convertLinks.php

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<?php
require_once __DIR__ . '/Maintenance.php';

class ConvertLinks extends Maintenance {
    private $logPerformance;

    public function __construct() {
        parent::__construct();
        $this->addDescription(
            'Convert from the old links schema (string->ID) to the new schema (ID->ID). '
                . 'The wiki should be put into read-only mode while this script executes' );

        $this->addArg( 'logperformance', "Log performance to perfLogFilename.", false );
        $this->addArg(
            'perfLogFilename',
            "Filename where performance is logged if --logperformance was set "
                . "(defaults to 'convLinksPerf.txt').",
            false
        );
        $this->addArg(
            'keep-links-table',
            "Don't overwrite the old links table with the new one, leave the new table at links_temp.",
            false
        );
        $this->addArg(
            'nokeys',
            /* (What about InnoDB?) */
            "Don't create keys, and so allow duplicates in the new links table.\n"
                . "This gives a huge speed improvement for very large links tables which are MyISAM.",
            false
        );
    }

    public function getDbType() {
        return Maintenance::DB_ADMIN;
    }

    public function execute() {
        $dbw = $this->getDB( DB_MASTER );

        $type = $dbw->getType();
        if ( $type != 'mysql' ) {
            $this->output( "Link table conversion not necessary for $type\n" );

            return;
        }

        global $wgContLang;

        # counters etc
        $numBadLinks = $curRowsRead = 0;

        # total tuples INSERTed into links_temp
        $totalTuplesInserted = 0;

        # whether or not to give progress reports while reading IDs from cur table
        $reportCurReadProgress = true;

        # number of rows between progress reports
        $curReadReportInterval = 1000;

        # whether or not to give progress reports during conversion
        $reportLinksConvProgress = true;

        # number of rows per INSERT
        $linksConvInsertInterval = 1000;

        $initialRowOffset = 0;

        # not used yet; highest row number from links table to process
        # $finalRowOffset = 0;

        $overwriteLinksTable = !$this->hasOption( 'keep-links-table' );
        $noKeys = $this->hasOption( 'noKeys' );
        $this->logPerformance = $this->hasOption( 'logperformance' );
        $perfLogFilename = $this->getArg( 'perfLogFilename', "convLinksPerf.txt" );

        # --------------------------------------------------------------------

        list( $cur, $links, $links_temp, $links_backup ) =
            $dbw->tableNamesN( 'cur', 'links', 'links_temp', 'links_backup' );

        if ( $dbw->tableExists( 'pagelinks' ) ) {
            $this->output( "...have pagelinks; skipping old links table updates\n" );

            return;
        }

        $res = $dbw->query( "SELECT l_from FROM $links LIMIT 1" );
        if ( $dbw->fieldType( $res, 0 ) == "int" ) {
            $this->output( "Schema already converted\n" );

            return;
        }

        $res = $dbw->query( "SELECT COUNT(*) AS count FROM $links" );
        $row = $dbw->fetchObject( $res );
        $numRows = $row->count;
        $dbw->freeResult( $res );

        if ( $numRows == 0 ) {
            $this->output( "Updating schema (no rows to convert)...\n" );
            $this->createTempTable();
        } else {
            $fh = false;
            if ( $this->logPerformance ) {
                $fh = fopen( $perfLogFilename, "w" );
                if ( !$fh ) {
                    $this->error( "Couldn't open $perfLogFilename" );
                    $this->logPerformance = false;
                }
            }
            $baseTime = $startTime = microtime( true );
            # Create a title -> cur_id map
            $this->output( "Loading IDs from $cur table...\n" );
            $this->performanceLog( $fh, "Reading $numRows rows from cur table...\n" );
            $this->performanceLog( $fh, "rows read vs seconds elapsed:\n" );

            $dbw->bufferResults( false );
            $res = $dbw->query( "SELECT cur_namespace,cur_title,cur_id FROM $cur" );
            $ids = [];

            foreach ( $res as $row ) {
                $title = $row->cur_title;
                if ( $row->cur_namespace ) {
                    $title = $wgContLang->getNsText( $row->cur_namespace ) . ":$title";
                }
                $ids[$title] = $row->cur_id;
                $curRowsRead++;
                if ( $reportCurReadProgress ) {
                    if ( ( $curRowsRead % $curReadReportInterval ) == 0 ) {
                        $this->performanceLog(
                            $fh,
                            $curRowsRead . " " . ( microtime( true ) - $baseTime ) . "\n"
                        );
                        $this->output( "\t$curRowsRead rows of $cur table read.\n" );
                    }
                }
            }
            $dbw->freeResult( $res );
            $dbw->bufferResults( true );
            $this->output( "Finished loading IDs.\n\n" );
            $this->performanceLog(
                $fh,
                "Took " . ( microtime( true ) - $baseTime ) . " seconds to load IDs.\n\n"
            );

