SwiftFileBackend.php

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<?php
class SwiftFileBackend extends FileBackendStore {
    protected $auth; // Swift authentication handler
    protected $authTTL; // integer seconds
    protected $swiftTempUrlKey; // string; shared secret value for making temp urls
    protected $swiftAnonUser; // string; username to handle unauthenticated requests
    protected $swiftUseCDN; // boolean; whether CloudFiles CDN is enabled
    protected $swiftCDNExpiry; // integer; how long to cache things in the CDN
    protected $swiftCDNPurgable; // boolean; whether object CDN purging is enabled

    // Rados Gateway specific options
    protected $rgwS3AccessKey; // string; S3 access key
    protected $rgwS3SecretKey; // string; S3 authentication key

    protected $conn; // Swift connection handle
    protected $sessionStarted = 0; // integer UNIX timestamp

    protected $connException;
    protected $connErrorTime = 0; // UNIX timestamp

    protected $srvCache;

    protected $connContainerCache; // container object cache

    public function __construct( array $config ) {
        parent::__construct( $config );
        if ( !class_exists( 'CF_Constants' ) ) {
            throw new MWException( 'SwiftCloudFiles extension not installed.' );
        }
        // Required settings
        $this->auth = new CF_Authentication(
            $config['swiftUser'],
            $config['swiftKey'],
            null, // account; unused
            $config['swiftAuthUrl']
        );
        // Optional settings
        $this->authTTL = isset( $config['swiftAuthTTL'] )
            ? $config['swiftAuthTTL']
            : 5 * 60; // some sane number
        $this->swiftAnonUser = isset( $config['swiftAnonUser'] )
            ? $config['swiftAnonUser']
            : '';
        $this->swiftTempUrlKey = isset( $config['swiftTempUrlKey'] )
            ? $config['swiftTempUrlKey']
            : '';
        $this->shardViaHashLevels = isset( $config['shardViaHashLevels'] )
            ? $config['shardViaHashLevels']
            : '';
        $this->swiftUseCDN = isset( $config['swiftUseCDN'] )
            ? $config['swiftUseCDN']
            : false;
        $this->swiftCDNExpiry = isset( $config['swiftCDNExpiry'] )
            ? $config['swiftCDNExpiry']
            : 12 * 3600; // 12 hours is safe (tokens last 24 hours per http://docs.openstack.org)
        $this->swiftCDNPurgable = isset( $config['swiftCDNPurgable'] )
            ? $config['swiftCDNPurgable']
            : true;
        $this->rgwS3AccessKey = isset( $config['rgwS3AccessKey'] )
            ? $config['rgwS3AccessKey']
            : '';
        $this->rgwS3SecretKey = isset( $config['rgwS3SecretKey'] )
            ? $config['rgwS3SecretKey']
            : '';
        // Cache container information to mask latency
        $this->memCache = wfGetMainCache();
        // Process cache for container info
        $this->connContainerCache = new ProcessCacheLRU( 300 );
        // Cache auth token information to avoid RTTs
        if ( !empty( $config['cacheAuthInfo'] ) ) {
            if ( PHP_SAPI === 'cli' ) {
                $this->srvCache = wfGetMainCache(); // preferrably memcached
            } else {
                try { // look for APC, XCache, WinCache, ect...
                    $this->srvCache = ObjectCache::newAccelerator( array() );
                } catch ( Exception $e ) {}
            }
        }
        $this->srvCache = $this->srvCache ? $this->srvCache : new EmptyBagOStuff();
    }

    protected function resolveContainerPath( $container, $relStoragePath ) {
        if ( !mb_check_encoding( $relStoragePath, 'UTF-8' ) ) { // mb_string required by CF
            return null; // not UTF-8, makes it hard to use CF and the swift HTTP API
        } elseif ( strlen( urlencode( $relStoragePath ) ) > 1024 ) {
            return null; // too long for Swift
        }
        return $relStoragePath;
    }

    public function isPathUsableInternal( $storagePath ) {
        list( $container, $rel ) = $this->resolveStoragePathReal( $storagePath );
        if ( $rel === null ) {
            return false; // invalid
        }

        try {
            $this->getContainer( $container );
            return true; // container exists
        } catch ( NoSuchContainerException $e ) {
        } catch ( CloudFilesException $e ) { // some other exception?
            $this->handleException( $e, null, __METHOD__, array( 'path' => $storagePath ) );
        }

        return false;
    }

    protected function sanitizeHdrs( array $headers ) {
        // By default, Swift has annoyingly low maximum header value limits
        if ( isset( $headers['Content-Disposition'] ) ) {
            $headers['Content-Disposition'] = $this->truncDisp( $headers['Content-Disposition'] );
        }
        return $headers;
    }

    protected function truncDisp( $disposition ) {
        $res = '';
        foreach ( explode( ';', $disposition ) as $part ) {
            $part = trim( $part );
            $new = ( $res === '' ) ? $part : "{$res};{$part}";
            if ( strlen( $new ) <= 255 ) {
                $res = $new;
            } else {
                break; // too long; sigh
            }
        }
        return $res;
    }

    protected function doCreateInternal( array $params ) {
        $status = Status::newGood();

        list( $dstCont, $dstRel ) = $this->resolveStoragePathReal( $params['dst'] );
        if ( $dstRel === null ) {
            $status->fatal( 'backend-fail-invalidpath', $params['dst'] );
            return $status;
        }

        // (a) Check the destination container and object
        try {
            $dContObj = $this->getContainer( $dstCont );
        } catch ( NoSuchContainerException $e ) {
            $status->fatal( 'backend-fail-create', $params['dst'] );
            return $status;
        } catch ( CloudFilesException $e ) { // some other exception?
            $this->handleException( $e, $status, __METHOD__, $params );
            return $status;
        }

        // (b) Get a SHA-1 hash of the object
        $sha1Hash = wfBaseConvert( sha1( $params['content'] ), 16, 36, 31 );

