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;
  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|null $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, $dropCurrentTables = true
  54         ) {
  55                 if ( !$tablesToClone ) {
  56                         throw new InvalidArgumentException( 'Empty list of tables to clone' );
  57                 }
  58                 $this->db = $db;
  59                 $this->tablesToClone = $tablesToClone;
  60                 $this->newTablePrefix = $newTablePrefix;
  61                 $this->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                         $this->db->tablePrefix( $this->oldTablePrefix );
  89                         $oldTableName = $this->db->tableName( $tbl, 'raw' );
  90
  91                         $this->db->tablePrefix( $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                                 if ( $oldTableName === $newTableName ) {
  98                                         // Last ditch check to avoid data loss
  99                                         throw new LogicException( "Not dropping new table, as '$newTableName'"
 100                                                 . " is name of both the old and the new table." );
 101                                 }
 102                                 $this->db->dropTable( $tbl, __METHOD__ );
 103                                 wfDebug( __METHOD__ . " dropping {$newTableName}\n" );
 104                                 // Dropping the oldTable because the prefix was changed
 105                         }
 106
 107                         # Create new table
 108                         wfDebug( __METHOD__ . " duplicating $oldTableName to $newTableName\n" );
 109                         $this->db->duplicateTableStructure(
 110                                 $oldTableName, $newTableName, $this->useTemporaryTables );
 111                 }
 112         }
 113
 114         /**
 115          * Change the prefix back to the original.
 116          * @param bool $dropTables Optionally drop the tables we created
 117          */
 118         public function destroy( $dropTables = false ) {
 119                 if ( $dropTables ) {
 120                         $this->db->tablePrefix( $this->newTablePrefix );
 121                         foreach ( $this->tablesToClone as $tbl ) {
 122                                 $this->db->dropTable( $tbl );
 123                         }
 124                 }
 125                 $this->db->tablePrefix( $this->oldTablePrefix );
 126         }
 127
 128         /**
 129          * Change the table prefix on all open DB connections
 130          *
 131          * @param string $prefix
 132          * @return void
 133          */
 134         public static function changePrefix( $prefix ) {
 135                 global $wgDBprefix;
 136
 137                 $lbFactory = MediaWikiServices::getInstance()->getDBLoadBalancerFactory();
 138                 $lbFactory->setLocalDomainPrefix( $prefix );
 139                 $wgDBprefix = $prefix;
 140         }
 141 }