org.apache.lucene.facet.encoding

Class ChunksIntEncoder

java.lang.Object

org.apache.lucene.facet.encoding.IntEncoder

org.apache.lucene.facet.encoding.ChunksIntEncoder

Direct Known Subclasses:

EightFlagsIntEncoder, FourFlagsIntEncoder

public abstract class ChunksIntEncoder
extends IntEncoder

An IntEncoder which encodes values in chunks. Implementations of this class assume the data which needs encoding consists of small, consecutive values, and therefore the encoder is able to compress them better. You can read more on the two implementations FourFlagsIntEncoder and EightFlagsIntEncoder.

Extensions of this class need to implement IntEncoder.encode(IntsRef, BytesRef) in order to build the proper indicator (flags). When enough values were accumulated (typically the batch size), extensions can call encodeChunk(BytesRef) to flush the indicator and the rest of the values.

NOTE: flags encoders do not accept values ≤ 0 (zero) in their IntEncoder.encode(IntsRef, BytesRef). For performance reasons they do not check that condition, however if such value is passed the result stream may be corrupt or an exception will be thrown. Also, these encoders perform the best when there are many consecutive small values (depends on the encoder implementation). If that is not the case, the encoder will occupy 1 more byte for every batch number of integers, over whatever VInt8IntEncoder would have occupied. Therefore make sure to check whether your data fits into the conditions of the specific encoder.

For the reasons mentioned above, these encoders are usually chained with UniqueValuesIntEncoder and DGapIntEncoder.

WARNING: This API is experimental and might change in incompatible ways in the next release.

Field Summary

Fields

Modifier and Type	Field and Description
protected IntsRef	encodeQueue Holds the values which must be encoded, outside the indicator.
protected int	indicator Represents bits flag byte.
protected byte	ordinal Counts the current ordinal of the encoded value.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	ChunksIntEncoder(int chunkSize)

Method Summary

Methods

Modifier and Type	Method and Description
protected void	encodeChunk(BytesRef buf) Encodes the values of the current chunk.

Methods inherited from class org.apache.lucene.facet.encoding.IntEncoder

createMatchingDecoder, encode

Methods inherited from class java.lang.Object

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

Field Detail

encodeQueue

protected final IntsRef encodeQueue

Holds the values which must be encoded, outside the indicator.

indicator

protected int indicator

Represents bits flag byte.

ordinal

protected byte ordinal

Counts the current ordinal of the encoded value.

Constructor Detail

ChunksIntEncoder

protected ChunksIntEncoder(int chunkSize)

Method Detail

encodeChunk

protected void encodeChunk(BytesRef buf)

Encodes the values of the current chunk. First it writes the indicator, and then it encodes the values outside the indicator.