        // (c) Actually create the object
        try {
            // Create a fresh CF_Object with no fields preloaded.
            // We don't want to preserve headers, metadata, and such.
            $obj = new CF_Object( $dContObj, $dstRel, false, false ); // skip HEAD
            $obj->setMetadataValues( array( 'Sha1base36' => $sha1Hash ) );
            // Manually set the ETag (https://github.com/rackspace/php-cloudfiles/issues/59).
            // The MD5 here will be checked within Swift against its own MD5.
            $obj->set_etag( md5( $params['content'] ) );
            // Use the same content type as StreamFile for security
            $obj->content_type = $this->getContentType( $params['dst'], $params['content'], null );
            // Set any other custom headers if requested
            if ( isset( $params['headers'] ) ) {
                $obj->headers += $this->sanitizeHdrs( $params['headers'] );
            }
            if ( !empty( $params['async'] ) ) { // deferred
                $op = $obj->write_async( $params['content'] );
                $status->value = new SwiftFileOpHandle( $this, $params, 'Create', $op );
                $status->value->affectedObjects[] = $obj;
            } else { // actually write the object in Swift
                $obj->write( $params['content'] );
                $this->purgeCDNCache( array( $obj ) );
            }
        } catch ( CDNNotEnabledException $e ) {
            // CDN not enabled; nothing to see here
        } catch ( BadContentTypeException $e ) {
            $status->fatal( 'backend-fail-contenttype', $params['dst'] );
        } catch ( CloudFilesException $e ) { // some other exception?
            $this->handleException( $e, $status, __METHOD__, $params );
        }

        return $status;
    }

    protected function _getResponseCreate( CF_Async_Op $cfOp, Status $status, array $params ) {
        try {
            $cfOp->getLastResponse();
        } catch ( BadContentTypeException $e ) {
            $status->fatal( 'backend-fail-contenttype', $params['dst'] );
        }
    }

    protected function doStoreInternal( array $params ) {
        $status = Status::newGood();

        list( $dstCont, $dstRel ) = $this->resolveStoragePathReal( $params['dst'] );
        if ( $dstRel === null ) {
            $status->fatal( 'backend-fail-invalidpath', $params['dst'] );
            return $status;
        }

        // (a) Check the destination container and object
        try {
            $dContObj = $this->getContainer( $dstCont );
        } catch ( NoSuchContainerException $e ) {
            $status->fatal( 'backend-fail-copy', $params['src'], $params['dst'] );
            return $status;
        } catch ( CloudFilesException $e ) { // some other exception?
            $this->handleException( $e, $status, __METHOD__, $params );
            return $status;
        }

        // (b) Get a SHA-1 hash of the object
        wfSuppressWarnings();
        $sha1Hash = sha1_file( $params['src'] );
        wfRestoreWarnings();
        if ( $sha1Hash === false ) { // source doesn't exist?
            $status->fatal( 'backend-fail-copy', $params['src'], $params['dst'] );
            return $status;
        }
        $sha1Hash = wfBaseConvert( $sha1Hash, 16, 36, 31 );

        // (c) Actually store the object
        try {
            // Create a fresh CF_Object with no fields preloaded.
            // We don't want to preserve headers, metadata, and such.
            $obj = new CF_Object( $dContObj, $dstRel, false, false ); // skip HEAD
            $obj->setMetadataValues( array( 'Sha1base36' => $sha1Hash ) );
            // The MD5 here will be checked within Swift against its own MD5.
            $obj->set_etag( md5_file( $params['src'] ) );
            // Use the same content type as StreamFile for security
            $obj->content_type = $this->getContentType( $params['dst'], null, $params['src'] );
            // Set any other custom headers if requested
            if ( isset( $params['headers'] ) ) {
                $obj->headers += $this->sanitizeHdrs( $params['headers'] );
            }
            if ( !empty( $params['async'] ) ) { // deferred
                wfSuppressWarnings();
                $fp = fopen( $params['src'], 'rb' );
                wfRestoreWarnings();
                if ( !$fp ) {
                    $status->fatal( 'backend-fail-copy', $params['src'], $params['dst'] );
                } else {
                    $op = $obj->write_async( $fp, filesize( $params['src'] ), true );
                    $status->value = new SwiftFileOpHandle( $this, $params, 'Store', $op );
                    $status->value->resourcesToClose[] = $fp;
                    $status->value->affectedObjects[] = $obj;
                }
            } else { // actually write the object in Swift
                $obj->load_from_filename( $params['src'], true ); // calls $obj->write()
                $this->purgeCDNCache( array( $obj ) );
            }
        } catch ( CDNNotEnabledException $e ) {
            // CDN not enabled; nothing to see here
        } catch ( BadContentTypeException $e ) {
            $status->fatal( 'backend-fail-contenttype', $params['dst'] );
        } catch ( IOException $e ) {
            $status->fatal( 'backend-fail-copy', $params['src'], $params['dst'] );
        } catch ( CloudFilesException $e ) { // some other exception?
            $this->handleException( $e, $status, __METHOD__, $params );
        }

        return $status;
    }

    protected function _getResponseStore( CF_Async_Op $cfOp, Status $status, array $params ) {
        try {
            $cfOp->getLastResponse();
        } catch ( BadContentTypeException $e ) {
            $status->fatal( 'backend-fail-contenttype', $params['dst'] );
        } catch ( IOException $e ) {
            $status->fatal( 'backend-fail-copy', $params['src'], $params['dst'] );
        }
    }

    protected function doCopyInternal( array $params ) {
        $status = Status::newGood();

        list( $srcCont, $srcRel ) = $this->resolveStoragePathReal( $params['src'] );
        if ( $srcRel === null ) {
            $status->fatal( 'backend-fail-invalidpath', $params['src'] );
            return $status;
        }

        list( $dstCont, $dstRel ) = $this->resolveStoragePathReal( $params['dst'] );
        if ( $dstRel === null ) {
            $status->fatal( 'backend-fail-invalidpath', $params['dst'] );
            return $status;
        }

        // (a) Check the source/destination containers and destination object
        try {
            $sContObj = $this->getContainer( $srcCont );
            $dContObj = $this->getContainer( $dstCont );
        } catch ( NoSuchContainerException $e ) {
            if ( empty( $params['ignoreMissingSource'] ) || isset( $sContObj ) ) {
                $status->fatal( 'backend-fail-copy', $params['src'], $params['dst'] );
            }
            return $status;
        } catch ( CloudFilesException $e ) { // some other exception?
            $this->handleException( $e, $status, __METHOD__, $params );
            return $status;
        }

