lib/dml/moodle_transaction.php

   1 <?php
   2
   3 // This file is part of Moodle - http://moodle.org/
   4 //
   5 // Moodle is free software: you can redistribute it and/or modify
   6 // it under the terms of the GNU General Public License as published by
   7 // the Free Software Foundation, either version 3 of the License, or
   8 // (at your option) any later version.
   9 //
  10 // Moodle is distributed in the hope that it will be useful,
  11 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 // GNU General Public License for more details.
  14 //
  15 // You should have received a copy of the GNU General Public License
  16 // along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
  17
  18
  19 /**
  20  * Delegated database transaction support.
  21  *
  22  * @package    core
  23  * @subpackage dml
  24  * @copyright  2009 Petr Skoda (http://skodak.org)
  25  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  26  */
  27
  28 defined('MOODLE_INTERNAL') || die();
  29
  30 /**
  31  * Delegated transaction class.
  32  */
  33 class moodle_transaction {
  34     private $start_backtrace;
  35     private $database = null;
  36
  37     /**
  38      * Delegated transaction constructor,
  39      * can be called only from moodle_database class.
  40      * Unfortunately PHP's protected keyword is useless.
  41      * @param moodle_database $database
  42      */
  43     public function __construct($database) {
  44         $this->database = $database;
  45         $this->start_backtrace = debug_backtrace();
  46         array_shift($this->start_backtrace);
  47     }
  48
  49     /**
  50      * Returns backtrace of the code starting exception.
  51      * @return array
  52      */
  53     public function get_backtrace() {
  54         return $this->start_backtrace;
  55     }
  56
  57     /**
  58      * Is the delegated transaction already used?
  59      * @return bool true if commit and rollback allowed, false if already done
  60      */
  61     public function is_disposed() {
  62         return empty($this->database);
  63     }
  64
  65     /**
  66      * Mark transaction as disposed, no more
  67      * commits and rollbacks allowed.
  68      * To be used only from moodle_database class
  69      * @return unknown_type
  70      */
  71     public function dispose() {
  72         return $this->database = null;
  73     }
  74
  75     /**
  76      * Commit delegated transaction.
  77      * The real database commit SQL is executed
  78      * only after committing all delegated transactions.
  79      *
  80      * Incorrect order of nested commits or rollback
  81      * at any level is resulting in rollback of SQL transaction.
  82      *
  83      * @return void
  84      */
  85     public function allow_commit() {
  86         if ($this->is_disposed()) {
  87             throw new dml_transaction_exception('Transactions already disposed', $this);
  88         }
  89         $this->database->commit_delegated_transaction($this);
  90     }
  91
  92     /**
  93      * Rollback all current delegated transactions.
  94      *
  95      * @param Exception $e mandatory exception
  96      * @return void
  97      */
  98     public function rollback(Exception $e) {
  99         if ($this->is_disposed()) {
 100             throw new dml_transaction_exception('Transactions already disposed', $this);
 101         }
 102         $this->database->rollback_delegated_transaction($this, $e);
 103     }
 104 }