syncFileBackend.php

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

class SyncFileBackend extends Maintenance {
        public function __construct() {
                parent::__construct();
                $this->mDescription = "Sync one file backend with another using the journal";
                $this->addOption( 'src', 'Name of backend to sync from', true, true );
                $this->addOption( 'dst', 'Name of destination backend to sync', true, true );
                $this->addOption( 'start', 'Starting journal ID', false, true );
                $this->addOption( 'end', 'Ending journal ID', false, true );
                $this->addOption( 'posdir', 'Directory to read/record journal positions', false, true );
                $this->addOption( 'verbose', 'Verbose mode', false, false, 'v' );
                $this->setBatchSize( 50 );
        }

        public function execute() {
                $src = FileBackendGroup::singleton()->get( $this->getOption( 'src' ) );
                $dst = FileBackendGroup::singleton()->get( $this->getOption( 'dst' ) );

                $posDir = $this->getOption( 'posdir' );
                $posFile = $posDir ? $posDir . '/' . wfWikiID() : false;

                $start = $this->getOption( 'start', 0 );
                if ( !$start && $posFile && is_dir( $posDir ) ) {
                        $start = is_file( $posFile )
                                ? (int)trim( file_get_contents( $posFile ) )
                                : 0;
                        ++$start; // we already did this ID, start with the next one
                        $startFromPosFile = true;
                } else {
                        $startFromPosFile = false;
                }
                $end = $this->getOption( 'end', INF );

                $this->output( "Synchronizing backend '{$dst->getName()}' to '{$src->getName()}'...\n" );
                $this->output( "Starting journal position is $start.\n" );
                if ( is_finite( $end ) ) {
                        $this->output( "Ending journal position is $end.\n" );
                }

                // Actually sync the dest backend with the reference backend
                $lastOKPos = $this->syncBackends( $src, $dst, $start, $end );

                // Update the sync position file
                if ( $startFromPosFile && $lastOKPos >= $start ) { // successfully advanced
                        if ( file_put_contents( $posFile, $lastOKPos, LOCK_EX ) !== false ) {
                                $this->output( "Updated journal position file.\n" );
                        } else {
                                $this->output( "Could not update journal position file.\n" );
                        }
                }

                if ( $lastOKPos === false ) {
                        if ( !$start ) {
                                $this->output( "No journal entries found.\n" );
                        } else {
                                $this->output( "No new journal entries found.\n" );
                        }
                } else {
                        $this->output( "Stopped synchronization at journal position $lastOKPos.\n" );
                }

                if ( $this->isQuiet() ) {
                        print $lastOKPos; // give a single machine-readable number
                }
        }

        protected function syncBackends( FileBackend $src, FileBackend $dst, $start, $end ) {
                $lastOKPos = 0; // failed
                $first = true; // first batch

                if ( $start > $end ) { // sanity
                        $this->error( "Error: given starting ID greater than ending ID.", 1 );
                }

                do {
                        $limit = min( $this->mBatchSize, $end - $start + 1 ); // don't go pass ending ID
                        $this->output( "Doing id $start to " . ( $start + $limit - 1 ) . "...\n" );

                        $entries = $src->getJournal()->getChangeEntries( $start, $limit, $next );
                        $start = $next; // start where we left off next time
                        if ( $first && !count( $entries ) ) {
                                return false; // nothing to do
                        }
                        $first = false;

                        $lastPosInBatch = 0;
                        $pathsInBatch = array(); // changed paths
                        foreach ( $entries as $entry ) {
                                if ( $entry['op'] !== 'null' ) { // null ops are just for reference
                                        $pathsInBatch[$entry['path']] = 1; // remove duplicates
                                }
                                $lastPosInBatch = $entry['id'];
                        }

                        $status = $this->syncFileBatch( array_keys( $pathsInBatch ), $src, $dst );
                        if ( $status->isOK() ) {
                                $lastOKPos = max( $lastOKPos, $lastPosInBatch );
                        } else {
                                $this->error( print_r( $status->getErrorsArray(), true ) );
                                break; // no gaps; everything up to $lastPos must be OK
                        }