        // (b) Actually copy the file to the destination
        try {
            $dstObj = new CF_Object( $dContObj, $dstRel, false, false ); // skip HEAD
            $hdrs = array(); // source file headers to override with new values
            // Set any other custom headers if requested
            if ( isset( $params['headers'] ) ) {
                $hdrs += $this->sanitizeHdrs( $params['headers'] );
            }
            if ( !empty( $params['async'] ) ) { // deferred
                $op = $sContObj->copy_object_to_async( $srcRel, $dContObj, $dstRel, null, $hdrs );
                $status->value = new SwiftFileOpHandle( $this, $params, 'Copy', $op );
                $status->value->affectedObjects[] = $dstObj;
            } else { // actually write the object in Swift
                $sContObj->copy_object_to( $srcRel, $dContObj, $dstRel, null, $hdrs );
                $this->purgeCDNCache( array( $dstObj ) );
            }
        } catch ( CDNNotEnabledException $e ) {
            // CDN not enabled; nothing to see here
        } catch ( NoSuchObjectException $e ) { // source object does not exist
            if ( empty( $params['ignoreMissingSource'] ) ) {
                $status->fatal( 'backend-fail-copy', $params['src'], $params['dst'] );
            }
        } catch ( CloudFilesException $e ) { // some other exception?
            $this->handleException( $e, $status, __METHOD__, $params );
        }

        return $status;
    }

    protected function _getResponseCopy( CF_Async_Op $cfOp, Status $status, array $params ) {
        try {
            $cfOp->getLastResponse();
        } catch ( NoSuchObjectException $e ) { // source object does not exist
            $status->fatal( 'backend-fail-copy', $params['src'], $params['dst'] );
        }
    }

    protected function doMoveInternal( array $params ) {
        $status = Status::newGood();

        list( $srcCont, $srcRel ) = $this->resolveStoragePathReal( $params['src'] );
        if ( $srcRel === null ) {
            $status->fatal( 'backend-fail-invalidpath', $params['src'] );
            return $status;
        }

        list( $dstCont, $dstRel ) = $this->resolveStoragePathReal( $params['dst'] );
        if ( $dstRel === null ) {
            $status->fatal( 'backend-fail-invalidpath', $params['dst'] );
            return $status;
        }

        // (a) Check the source/destination containers and destination object
        try {
            $sContObj = $this->getContainer( $srcCont );
            $dContObj = $this->getContainer( $dstCont );
        } catch ( NoSuchContainerException $e ) {
            if ( empty( $params['ignoreMissingSource'] ) || isset( $sContObj ) ) {
                $status->fatal( 'backend-fail-move', $params['src'], $params['dst'] );
            }
            return $status;
        } catch ( CloudFilesException $e ) { // some other exception?
            $this->handleException( $e, $status, __METHOD__, $params );
            return $status;
        }

        // (b) Actually move the file to the destination
        try {
            $srcObj = new CF_Object( $sContObj, $srcRel, false, false ); // skip HEAD
            $dstObj = new CF_Object( $dContObj, $dstRel, false, false ); // skip HEAD
            $hdrs = array(); // source file headers to override with new values
            // Set any other custom headers if requested
            if ( isset( $params['headers'] ) ) {
                $hdrs += $this->sanitizeHdrs( $params['headers'] );
            }
            if ( !empty( $params['async'] ) ) { // deferred
                $op = $sContObj->move_object_to_async( $srcRel, $dContObj, $dstRel, null, $hdrs );
                $status->value = new SwiftFileOpHandle( $this, $params, 'Move', $op );
                $status->value->affectedObjects[] = $srcObj;
                $status->value->affectedObjects[] = $dstObj;
            } else { // actually write the object in Swift
                $sContObj->move_object_to( $srcRel, $dContObj, $dstRel, null, $hdrs );
                $this->purgeCDNCache( array( $srcObj ) );
                $this->purgeCDNCache( array( $dstObj ) );
            }
        } catch ( CDNNotEnabledException $e ) {
            // CDN not enabled; nothing to see here
        } catch ( NoSuchObjectException $e ) { // source object does not exist
            if ( empty( $params['ignoreMissingSource'] ) ) {
                $status->fatal( 'backend-fail-move', $params['src'], $params['dst'] );
            }
        } catch ( CloudFilesException $e ) { // some other exception?
            $this->handleException( $e, $status, __METHOD__, $params );
        }

        return $status;
    }

    protected function _getResponseMove( CF_Async_Op $cfOp, Status $status, array $params ) {
        try {
            $cfOp->getLastResponse();
        } catch ( NoSuchObjectException $e ) { // source object does not exist
            $status->fatal( 'backend-fail-move', $params['src'], $params['dst'] );
        }
    }

    protected function doDeleteInternal( array $params ) {
        $status = Status::newGood();

        list( $srcCont, $srcRel ) = $this->resolveStoragePathReal( $params['src'] );
        if ( $srcRel === null ) {
            $status->fatal( 'backend-fail-invalidpath', $params['src'] );
            return $status;
        }

        try {
            $sContObj = $this->getContainer( $srcCont );
            $srcObj = new CF_Object( $sContObj, $srcRel, false, false ); // skip HEAD
            if ( !empty( $params['async'] ) ) { // deferred
                $op = $sContObj->delete_object_async( $srcRel );
                $status->value = new SwiftFileOpHandle( $this, $params, 'Delete', $op );
                $status->value->affectedObjects[] = $srcObj;
            } else { // actually write the object in Swift
                $sContObj->delete_object( $srcRel );
                $this->purgeCDNCache( array( $srcObj ) );
            }
        } catch ( CDNNotEnabledException $e ) {
            // CDN not enabled; nothing to see here
        } catch ( NoSuchContainerException $e ) {
            if ( empty( $params['ignoreMissingSource'] ) ) {
                $status->fatal( 'backend-fail-delete', $params['src'] );
            }
        } catch ( NoSuchObjectException $e ) {
            if ( empty( $params['ignoreMissingSource'] ) ) {
                $status->fatal( 'backend-fail-delete', $params['src'] );
            }
        } catch ( CloudFilesException $e ) { // some other exception?
            $this->handleException( $e, $status, __METHOD__, $params );
        }

        return $status;
    }

    protected function _getResponseDelete( CF_Async_Op $cfOp, Status $status, array $params ) {
        try {
            $cfOp->getLastResponse();
        } catch ( NoSuchContainerException $e ) {
            $status->fatal( 'backend-fail-delete', $params['src'] );
        } catch ( NoSuchObjectException $e ) {
            if ( empty( $params['ignoreMissingSource'] ) ) {
                $status->fatal( 'backend-fail-delete', $params['src'] );
            }
        }
    }

    protected function doDescribeInternal( array $params ) {
        $status = Status::newGood();

        list( $srcCont, $srcRel ) = $this->resolveStoragePathReal( $params['src'] );
        if ( $srcRel === null ) {
            $status->fatal( 'backend-fail-invalidpath', $params['src'] );
            return $status;
        }

        try {
            $sContObj = $this->getContainer( $srcCont );
            // Get the latest version of the current metadata
            $srcObj = $sContObj->get_object( $srcRel,
                $this->headersFromParams( array( 'latest' => true ) ) );
            // Merge in the metadata updates...
            if ( isset( $params['headers'] ) ) {
                $srcObj->headers = $this->sanitizeHdrs( $params['headers'] ) + $srcObj->headers;
            }
            $srcObj->sync_metadata(); // save to Swift
            $this->purgeCDNCache( array( $srcObj ) );
        } catch ( CDNNotEnabledException $e ) {
            // CDN not enabled; nothing to see here
        } catch ( NoSuchContainerException $e ) {
            $status->fatal( 'backend-fail-describe', $params['src'] );
        } catch ( NoSuchObjectException $e ) {
            $status->fatal( 'backend-fail-describe', $params['src'] );
        } catch ( CloudFilesException $e ) { // some other exception?
            $this->handleException( $e, $status, __METHOD__, $params );
        }

        return $status;
    }

    protected function doPrepareInternal( $fullCont, $dir, array $params ) {
        $status = Status::newGood();

