DBSerialProvider.php

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<?php
 
namespace MediaWiki\User\TempUser;
 
use Wikimedia\Rdbms\IDatabase;
 
abstract class DBSerialProvider implements SerialProvider {
    private $numShards;
 
    public function __construct( $config ) {
        $this->numShards = $config['numShards'] ?? 1;
    }
 
    public function acquireIndex( int $year = 0 ): int {
        if ( $this->numShards ) {
            $shard = mt_rand( 0, $this->numShards - 1 );
        } else {
            $shard = 0;
        }
 
        $dbw = $this->getDB();
        $table = $this->getTableName();
        $dbw->startAtomic( __METHOD__ );
        $dbw->newInsertQueryBuilder()
            ->insertInto( $table )
            ->row( [
                'uas_shard' => $shard,
                'uas_year' => $year,
                'uas_value' => 1
            ] )
            ->onDuplicateKeyUpdate()
            ->uniqueIndexFields( [ 'uas_shard', 'uas_year' ] )
            ->set( [ 'uas_value=uas_value+1' ] )
            ->caller( __METHOD__ )->execute();
        $value = $dbw->newSelectQueryBuilder()
            ->select( 'uas_value' )
            ->from( $table )
            ->where( [ 'uas_shard' => $shard ] )
            ->andWhere( [ 'uas_year' => $year ] )
            ->caller( __METHOD__ )
            ->fetchField();
        $dbw->endAtomic( __METHOD__ );
        return $value * $this->numShards + $shard;
    }
 
    abstract protected function getDB();
 
    abstract protected function getTableName();
}