Class PackBitmapIndex

java.lang.Object
org.eclipse.jgit.internal.storage.file.PackBitmapIndex
Direct Known Subclasses:
BasePackBitmapIndex, 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 final int
    Flag bit denoting the bitmap should be reused during index creation.
    (package private) byte[]
    Footer checksum applied on the bottom of the pack file.
  • Constructor Summary

    Constructors
    Constructor
    Description
     
  • Method Summary

    Modifier and Type
    Method
    Description
    abstract int
    Finds the position in the bitmap of the object.
    abstract com.googlecode.javaewah.EWAHCompressedBitmap
    Returns the previously constructed bitmap for the object.
    abstract int
    Returns the number of bitmaps in this bitmap index.
    abstract ObjectId
    getObject(int position)
    Get the object at the bitmap position.
    abstract int
    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.
    open(File idxFile, PackIndex packIndex, PackReverseIndex reverseIndex)
    Read an existing pack bitmap index file from a buffered stream.
    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 Details

    • FLAG_REUSE

      public static final int FLAG_REUSE
      Flag bit denoting the bitmap should be reused during index creation.
      See Also:
    • packChecksum

      byte[] packChecksum
      Footer checksum applied on the bottom of the pack file.
  • Constructor Details

    • PackBitmapIndex

      public PackBitmapIndex()
  • Method Details

    • 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.
    • getBitmapCount

      public abstract int getBitmapCount()
      Returns the number of bitmaps in this bitmap index.
      Returns:
      the number of bitmaps in this bitmap index.