includes/libs/rdbms/loadbalancer/LoadBalancerSingle.php

   1 <?php
   2 /**
   3  * Simple generator of database connections that always returns the same object.
   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
  24 namespace Wikimedia\Rdbms;
  25
  26 use InvalidArgumentException;
  27
  28 /**
  29  * Trivial LoadBalancer that always returns an injected connection handle.
  30  *
  31  * Note that, while this LoadBalancer does not open any connections itself,
  32  * it still closes the injected connection at times, including during destruction.
  33  * It is therefore unsuitable for use in tests unless you have a Database instance
  34  * separate from the main test database (which is expected to stay open).
  35  */
  36 class LoadBalancerSingle extends LoadBalancer {
  37         /** @var IDatabase */
  38         private $db;
  39
  40         /**
  41          * @param array $params An associative array with one member:
  42          *   - connection: An IDatabase connection object
  43          */
  44         public function __construct( array $params ) {
  45                 if ( !isset( $params['connection'] ) ) {
  46                         throw new InvalidArgumentException( "Missing 'connection' argument." );
  47                 }
  48
  49                 $this->db = $params['connection'];
  50
  51                 parent::__construct( [
  52                         'servers' => [
  53                                 [
  54                                         'type' => $this->db->getType(),
  55                                         'host' => $this->db->getServer(),
  56                                         'dbname' => $this->db->getDBname(),
  57                                         'load' => 1,
  58                                 ]
  59                         ],
  60                         'trxProfiler' => $params['trxProfiler'] ?? null,
  61                         'srvCache' => $params['srvCache'] ?? null,
  62                         'wanCache' => $params['wanCache'] ?? null,
  63                         'localDomain' => $params['localDomain'] ?? $this->db->getDomainID(),
  64                         'readOnlyReason' => $params['readOnlyReason'] ?? false,
  65                 ] );
  66
  67                 if ( isset( $params['readOnlyReason'] ) ) {
  68                         $this->db->setLBInfo( 'readOnlyReason', $params['readOnlyReason'] );
  69                 }
  70         }
  71
  72         /**
  73          * @param IDatabase $db Live connection handle
  74          * @param array $params Parameter map to LoadBalancerSingle::__constructs()
  75          * @return LoadBalancerSingle
  76          * @since 1.28
  77          */
  78         public static function newFromConnection( IDatabase $db, array $params = [] ) {
  79                 return new static( array_merge(
  80                         [ 'localDomain' => $db->getDomainID() ],
  81                         $params,
  82                         [ 'connection' => $db ]
  83                 ) );
  84         }
  85
  86         protected function reallyOpenConnection( $i, DatabaseDomain $domain, array $lbInfo = [] ) {
  87                 return $this->db;
  88         }
  89
  90         public function __destruct() {
  91                 // do nothing since the connection was injected
  92         }
  93 }
  94
  95 /**
  96  * @deprecated since 1.29
  97  */
  98 class_alias( LoadBalancerSingle::class, 'LoadBalancerSingle' );