includes/db/CloneDatabase.php

   1 <?php
   2 /**
   3  * Helper class for making a copy of the database, mostly for unit testing.
   4  *
   5  * Copyright © 2010 Chad Horohoe <chad@anyonecanedit.org>
   6  * https://www.mediawiki.org/
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License along
  19  * with this program; if not, write to the Free Software Foundation, Inc.,
  20  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  21  * http://www.gnu.org/copyleft/gpl.html
  22  *
  23  * @file
  24  * @ingroup Database
  25  */
  26 use MediaWiki\MediaWikiServices;
  27 use Wikimedia\Rdbms\IMaintainableDatabase;
  28
  29 class CloneDatabase {
  30         /** @var string Table prefix for cloning */
  31         private $newTablePrefix = '';
  32
  33         /** @var string Current table prefix */
  34         private $oldTablePrefix = '';
  35
  36         /** @var array List of tables to be cloned */
  37         private $tablesToClone = [];
  38
  39         /** @var bool Should we DROP tables containing the new names? */
  40         private $dropCurrentTables = true;
  41
  42         /** @var bool Whether to use temporary tables or not */
  43         private $useTemporaryTables = true;
  44
  45         /** @var IMaintainableDatabase */
  46         private $db;
  47
  48         /**
  49          * @param IMaintainableDatabase $db A database subclass
  50          * @param array $tablesToClone An array of tables to clone, unprefixed
  51          * @param string $newTablePrefix Prefix to assign to the tables
  52          * @param string $oldTablePrefix Prefix on current tables, if not $wgDBprefix
  53          * @param bool $dropCurrentTables
  54          */
  55         public function __construct( IMaintainableDatabase $db, array $tablesToClone,
  56                 $newTablePrefix, $oldTablePrefix = '', $dropCurrentTables = true
  57         ) {
  58                 $this->db = $db;
  59                 $this->tablesToClone = $tablesToClone;
  60                 $this->newTablePrefix = $newTablePrefix;
  61                 $this->oldTablePrefix = $oldTablePrefix ? $oldTablePrefix : $this->db->tablePrefix();
  62                 $this->dropCurrentTables = $dropCurrentTables;
  63         }
  64
  65         /**
  66          * Set whether to use temporary tables or not
  67          * @param bool $u Use temporary tables when cloning the structure
  68          */
  69         public function useTemporaryTables( $u = true ) {
  70                 $this->useTemporaryTables = $u;
  71         }
  72
  73         /**
  74          * Clone the table structure
  75          */
  76         public function cloneTableStructure() {
  77                 global $wgSharedTables, $wgSharedDB;
  78                 foreach ( $this->tablesToClone as $tbl ) {
  79                         if ( $wgSharedDB && in_array( $tbl, $wgSharedTables, true ) ) {
  80                                 // Shared tables don't work properly when cloning due to
  81                                 // how prefixes are handled (T67654)
  82                                 throw new RuntimeException( "Cannot clone shared table $tbl." );
  83                         }
  84                         # Clean up from previous aborted run.  So that table escaping
  85                         # works correctly across DB engines, we need to change the pre-
  86                         # fix back and forth so tableName() works right.
  87
  88                         self::changePrefix( $this->oldTablePrefix );
  89                         $oldTableName = $this->db->tableName( $tbl, 'raw' );
  90
  91                         self::changePrefix( $this->newTablePrefix );
  92                         $newTableName = $this->db->tableName( $tbl, 'raw' );
  93
  94                         // Postgres: Temp tables are automatically deleted upon end of session
  95                         //           Same Temp table name hides existing table for current session
  96                         if ( $this->dropCurrentTables
  97                                 && !in_array( $this->db->getType(), [ 'oracle' ] )
  98                         ) {
  99                                 if ( $oldTableName === $newTableName ) {
 100                                         // Last ditch check to avoid data loss
 101                                         throw new LogicException( "Not dropping new table, as '$newTableName'"
 102                                                 . " is name of both the old and the new table." );
 103                                 }
 104                                 $this->db->dropTable( $tbl, __METHOD__ );
 105                                 wfDebug( __METHOD__ . " dropping {$newTableName}\n" );
 106                                 // Dropping the oldTable because the prefix was changed
 107                         }
 108
 109                         # Create new table
 110                         wfDebug( __METHOD__ . " duplicating $oldTableName to $newTableName\n" );
 111                         $this->db->duplicateTableStructure(
 112                                 $oldTableName, $newTableName, $this->useTemporaryTables );
 113                 }
 114         }
 115
 116         /**
 117          * Change the prefix back to the original.
 118          * @param bool $dropTables Optionally drop the tables we created
 119          */
 120         public function destroy( $dropTables = false ) {
 121                 if ( $dropTables ) {
 122                         self::changePrefix( $this->newTablePrefix );
 123                         foreach ( $this->tablesToClone as $tbl ) {
 124                                 $this->db->dropTable( $tbl );
 125                         }
 126                 }
 127                 self::changePrefix( $this->oldTablePrefix );
 128         }
 129
 130         /**
 131          * Change the table prefix on all open DB connections/
 132          *
 133          * @param string $prefix
 134          * @return void
 135          */
 136         public static function changePrefix( $prefix ) {
 137                 global $wgDBprefix;
 138
 139                 $lbFactory = MediaWikiServices::getInstance()->getDBLoadBalancerFactory();
 140                 $lbFactory->setDomainPrefix( $prefix );
 141                 $wgDBprefix = $prefix;
 142         }
 143 }