com.nothome.delta
Class Delta

java.lang.Object
  com.nothome.delta.Delta

public class Delta
extends Object

Class for computing deltas against a source. The source file is read by blocks and a hash is computed per block. Then the target is scanned for matching blocks.

This class is not thread safe. Use one instance per thread.

This class should support files over 4GB in length, although you must use a larger checksum size, such as 1K, as all checksums use "int" indexing. Newer versions may eventually support paging in/out of checksums.

Field Summary

static int

DEFAULT_CHUNK_SIZE Default size of 16.

Constructor Summary

Delta()
Constructs a new Delta.

Method Summary

byte[]	compute(byte[] source, byte[] target) Compares the source bytes with target bytes, returning output.
void	compute(byte[] source, byte[] target, OutputStream output) Compares the source bytes with target bytes, writing to output.
void	compute(byte[] sourceBytes, InputStream inputStream, DiffWriter diffWriter) Compares the source bytes with target input, writing to output.
void	compute(File sourceFile, File targetFile, DiffWriter output) Compares the source file with a target file, writing to output.
void	compute(SeekableSource seekSource, InputStream targetIS, DiffWriter output) Compares the source with a target, writing to output.
static void	main(String[] argv) Creates a patch using file names.
void	setChunkSize(int size) Sets the chunk size used.

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_CHUNK_SIZE

public static final int DEFAULT_CHUNK_SIZE

Default size of 16. For "Lorem ipsum" text files (see the tests) the ideal size is about 14. Any smaller and the patch size becomes actually be larger.

Use a size like 64 or 128 for large files.

See Also:

Constant Field Values

Constructor Detail

Delta

public Delta()

Constructs a new Delta. In the future, additional constructor arguments will set the algorithm details.

Method Detail

setChunkSize

public void setChunkSize(int size)

Sets the chunk size used. Larger chunks are faster and use less memory, but create larger patches as well.

Parameters:

size -

compute

public void compute(byte[] source,
                    byte[] target,
                    OutputStream output)
             throws IOException

Compares the source bytes with target bytes, writing to output.

Throws:

IOException

compute

public byte[] compute(byte[] source,
                      byte[] target)
               throws IOException

Compares the source bytes with target bytes, returning output.

Throws:

IOException

compute

public void compute(byte[] sourceBytes,
                    InputStream inputStream,
                    DiffWriter diffWriter)
             throws IOException

Compares the source bytes with target input, writing to output.

Throws:

IOException

compute

public void compute(File sourceFile,
                    File targetFile,
                    DiffWriter output)
             throws IOException

Compares the source file with a target file, writing to output.

Parameters:

output - will be closed

Throws:

IOException

compute

public void compute(SeekableSource seekSource,
                    InputStream targetIS,
                    DiffWriter output)
             throws IOException

Compares the source with a target, writing to output.

Parameters:

output - will be closed

Throws:

IOException

main

public static void main(String[] argv)
                 throws Exception

Creates a patch using file names.

Throws:

Exception