                        if ( !$start ) {
                                $this->output( "End of journal entries.\n" );
                        }
                } while ( $start && $start <= $end );

                return $lastOKPos;
        }

        protected function syncFileBatch( array $paths, FileBackend $src, FileBackend $dst ) {
                $status = Status::newGood();
                if ( !count( $paths ) ) {
                        return $status; // nothing to do
                }

                // Source: convert internal backend names (FileBackendMultiWrite) to the public one
                $sPaths = $this->replaceNamePaths( $paths, $src );
                // Destination: get corresponding path name
                $dPaths = $this->replaceNamePaths( $paths, $dst );

                // Lock the live backend paths from modification
                $sLock = $src->getScopedFileLocks( $sPaths, LockManager::LOCK_UW, $status );
                $eLock = $dst->getScopedFileLocks( $dPaths, LockManager::LOCK_EX, $status );
                if ( !$status->isOK() ) {
                        return $status;
                }

                $ops = array();
                $fsFiles = array();
                foreach ( $sPaths as $i => $sPath ) {
                        $dPath = $dPaths[$i]; // destination
                        $sExists = $src->fileExists( array( 'src' => $sPath, 'latest' => 1 ) );
                        if ( $sExists === true ) { // exists in source
                                if ( $this->filesAreSame( $src, $dst, $sPath, $dPath ) ) {
                                        continue; // avoid local copies for non-FS backends
                                }
                                // Note: getLocalReference() is fast for FS backends
                                $fsFile = $src->getLocalReference( array( 'src' => $sPath, 'latest' => 1 ) );
                                if ( !$fsFile ) {
                                        $this->error( "Unable to sync '$dPath': could not get local copy." );
                                        $status->fatal( 'backend-fail-internal', $src->getName() );
                                        return $status;
                                }
                                $fsFiles[] = $fsFile; // keep TempFSFile objects alive as needed
                                // Note: prepare() is usually fast for key/value backends
                                $status->merge( $dst->prepare( array(
                                        'dir' => dirname( $dPath ), 'bypassReadOnly' => 1 ) ) );
                                if ( !$status->isOK() ) {
                                        return $status;
                                }
                                $ops[] = array( 'op' => 'store',
                                        'src' => $fsFile->getPath(), 'dst' => $dPath, 'overwrite' => 1 );
                        } elseif ( $sExists === false ) { // does not exist in source
                                $ops[] = array( 'op' => 'delete', 'src' => $dPath, 'ignoreMissingSource' => 1 );
                        } else { // error
                                $this->error( "Unable to sync '$dPath': could not stat file." );
                                $status->fatal( 'backend-fail-internal', $src->getName() );
                                return $status;
                        }
                }

                $t_start = microtime( true );
                $status = $dst->doQuickOperations( $ops, array( 'bypassReadOnly' => 1 ) );
                if ( !$status->isOK() ) {
                        sleep( 10 ); // wait and retry copy again
                        $status = $dst->doQuickOperations( $ops, array( 'bypassReadOnly' => 1 ) );
                }
                $ellapsed_ms = floor( ( microtime( true ) - $t_start ) * 1000 );
                if ( $status->isOK() && $this->getOption( 'verbose' ) ) {
                        $this->output( "Synchronized these file(s) [{$ellapsed_ms}ms]:\n" .
                                implode( "\n", $dPaths ) . "\n" );
                }

                return $status;
        }

        protected function replaceNamePaths( $paths, FileBackend $backend ) {
                return preg_replace(
                        '!^mwstore://([^/]+)!',
                        StringUtils::escapeRegexReplacement( "mwstore://" . $backend->getName() ),
                        $paths // string or array
                );
        }

        protected function filesAreSame( FileBackend $src, FileBackend $dst, $sPath, $dPath ) {
                return (
                        ( $src->getFileSize( array( 'src' => $sPath ) )
                                === $dst->getFileSize( array( 'src' => $dPath ) ) // short-circuit
                        ) && ( $src->getFileSha1Base36( array( 'src' => $sPath ) )
                                === $dst->getFileSha1Base36( array( 'src' => $dPath ) )
                        )
                );
        }
}

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