        // (a) Check if container already exists
        try {
            $this->getContainer( $fullCont );
            // NoSuchContainerException not thrown: container must exist
            return $status; // already exists
        } catch ( NoSuchContainerException $e ) {
            // NoSuchContainerException thrown: container does not exist
        } catch ( CloudFilesException $e ) { // some other exception?
            $this->handleException( $e, $status, __METHOD__, $params );
            return $status;
        }

        // (b) Create container as needed
        try {
            $contObj = $this->createContainer( $fullCont );
            if ( !empty( $params['noAccess'] ) ) {
                // Make container private to end-users...
                $status->merge( $this->doSecureInternal( $fullCont, $dir, $params ) );
            } else {
                // Make container public to end-users...
                $status->merge( $this->doPublishInternal( $fullCont, $dir, $params ) );
            }
            if ( $this->swiftUseCDN ) { // Rackspace style CDN
                $contObj->make_public( $this->swiftCDNExpiry );
            }
        } catch ( CDNNotEnabledException $e ) {
            // CDN not enabled; nothing to see here
        } catch ( CloudFilesException $e ) { // some other exception?
            $this->handleException( $e, $status, __METHOD__, $params );
            return $status;
        }

        return $status;
    }

    protected function doSecureInternal( $fullCont, $dir, array $params ) {
        $status = Status::newGood();
        if ( empty( $params['noAccess'] ) ) {
            return $status; // nothing to do
        }

        // Restrict container from end-users...
        try {
            // doPrepareInternal() should have been called,
            // so the Swift container should already exist...
            $contObj = $this->getContainer( $fullCont ); // normally a cache hit
            // NoSuchContainerException not thrown: container must exist

            // Make container private to end-users...
            $status->merge( $this->setContainerAccess(
                $contObj,
                array( $this->auth->username ), // read
                array( $this->auth->username ) // write
            ) );
            if ( $this->swiftUseCDN && $contObj->is_public() ) { // Rackspace style CDN
                $contObj->make_private();
            }
        } catch ( CDNNotEnabledException $e ) {
            // CDN not enabled; nothing to see here
        } catch ( CloudFilesException $e ) { // some other exception?
            $this->handleException( $e, $status, __METHOD__, $params );
        }

        return $status;
    }

    protected function doPublishInternal( $fullCont, $dir, array $params ) {
        $status = Status::newGood();

        // Unrestrict container from end-users...
        try {
            // doPrepareInternal() should have been called,
            // so the Swift container should already exist...
            $contObj = $this->getContainer( $fullCont ); // normally a cache hit
            // NoSuchContainerException not thrown: container must exist

            // Make container public to end-users...
            if ( $this->swiftAnonUser != '' ) {
                $status->merge( $this->setContainerAccess(
                    $contObj,
                    array( $this->auth->username, $this->swiftAnonUser ), // read
                    array( $this->auth->username, $this->swiftAnonUser ) // write
                ) );
            } else {
                $status->merge( $this->setContainerAccess(
                    $contObj,
                    array( $this->auth->username, '.r:*' ), // read
                    array( $this->auth->username ) // write
                ) );
            }
            if ( $this->swiftUseCDN && !$contObj->is_public() ) { // Rackspace style CDN
                $contObj->make_public();
            }
        } catch ( CDNNotEnabledException $e ) {
            // CDN not enabled; nothing to see here
        } catch ( CloudFilesException $e ) { // some other exception?
            $this->handleException( $e, $status, __METHOD__, $params );
        }

        return $status;
    }

    protected function doCleanInternal( $fullCont, $dir, array $params ) {
        $status = Status::newGood();

        // Only containers themselves can be removed, all else is virtual
        if ( $dir != '' ) {
            return $status; // nothing to do
        }

        // (a) Check the container
        try {
            $contObj = $this->getContainer( $fullCont, true );
        } catch ( NoSuchContainerException $e ) {
            return $status; // ok, nothing to do
        } catch ( CloudFilesException $e ) { // some other exception?
            $this->handleException( $e, $status, __METHOD__, $params );
            return $status;
        }

        // (b) Delete the container if empty
        if ( $contObj->object_count == 0 ) {
            try {
                $this->deleteContainer( $fullCont );
            } catch ( NoSuchContainerException $e ) {
                return $status; // race?
            } catch ( NonEmptyContainerException $e ) {
                return $status; // race? consistency delay?
            } catch ( CloudFilesException $e ) { // some other exception?
                $this->handleException( $e, $status, __METHOD__, $params );
                return $status;
            }
        }

        return $status;
    }

    protected function doGetFileStat( array $params ) {
        list( $srcCont, $srcRel ) = $this->resolveStoragePathReal( $params['src'] );
        if ( $srcRel === null ) {
            return false; // invalid storage path
        }

        $stat = false;
        try {
            $contObj = $this->getContainer( $srcCont );
            $srcObj = $contObj->get_object( $srcRel, $this->headersFromParams( $params ) );
            $this->addMissingMetadata( $srcObj, $params['src'] );
            $stat = array(
                // Convert dates like "Tue, 03 Jan 2012 22:01:04 GMT" to TS_MW
                'mtime' => wfTimestamp( TS_MW, $srcObj->last_modified ),
                'size' => (int)$srcObj->content_length,
                'sha1' => $srcObj->getMetadataValue( 'Sha1base36' )
            );
        } catch ( NoSuchContainerException $e ) {
        } catch ( NoSuchObjectException $e ) {
        } catch ( CloudFilesException $e ) { // some other exception?
            $stat = null;
            $this->handleException( $e, null, __METHOD__, $params );
        }

        return $stat;
    }

    protected function addMissingMetadata( CF_Object $obj, $path ) {
        if ( $obj->getMetadataValue( 'Sha1base36' ) !== null ) {
            return true; // nothing to do
        }
        wfProfileIn( __METHOD__ );
        trigger_error( "$path was not stored with SHA-1 metadata.", E_USER_WARNING );
        $status = Status::newGood();
        $scopeLockS = $this->getScopedFileLocks( array( $path ), LockManager::LOCK_UW, $status );
        if ( $status->isOK() ) {
            $tmpFile = $this->getLocalCopy( array( 'src' => $path, 'latest' => 1 ) );
            if ( $tmpFile ) {
                $hash = $tmpFile->getSha1Base36();
                if ( $hash !== false ) {
                    $obj->setMetadataValues( array( 'Sha1base36' => $hash ) );
                    $obj->sync_metadata(); // save to Swift
                    wfProfileOut( __METHOD__ );
                    return true; // success
                }
            }
        }
        trigger_error( "Unable to set SHA-1 metadata for $path", E_USER_WARNING );
        $obj->setMetadataValues( array( 'Sha1base36' => false ) );
        wfProfileOut( __METHOD__ );
        return false; // failed
    }

    protected function doGetFileContentsMulti( array $params ) {
        $contents = array();

