migrateComments.php

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<?php
use MediaWiki\MediaWikiServices;
use Wikimedia\Rdbms\IDatabase;
 
require_once __DIR__ . '/Maintenance.php';
 
class MigrateComments extends LoggedUpdateMaintenance {
    public function __construct() {
        parent::__construct();
        $this->addDescription( 'Migrates comments from pre-1.30 columns to the \'comment\' table' );
        $this->setBatchSize( 100 );
    }
 
    protected function getUpdateKey() {
        return __CLASS__;
    }
 
    protected function updateSkippedMessage() {
        return 'comments already migrated.';
    }
 
    protected function doDBUpdates() {
        $this->migrateToTemp(
            'revision', 'rev_id', 'rev_comment', 'revcomment_rev', 'revcomment_comment_id'
        );
        $this->migrate( 'archive', 'ar_id', 'ar_comment' );
        $this->migrate( 'ipblocks', 'ipb_id', 'ipb_reason' );
        $this->migrate( 'image', 'img_name', 'img_description' );
        $this->migrate( 'oldimage', [ 'oi_name', 'oi_timestamp' ], 'oi_description' );
        $this->migrate( 'filearchive', 'fa_id', 'fa_deleted_reason' );
        $this->migrate( 'filearchive', 'fa_id', 'fa_description' );
        $this->migrate( 'recentchanges', 'rc_id', 'rc_comment' );
        $this->migrate( 'logging', 'log_id', 'log_comment' );
        $this->migrate( 'protected_titles', [ 'pt_namespace', 'pt_title' ], 'pt_reason' );
        return true;
    }
 
    private function loadCommentIDs( IDatabase $dbw, array &$comments ) {
        $count = 0;
        $needComments = $comments;
 
        while ( true ) {
            $where = [];
            foreach ( $needComments as $need => $dummy ) {
                $need = (string)$need; // T268887
                $where[] = $dbw->makeList(
                    [
                        'comment_hash' => CommentStore::hash( $need, null ),
                        'comment_text' => $need,
                    ],
                    LIST_AND
                );
            }
 
            $res = $dbw->select(
                'comment',
                [ 'comment_id', 'comment_text' ],
                [
                    $dbw->makeList( $where, LIST_OR ),
                    'comment_data' => null,
                ],
                __METHOD__
            );
            foreach ( $res as $row ) {
                $comments[$row->comment_text] = $row->comment_id;
                unset( $needComments[$row->comment_text] );
            }
 
            if ( !$needComments ) {
                break;
            }
 
            $dbw->insert(
                'comment',
                array_map( function ( $v ) {
                    return [
                        'comment_hash' => CommentStore::hash( $v, null ),
                        'comment_text' => $v,
                    ];
                }, array_keys( $needComments ) ),
                __METHOD__
            );
            $count += $dbw->affectedRows();
        }
        return $count;
    }
 
    protected function migrate( $table, $primaryKey, $oldField ) {
        $dbw = $this->getDB( DB_MASTER );
        if ( !$dbw->fieldExists( $table, $oldField, __METHOD__ ) ) {
            $this->output( "No need to migrate $table.$oldField, field does not exist\n" );
            return;
        }
 
        $newField = $oldField . '_id';
        $primaryKey = (array)$primaryKey;
        $pkFilter = array_flip( $primaryKey );
        $this->output( "Beginning migration of $table.$oldField to $table.$newField\n" );
        $lbFactory = MediaWikiServices::getInstance()->getDBLoadBalancerFactory();
        $lbFactory->waitForReplication();
 
        $next = '1=1';
        $countUpdated = 0;
        $countComments = 0;
        while ( true ) {
            // Fetch the rows needing update
            $res = $dbw->select(
                $table,
                array_merge( $primaryKey, [ $oldField ] ),
                [
                    $newField => 0,
                    $next,
                ],
                __METHOD__,
                [
                    'ORDER BY' => $primaryKey,
                    'LIMIT' => $this->getBatchSize(),
                ]
            );
            if ( !$res->numRows() ) {
                break;
            }
 
