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         /** @var int */
  45         private $maxLag;
  46
  47         /** @var int Default 'maxLag' when unspecified */
  48         const MAX_LAG_DEFAULT = 10;
  49
  50         /**
  51          * @see LBFactory::__construct()
  52          * @param array $conf Parameters of LBFactory::__construct() as well as:
  53          *   - servers : list of server configuration maps to Database::factory().
  54          *      Additionally, the server maps should have a 'load' key, which is used to decide
  55          *      how often clients connect to one server verses the others. A 'max lag' key should
  56          *      also be set on server maps, indicating how stale the data can be before the load
  57          *      balancer tries to avoid using it. The map can have 'is static' set to disable blocking
  58          *      replication sync checks (intended for archive servers with unchanging data).
  59          *   - externalClusters : map of cluster names to server arrays. The servers arrays have the
  60          *      same format as "servers" above.
  61          */
  62         public function __construct( array $conf ) {
  63                 parent::__construct( $conf );
  64
  65                 $this->servers = $conf['servers'] ?? [];
  66                 foreach ( $this->servers as $i => $server ) {
  67                         if ( $i == 0 ) {
  68                                 $this->servers[$i]['master'] = true;
  69                         } else {
  70                                 $this->servers[$i]['replica'] = true;
  71                         }
  72                 }
  73
  74                 $this->externalClusters = $conf['externalClusters'] ?? [];
  75                 $this->loadMonitorClass = $conf['loadMonitorClass'] ?? 'LoadMonitor';
  76                 $this->maxLag = $conf['maxLag'] ?? self::MAX_LAG_DEFAULT;
  77         }
  78
  79         /**
  80          * @param bool|string $domain
  81          * @return LoadBalancer
  82          */
  83         public function newMainLB( $domain = false ) {
  84                 return $this->newLoadBalancer( $this->servers );
  85         }
  86
  87         /**
  88          * @param bool|string $domain
  89          * @return LoadBalancer
  90          */
  91         public function getMainLB( $domain = false ) {
  92                 if ( !isset( $this->mainLB ) ) {
  93                         $this->mainLB = $this->newMainLB( $domain );
  94                 }
  95
  96                 return $this->mainLB;
  97         }
  98
  99         public function newExternalLB( $cluster ) {
 100                 if ( !isset( $this->externalClusters[$cluster] ) ) {
 101                         throw new InvalidArgumentException( __METHOD__ . ": Unknown cluster \"$cluster\"." );
 102                 }
 103
 104                 return $this->newLoadBalancer( $this->externalClusters[$cluster] );
 105         }
 106
 107         public function getExternalLB( $cluster ) {
 108                 if ( !isset( $this->extLBs[$cluster] ) ) {
 109                         $this->extLBs[$cluster] = $this->newExternalLB( $cluster );
 110                 }
 111
 112                 return $this->extLBs[$cluster];
 113         }
 114
 115         public function getAllMainLBs() {
 116                 return [ 'DEFAULT' => $this->getMainLB() ];
 117         }
 118
 119         public function getAllExternalLBs() {
 120                 $lbs = [];
 121                 foreach ( $this->externalClusters as $cluster => $unused ) {
 122                         $lbs[$cluster] = $this->getExternalLB( $cluster );
 123                 }
 124
 125                 return $lbs;
 126         }
 127
 128         private function newLoadBalancer( array $servers ) {
 129                 $lb = new LoadBalancer( array_merge(
 130                         $this->baseLoadBalancerParams(),
 131                         [
 132                                 'servers' => $servers,
 133                                 'maxLag' => $this->maxLag,
 134                                 'loadMonitor' => [ 'class' => $this->loadMonitorClass ],
 135                         ]
 136                 ) );
 137                 $this->initLoadBalancer( $lb );
 138
 139                 return $lb;
 140         }
 141
 142         /**
 143          * Execute a function for each tracked load balancer
 144          * The callback is called with the load balancer as the first parameter,
 145          * and $params passed as the subsequent parameters.
 146          *
 147          * @param callable $callback
 148          * @param array $params
 149          */
 150         public function forEachLB( $callback, array $params = [] ) {
 151                 if ( isset( $this->mainLB ) ) {
 152                         $callback( $this->mainLB, ...$params );
 153                 }
 154                 foreach ( $this->extLBs as $lb ) {
 155                         $callback( $lb, ...$params );
 156                 }
 157         }
 158 }