Package org.eclipse.jgit.internal.storage.file

Class PackBitmapIndex

java.lang.Object

org.eclipse.jgit.internal.storage.file.PackBitmapIndex

Direct Known Subclasses:

PackBitmapIndexBuilder, PackBitmapIndexRemapper

public abstract class PackBitmapIndex
extends Object

Logical representation of the bitmap data stored in the pack index. ObjectIds are encoded as a single integer in the range [0, getObjectCount()). Compressed bitmaps are available at certain ObjectIds, which represent all of the objects reachable from that ObjectId (include the ObjectId itself). The meaning of the positions in the bitmaps can be decoded using getObject(int) and ofObjectType(EWAHCompressedBitmap, int). Furthermore, findPosition(AnyObjectId) can be used to build other bitmaps that a compatible with the encoded bitmaps available from the index.

Field Summary

Fields

Modifier and Type	Field	Description
static int	FLAG_REUSE	Flag bit denoting the bitmap should be reused during index creation.

Constructor Summary

Constructors

Constructor	Description
PackBitmapIndex()

Method Summary

Modifier and Type	Method	Description
abstract int	findPosition(AnyObjectId objectId)	Finds the position in the bitmap of the object.
abstract com.googlecode.javaewah.EWAHCompressedBitmap	getBitmap(AnyObjectId objectId)	Returns the previously constructed bitmap for the object.
abstract ObjectId	getObject(int position)	Get the object at the bitmap position.
abstract int	getObjectCount()	Obtain the total number of objects described by this index.
abstract com.googlecode.javaewah.EWAHCompressedBitmap	ofObjectType(com.googlecode.javaewah.EWAHCompressedBitmap bitmap, int type)	Returns a bitmap containing positions for objects that have the given Git type.
static PackBitmapIndex	open(File idxFile, PackIndex packIndex, PackReverseIndex reverseIndex)	Read an existing pack bitmap index file from a buffered stream.
static PackBitmapIndex	read(InputStream fd, PackIndex packIndex, PackReverseIndex reverseIndex)	Read an existing pack bitmap index file from a buffered stream.

Methods inherited from class java.lang.Object

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

Field Detail

FLAG_REUSE

public static final int FLAG_REUSE

Flag bit denoting the bitmap should be reused during index creation.

See Also:

Constant Field Values

Constructor Detail

PackBitmapIndex

public PackBitmapIndex()

Method Detail

open

public static PackBitmapIndex open(File idxFile,
                                   PackIndex packIndex,
                                   PackReverseIndex reverseIndex)
                            throws IOException

Read an existing pack bitmap index file from a buffered stream.

The format of the file will be automatically detected and a proper access implementation for that format will be constructed and returned to the caller. The file may or may not be held open by the returned instance.

Parameters:

idxFile - existing pack .bitmap to read.

packIndex - the pack index for the corresponding pack file.

reverseIndex - the pack reverse index for the corresponding pack file.

Returns:

a copy of the index in-memory.

Throws:

IOException - the stream cannot be read.

CorruptObjectException - the stream does not contain a valid pack bitmap index.

read

public static PackBitmapIndex read(InputStream fd,
                                   PackIndex packIndex,
                                   PackReverseIndex reverseIndex)
                            throws IOException

Read an existing pack bitmap index file from a buffered stream.

The format of the file will be automatically detected and a proper access implementation for that format will be constructed and returned to the caller. The file may or may not be held open by the returned instance.

Parameters:

fd - stream to read the bitmap index file from. The stream must be buffered as some small IOs are performed against the stream. The caller is responsible for closing the stream.

packIndex - the pack index for the corresponding pack file.

reverseIndex - the pack reverse index for the corresponding pack file.

Returns:

a copy of the index in-memory.

Throws:

IOException - the stream cannot be read.

CorruptObjectException - the stream does not contain a valid pack bitmap index.

findPosition

public abstract int findPosition(AnyObjectId objectId)

Finds the position in the bitmap of the object.

Parameters:

objectId - the id for which the bitmap position will be found.

Returns:

the bitmap id or -1 if the object was not found.

getObject

public abstract ObjectId getObject(int position)
                            throws IllegalArgumentException

Get the object at the bitmap position.

Parameters:

position - the id for which the object will be found.

Returns:

the ObjectId.

Throws:

IllegalArgumentException - when the item is not found.

ofObjectType

public abstract com.googlecode.javaewah.EWAHCompressedBitmap ofObjectType(com.googlecode.javaewah.EWAHCompressedBitmap bitmap,
                                                                          int type)

Returns a bitmap containing positions for objects that have the given Git type.

Parameters:

bitmap - the object bitmap.

type - the Git type.

Returns:

the object bitmap with only objects of the Git type.

getBitmap

public abstract com.googlecode.javaewah.EWAHCompressedBitmap getBitmap(AnyObjectId objectId)

Returns the previously constructed bitmap for the object.

Parameters:

objectId - the id for which the bitmap will be found.

Returns:

the bitmap or null if the object was not found.

getObjectCount

public abstract int getObjectCount()

Obtain the total number of objects described by this index. getObjectCount() - 1 is the largest bit that will be set in a bitmap.

Returns:

number of objects in this index, and likewise in the associated pack that this index was generated from.