includes/libs/rdbms/lbfactory/LBFactorySimple.php

   1 <?php
   2 /**
   3  * Generator of database load balancing objects.
   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  * A simple single-master LBFactory that gets its configuration from the b/c globals
  30  */
  31 class LBFactorySimple extends LBFactory {
  32         /** @var LoadBalancer */
  33         private $mainLB;
  34         /** @var LoadBalancer[] */
  35         private $externalLBs = [];
  36
  37         /** @var array[] Map of (server index => server config map) */
  38         private $mainServers = [];
  39         /** @var array[][] Map of (cluster => server index => server config map) */
  40         private $externalServersByCluster = [];
  41
  42         /** @var string */
  43         private $loadMonitorClass;
  44
  45         /**
  46          * @see LBFactory::__construct()
  47          * @param array $conf Additional parameters include:
  48          *   - servers : list of server config maps to Database::factory().
  49          *      Additionally, the server maps should have a 'load' key, which is used to decide
  50          *      how often clients connect to one server verses the others. A 'max lag' key should
  51          *      also be set on server maps, indicating how stale the data can be before the load
  52          *      balancer tries to avoid using it. The map can have 'is static' set to disable blocking
  53          *      replication sync checks (intended for archive servers with unchanging data).
  54          *   - externalClusters : map of cluster names to server arrays. The servers arrays have the
  55          *      same format as "servers" above.
  56          */
  57         public function __construct( array $conf ) {
  58                 parent::__construct( $conf );
  59
  60                 $this->mainServers = $conf['servers'] ?? [];
  61                 foreach ( $this->mainServers as $i => $server ) {
  62                         if ( $i == 0 ) {
  63                                 $this->mainServers[$i]['master'] = true;
  64                         } else {
  65                                 $this->mainServers[$i]['replica'] = true;
  66                         }
  67                 }
  68
  69                 foreach ( ( $conf['externalClusters'] ?? [] ) as $cluster => $servers ) {
  70                         foreach ( $servers as $index => $server ) {
  71                                 $this->externalServersByCluster[$cluster][$index] = $server;
  72                         }
  73                 }
  74
  75                 $this->loadMonitorClass = $conf['loadMonitorClass'] ?? LoadMonitor::class;
  76         }
  77
  78         public function newMainLB( $domain = false, $owner = null ) {
  79                 return $this->newLoadBalancer( $this->mainServers, $owner );
  80         }
  81
  82         public function getMainLB( $domain = false ) {
  83                 if ( $this->mainLB === null ) {
  84                         $this->mainLB = $this->newMainLB( $domain, $this->getOwnershipId() );
  85                 }
  86
  87                 return $this->mainLB;
  88         }
  89
  90         public function newExternalLB( $cluster, $owner = null ) {
  91                 if ( !isset( $this->externalServersByCluster[$cluster] ) ) {
  92                         throw new InvalidArgumentException( "Unknown cluster '$cluster'." );
  93                 }
  94
  95                 return $this->newLoadBalancer( $this->externalServersByCluster[$cluster], $owner );
  96         }
  97
  98         public function getExternalLB( $cluster ) {
  99                 if ( !isset( $this->externalLBs[$cluster] ) ) {
 100                         $this->externalLBs[$cluster] = $this->newExternalLB( $cluster, $this->getOwnershipId() );
 101                 }
 102
 103                 return $this->externalLBs[$cluster];
 104         }
 105
 106         public function getAllMainLBs() {
 107                 return [ self::CLUSTER_MAIN_DEFAULT => $this->getMainLB() ];
 108         }
 109
 110         public function getAllExternalLBs() {
 111                 $lbs = [];
 112                 foreach ( array_keys( $this->externalServersByCluster ) as $cluster ) {
 113                         $lbs[$cluster] = $this->getExternalLB( $cluster );
 114                 }
 115
 116                 return $lbs;
 117         }
 118
 119         private function newLoadBalancer( array $servers, $owner ) {
 120                 $lb = new LoadBalancer( array_merge(
 121                         $this->baseLoadBalancerParams( $owner ),
 122                         [
 123                                 'servers' => $servers,
 124                                 'loadMonitor' => [ 'class' => $this->loadMonitorClass ],
 125                         ]
 126                 ) );
 127                 $this->initLoadBalancer( $lb );
 128
 129                 return $lb;
 130         }
 131
 132         public function forEachLB( $callback, array $params = [] ) {
 133                 if ( $this->mainLB !== null ) {
 134                         $callback( $this->mainLB, ...$params );
 135                 }
 136                 foreach ( $this->externalLBs as $lb ) {
 137                         $callback( $lb, ...$params );
 138                 }
 139         }
 140 }