org.eclipse.jgit.util.io

Class BinaryDeltaInputStream

java.lang.Object

java.io.InputStream

org.eclipse.jgit.util.io.BinaryDeltaInputStream

All Implemented Interfaces:

Closeable, AutoCloseable

public class BinaryDeltaInputStream
extends InputStream

An InputStream that applies a binary delta to a base on the fly.

Delta application to a base needs random access to the base data. The delta is expressed as a sequence of copy and insert instructions. A copy instruction has the form "COPY fromOffset length" and says "copy length bytes from the base, starting at offset fromOffset, to the result". An insert instruction has the form "INSERT length" followed by length bytes and says "copy the next length bytes from the delta to the result".

These instructions are generated using a content-defined chunking algorithm (currently C git uses the standard Rabin variant; but there are others that could be used) that identifies equal chunks. It is entirely possible that a later copy instruction has a fromOffset that is before the fromOffset of an earlier copy instruction.

This makes it impossible to stream the base.

JGit is limited to 2GB maximum size for the base since array indices are signed 32bit values.

Since:

5.12

Constructor Summary

Constructors

Constructor and Description
BinaryDeltaInputStream(byte[] base, InputStream delta) Creates a new BinaryDeltaInputStream that applies delta to base.

Method Summary

Modifier and Type	Method and Description
void	close()
long	getExpectedResultSize() Tells the expected size of the final result.
boolean	isFullyConsumed() Tells whether the delta has been fully consumed, and the expected number of bytes for the combined result have been read from this BinaryDeltaInputStream.
int	read()
int	read(byte[] b, int off, int len)

Methods inherited from class java.io.InputStream

available, mark, markSupported, read, reset, skip

Methods inherited from class java.lang.Object

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

Constructor Detail

BinaryDeltaInputStream

public BinaryDeltaInputStream(byte[] base,
                              InputStream delta)

Creates a new BinaryDeltaInputStream that applies delta to base.

Parameters:

base - data to apply the delta to

delta - InputStream delivering the delta to apply

Method Detail

read

public int read()
         throws IOException

Specified by:

read in class InputStream

Throws:

IOException

read

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

Overrides:

read in class InputStream

Throws:

IOException

getExpectedResultSize

public long getExpectedResultSize()
                           throws IOException

Tells the expected size of the final result.

Returns:

the size

Throws:

IOException - if the size cannot be determined from delta

isFullyConsumed

public boolean isFullyConsumed()

Tells whether the delta has been fully consumed, and the expected number of bytes for the combined result have been read from this BinaryDeltaInputStream.

Returns:

whether delta application was successful

close

public void close()
           throws IOException

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Overrides:

close in class InputStream

Throws:

IOException