LBFactoryMulti.php

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<?php
class LBFactoryMulti extends LBFactory {
    private $sectionsByDB;

    private $sectionLoads;

    private $serverTemplate;

    // Optional settings

    private $groupLoadsBySection = [];

    private $groupLoadsByDB = [];

    private $hostsByName = [];

    private $externalLoads = [];

    private $externalTemplateOverrides;

    private $templateOverridesByServer;

    private $templateOverridesBySection;

    private $templateOverridesByCluster;

    private $masterTemplateOverrides;

    private $readOnlyBySection = [];

    // Other stuff

    private $conf;

    private $mainLBs = [];

    private $extLBs = [];

    private $loadMonitorClass;

    private $lastWiki;

    private $lastSection;

    public function __construct( array $conf ) {
        parent::__construct( $conf );

        $this->conf = $conf;
        $required = [ 'sectionsByDB', 'sectionLoads', 'serverTemplate' ];
        $optional = [ 'groupLoadsBySection', 'groupLoadsByDB', 'hostsByName',
            'externalLoads', 'externalTemplateOverrides', 'templateOverridesByServer',
            'templateOverridesByCluster', 'templateOverridesBySection', 'masterTemplateOverrides',
            'readOnlyBySection', 'loadMonitorClass' ];

        foreach ( $required as $key ) {
            if ( !isset( $conf[$key] ) ) {
                throw new MWException( __CLASS__ . ": $key is required in configuration" );
            }
            $this->$key = $conf[$key];
        }

        foreach ( $optional as $key ) {
            if ( isset( $conf[$key] ) ) {
                $this->$key = $conf[$key];
            }
        }
    }

    private function getSectionForWiki( $wiki = false ) {
        if ( $this->lastWiki === $wiki ) {
            return $this->lastSection;
        }
        list( $dbName, ) = $this->getDBNameAndPrefix( $wiki );
        if ( isset( $this->sectionsByDB[$dbName] ) ) {
            $section = $this->sectionsByDB[$dbName];
        } else {
            $section = 'DEFAULT';
        }
        $this->lastSection = $section;
        $this->lastWiki = $wiki;

        return $section;
    }

    public function newMainLB( $wiki = false ) {
        list( $dbName, ) = $this->getDBNameAndPrefix( $wiki );
        $section = $this->getSectionForWiki( $wiki );
        if ( isset( $this->groupLoadsByDB[$dbName] ) ) {
            $groupLoads = $this->groupLoadsByDB[$dbName];
        } else {
            $groupLoads = [];
        }

        if ( isset( $this->groupLoadsBySection[$section] ) ) {
            $groupLoads = array_merge_recursive( $groupLoads, $this->groupLoadsBySection[$section] );
        }

        $readOnlyReason = $this->readOnlyReason;
        // Use the LB-specific read-only reason if everything isn't already read-only
        if ( $readOnlyReason === false && isset( $this->readOnlyBySection[$section] ) ) {
            $readOnlyReason = $this->readOnlyBySection[$section];
        }

        $template = $this->serverTemplate;
        if ( isset( $this->templateOverridesBySection[$section] ) ) {
            $template = $this->templateOverridesBySection[$section] + $template;
        }

        return $this->newLoadBalancer(
            $template,
            $this->sectionLoads[$section],
            $groupLoads,
            $readOnlyReason
        );
    }

    public function getMainLB( $wiki = false ) {
        $section = $this->getSectionForWiki( $wiki );
        if ( !isset( $this->mainLBs[$section] ) ) {
            $lb = $this->newMainLB( $wiki );
            $lb->parentInfo( [ 'id' => "main-$section" ] );
            $this->chronProt->initLB( $lb );
            $this->mainLBs[$section] = $lb;
        }

