Class FileUtils

java.lang.Object

ubic.gemma.core.util.FileUtils

public class FileUtils
extends Object

Author:

poirigui

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static interface	FileUtils.PathWriter<E extends Exception>	Writes a file or a directory at a given path, handed to it by writeAtomically(Path, PathWriter).

Constructor Summary

Constructors

Constructor	Description
FileUtils()

Method Summary

Modifier and Type	Method	Description
static InputStream	openCompressedFile(Path path)	Open a GZIP-compressed file safely.
static <E extends Exception> void	writeAtomically(Path destination, FileUtils.PathWriter<E> writer)	Write destination through a temporary sibling that is moved over it only once writer has returned normally.

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

FileUtils

public FileUtils()

Method Details

openCompressedFile

public static InputStream openCompressedFile(Path path)
                                      throws IOException

Open a GZIP-compressed file safely.

This ensures that if an exception is thrown by GZIPInputStream(InputStream), the stream will be closed.

Throws:

IOException

writeAtomically

public static <E extends Exception> void writeAtomically(Path destination,
 FileUtils.PathWriter<E> writer)
                                                  throws IOException,
E

Write destination through a temporary sibling that is moved over it only once writer has returned normally.

A partial result is never at destination: not when the writer throws, an Error included, and not when the JVM dies or a daemon writer thread is halted mid-write, which no catch block can cover. On failure, destination keeps whatever it held before.

The temporary is named .<name>.tmp-<random> and lives in the same directory, so the move is a rename within one file system. It is deleted on failure. One left behind by a JVM that died stays until removed by hand; its name ends in neither the destination's name nor its suffix, so a lookup by name or by suffix does not find it, but code that lists the directory must skip it.

A directory already at destination is deleted just before the move, because a rename cannot replace a non-empty directory: a crash between the two leaves no directory rather than a partial one.

The temporary is not synced to disk before the move, so this covers the process dying, not the host crashing. Nothing here locks destination: a caller that coordinates with readers holds its lock on destination across this call.

Parameters:

destination - the file or directory to create or replace

writer - writes the content at the temporary path it is given

Throws:

IOException

E