        $ep = array_diff_key( $params, array( 'srcs' => 1 ) ); // for error logging
        // Blindly create tmp files and stream to them, catching any exception if the file does
        // not exist. Doing stats here is useless and will loop infinitely in addMissingMetadata().
        foreach ( array_chunk( $params['srcs'], $params['concurrency'] ) as $pathBatch ) {
            $cfOps = array(); // (path => CF_Async_Op)

            foreach ( $pathBatch as $path ) { // each path in this concurrent batch
                list( $srcCont, $srcRel ) = $this->resolveStoragePathReal( $path );
                if ( $srcRel === null ) {
                    $contents[$path] = false;
                    continue;
                }
                $data = false;
                try {
                    $sContObj = $this->getContainer( $srcCont );
                    $obj = new CF_Object( $sContObj, $srcRel, false, false ); // skip HEAD
                    // Create a new temporary memory file...
                    $handle = fopen( 'php://temp', 'wb' );
                    if ( $handle ) {
                        $headers = $this->headersFromParams( $params );
                        if ( count( $pathBatch ) > 1 ) {
                            $cfOps[$path] = $obj->stream_async( $handle, $headers );
                            $cfOps[$path]->_file_handle = $handle; // close this later
                        } else {
                            $obj->stream( $handle, $headers );
                            rewind( $handle ); // start from the beginning
                            $data = stream_get_contents( $handle );
                            fclose( $handle );
                        }
                    } else {
                        $data = false;
                    }
                } catch ( NoSuchContainerException $e ) {
                    $data = false;
                } catch ( NoSuchObjectException $e ) {
                    $data = false;
                } catch ( CloudFilesException $e ) { // some other exception?
                    $data = false;
                    $this->handleException( $e, null, __METHOD__, array( 'src' => $path ) + $ep );
                }
                $contents[$path] = $data;
            }

            $batch = new CF_Async_Op_Batch( $cfOps );
            $cfOps = $batch->execute();
            foreach ( $cfOps as $path => $cfOp ) {
                try {
                    $cfOp->getLastResponse();
                    rewind( $cfOp->_file_handle ); // start from the beginning
                    $contents[$path] = stream_get_contents( $cfOp->_file_handle );
                } catch ( NoSuchContainerException $e ) {
                    $contents[$path] = false;
                } catch ( NoSuchObjectException $e ) {
                    $contents[$path] = false;
                } catch ( CloudFilesException $e ) { // some other exception?
                    $contents[$path] = false;
                    $this->handleException( $e, null, __METHOD__, array( 'src' => $path ) + $ep );
                }
                fclose( $cfOp->_file_handle ); // close open handle
            }
        }

        return $contents;
    }

    protected function doDirectoryExists( $fullCont, $dir, array $params ) {
        try {
            $container = $this->getContainer( $fullCont );
            $prefix = ( $dir == '' ) ? null : "{$dir}/";
            return ( count( $container->list_objects( 1, null, $prefix ) ) > 0 );
        } catch ( NoSuchContainerException $e ) {
            return false;
        } catch ( CloudFilesException $e ) { // some other exception?
            $this->handleException( $e, null, __METHOD__,
                array( 'cont' => $fullCont, 'dir' => $dir ) );
        }

        return null; // error
    }

    public function getDirectoryListInternal( $fullCont, $dir, array $params ) {
        return new SwiftFileBackendDirList( $this, $fullCont, $dir, $params );
    }

    public function getFileListInternal( $fullCont, $dir, array $params ) {
        return new SwiftFileBackendFileList( $this, $fullCont, $dir, $params );
    }

    public function getDirListPageInternal( $fullCont, $dir, &$after, $limit, array $params ) {
        $dirs = array();
        if ( $after === INF ) {
            return $dirs; // nothing more
        }

        $section = new ProfileSection( __METHOD__ . '-' . $this->name );
        try {
            $container = $this->getContainer( $fullCont );
            $prefix = ( $dir == '' ) ? null : "{$dir}/";
            // Non-recursive: only list dirs right under $dir
            if ( !empty( $params['topOnly'] ) ) {
                $objects = $container->list_objects( $limit, $after, $prefix, null, '/' );
                foreach ( $objects as $object ) { // files and directories
                    if ( substr( $object, -1 ) === '/' ) {
                        $dirs[] = $object; // directories end in '/'
                    }
                }
            // Recursive: list all dirs under $dir and its subdirs
            } else {
                // Get directory from last item of prior page
                $lastDir = $this->getParentDir( $after ); // must be first page
                $objects = $container->list_objects( $limit, $after, $prefix );
                foreach ( $objects as $object ) { // files
                    $objectDir = $this->getParentDir( $object ); // directory of object
                    if ( $objectDir !== false && $objectDir !== $dir ) {
                        // Swift stores paths in UTF-8, using binary sorting.
                        // See function "create_container_table" in common/db.py.
                        // If a directory is not "greater" than the last one,
                        // then it was already listed by the calling iterator.
                        if ( strcmp( $objectDir, $lastDir ) > 0 ) {
                            $pDir = $objectDir;
                            do { // add dir and all its parent dirs
                                $dirs[] = "{$pDir}/";
                                $pDir = $this->getParentDir( $pDir );
                            } while ( $pDir !== false // sanity
                                && strcmp( $pDir, $lastDir ) > 0 // not done already
                                && strlen( $pDir ) > strlen( $dir ) // within $dir
                            );
                        }
                        $lastDir = $objectDir;
                    }
                }
            }
            // Page on the unfiltered directory listing (what is returned may be filtered)
            if ( count( $objects ) < $limit ) {
                $after = INF; // avoid a second RTT
            } else {
                $after = end( $objects ); // update last item
            }
        } catch ( NoSuchContainerException $e ) {
        } catch ( CloudFilesException $e ) { // some other exception?
            $this->handleException( $e, null, __METHOD__,
                array( 'cont' => $fullCont, 'dir' => $dir ) );
            throw new FileBackendError( "Got " . get_class( $e ) . " exception." );
        }

        return $dirs;
    }

    protected function getParentDir( $path ) {
        return ( strpos( $path, '/' ) !== false ) ? dirname( $path ) : false;
    }

    public function getFileListPageInternal( $fullCont, $dir, &$after, $limit, array $params ) {
        $files = array();
        if ( $after === INF ) {
            return $files; // nothing more
        }

