includes/db/CloneDatabase.php

   1 <?php
   2 /**
   3  * Helper class for making a copy of the database, mostly for unit testing.
   4  *
   5  * This program 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 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program 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 along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * @file
  21  * @ingroup Database
  22  */
  23 use MediaWiki\MediaWikiServices;
  24 use Wikimedia\Rdbms\IMaintainableDatabase;
  25
  26 class CloneDatabase {
  27         /** @var string Table prefix for cloning */
  28         private $newTablePrefix = '';
  29
  30         /** @var string Current table prefix */
  31         private $oldTablePrefix = '';
  32
  33         /** @var array List of tables to be cloned */
  34         private $tablesToClone = [];
  35
  36         /** @var bool Should we DROP tables containing the new names? */
  37         private $dropCurrentTables = true;
  38
  39         /** @var bool Whether to use temporary tables or not */
  40         private $useTemporaryTables = true;
  41
  42         /** @var IMaintainableDatabase */
  43         private $db;
  44
  45         /**
  46          * @param IMaintainableDatabase $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( IMaintainableDatabase $db, array $tablesToClone,
  53                 $newTablePrefix, $oldTablePrefix = null, $dropCurrentTables = true
  54         ) {
  55                 $this->db = $db;
  56                 $this->tablesToClone = $tablesToClone;
  57                 $this->newTablePrefix = $newTablePrefix;
  58                 $this->oldTablePrefix = $oldTablePrefix !== null ? $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 (T67654)
  79                                 throw new RuntimeException( "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                         // Postgres: Temp tables are automatically deleted upon end of session
  92                         //           Same Temp table name hides existing table for current session
  93                         if ( $this->dropCurrentTables
  94                                 && !in_array( $this->db->getType(), [ 'oracle' ] )
  95                         ) {
  96                                 if ( $oldTableName === $newTableName ) {
  97                                         // Last ditch check to avoid data loss
  98                                         throw new LogicException( "Not dropping new table, as '$newTableName'"
  99                                                 . " is name of both the old and the new table." );
 100                                 }
 101                                 $this->db->dropTable( $tbl, __METHOD__ );
 102                                 wfDebug( __METHOD__ . " dropping {$newTableName}\n" );
 103                                 // Dropping the oldTable because the prefix was changed
 104                         }
 105
 106                         # Create new table
 107                         wfDebug( __METHOD__ . " duplicating $oldTableName to $newTableName\n" );
 108                         $this->db->duplicateTableStructure(
 109                                 $oldTableName, $newTableName, $this->useTemporaryTables );
 110                 }
 111         }
 112
 113         /**
 114          * Change the prefix back to the original.
 115          * @param bool $dropTables Optionally drop the tables we created
 116          */
 117         public function destroy( $dropTables = false ) {
 118                 if ( $dropTables ) {
 119                         self::changePrefix( $this->newTablePrefix );
 120                         foreach ( $this->tablesToClone as $tbl ) {
 121                                 $this->db->dropTable( $tbl );
 122                         }
 123                 }
 124                 self::changePrefix( $this->oldTablePrefix );
 125         }
 126
 127         /**
 128          * Change the table prefix on all open DB connections/
 129          *
 130          * @param string $prefix
 131          * @return void
 132          */
 133         public static function changePrefix( $prefix ) {
 134                 global $wgDBprefix;
 135
 136                 $lbFactory = MediaWikiServices::getInstance()->getDBLoadBalancerFactory();
 137                 $lbFactory->setDomainPrefix( $prefix );
 138                 $wgDBprefix = $prefix;
 139         }
 140 }