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 class LoadBalancerSingle extends LoadBalancer {
  32         /** @var IDatabase */
  33         private $db;
  34
  35         /**
  36          * @param array $params An associative array with one member:
  37          *   - connection: An IDatabase connection object
  38          */
  39         public function __construct( array $params ) {
  40                 if ( !isset( $params['connection'] ) ) {
  41                         throw new InvalidArgumentException( "Missing 'connection' argument." );
  42                 }
  43
  44                 $this->db = $params['connection'];
  45
  46                 parent::__construct( [
  47                         'servers' => [
  48                                 [
  49                                         'type' => $this->db->getType(),
  50                                         'host' => $this->db->getServer(),
  51                                         'dbname' => $this->db->getDBname(),
  52                                         'load' => 1,
  53                                 ]
  54                         ],
  55                         'trxProfiler' => $params['trxProfiler'] ?? null,
  56                         'srvCache' => $params['srvCache'] ?? null,
  57                         'wanCache' => $params['wanCache'] ?? null,
  58                         'localDomain' => $params['localDomain'] ?? $this->db->getDomainID(),
  59                         'readOnlyReason' => $params['readOnlyReason'] ?? false,
  60                 ] );
  61
  62                 if ( isset( $params['readOnlyReason'] ) ) {
  63                         $this->db->setLBInfo( 'readOnlyReason', $params['readOnlyReason'] );
  64                 }
  65         }
  66
  67         /**
  68          * @param IDatabase $db Live connection handle
  69          * @param array $params Parameter map to LoadBalancerSingle::__constructs()
  70          * @return LoadBalancerSingle
  71          * @since 1.28
  72          */
  73         public static function newFromConnection( IDatabase $db, array $params = [] ) {
  74                 return new static( array_merge(
  75                         [ 'localDomain' => $db->getDomainID() ],
  76                         $params,
  77                         [ 'connection' => $db ]
  78                 ) );
  79         }
  80
  81         protected function reallyOpenConnection( array $server, DatabaseDomain $domain ) {
  82                 return $this->db;
  83         }
  84
  85         public function __destruct() {
  86                 // do nothing since the connection was injected
  87         }
  88 }
  89
  90 /**
  91  * @deprecated since 1.29
  92  */
  93 class_alias( LoadBalancerSingle::class, 'LoadBalancerSingle' );