convertLinks.php

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<?php
require_once( dirname( __FILE__ ) . '/Maintenance.php' );

class ConvertLinks extends Maintenance {
        private $logPerformance;

        public function __construct() {
                parent::__construct();
                $this->mDescription = "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', "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." /* (What about InnoDB?) */, false );
        }

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

        public function execute() {
                $dbw = wfGetDB( DB_MASTER );

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

                global $wgContLang;

                $numBadLinks = $curRowsRead = 0; # counters etc
                $totalTuplesInserted = 0; # total tuples INSERTed into links_temp

                $reportCurReadProgress = true; # whether or not to give progress reports while reading IDs from cur table
                $curReadReportInterval = 1000; # number of rows between progress reports

                $reportLinksConvProgress = true; # whether or not to give progress reports during conversion
                $linksConvInsertInterval = 1000; # number of rows per INSERT

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

                $overwriteLinksTable = !$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 = $this->getMicroTime();
                        # 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 = array();

                        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 . " " . ( $this->getMicroTime() - $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 " . ( $this->getMicroTime() - $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 = $this->getMicroTime();
                        $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 = array( "INSERT INTO $links_temp (l_from,l_to) VALUES " );
                                } else {
                                        $sqlWrite = array( "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 . " " . ( $this->getMicroTime() - $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: " . ( $this->getMicroTime() - $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" );

                        $dbw->close();
                        $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 = wfGetDB( 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 );
                }
        }

        private function getMicroTime() { # return time in seconds, with microsecond accuracy
                list( $usec, $sec ) = explode( " ", microtime() );
                return ( (float)$usec + (float)$sec );
        }
}

$maintClass = "ConvertLinks";
require_once( RUN_MAINTENANCE_IF_MAIN );