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
  27 class CloneDatabase {
  28         /** @var string Table prefix for cloning */
  29         private $newTablePrefix = '';
  30
  31         /** @var string Current table prefix */
  32         private $oldTablePrefix = '';
  33
  34         /** @var array List of tables to be cloned */
  35         private $tablesToClone = [];
  36
  37         /** @var bool Should we DROP tables containing the new names? */
  38         private $dropCurrentTables = true;
  39
  40         /** @var bool Whether to use temporary tables or not */
  41         private $useTemporaryTables = true;
  42
  43         /**
  44          * Constructor
  45          *
  46          * @param DatabaseBase $db A database subclass
  47          * @param array $tablesToClone An array of tables to clone, unprefixed
  48          * @param string $newTablePrefix Prefix to assign to the tables
  49          * @param string $oldTablePrefix Prefix on current tables, if not $wgDBprefix
  50          * @param bool $dropCurrentTables
  51          */
  52         public function __construct( DatabaseBase $db, array $tablesToClone,
  53                 $newTablePrefix, $oldTablePrefix = '', $dropCurrentTables = true
  54         ) {
  55                 $this->db = $db;
  56                 $this->tablesToClone = $tablesToClone;
  57                 $this->newTablePrefix = $newTablePrefix;
  58                 $this->oldTablePrefix = $oldTablePrefix ? $oldTablePrefix : $this->db->tablePrefix();
  59                 $this->dropCurrentTables = $dropCurrentTables;
  60         }
  61
  62         /**
  63          * Set whether to use temporary tables or not
  64          * @param bool $u Use temporary tables when cloning the structure
  65          */
  66         public function useTemporaryTables( $u = true ) {
  67                 $this->useTemporaryTables = $u;
  68         }
  69
  70         /**
  71          * Clone the table structure
  72          */
  73         public function cloneTableStructure() {
  74                 global $wgSharedTables, $wgSharedDB;
  75                 foreach ( $this->tablesToClone as $tbl ) {
  76                         if ( $wgSharedDB && in_array( $tbl, $wgSharedTables, true ) ) {
  77                                 // Shared tables don't work properly when cloning due to
  78                                 // how prefixes are handled (bug 65654)
  79                                 throw new MWException( "Cannot clone shared table $tbl." );
  80                         }
  81                         # Clean up from previous aborted run.  So that table escaping
  82                         # works correctly across DB engines, we need to change the pre-
  83                         # fix back and forth so tableName() works right.
  84
  85                         self::changePrefix( $this->oldTablePrefix );
  86                         $oldTableName = $this->db->tableName( $tbl, 'raw' );
  87
  88                         self::changePrefix( $this->newTablePrefix );
  89                         $newTableName = $this->db->tableName( $tbl, 'raw' );
  90
  91                         if ( $this->dropCurrentTables
  92                                 && !in_array( $this->db->getType(), [ 'postgres', 'oracle' ] )
  93                         ) {
  94                                 if ( $oldTableName === $newTableName ) {
  95                                         // Last ditch check to avoid data loss
  96                                         throw new MWException( "Not dropping new table, as '$newTableName'"
  97                                                 . " is name of both the old and the new table." );
  98                                 }
  99                                 $this->db->dropTable( $tbl, __METHOD__ );
 100                                 wfDebug( __METHOD__ . " dropping {$newTableName}\n" );
 101                                 // Dropping the oldTable because the prefix was changed
 102                         }
 103
 104                         # Create new table
 105                         wfDebug( __METHOD__ . " duplicating $oldTableName to $newTableName\n" );
 106                         $this->db->duplicateTableStructure( $oldTableName, $newTableName, $this->useTemporaryTables );
 107                 }
 108         }
 109
 110         /**
 111          * Change the prefix back to the original.
 112          * @param bool $dropTables Optionally drop the tables we created
 113          */
 114         public function destroy( $dropTables = false ) {
 115                 if ( $dropTables ) {
 116                         self::changePrefix( $this->newTablePrefix );
 117                         foreach ( $this->tablesToClone as $tbl ) {
 118                                 $this->db->dropTable( $tbl );
 119                         }
 120                 }
 121                 self::changePrefix( $this->oldTablePrefix );
 122         }
 123
 124         /**
 125          * Change the table prefix on all open DB connections/
 126          *
 127          * @param string $prefix
 128          * @return void
 129          */
 130         public static function changePrefix( $prefix ) {
 131                 global $wgDBprefix;
 132                 wfGetLBFactory()->forEachLB( [ 'CloneDatabase', 'changeLBPrefix' ], [ $prefix ] );
 133                 $wgDBprefix = $prefix;
 134         }
 135
 136         /**
 137          * @param LoadBalancer $lb
 138          * @param string $prefix
 139          * @return void
 140          */
 141         public static function changeLBPrefix( $lb, $prefix ) {
 142                 $lb->forEachOpenConnection( [ 'CloneDatabase', 'changeDBPrefix' ], [ $prefix ] );
 143         }
 144
 145         /**
 146          * @param DatabaseBase $db
 147          * @param string $prefix
 148          * @return void
 149          */
 150         public static function changeDBPrefix( $db, $prefix ) {
 151                 $db->tablePrefix( $prefix );
 152         }
 153 }