org.eclipse.jgit.storage.pack
Class DeltaStream

java.lang.Object
  java.io.InputStream
      org.eclipse.jgit.storage.pack.DeltaStream

All Implemented Interfaces:

Closeable

public abstract class DeltaStream
extends InputStream

Inflates a delta in an incremental way.

Implementations must provide a means to access a stream for the base object. This stream may be accessed multiple times, in order to randomly position it to match the copy instructions. A DeltaStream performs an efficient skip by only moving through the delta stream, making restarts of stacked deltas reasonably efficient.

Constructor Summary

DeltaStream(InputStream deltaStream)
Construct a delta application stream, reading instructions.

Method Summary

void	close()
protected abstract long	getBaseSize()
long	getSize()
protected abstract InputStream	openBase() Open the base stream.
int	read()
int	read(byte[] buf, int off, int len)
long	skip(long len)

Methods inherited from class java.io.InputStream

available, mark, markSupported, read, reset

Methods inherited from class java.lang.Object

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

Constructor Detail

DeltaStream

public DeltaStream(InputStream deltaStream)
            throws IOException

Construct a delta application stream, reading instructions.

Parameters:

deltaStream - the stream to read delta instructions from.

Throws:

IOException - the delta instruction stream cannot be read, or is inconsistent with the the base object information.

Method Detail

openBase

protected abstract InputStream openBase()
                                 throws IOException

Open the base stream.

The DeltaStream may close and reopen the base stream multiple times if copy instructions use offsets out of order. This can occur if a large block in the file was moved from near the top, to near the bottom. In such cases the reopened stream is skipped to the target offset, so skip(long) should be as efficient as possible.

Returns:

stream to read from the base object. This stream should not be buffered (or should be only minimally buffered), and does not need to support mark/reset.

Throws:

IOException - the base object cannot be opened for reading.

getBaseSize

protected abstract long getBaseSize()
                             throws IOException

Returns:

length of the base object, in bytes.

Throws:

IOException - the length of the base cannot be determined.

getSize

public long getSize()

Returns:

total size of this stream, in bytes.

read

public int read()
         throws IOException

Specified by:

read in class InputStream

Throws:

IOException

close

public void close()
           throws IOException

Specified by:

close in interface Closeable

Overrides:

close in class InputStream

Throws:

IOException

skip

public long skip(long len)
          throws IOException

Overrides:

skip in class InputStream

Throws:

IOException

read

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

Overrides:

read in class InputStream

Throws:

IOException