_parse_undo_rec(
 	if (clust_index == NULL) {
 		/* The table was corrupt in the data dictionary */
 
-		row_mysql_unfreeze_data_dictionary(trx);
-
-		return(FALSE);
+		goto err_exit;
 	}
 
 	ptr = trx_undo_rec_get_row_ref(ptr, clust_index, &(node->ref),

row/row0uins.c

@@ -53,24 +53,7 @@ row_undo_ins_remove_clust_rec(
 	ut_a(success);
 
 	if (ut_dulint_cmp(node->table->id, DICT_INDEXES_ID) == 0) {
-		trx_t*	trx;
-		ibool	thawed_dictionary = FALSE;
-		ibool	locked_dictionary = FALSE;
-
-		trx = node->trx;
-
-		if (trx->dict_operation_lock_mode == RW_S_LATCH) {
-			row_mysql_unfreeze_data_dictionary(trx);
-
-			thawed_dictionary = TRUE;
-		}
-
-		if (trx->dict_operation_lock_mode != RW_X_LATCH) {
-
-			row_mysql_lock_data_dictionary(trx);
-
-			locked_dictionary = TRUE;
-		}
+		ut_ad(node->trx->dict_operation_lock_mode == RW_X_LATCH);
 
 		/* Drop the index tree associated with the row in
 		SYS_INDEXES table: */
@@ -84,14 +67,6 @@ row_undo_ins_remove_clust_rec(
 		success = btr_pcur_restore_position(BTR_MODIFY_LEAF,
 						    &(node->pcur), &mtr);
 		ut_a(success);
-
-		if (locked_dictionary) {
-			row_mysql_unlock_data_dictionary(trx);
-		}
-
-		if (thawed_dictionary) {
-			row_mysql_freeze_data_dictionary(trx);
-		}
 	}
 
 	btr_cur = btr_pcur_get_btr_cur(&(node->pcur));
@@ -288,31 +263,7 @@ row_undo_ins_parse_undo_rec(
 
 	if (node->rec_type == TRX_UNDO_INSERT_REC) {
 
-		trx_t*	trx;
-		ibool	thawed_dictionary = FALSE;
-		ibool	locked_dictionary = FALSE;
-
-		trx = node->trx;
-
-		/* If it is a system table, acquire the
-		dictionary lock in exclusive mode. */
-
-		if (ut_dulint_cmp(table_id, DICT_FIELDS_ID) <= 0) {
-			if (trx->dict_operation_lock_mode == RW_S_LATCH) {
-				row_mysql_unfreeze_data_dictionary(trx);
-
-				thawed_dictionary = TRUE;
-			}
-
-			if (trx->dict_operation_lock_mode != RW_X_LATCH) {
-
-				row_mysql_lock_data_dictionary(trx);
-
-				locked_dictionary = TRUE;
-			}
-		}
-
-		node->table = dict_table_get_on_id(table_id, trx);
+		node->table = dict_table_get_on_id(table_id, node->trx);
 
 		/* If we can't find the table or .ibd file is missing,
 		we skip the UNDO.*/
@@ -327,14 +278,6 @@ row_undo_ins_parse_undo_rec(
 			ptr = trx_undo_rec_get_row_ref(
 				ptr, clust_index, &node->ref, node->heap);
 		}
-
-		if (locked_dictionary) {
-			row_mysql_unlock_data_dictionary(trx);
-		}
-
-		if (thawed_dictionary) {
-			row_mysql_freeze_data_dictionary(trx);
-		}
 	}
 }
 

row/row0upd.c

@@ -107,6 +107,7 @@ row_upd_index_is_referenced(
 	dict_table_t*	table		= index->table;
 	dict_foreign_t*	foreign;
 	ibool		froze_data_dict	= FALSE;
+	ibool		is_referenced	= FALSE;
 
 	if (!UT_LIST_GET_FIRST(table->referenced_list)) {
 
@@ -123,21 +124,19 @@ row_upd_index_is_referenced(
 	while (foreign) {
 		if (foreign->referenced_index == index) {
 
-			if (froze_data_dict) {
-				row_mysql_unfreeze_data_dictionary(trx);
-			}
-
-			return(TRUE);
+			is_referenced = TRUE;
+			goto func_exit;
 		}
 
 		foreign = UT_LIST_GET_NEXT(referenced_list, foreign);
 	}
 
+func_exit:
 	if (froze_data_dict) {
 		row_mysql_unfreeze_data_dictionary(trx);
 	}
 
-	return(FALSE);
+	return(is_referenced);
 }
 
 /*************************************************************************
@@ -237,27 +236,24 @@ row_upd_check_references_constraints(
 			}
 
 			if (err != DB_SUCCESS) {
-				if (got_s_lock) {
-					row_mysql_unfreeze_data_dictionary(
-						trx);
-				}
 
-				mem_heap_free(heap);
-
-				return(err);
+				goto func_exit;
 			}
 		}
 
 		foreign = UT_LIST_GET_NEXT(referenced_list, foreign);
 	}
 
+	err = DB_SUCCESS;
+
+func_exit:
 	if (got_s_lock) {
 		row_mysql_unfreeze_data_dictionary(trx);
 	}
 
 	mem_heap_free(heap);
 
-	return(DB_SUCCESS);
+	return(err);
 }
 
 /*************************************************************************