Ticket #9422: 9422-new-wpdb-methods.diff

Users/denis/Sites/wp/wp-includes/wp-db.php

@@ -280 +280 @@
          * @var bool
          */
         var $real_escape = false;
+        
+        /**
+         * The current transaction id
+         *
+         * @var string
+         **/
+        var $tx_id = false;
 
         /**
          * Connects to the database server and selects a database
@@ -1050 +1057 @@
 
                 return $caller;
         }
+        
+        /**
+         * Start an SQL transaction if and only if none is already entered into
+         * Note: This function is useless unless you use MySQL's InnoDB or NDBCluster engines
+         *
+         * Using this function, alongside rollback() and commit() below, will allows to work around the following MySQL quirk:
+         *
+         * START TRANSACTION;
+         * SELECT * FROM foo; -- 2 rows
+         * DELETE FROM foo WHERE bar1; -- delete 1 row
+         * DELETE FROM foo WHERE bar2; -- MySQL complains and returns an error
+         * COMMIT;
+         * SELECT * FROM foo; -- 1 row, instead of the 2 you'd get in PGSQL or TSQL
+         *
+         * @param string $tx_id a unique transaction id that may wrap several sql statements, e.g. 'delete_post_3'
+         * @return true on transaction start
+         **/
 
+        function begin($tx_id) {
+                if ( $this->tx_id === false && $tx_id ) {
+                        $this->tx_id = $tx_id;
+                        $this->query("START TRANSACTION;");
+                        return true;
+                } else {
+                        // already in a transaction, or invalid tx_id
+                        return false;
+                }
+        }
+        
         /**
+         * Signal the end of a transaction that spans multiple database statements.
+         *
+         * Commits if and only if the specified transaction id is that of the first transaction that was started.
+         *
+         * @param string $tx_id a unique transaction id that may wrap several sql statements, e.g. 'delete_post_3'
+         * @return true on commit
+         **/
+
+        function commit($tx_id) {
+                if ( isset($this->tx_id) && $tx_id && $this->tx_id == $tx_id ) {
+                        $this->tx_id = false;
+                        $this->query("COMMIT;");
+                        return true;
+                } else {
+                        // still in a transaction, or invalid tx_id
+                        return false;
+                }
+        }
+        
+        /**
+         * Rollback the current transaction and die with the error message
+         * Note: If you've any use for this, you actually *want* WP to die on a failed transaction, rather than catch the error, because it would only ever get called when a workflow error occurs.
+         *
+         * @param string $message Error message.
+         * @param string $title Error title.
+         * @param string|array $args Optional arguements to control behaviour.
+         * @return void
+         **/
+
+        function rollback($message, $title = '', $args = array()) {
+                if ( $this->tx_id ) {
+                        $this->tx_id = false;
+                        $wpdb->query("ROLLBACK;");
+                }
+                // die no matter what, to highlight the workflow error
+                wp_die($message, $title, $args);
+        }
+
+        /**
          * The database version number
          * @return false|string false on failure, version number on success
          */