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 /**
  25  * A simple single-master LBFactory that gets its configuration from the b/c globals
  26  */
  27 class LBFactorySimple extends LBFactory {
  28         /** @var LoadBalancer */
  29         private $mainLB;
  30         /** @var LoadBalancer[] */
  31         private $extLBs = [];
  32
  33         /** @var array[] Map of (server index => server config) */
  34         private $servers = [];
  35         /** @var array[] Map of (cluster => (server index => server config)) */
  36         private $externalClusters = [];
  37
  38         /** @var string */
  39         private $loadMonitorClass;
  40
  41         /**
  42          * @see LBFactory::__construct()
  43          * @param array $conf Parameters of LBFactory::__construct() as well as:
  44          *   - servers : list of server configuration maps to Database::factory().
  45          *      Additionally, the server maps should have a 'load' key, which is used to decide
  46          *      how often clients connect to one server verses the others. A 'max lag' key should
  47          *      also be set on server maps, indicating how stale the data can be before the load
  48          *      balancer tries to avoid using it. The map can have 'is static' set to disable blocking
  49          *      replication sync checks (intended for archive servers with unchanging data).
  50          *   - externalClusters : map of cluster names to server arrays. The servers arrays have the
  51          *      same format as "servers" above.
  52          */
  53         public function __construct( array $conf ) {
  54                 parent::__construct( $conf );
  55
  56                 $this->servers = isset( $conf['servers'] ) ? $conf['servers'] : [];
  57                 foreach ( $this->servers as $i => $server ) {
  58                         if ( $i == 0 ) {
  59                                 $this->servers[$i]['master'] = true;
  60                         } else {
  61                                 $this->servers[$i]['replica'] = true;
  62                         }
  63                 }
  64
  65                 $this->externalClusters = isset( $conf['externalClusters'] )
  66                         ? $conf['externalClusters']
  67                         : [];
  68                 $this->loadMonitorClass = isset( $conf['loadMonitorClass'] )
  69                         ? $conf['loadMonitorClass']
  70                         : '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                         $this->getChronologyProtector()->initLB( $this->mainLB );
  89                 }
  90
  91                 return $this->mainLB;
  92         }
  93
  94         /**
  95          * @param string $cluster
  96          * @param bool|string $domain
  97          * @return LoadBalancer
  98          * @throws InvalidArgumentException
  99          */
 100         public function newExternalLB( $cluster, $domain = false ) {
 101                 if ( !isset( $this->externalClusters[$cluster] ) ) {
 102                         throw new InvalidArgumentException( __METHOD__ . ": Unknown cluster \"$cluster\"." );
 103                 }
 104
 105                 return $this->newLoadBalancer( $this->externalClusters[$cluster] );
 106         }
 107
 108         /**
 109          * @param string $cluster
 110          * @param bool|string $domain
 111          * @return LoadBalancer
 112          */
 113         public function getExternalLB( $cluster, $domain = false ) {
 114                 if ( !isset( $this->extLBs[$cluster] ) ) {
 115                         $this->extLBs[$cluster] = $this->newExternalLB( $cluster, $domain );
 116                         $this->getChronologyProtector()->initLB( $this->extLBs[$cluster] );
 117                 }
 118
 119                 return $this->extLBs[$cluster];
 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                         call_user_func_array( $callback, array_merge( [ $this->mainLB ], $params ) );
 146                 }
 147                 foreach ( $this->extLBs as $lb ) {
 148                         call_user_func_array( $callback, array_merge( [ $lb ], $params ) );
 149                 }
 150         }
 151 }