            # --------------------------------------------------------------------

            # Now, step through the links table (in chunks of $linksConvInsertInterval rows),
            # convert, and write to the new table.
            $this->createTempTable();
            $this->performanceLog( $fh, "Resetting timer.\n\n" );
            $baseTime = microtime( true );
            $this->output( "Processing $numRows rows from $links table...\n" );
            $this->performanceLog( $fh, "Processing $numRows rows from $links table...\n" );
            $this->performanceLog( $fh, "rows inserted vs seconds elapsed:\n" );

            for ( $rowOffset = $initialRowOffset; $rowOffset < $numRows;
                $rowOffset += $linksConvInsertInterval
            ) {
                $sqlRead = "SELECT * FROM $links ";
                $sqlRead = $dbw->limitResult( $sqlRead, $linksConvInsertInterval, $rowOffset );
                $res = $dbw->query( $sqlRead );
                if ( $noKeys ) {
                    $sqlWrite = [ "INSERT INTO $links_temp (l_from,l_to) VALUES " ];
                } else {
                    $sqlWrite = [ "INSERT IGNORE INTO $links_temp (l_from,l_to) VALUES " ];
                }

                $tuplesAdded = 0; # no tuples added to INSERT yet
                foreach ( $res as $row ) {
                    $fromTitle = $row->l_from;
                    if ( array_key_exists( $fromTitle, $ids ) ) { # valid title
                        $from = $ids[$fromTitle];
                        $to = $row->l_to;
                        if ( $tuplesAdded != 0 ) {
                            $sqlWrite[] = ",";
                        }
                        $sqlWrite[] = "($from,$to)";
                        $tuplesAdded++;
                    } else { # invalid title
                        $numBadLinks++;
                    }
                }
                $dbw->freeResult( $res );
                # $this->output( "rowOffset: $rowOffset\ttuplesAdded: "
                #   . "$tuplesAdded\tnumBadLinks: $numBadLinks\n" );
                if ( $tuplesAdded != 0 ) {
                    if ( $reportLinksConvProgress ) {
                        $this->output( "Inserting $tuplesAdded tuples into $links_temp..." );
                    }
                    $dbw->query( implode( "", $sqlWrite ) );
                    $totalTuplesInserted += $tuplesAdded;
                    if ( $reportLinksConvProgress ) {
                        $this->output( " done. Total $totalTuplesInserted tuples inserted.\n" );
                        $this->performanceLog(
                            $fh,
                            $totalTuplesInserted . " " . ( microtime( true ) - $baseTime ) . "\n"
                        );
                    }
                }
            }
            $this->output( "$totalTuplesInserted valid titles and "
                . "$numBadLinks invalid titles were processed.\n\n" );
            $this->performanceLog(
                $fh,
                "$totalTuplesInserted valid titles and $numBadLinks invalid titles were processed.\n"
            );
            $this->performanceLog(
                $fh,
                "Total execution time: " . ( microtime( true ) - $startTime ) . " seconds.\n"
            );
            if ( $this->logPerformance ) {
                fclose( $fh );
            }
        }
        # --------------------------------------------------------------------

        if ( $overwriteLinksTable ) {
            # Check for existing links_backup, and delete it if it exists.
            $this->output( "Dropping backup links table if it exists..." );
            $dbw->query( "DROP TABLE IF EXISTS $links_backup", __METHOD__ );
            $this->output( " done.\n" );

            # Swap in the new table, and move old links table to links_backup
            $this->output( "Swapping tables '$links' to '$links_backup'; '$links_temp' to '$links'..." );
            $dbw->query( "RENAME TABLE links TO $links_backup, $links_temp TO $links", __METHOD__ );
            $this->output( " done.\n\n" );

            $this->output( "Conversion complete. The old table remains at $links_backup;\n" );
            $this->output( "delete at your leisure.\n" );
        } else {
            $this->output( "Conversion complete.  The converted table is at $links_temp;\n" );
            $this->output( "the original links table is unchanged.\n" );
        }
    }

    private function createTempTable() {
        $dbConn = $this->getDB( DB_MASTER );

        if ( !( $dbConn->isOpen() ) ) {
            $this->output( "Opening connection to database failed.\n" );

            return;
        }
        $links_temp = $dbConn->tableName( 'links_temp' );

        $this->output( "Dropping temporary links table if it exists..." );
        $dbConn->query( "DROP TABLE IF EXISTS $links_temp" );
        $this->output( " done.\n" );

        $this->output( "Creating temporary links table..." );
        if ( $this->hasOption( 'noKeys' ) ) {
            $dbConn->query( "CREATE TABLE $links_temp ( " .
                "l_from int(8) unsigned NOT NULL default '0', " .
                "l_to int(8) unsigned NOT NULL default '0')" );
        } else {
            $dbConn->query( "CREATE TABLE $links_temp ( " .
                "l_from int(8) unsigned NOT NULL default '0', " .
                "l_to int(8) unsigned NOT NULL default '0', " .
                "UNIQUE KEY l_from(l_from,l_to), " .
                "KEY (l_to))" );
        }
        $this->output( " done.\n\n" );
    }

    private function performanceLog( $fh, $text ) {
        if ( $this->logPerformance ) {
            fwrite( $fh, $text );
        }
    }
}

$maintClass = "ConvertLinks";
require_once RUN_MAINTENANCE_IF_MAIN;