        $section = new ProfileSection( __METHOD__ . '-' . $this->name );
        try {
            $container = $this->getContainer( $fullCont );
            $prefix = ( $dir == '' ) ? null : "{$dir}/";
            // Non-recursive: only list files right under $dir
            if ( !empty( $params['topOnly'] ) ) { // files and dirs
                if ( !empty( $params['adviseStat'] ) ) {
                    $limit = min( $limit, self::CACHE_CHEAP_SIZE );
                    // Note: get_objects() does not include directories
                    $objects = $this->loadObjectListing( $params, $dir,
                        $container->get_objects( $limit, $after, $prefix, null, '/' ) );
                    $files = $objects;
                } else {
                    $objects = $container->list_objects( $limit, $after, $prefix, null, '/' );
                    foreach ( $objects as $object ) { // files and directories
                        if ( substr( $object, -1 ) !== '/' ) {
                            $files[] = $object; // directories end in '/'
                        }
                    }
                }
            // Recursive: list all files under $dir and its subdirs
            } else { // files
                if ( !empty( $params['adviseStat'] ) ) {
                    $limit = min( $limit, self::CACHE_CHEAP_SIZE );
                    $objects = $this->loadObjectListing( $params, $dir,
                        $container->get_objects( $limit, $after, $prefix ) );
                } else {
                    $objects = $container->list_objects( $limit, $after, $prefix );
                }
                $files = $objects;
            }
            // Page on the unfiltered object listing (what is returned may be filtered)
            if ( count( $objects ) < $limit ) {
                $after = INF; // avoid a second RTT
            } else {
                $after = end( $objects ); // update last item
            }
        } catch ( NoSuchContainerException $e ) {
        } catch ( CloudFilesException $e ) { // some other exception?
            $this->handleException( $e, null, __METHOD__,
                array( 'cont' => $fullCont, 'dir' => $dir ) );
            throw new FileBackendError( "Got " . get_class( $e ) . " exception." );
        }

        return $files;
    }

    private function loadObjectListing( array $params, $dir, array $cfObjects ) {
        $names = array();
        $storageDir = rtrim( $params['dir'], '/' );
        $suffixStart = ( $dir === '' ) ? 0 : strlen( $dir ) + 1; // size of "path/to/dir/"
        // Iterate over the list *backwards* as this primes the stat cache, which is LRU.
        // If this fills the cache and the caller stats an uncached file before stating
        // the ones on the listing, there would be zero cache hits if this went forwards.
        for ( end( $cfObjects ); key( $cfObjects ) !== null; prev( $cfObjects ) ) {
            $object = current( $cfObjects );
            $path = "{$storageDir}/" . substr( $object->name, $suffixStart );
            $val = array(
                // Convert dates like "Tue, 03 Jan 2012 22:01:04 GMT" to TS_MW
                'mtime'  => wfTimestamp( TS_MW, $object->last_modified ),
                'size'   => (int)$object->content_length,
                'latest' => false // eventually consistent
            );
            $this->cheapCache->set( $path, 'stat', $val );
            $names[] = $object->name;
        }
        return array_reverse( $names ); // keep the paths in original order
    }

    protected function doGetFileSha1base36( array $params ) {
        $stat = $this->getFileStat( $params );
        if ( $stat ) {
            if ( !isset( $stat['sha1'] ) ) {
                // Stat entries filled by file listings don't include SHA1
                $this->clearCache( array( $params['src'] ) );
                $stat = $this->getFileStat( $params );
            }
            return $stat['sha1'];
        } else {
            return false;
        }
    }

    protected function doStreamFile( array $params ) {
        $status = Status::newGood();

        list( $srcCont, $srcRel ) = $this->resolveStoragePathReal( $params['src'] );
        if ( $srcRel === null ) {
            $status->fatal( 'backend-fail-invalidpath', $params['src'] );
        }

        try {
            $cont = $this->getContainer( $srcCont );
        } catch ( NoSuchContainerException $e ) {
            $status->fatal( 'backend-fail-stream', $params['src'] );
            return $status;
        } catch ( CloudFilesException $e ) { // some other exception?
            $this->handleException( $e, $status, __METHOD__, $params );
            return $status;
        }

        try {
            $output = fopen( 'php://output', 'wb' );
            $obj = new CF_Object( $cont, $srcRel, false, false ); // skip HEAD
            $obj->stream( $output, $this->headersFromParams( $params ) );
        } catch ( NoSuchObjectException $e ) {
            $status->fatal( 'backend-fail-stream', $params['src'] );
        } catch ( CloudFilesException $e ) { // some other exception?
            $this->handleException( $e, $status, __METHOD__, $params );
        }

        return $status;
    }

    protected function doGetLocalCopyMulti( array $params ) {
        $tmpFiles = array();

        $ep = array_diff_key( $params, array( 'srcs' => 1 ) ); // for error logging
        // Blindly create tmp files and stream to them, catching any exception if the file does
        // not exist. Doing a stat here is useless causes infinite loops in addMissingMetadata().
        foreach ( array_chunk( $params['srcs'], $params['concurrency'] ) as $pathBatch ) {
            $cfOps = array(); // (path => CF_Async_Op)

            foreach ( $pathBatch as $path ) { // each path in this concurrent batch
                list( $srcCont, $srcRel ) = $this->resolveStoragePathReal( $path );
                if ( $srcRel === null ) {
                    $tmpFiles[$path] = null;
                    continue;
                }
                $tmpFile = null;
                try {
                    $sContObj = $this->getContainer( $srcCont );
                    $obj = new CF_Object( $sContObj, $srcRel, false, false ); // skip HEAD
                    // Get source file extension
                    $ext = FileBackend::extensionFromPath( $path );
                    // Create a new temporary file...
                    $tmpFile = TempFSFile::factory( 'localcopy_', $ext );
                    if ( $tmpFile ) {
                        $handle = fopen( $tmpFile->getPath(), 'wb' );
                        if ( $handle ) {
                            $headers = $this->headersFromParams( $params );
                            if ( count( $pathBatch ) > 1 ) {
                                $cfOps[$path] = $obj->stream_async( $handle, $headers );
                                $cfOps[$path]->_file_handle = $handle; // close this later
                            } else {
                                $obj->stream( $handle, $headers );
                                fclose( $handle );
                            }
                        } else {
                            $tmpFile = null;
                        }
                    }
                } catch ( NoSuchContainerException $e ) {
                    $tmpFile = null;
                } catch ( NoSuchObjectException $e ) {
                    $tmpFile = null;
                } catch ( CloudFilesException $e ) { // some other exception?
                    $tmpFile = null;
                    $this->handleException( $e, null, __METHOD__, array( 'src' => $path ) + $ep );
                }
                $tmpFiles[$path] = $tmpFile;
            }

