LBFactorySimple.php

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<?php
namespace Wikimedia\Rdbms;
 
use InvalidArgumentException;
 
class LBFactorySimple extends LBFactory {
    private $mainLB;
    private $extLBs = [];
 
    private $servers = [];
    private $externalClusters = [];
 
    private $loadMonitorClass;
    private $maxLag;
 
    const MAX_LAG_DEFAULT = 10;
 
    public function __construct( array $conf ) {
        parent::__construct( $conf );
 
        $this->servers = $conf['servers'] ?? [];
        foreach ( $this->servers as $i => $server ) {
            if ( $i == 0 ) {
                $this->servers[$i]['master'] = true;
            } else {
                $this->servers[$i]['replica'] = true;
            }
        }
 
        $this->externalClusters = $conf['externalClusters'] ?? [];
        $this->loadMonitorClass = $conf['loadMonitorClass'] ?? 'LoadMonitor';
        $this->maxLag = $conf['maxLag'] ?? self::MAX_LAG_DEFAULT;
    }
 
    public function newMainLB( $domain = false ) {
        return $this->newLoadBalancer( $this->servers );
    }
 
    public function getMainLB( $domain = false ) {
        if ( !isset( $this->mainLB ) ) {
            $this->mainLB = $this->newMainLB( $domain );
        }
 
        return $this->mainLB;
    }
 
    public function newExternalLB( $cluster ) {
        if ( !isset( $this->externalClusters[$cluster] ) ) {
            throw new InvalidArgumentException( __METHOD__ . ": Unknown cluster \"$cluster\"." );
        }
 
        return $this->newLoadBalancer( $this->externalClusters[$cluster] );
    }
 
    public function getExternalLB( $cluster ) {
        if ( !isset( $this->extLBs[$cluster] ) ) {
            $this->extLBs[$cluster] = $this->newExternalLB( $cluster );
        }
 
        return $this->extLBs[$cluster];
    }
 
    public function getAllMainLBs() {
        return [ 'DEFAULT' => $this->getMainLB() ];
    }
 
    public function getAllExternalLBs() {
        $lbs = [];
        foreach ( $this->externalClusters as $cluster => $unused ) {
            $lbs[$cluster] = $this->getExternalLB( $cluster );
        }
 
        return $lbs;
    }
 
    private function newLoadBalancer( array $servers ) {
        $lb = new LoadBalancer( array_merge(
            $this->baseLoadBalancerParams(),
            [
                'servers' => $servers,
                'maxLag' => $this->maxLag,
                'loadMonitor' => [ 'class' => $this->loadMonitorClass ],
            ]
        ) );
        $this->initLoadBalancer( $lb );
 
        return $lb;
    }
 
    public function forEachLB( $callback, array $params = [] ) {
        if ( isset( $this->mainLB ) ) {
            $callback( $this->mainLB, ...$params );
        }
        foreach ( $this->extLBs as $lb ) {
            $callback( $lb, ...$params );
        }
    }
}