Package org.apache.lucene.codecs.lucene40

Class Lucene40LiveDocsFormat

java.lang.Object

org.apache.lucene.codecs.LiveDocsFormat

org.apache.lucene.codecs.lucene40.Lucene40LiveDocsFormat

public class Lucene40LiveDocsFormat
extends LiveDocsFormat

Lucene 4.0 Live Documents Format.

The .del file is optional, and only exists when a segment contains deletions.

Although per-segment, this file is maintained exterior to compound segment files.

Deletions (.del) --> Format,Header,ByteCount,BitCount, Bits | DGaps (depending on Format)

• Format,ByteSize,BitCount --> Uint32
• Bits --> <Byte> ^ByteCount
• DGaps --> <DGap,NonOnesByte> ^{NonzeroBytesCount}
• DGap --> VInt
• NonOnesByte --> Byte
• Header --> CodecHeader

Format is 1: indicates cleared DGaps.

ByteCount indicates the number of bytes in Bits. It is typically (SegSize/8)+1.

BitCount indicates the number of bits that are currently set in Bits.

Bits contains one bit for each document indexed. When the bit corresponding to a document number is cleared, that document is marked as deleted. Bit ordering is from least to most significant. Thus, if Bits contains two bytes, 0x00 and 0x02, then document 9 is marked as alive (not deleted).

DGaps represents sparse bit-vectors more efficiently than Bits. It is made of DGaps on indexes of nonOnes bytes in Bits, and the nonOnes bytes themselves. The number of nonOnes bytes in Bits (NonOnesBytesCount) is not stored.

For example, if there are 8000 bits and only bits 10,12,32 are cleared, DGaps would be used:

(VInt) 1 , (byte) 20 , (VInt) 3 , (Byte) 1

Constructor Summary

Constructors

Constructor	Description
Lucene40LiveDocsFormat()	Sole constructor.

Method Summary

Modifier and Type	Method	Description
void	files(SegmentCommitInfo info, Collection<String> files)	Records all files in use by this SegmentCommitInfo into the files argument.
MutableBits	newLiveDocs(int size)	Creates a new MutableBits, with all bits set, for the specified size.
MutableBits	newLiveDocs(Bits existing)	Creates a new mutablebits of the same bits set and size of existing.
Bits	readLiveDocs(Directory dir, SegmentCommitInfo info, IOContext context)	Read live docs bits.
void	writeLiveDocs(MutableBits bits, Directory dir, SegmentCommitInfo info, int newDelCount, IOContext context)	Persist live docs bits.

Methods inherited from class java.lang.Object

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

Constructor Detail

Lucene40LiveDocsFormat

public Lucene40LiveDocsFormat()

Sole constructor.

Method Detail

newLiveDocs

public MutableBits newLiveDocs(int size)
                        throws IOException

Description copied from class: LiveDocsFormat

Creates a new MutableBits, with all bits set, for the specified size.

Specified by:

newLiveDocs in class LiveDocsFormat

Throws:

IOException

newLiveDocs

public MutableBits newLiveDocs(Bits existing)
                        throws IOException

Description copied from class: LiveDocsFormat

Creates a new mutablebits of the same bits set and size of existing.

Specified by:

newLiveDocs in class LiveDocsFormat

Throws:

IOException

readLiveDocs

public Bits readLiveDocs(Directory dir,
                         SegmentCommitInfo info,
                         IOContext context)
                  throws IOException

Description copied from class: LiveDocsFormat

Read live docs bits.

Specified by:

readLiveDocs in class LiveDocsFormat

Throws:

IOException

writeLiveDocs

public void writeLiveDocs(MutableBits bits,
                          Directory dir,
                          SegmentCommitInfo info,
                          int newDelCount,
                          IOContext context)
                   throws IOException

Description copied from class: LiveDocsFormat

Persist live docs bits. Use SegmentCommitInfo.getNextDelGen() to determine the generation of the deletes file you should write to.

Specified by:

writeLiveDocs in class LiveDocsFormat

Throws:

IOException

files

public void files(SegmentCommitInfo info,
                  Collection<String> files)
           throws IOException

Description copied from class: LiveDocsFormat

Records all files in use by this SegmentCommitInfo into the files argument.

Specified by:

files in class LiveDocsFormat

Throws:

IOException