            $batch = new CF_Async_Op_Batch( $cfOps );
            $cfOps = $batch->execute();
            foreach ( $cfOps as $path => $cfOp ) {
                try {
                    $cfOp->getLastResponse();
                } catch ( NoSuchContainerException $e ) {
                    $tmpFiles[$path] = null;
                } catch ( NoSuchObjectException $e ) {
                    $tmpFiles[$path] = null;
                } catch ( CloudFilesException $e ) { // some other exception?
                    $tmpFiles[$path] = null;
                    $this->handleException( $e, null, __METHOD__, array( 'src' => $path ) + $ep );
                }
                fclose( $cfOp->_file_handle ); // close open handle
            }
        }

        return $tmpFiles;
    }

    public function getFileHttpUrl( array $params ) {
        if ( $this->swiftTempUrlKey != '' ||
            ( $this->rgwS3AccessKey != '' && $this->rgwS3SecretKey != '' ) )
        {
            list( $srcCont, $srcRel ) = $this->resolveStoragePathReal( $params['src'] );
            if ( $srcRel === null ) {
                return null; // invalid path
            }
            try {
                $ttl = isset( $params['ttl'] ) ? $params['ttl'] : 86400;
                $sContObj = $this->getContainer( $srcCont );
                $obj = new CF_Object( $sContObj, $srcRel, false, false ); // skip HEAD
                if ( $this->swiftTempUrlKey != '' ) {
                    return $obj->get_temp_url( $this->swiftTempUrlKey, $ttl, "GET" );
                } else { // give S3 API URL for rgw
                    $expires = time() + $ttl;
                    // Path for signature starts with the bucket
                    $spath = '/' . rawurlencode( $srcCont ) . '/' .
                        str_replace( '%2F', '/', rawurlencode( $srcRel ) );
                    // Calculate the hash
                    $signature = base64_encode( hash_hmac(
                        'sha1',
                        "GET\n\n\n{$expires}\n{$spath}",
                        $this->rgwS3SecretKey,
                        true // raw
                    ) );
                    // See http://s3.amazonaws.com/doc/s3-developer-guide/RESTAuthentication.html.
                    // Note: adding a newline for empty CanonicalizedAmzHeaders does not work.
                    return wfAppendQuery(
                        str_replace( '/swift/v1', '', // S3 API is the rgw default
                            $sContObj->cfs_http->getStorageUrl() . $spath ),
                        array(
                            'Signature' => $signature,
                            'Expires' => $expires,
                            'AWSAccessKeyId' => $this->rgwS3AccessKey )
                    );
                }
            } catch ( NoSuchContainerException $e ) {
            } catch ( CloudFilesException $e ) { // some other exception?
                $this->handleException( $e, null, __METHOD__, $params );
            }
        }
        return null;
    }

    protected function directoriesAreVirtual() {
        return true;
    }

    protected function headersFromParams( array $params ) {
        $hdrs = array();
        if ( !empty( $params['latest'] ) ) {
            $hdrs[] = 'X-Newest: true';
        }
        return $hdrs;
    }

    protected function doExecuteOpHandlesInternal( array $fileOpHandles ) {
        $statuses = array();

        $cfOps = array(); // list of CF_Async_Op objects
        foreach ( $fileOpHandles as $index => $fileOpHandle ) {
            $cfOps[$index] = $fileOpHandle->cfOp;
        }
        $batch = new CF_Async_Op_Batch( $cfOps );

        $cfOps = $batch->execute();
        foreach ( $cfOps as $index => $cfOp ) {
            $status = Status::newGood();
            $function = '_getResponse' . $fileOpHandles[$index]->call;
            try { // catch exceptions; update status
                $this->$function( $cfOp, $status, $fileOpHandles[$index]->params );
                $this->purgeCDNCache( $fileOpHandles[$index]->affectedObjects );
            } catch ( CloudFilesException $e ) { // some other exception?
                $this->handleException( $e, $status,
                    __CLASS__ . ":$function", $fileOpHandles[$index]->params );
            }
            $statuses[$index] = $status;
        }

        return $statuses;
    }

    protected function setContainerAccess(
        CF_Container $contObj, array $readGrps, array $writeGrps
    ) {
        $creds = $contObj->cfs_auth->export_credentials();

        $url = $creds['storage_url'] . '/' . rawurlencode( $contObj->name );

        // Note: 10 second timeout consistent with php-cloudfiles
        $req = MWHttpRequest::factory( $url, array( 'method' => 'POST', 'timeout' => 10 ) );
        $req->setHeader( 'X-Auth-Token', $creds['auth_token'] );
        $req->setHeader( 'X-Container-Read', implode( ',', $readGrps ) );
        $req->setHeader( 'X-Container-Write', implode( ',', $writeGrps ) );

        return $req->execute(); // should return 204
    }

    public function purgeCDNCache( array $objects ) {
        if ( $this->swiftUseCDN && $this->swiftCDNPurgable ) {
            foreach ( $objects as $object ) {
                try {
                    $object->purge_from_cdn();
                } catch ( CDNNotEnabledException $e ) {
                    // CDN not enabled; nothing to see here
                } catch ( CloudFilesException $e ) {
                    $this->handleException( $e, null, __METHOD__,
                        array( 'cont' => $object->container->name, 'obj' => $object->name ) );
                }
            }
        }
    }

    protected function getConnection() {
        if ( $this->connException instanceof CloudFilesException ) {
            if ( ( time() - $this->connErrorTime ) < 60 ) {
                throw $this->connException; // failed last attempt; don't bother
            } else { // actually retry this time
                $this->connException = null;
                $this->connErrorTime = 0;
            }
        }
        // Session keys expire after a while, so we renew them periodically
        $reAuth = ( ( time() - $this->sessionStarted ) > $this->authTTL );
        // Authenticate with proxy and get a session key...
        if ( !$this->conn || $reAuth ) {
            $this->sessionStarted = 0;
            $this->connContainerCache->clear();
            $cacheKey = $this->getCredsCacheKey( $this->auth->username );
            $creds = $this->srvCache->get( $cacheKey ); // credentials
            if ( is_array( $creds ) ) { // cache hit
                $this->auth->load_cached_credentials(
                    $creds['auth_token'], $creds['storage_url'], $creds['cdnm_url'] );
                $this->sessionStarted = time() - ceil( $this->authTTL / 2 ); // skew for worst case
            } else { // cache miss
                try {
                    $this->auth->authenticate();
                    $creds = $this->auth->export_credentials();
                    $this->srvCache->add( $cacheKey, $creds, ceil( $this->authTTL / 2 ) ); // cache
                    $this->sessionStarted = time();
                } catch ( CloudFilesException $e ) {
                    $this->connException = $e; // don't keep re-trying
                    $this->connErrorTime = time();
                    throw $e; // throw it back
                }
            }
            if ( $this->conn ) { // re-authorizing?
                $this->conn->close(); // close active cURL handles in CF_Http object
            }
            $this->conn = new CF_Connection( $this->auth );
        }
        return $this->conn;
    }

