org.apache.zookeeper.common

Class AtomicFileOutputStream

java.lang.Object

java.io.OutputStream

java.io.FilterOutputStream

org.apache.zookeeper.common.AtomicFileOutputStream

All Implemented Interfaces:

Closeable, Flushable, AutoCloseable

public class AtomicFileOutputStream
extends FilterOutputStream

A FileOutputStream that has the property that it will only show up at its destination once it has been entirely written and flushed to disk. While being written, it will use a .tmp suffix. When the output stream is closed, it is flushed, fsynced, and will be moved into place, overwriting any file that already exists at that location. NOTE: on Windows platforms, it will not atomically replace the target file - instead the target file is deleted before this one is moved into place.

Field Summary

Fields

Modifier and Type	Field and Description
static String	TMP_EXTENSION

Fields inherited from class java.io.FilterOutputStream

out

Constructor Summary

Constructors

Constructor and Description
AtomicFileOutputStream(File f)

Method Summary

Modifier and Type	Method and Description
void	abort() Close the atomic file, but do not "commit" the temporary file on top of the destination.
void	close()
void	write(byte[] b, int off, int len) The default write method in FilterOutputStream does not call the write method of its underlying input stream with the same arguments.

Methods inherited from class java.io.FilterOutputStream

flush, write, write

Methods inherited from class java.lang.Object

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

Field Detail

TMP_EXTENSION

public static final String TMP_EXTENSION

See Also:

Constant Field Values

Constructor Detail

AtomicFileOutputStream

public AtomicFileOutputStream(File f)
                       throws FileNotFoundException

Throws:

FileNotFoundException

Method Detail

write

public void write(byte[] b,
                  int off,
                  int len)
           throws IOException

The default write method in FilterOutputStream does not call the write method of its underlying input stream with the same arguments. Instead it writes the data byte by byte, override it here to make it more efficient.

Overrides:

write in class FilterOutputStream

Throws:

IOException

close

public void close()
           throws IOException

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Overrides:

close in class FilterOutputStream

Throws:

IOException

abort

public void abort()

Close the atomic file, but do not "commit" the temporary file on top of the destination. This should be used if there is a failure in writing.