Top Description Fields Constructors Methods
org.eclipse.jgit.util.io

public Class BinaryDeltaInputStream

extends InputStream
Class Inheritance
Imports
java.io.EOFException, .IOException, .InputStream, .StreamCorruptedException, java.text.MessageFormat, org.eclipse.jgit.internal.JGitText
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

Field Summary

Modifier and TypeField and Description
private final byte[]
base

private int
baseOffset

private final InputStream
delta

private int
fromBase

private int
fromDelta

private long
resultLength

private long
toDeliver

Constructor Summary

AccessConstructor and Description
public
BinaryDeltaInputStream(byte[]
data to apply the delta to
base, InputStream
InputStream delivering the delta to apply
delta)

Creates a new BinaryDeltaInputStream that applies delta to base.

Method Summary

Modifier and TypeMethod and Description
public void
close()

Overrides java.io.InputStream.close.

Implements java.io.Closeable.close.

Closes this input stream and releases any system resources associated with the stream.

public long

Returns:

the size
getExpectedResultSize()

Tells the expected size of the final result.

private void
initialize()

public boolean

Returns:

whether delta application was successful
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.

private int
next(InputStream in)

public int
read()

Implements abstract java.io.InputStream.read.

Reads the next byte of data from the input stream.

public int
read(byte[]
the buffer into which the data is read.
b, int
the start offset in array b at which the data is written.
off, int
the maximum number of bytes to read.
len)

Overrides java.io.InputStream.read.

Reads up to len bytes of data from the input stream into an array of bytes.

private int
readNext()

private long
readVarInt(InputStream in)

Inherited from java.io.InputStream:
availablemarkmarkSupportednullInputStreamreadreadAllBytesreadNBytesreadNBytesresetskipskipNBytestransferTo

Field Detail

baseback to summary
private final byte[] base
baseOffsetback to summary
private int baseOffset
deltaback to summary
private final InputStream delta
fromBaseback to summary
private int fromBase
fromDeltaback to summary
private int fromDelta
resultLengthback to summary
private long resultLength
toDeliverback to summary
private long toDeliver

Constructor Detail

BinaryDeltaInputStreamback to summary
public BinaryDeltaInputStream(byte[] base, InputStream delta)

Creates a new BinaryDeltaInputStream that applies delta to base.

Parameters
base:byte[]

data to apply the delta to

delta:InputStream

InputStream delivering the delta to apply

Method Detail

closeback to summary
public void close() throws IOException

Overrides java.io.InputStream.close.

Implements java.io.Closeable.close.

Doc from java.io.InputStream.close.

Closes this input stream and releases any system resources associated with the stream.

Annotations
@Override
Exceptions
IOException:
if an I/O error occurs.
getExpectedResultSizeback to summary
public long getExpectedResultSize() throws IOException

Tells the expected size of the final result.

Returns:long

the size

Exceptions
IOException:
if the size cannot be determined from delta
initializeback to summary
private void initialize() throws IOException
isFullyConsumedback to summary
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:boolean

whether delta application was successful

nextback to summary
private int next(InputStream in) throws IOException
readback to summary
public int read() throws IOException

Implements abstract java.io.InputStream.read.

Doc from java.io.InputStream.read.

Reads the next byte of data from the input stream. The value byte is returned as an int in the range 0 to 255. If no byte is available because the end of the stream has been reached, the value -1 is returned. This method blocks until input data is available, the end of the stream is detected, or an exception is thrown.

Returns:int

the next byte of data, or -1 if the end of the stream is reached.

Annotations
@Override
Exceptions
IOException:
if an I/O error occurs.
readback to summary
public int read(byte[] b, int off, int len) throws IOException

Overrides java.io.InputStream.read.

Doc from java.io.InputStream.read.

Reads up to len bytes of data from the input stream into an array of bytes. An attempt is made to read as many as len bytes, but a smaller number may be read. The number of bytes actually read is returned as an integer.

This method blocks until input data is available, end of file is detected, or an exception is thrown.

If len is zero, then no bytes are read and 0 is returned; otherwise, there is an attempt to read at least one byte. If no byte is available because the stream is at end of file, the value -1 is returned; otherwise, at least one byte is read and stored into b.

The first byte read is stored into element b[off], the next one into b[off+1], and so on. The number of bytes read is, at most, equal to len. Let k be the number of bytes actually read; these bytes will be stored in elements b[off] through b[off+k-1], leaving elements b[off+k] through b[off+len-1] unaffected.

In every case, elements b[0] through b[off-1] and elements b[off+len] through b[b.length-1] are unaffected.

Parameters
b:byte[]

the buffer into which the data is read.

off:int

the start offset in array b at which the data is written.

len:int

the maximum number of bytes to read.

Returns:int

the total number of bytes read into the buffer, or -1 if there is no more data because the end of the stream has been reached.

Annotations
@Override
Exceptions
IOException:
If the first byte cannot be read for any reason other than end of file, or if the input stream has been closed, or if some other I/O error occurs.
readNextback to summary
private int readNext() throws IOException
readVarIntback to summary
private long readVarInt(InputStream in) throws IOException