        return $this->mainLBs[$section];
    }

    protected function newExternalLB( $cluster, $wiki = false ) {
        if ( !isset( $this->externalLoads[$cluster] ) ) {
            throw new MWException( __METHOD__ . ": Unknown cluster \"$cluster\"" );
        }
        $template = $this->serverTemplate;
        if ( isset( $this->externalTemplateOverrides ) ) {
            $template = $this->externalTemplateOverrides + $template;
        }
        if ( isset( $this->templateOverridesByCluster[$cluster] ) ) {
            $template = $this->templateOverridesByCluster[$cluster] + $template;
        }

        return $this->newLoadBalancer(
            $template,
            $this->externalLoads[$cluster],
            [],
            $this->readOnlyReason
        );
    }

    public function &getExternalLB( $cluster, $wiki = false ) {
        if ( !isset( $this->extLBs[$cluster] ) ) {
            $this->extLBs[$cluster] = $this->newExternalLB( $cluster, $wiki );
            $this->extLBs[$cluster]->parentInfo( [ 'id' => "ext-$cluster" ] );
            $this->chronProt->initLB( $this->extLBs[$cluster] );
        }

        return $this->extLBs[$cluster];
    }

    private function newLoadBalancer( $template, $loads, $groupLoads, $readOnlyReason ) {
        return new LoadBalancer( [
            'servers' => $this->makeServerArray( $template, $loads, $groupLoads ),
            'loadMonitor' => $this->loadMonitorClass,
            'readOnlyReason' => $readOnlyReason,
            'trxProfiler' => $this->trxProfiler
        ] );
    }

    private function makeServerArray( $template, $loads, $groupLoads ) {
        $servers = [];
        $master = true;
        $groupLoadsByServer = $this->reindexGroupLoads( $groupLoads );
        foreach ( $groupLoadsByServer as $server => $stuff ) {
            if ( !isset( $loads[$server] ) ) {
                $loads[$server] = 0;
            }
        }
        foreach ( $loads as $serverName => $load ) {
            $serverInfo = $template;
            if ( $master ) {
                $serverInfo['master'] = true;
                if ( isset( $this->masterTemplateOverrides ) ) {
                    $serverInfo = $this->masterTemplateOverrides + $serverInfo;
                }
                $master = false;
            } else {
                $serverInfo['slave'] = true;
            }
            if ( isset( $this->templateOverridesByServer[$serverName] ) ) {
                $serverInfo = $this->templateOverridesByServer[$serverName] + $serverInfo;
            }
            if ( isset( $groupLoadsByServer[$serverName] ) ) {
                $serverInfo['groupLoads'] = $groupLoadsByServer[$serverName];
            }
            if ( isset( $this->hostsByName[$serverName] ) ) {
                $serverInfo['host'] = $this->hostsByName[$serverName];
            } else {
                $serverInfo['host'] = $serverName;
            }
            $serverInfo['hostName'] = $serverName;
            $serverInfo['load'] = $load;
            $servers[] = $serverInfo;
        }

        return $servers;
    }

    private function reindexGroupLoads( $groupLoads ) {
        $reindexed = [];
        foreach ( $groupLoads as $group => $loads ) {
            foreach ( $loads as $server => $load ) {
                $reindexed[$server][$group] = $load;
            }
        }

        return $reindexed;
    }

    private function getDBNameAndPrefix( $wiki = false ) {
        if ( $wiki === false ) {
            global $wgDBname, $wgDBprefix;

            return [ $wgDBname, $wgDBprefix ];
        } else {
            return wfSplitWikiID( $wiki );
        }
    }

    public function forEachLB( $callback, array $params = [] ) {
        foreach ( $this->mainLBs as $lb ) {
            call_user_func_array( $callback, array_merge( [ $lb ], $params ) );
        }
        foreach ( $this->extLBs as $lb ) {
            call_user_func_array( $callback, array_merge( [ $lb ], $params ) );
        }
    }

    public function shutdown( $flags = 0 ) {
        if ( !( $flags & self::SHUTDOWN_NO_CHRONPROT ) ) {
            $this->shutdownChronologyProtector( $this->chronProt );
        }
        $this->commitMasterChanges( __METHOD__ ); // sanity
    }
}