LCStoreDB.php

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<?php
use Wikimedia\Rdbms\Database;
use Wikimedia\Rdbms\DBQueryError;
use Wikimedia\Rdbms\IDatabase;
use Wikimedia\ScopedCallback;
 
class LCStoreDB implements LCStore {
    private $code;
    private $server;
 
    private $batch = [];
 
    private $dbw;
    private $writesDone = false;
    private $readOnly = false;
 
    public function __construct( $params ) {
        $this->server = $params['server'] ?? [];
    }
 
    public function get( $code, $key ) {
        if ( $this->server || $this->writesDone ) {
            // If a server configuration map is specified, always used that connection
            // for reads and writes. Otherwise, if writes occurred in finishWrite(), make
            // sure those changes are always visible.
            $db = $this->getWriteConnection();
        } else {
            $db = wfGetDB( DB_REPLICA );
        }
 
        $value = $db->selectField(
            'l10n_cache',
            'lc_value',
            [ 'lc_lang' => $code, 'lc_key' => $key ],
            __METHOD__
        );
 
        return ( $value !== false ) ? unserialize( $db->decodeBlob( $value ) ) : null;
    }
 
    public function startWrite( $code ) {
        if ( $this->readOnly ) {
            return;
        } elseif ( !$code ) {
            throw new MWException( __METHOD__ . ": Invalid language \"$code\"" );
        }
 
        $dbw = $this->getWriteConnection();
        $this->readOnly = $dbw->isReadOnly();
 
        $this->code = $code;
        $this->batch = [];
    }
 
    public function finishWrite() {
        if ( $this->readOnly ) {
            return;
        } elseif ( $this->code === null ) {
            throw new MWException( __CLASS__ . ': must call startWrite() before finishWrite()' );
        }
 
        $scope = Profiler::instance()->getTransactionProfiler()->silenceForScope();
        $dbw = $this->getWriteConnection();
        $dbw->startAtomic( __METHOD__ );
        try {
            $dbw->delete( 'l10n_cache', [ 'lc_lang' => $this->code ], __METHOD__ );
            foreach ( array_chunk( $this->batch, 500 ) as $rows ) {
                $dbw->insert( 'l10n_cache', $rows, __METHOD__ );
            }
            $this->writesDone = true;
        } catch ( DBQueryError $e ) {
            if ( $dbw->wasReadOnlyError() ) {
                $this->readOnly = true; // just avoid site down time
            } else {
                throw $e;
            }
        }
        $dbw->endAtomic( __METHOD__ );
        ScopedCallback::consume( $scope );
 
        $this->code = null;
        $this->batch = [];
    }
 
    public function set( $key, $value ) {
        if ( $this->readOnly ) {
            return;
        } elseif ( $this->code === null ) {
            throw new MWException( __CLASS__ . ': must call startWrite() before set()' );
        }
 
        $dbw = $this->getWriteConnection();
 
        $this->batch[] = [
            'lc_lang' => $this->code,
            'lc_key' => $key,
            'lc_value' => $dbw->encodeBlob( serialize( $value ) )
        ];
    }
 
    private function getWriteConnection() {
        if ( !$this->dbw ) {
            if ( $this->server ) {
                $this->dbw = Database::factory( $this->server['type'], $this->server );
                if ( !$this->dbw ) {
                    throw new MWException( __CLASS__ . ': failed to obtain a DB connection' );
                }
            } else {
                $this->dbw = wfGetDB( DB_PRIMARY );
            }
        }
 
        return $this->dbw;
    }
}