    protected function closeConnection() {
        if ( $this->conn ) {
            $this->conn->close(); // close active cURL handles in CF_Http object
            $this->conn = null;
            $this->sessionStarted = 0;
            $this->connContainerCache->clear();
        }
    }

    private function getCredsCacheKey( $username ) {
        return wfMemcKey( 'backend', $this->getName(), 'usercreds', $username );
    }

    protected function getContainer( $container, $bypassCache = false ) {
        $conn = $this->getConnection(); // Swift proxy connection
        if ( $bypassCache ) { // purge cache
            $this->connContainerCache->clear( $container );
        } elseif ( !$this->connContainerCache->has( $container, 'obj' ) ) {
            $this->primeContainerCache( array( $container ) ); // check persistent cache
        }
        if ( !$this->connContainerCache->has( $container, 'obj' ) ) {
            $contObj = $conn->get_container( $container );
            // NoSuchContainerException not thrown: container must exist
            $this->connContainerCache->set( $container, 'obj', $contObj ); // cache it
            if ( !$bypassCache ) {
                $this->setContainerCache( $container, // update persistent cache
                    array( 'bytes' => $contObj->bytes_used, 'count' => $contObj->object_count )
                );
            }
        }
        return $this->connContainerCache->get( $container, 'obj' );
    }

    protected function createContainer( $container ) {
        $conn = $this->getConnection(); // Swift proxy connection
        $contObj = $conn->create_container( $container );
        $this->connContainerCache->set( $container, 'obj', $contObj ); // cache
        return $contObj;
    }

    protected function deleteContainer( $container ) {
        $conn = $this->getConnection(); // Swift proxy connection
        $this->connContainerCache->clear( $container ); // purge
        $conn->delete_container( $container );
    }

    protected function doPrimeContainerCache( array $containerInfo ) {
        try {
            $conn = $this->getConnection(); // Swift proxy connection
            foreach ( $containerInfo as $container => $info ) {
                $contObj = new CF_Container( $conn->cfs_auth, $conn->cfs_http,
                    $container, $info['count'], $info['bytes'] );
                $this->connContainerCache->set( $container, 'obj', $contObj );
            }
        } catch ( CloudFilesException $e ) { // some other exception?
            $this->handleException( $e, null, __METHOD__, array() );
        }
    }

    protected function handleException( Exception $e, $status, $func, array $params ) {
        if ( $status instanceof Status ) {
            if ( $e instanceof AuthenticationException ) {
                $status->fatal( 'backend-fail-connect', $this->name );
            } else {
                $status->fatal( 'backend-fail-internal', $this->name );
            }
        }
        if ( $e->getMessage() ) {
            trigger_error( "$func: " . $e->getMessage(), E_USER_WARNING );
        }
        if ( $e instanceof InvalidResponseException ) { // possibly a stale token
            $this->srvCache->delete( $this->getCredsCacheKey( $this->auth->username ) );
            $this->closeConnection(); // force a re-connect and re-auth next time
        }
        wfDebugLog( 'SwiftBackend',
            get_class( $e ) . " in '{$func}' (given '" . FormatJson::encode( $params ) . "')" .
            ( $e->getMessage() ? ": {$e->getMessage()}" : "" )
        );
    }
}

class SwiftFileOpHandle extends FileBackendStoreOpHandle {
    public $cfOp;
    public $affectedObjects = array();

    public function __construct(
        SwiftFileBackend $backend, array $params, $call, CF_Async_Op $cfOp
    ) {
        $this->backend = $backend;
        $this->params = $params;
        $this->call = $call;
        $this->cfOp = $cfOp;
    }
}

abstract class SwiftFileBackendList implements Iterator {
    protected $bufferIter = array();
    protected $bufferAfter = null; // string; list items *after* this path
    protected $pos = 0; // integer
    protected $params = array();

    protected $backend;
    protected $container; // string; container name
    protected $dir; // string; storage directory
    protected $suffixStart; // integer

    const PAGE_SIZE = 9000; // file listing buffer size

    public function __construct( SwiftFileBackend $backend, $fullCont, $dir, array $params ) {
        $this->backend = $backend;
        $this->container = $fullCont;
        $this->dir = $dir;
        if ( substr( $this->dir, -1 ) === '/' ) {
            $this->dir = substr( $this->dir, 0, -1 ); // remove trailing slash
        }
        if ( $this->dir == '' ) { // whole container
            $this->suffixStart = 0;
        } else { // dir within container
            $this->suffixStart = strlen( $this->dir ) + 1; // size of "path/to/dir/"
        }
        $this->params = $params;
    }

    public function key() {
        return $this->pos;
    }

    public function next() {
        // Advance to the next file in the page
        next( $this->bufferIter );
        ++$this->pos;
        // Check if there are no files left in this page and
        // advance to the next page if this page was not empty.
        if ( !$this->valid() && count( $this->bufferIter ) ) {
            $this->bufferIter = $this->pageFromList(
                $this->container, $this->dir, $this->bufferAfter, self::PAGE_SIZE, $this->params
            ); // updates $this->bufferAfter
        }
    }

    public function rewind() {
        $this->pos = 0;
        $this->bufferAfter = null;
        $this->bufferIter = $this->pageFromList(
            $this->container, $this->dir, $this->bufferAfter, self::PAGE_SIZE, $this->params
        ); // updates $this->bufferAfter
    }

    public function valid() {
        if ( $this->bufferIter === null ) {
            return false; // some failure?
        } else {
            return ( current( $this->bufferIter ) !== false ); // no paths can have this value
        }
    }

    abstract protected function pageFromList( $container, $dir, &$after, $limit, array $params );
}

class SwiftFileBackendDirList extends SwiftFileBackendList {
    public function current() {
        return substr( current( $this->bufferIter ), $this->suffixStart, -1 );
    }

    protected function pageFromList( $container, $dir, &$after, $limit, array $params ) {
        return $this->backend->getDirListPageInternal( $container, $dir, $after, $limit, $params );
    }
}

class SwiftFileBackendFileList extends SwiftFileBackendList {
    public function current() {
        return substr( current( $this->bufferIter ), $this->suffixStart );
    }

    protected function pageFromList( $container, $dir, &$after, $limit, array $params ) {
        return $this->backend->getFileListPageInternal( $container, $dir, $after, $limit, $params );
    }
}