question: private long downloadTlogFiles ( File tmpTlogDir , long latestGeneration ) throws Exception { LOG . info ( "Starting download of tlog files from master: " + tlogFilesToDownload ) ; tlogFilesDownloaded = Collections . synchronizedList ( new ArrayList < > ( ) ) ; long bytesDownloaded = 0 ; boolean status = tmpTlogDir . mkdirs ( ) ; if ( ! status ) { throw new SolrException ( SolrException . ErrorCode . SERVER_ERROR , "Failed to create temporary tlog folder: " + tmpTlogDir . getName ( ) ) ; } for ( Map < String , Object > file : tlogFilesToDownload ) { String saveAs = ( String ) ( file . get ( ALIAS ) == null ? file . get ( NAME ) : file . get ( ALIAS ) ) ; localFileFetcher = new LocalFsFileFetcher ( tmpTlogDir , file , saveAs , TLOG_FILE , latestGeneration ) ; currentFile = file ; localFileFetcher . fetchFile ( ) ; bytesDownloaded += localFileFetcher . getBytesDownloaded ( ) ; tlogFilesDownloaded . add ( new HashMap < > ( file ) ) ; } return bytesDownloaded ; }
target:  Download all the tlog files to the temp tlog directory.