Package org.elasticsearch.transport

Class ReuseBuffersLZ4BlockOutputStream

java.lang.Object

java.io.OutputStream

java.io.FilterOutputStream

org.elasticsearch.transport.ReuseBuffersLZ4BlockOutputStream

All Implemented Interfaces:

Closeable, Flushable, AutoCloseable

public class ReuseBuffersLZ4BlockOutputStream
extends FilterOutputStream

This file is forked from https://github.com/lz4/lz4-java. In particular it forks the following file net.jpountz.lz4.LZ4BlockOutputStream. It modifies the original lz4-java code to allow the reuse of local thread local byte arrays. This prevents the need to allocate two new byte arrays everytime a new stream is created. For the Elasticsearch use case, a single thread should fully compress the stream in one go to avoid memory corruption. Additionally, it does not checksum (or write a check) for the data compressed. We do not read the checksum when decompressing in Elasticsearch. Streaming LZ4 (not compatible with the LZ4 Frame format). This class compresses data into fixed-size blocks of compressed data. This class uses its own format and is not compatible with the LZ4 Frame format. For interoperability with other LZ4 tools, use LZ4FrameOutputStream, which is compatible with the LZ4 Frame format. This class remains for backward compatibility.

See Also:

• LZ4BlockInputStream
• LZ4FrameOutputStream

Field Summary

Fields inherited from class java.io.FilterOutputStream

out

Constructor Summary

Constructors

Constructor	Description
ReuseBuffersLZ4BlockOutputStream(OutputStream out, int blockSize, net.jpountz.lz4.LZ4Compressor compressor)	Creates a new OutputStream with configurable block size.

Method Summary

Modifier and Type	Method	Description
void	close()
void	finish()	Same as close() except that it doesn't close the underlying stream.
void	flush()	Flushes this compressed OutputStream.
String	toString()
void	write(byte[] b)
void	write(byte[] b, int off, int len)
void	write(int b)

Methods inherited from class java.io.OutputStream

nullOutputStream

Methods inherited from class java.lang.Object

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

Constructor Details

ReuseBuffersLZ4BlockOutputStream

public ReuseBuffersLZ4BlockOutputStream(OutputStream out,
 int blockSize,
 net.jpountz.lz4.LZ4Compressor compressor)

Creates a new OutputStream with configurable block size. Large blocks require more memory at compression and decompression time but should improve the compression ratio.

Parameters:

out - the OutputStream to feed

blockSize - the maximum number of bytes to try to compress at once, must be >= 64 and <= 32 M

compressor - the LZ4Compressor instance to use to compress data

Method Details

write

public void write(int b)
           throws IOException

Overrides:

write in class FilterOutputStream

Throws:

IOException

write

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

Overrides:

write in class FilterOutputStream

Throws:

IOException

write

public void write(byte[] b)
           throws IOException

Overrides:

write in class FilterOutputStream

Throws:

IOException

close

public void close()
           throws IOException

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Closeable

Overrides:

close in class FilterOutputStream

Throws:

IOException

flush

public void flush()
           throws IOException

Flushes this compressed OutputStream. If the stream has been created with syncFlush=true, pending data will be compressed and appended to the underlying OutputStream before calling OutputStream.flush() on the underlying stream. Otherwise, this method just flushes the underlying stream, so pending data might not be available for reading until finish() or close() is called.

Specified by:

flush in interface Flushable

Overrides:

flush in class FilterOutputStream

Throws:

IOException

finish

public void finish()
            throws IOException

Same as close() except that it doesn't close the underlying stream. This can be useful if you want to keep on using the underlying stream.

Throws:

IOException - if an I/O error occurs.

toString

public String toString()

Overrides:

toString in class Object