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 $extLBs = [];
  36
  37         /** @var array[] Map of (server index => server config) */
  38         private $servers = [];
  39         /** @var array[] Map of (cluster => (server index => server config)) */
  40         private $externalClusters = [];
  41
  42         /** @var string */
  43         private $loadMonitorClass;
  44
  45         /**
  46          * @see LBFactory::__construct()
  47          * @param array $conf Parameters of LBFactory::__construct() as well as:
  48          *   - servers : list of server configuration 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->servers = $conf['servers'] ?? [];
  61                 foreach ( $this->servers as $i => $server ) {
  62                         if ( $i == 0 ) {
  63                                 $this->servers[$i]['master'] = true;
  64                         } else {
  65                                 $this->servers[$i]['replica'] = true;
  66                         }
  67                 }
  68
  69                 $this->externalClusters = $conf['externalClusters'] ?? [];
  70                 $this->loadMonitorClass = $conf['loadMonitorClass'] ?? 'LoadMonitor';
  71         }
  72
  73         /**
  74          * @param bool|string $domain
  75          * @return LoadBalancer
  76          */
  77         public function newMainLB( $domain = false ) {
  78                 return $this->newLoadBalancer( $this->servers );
  79         }
  80
  81         /**
  82          * @param bool|string $domain
  83          * @return LoadBalancer
  84          */
  85         public function getMainLB( $domain = false ) {
  86                 if ( !isset( $this->mainLB ) ) {
  87                         $this->mainLB = $this->newMainLB( $domain );
  88                 }
  89
  90                 return $this->mainLB;
  91         }
  92
  93         public function newExternalLB( $cluster ) {
  94                 if ( !isset( $this->externalClusters[$cluster] ) ) {
  95                         throw new InvalidArgumentException( __METHOD__ . ": Unknown cluster \"$cluster\"." );
  96                 }
  97
  98                 return $this->newLoadBalancer( $this->externalClusters[$cluster] );
  99         }
 100
 101         public function getExternalLB( $cluster ) {
 102                 if ( !isset( $this->extLBs[$cluster] ) ) {
 103                         $this->extLBs[$cluster] = $this->newExternalLB( $cluster );
 104                 }
 105
 106                 return $this->extLBs[$cluster];
 107         }
 108
 109         public function getAllMainLBs() {
 110                 return [ 'DEFAULT' => $this->getMainLB() ];
 111         }
 112
 113         public function getAllExternalLBs() {
 114                 $lbs = [];
 115                 foreach ( $this->externalClusters as $cluster => $unused ) {
 116                         $lbs[$cluster] = $this->getExternalLB( $cluster );
 117                 }
 118
 119                 return $lbs;
 120         }
 121
 122         private function newLoadBalancer( array $servers ) {
 123                 $lb = new LoadBalancer( array_merge(
 124                         $this->baseLoadBalancerParams(),
 125                         [
 126                                 'servers' => $servers,
 127                                 'loadMonitor' => [ 'class' => $this->loadMonitorClass ],
 128                         ]
 129                 ) );
 130                 $this->initLoadBalancer( $lb );
 131
 132                 return $lb;
 133         }
 134
 135         /**
 136          * Execute a function for each tracked load balancer
 137          * The callback is called with the load balancer as the first parameter,
 138          * and $params passed as the subsequent parameters.
 139          *
 140          * @param callable $callback
 141          * @param array $params
 142          */
 143         public function forEachLB( $callback, array $params = [] ) {
 144                 if ( isset( $this->mainLB ) ) {
 145                         $callback( $this->mainLB, ...$params );
 146                 }
 147                 foreach ( $this->extLBs as $lb ) {
 148                         $callback( $lb, ...$params );
 149                 }
 150         }
 151 }