            // Collect the distinct comments from those rows
            $comments = [];
            foreach ( $res as $row ) {
                $comments[$row->$oldField] = 0;
            }
            $countComments += $this->loadCommentIDs( $dbw, $comments );
 
            // Update the existing rows
            foreach ( $res as $row ) {
                $dbw->update(
                    $table,
                    [
                        $newField => $comments[$row->$oldField],
                        $oldField => '',
                    ],
                    array_intersect_key( (array)$row, $pkFilter ) + [
                        $newField => 0
                    ],
                    __METHOD__
                );
                $countUpdated += $dbw->affectedRows();
            }
 
            // Calculate the "next" condition
            $next = '';
            $prompt = [];
            for ( $i = count( $primaryKey ) - 1; $i >= 0; $i-- ) {
                $field = $primaryKey[$i];
                $prompt[] = $row->$field;
                $value = $dbw->addQuotes( $row->$field );
                if ( $next === '' ) {
                    $next = "$field > $value";
                } else {
                    $next = "$field > $value OR $field = $value AND ($next)";
                }
            }
            $prompt = implode( ' ', array_reverse( $prompt ) );
            $this->output( "... $prompt\n" );
            $lbFactory->waitForReplication();
        }
 
        $this->output(
            "Completed migration, updated $countUpdated row(s) with $countComments new comment(s)\n"
        );
    }
 
    protected function migrateToTemp( $table, $primaryKey, $oldField, $newPrimaryKey, $newField ) {
        $dbw = $this->getDB( DB_MASTER );
        if ( !$dbw->fieldExists( $table, $oldField, __METHOD__ ) ) {
            $this->output( "No need to migrate $table.$oldField, field does not exist\n" );
            return;
        }
 
        $newTable = $table . '_comment_temp';
        $this->output( "Beginning migration of $table.$oldField to $newTable.$newField\n" );
        MediaWikiServices::getInstance()->getDBLoadBalancerFactory()->waitForReplication();
 
        $dbw = $this->getDB( DB_MASTER );
        $next = [];
        $countUpdated = 0;
        $countComments = 0;
        while ( true ) {
            // Fetch the rows needing update
            $res = $dbw->select(
                [ $table, $newTable ],
                [ $primaryKey, $oldField ],
                [ $newPrimaryKey => null ] + $next,
                __METHOD__,
                [
                    'ORDER BY' => $primaryKey,
                    'LIMIT' => $this->getBatchSize(),
                ],
                [ $newTable => [ 'LEFT JOIN', "{$primaryKey}={$newPrimaryKey}" ] ]
            );
            if ( !$res->numRows() ) {
                break;
            }
 
            // Collect the distinct comments from those rows
            $comments = [];
            foreach ( $res as $row ) {
                $comments[$row->$oldField] = 0;
            }
            $countComments += $this->loadCommentIDs( $dbw, $comments );
 
            // Update rows
            $inserts = [];
            $updates = [];
            foreach ( $res as $row ) {
                $inserts[] = [
                    $newPrimaryKey => $row->$primaryKey,
                    $newField => $comments[$row->$oldField]
                ];
                $updates[] = $row->$primaryKey;
            }
            $this->beginTransaction( $dbw, __METHOD__ );
            $dbw->insert( $newTable, $inserts, __METHOD__ );
            $dbw->update( $table, [ $oldField => '' ], [ $primaryKey => $updates ], __METHOD__ );
            $countUpdated += $dbw->affectedRows();
            $this->commitTransaction( $dbw, __METHOD__ );
 
            // Calculate the "next" condition
            $next = [ $primaryKey . ' > ' . $dbw->addQuotes( $row->$primaryKey ) ];
            $this->output( "... {$row->$primaryKey}\n" );
        }
 
        $this->output(
            "Completed migration, updated $countUpdated row(s) with $countComments new comment(s)\n"
        );
    }
}
 
$maintClass = MigrateComments::class;
require_once RUN_MAINTENANCE_IF_MAIN;