org.apache.lucene.codecs.uniformsplit

Class BlockWriter

java.lang.Object

org.apache.lucene.codecs.uniformsplit.BlockWriter

Direct Known Subclasses:

STBlockWriter

public class BlockWriter
extends Object

Writes blocks in the block file.

According the Uniform Split technique, the writing combines three steps per block, and it is repeated for all the field blocks:

1. Select the term with the shortest minimal distinguishing prefix (MDP) in the neighborhood of the target block size (+- delta size)
2. The selected term becomes the first term of the next block, and its MDP is the next block key.
3. The current block is written to the block file. And its block key is added to the index dictionary.

This stateful BlockWriter is called repeatedly to add all the BlockLine terms of a field. Then finishLastBlock(org.apache.lucene.codecs.uniformsplit.IndexDictionary.Builder) is called. And then this BlockWriter can be reused to add the terms of another field.

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 BlockEncoder	blockEncoder
protected BlockHeader.Serializer	blockHeaderWriter
protected List<BlockLine>	blockLines
protected ByteBuffersDataOutput	blockLinesWriteBuffer
protected BlockLine.Serializer	blockLineWriter
protected IndexOutput	blockOutput
protected ByteBuffersDataOutput	blockWriteBuffer
protected int	deltaNumLines
protected FieldMetadata	fieldMetadata
protected BytesRef	lastTerm
protected BlockHeader	reusableBlockHeader
protected BytesRef	scratchBytesRef
protected int	targetNumBlockLines
protected DeltaBaseTermStateSerializer	termStateSerializer
protected ByteBuffersDataOutput	termStatesWriteBuffer

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	BlockWriter(IndexOutput blockOutput, int targetNumBlockLines, int deltaNumLines, BlockEncoder blockEncoder)

Method Summary

Modifier and Type	Method and Description
protected void	addBlockKey(List<BlockLine> blockLines, IndexDictionary.Builder dictionaryBuilder) Adds a new block key with its corresponding block file pointer to the IndexDictionary.Builder .
protected void	addLine(BytesRef term, BlockTermState blockTermState, IndexDictionary.Builder dictionaryBuilder) Adds a new BlockLine term for the current field.
protected BlockHeader.Serializer	createBlockHeaderSerializer()
protected BlockLine.Serializer	createBlockLineSerializer()
protected DeltaBaseTermStateSerializer	createDeltaBaseTermStateSerializer()
protected void	finishLastBlock(IndexDictionary.Builder dictionaryBuilder) This method is called when there is no more term for the field.
protected void	splitAndWriteBlock(IndexDictionary.Builder dictionaryBuilder) Defines the new block start according to targetNumBlockLines and deltaNumLines.
protected void	updateFieldMetadata(long blockStartFP) updates the field metadata after all lines were written for the block.
protected void	writeBlock(List<BlockLine> blockLines, IndexDictionary.Builder dictionaryBuilder) Writes a block and adds its block key to the dictionary builder.
protected void	writeBlockLine(boolean isIncrementalEncodingSeed, BlockLine line, BlockLine previousLine)

Methods inherited from class java.lang.Object

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

Field Detail

targetNumBlockLines

protected final int targetNumBlockLines

deltaNumLines

protected final int deltaNumLines

blockLines

protected final List<BlockLine> blockLines

blockOutput

protected final IndexOutput blockOutput

blockLinesWriteBuffer

protected final ByteBuffersDataOutput blockLinesWriteBuffer

termStatesWriteBuffer

protected final ByteBuffersDataOutput termStatesWriteBuffer

blockHeaderWriter

protected final BlockHeader.Serializer blockHeaderWriter

blockLineWriter

protected final BlockLine.Serializer blockLineWriter

termStateSerializer

protected final DeltaBaseTermStateSerializer termStateSerializer

blockEncoder

protected final BlockEncoder blockEncoder

blockWriteBuffer

protected final ByteBuffersDataOutput blockWriteBuffer

fieldMetadata

protected FieldMetadata fieldMetadata

lastTerm

protected BytesRef lastTerm

reusableBlockHeader

protected final BlockHeader reusableBlockHeader

scratchBytesRef

protected BytesRef scratchBytesRef

Constructor Detail

BlockWriter

protected BlockWriter(IndexOutput blockOutput,
                      int targetNumBlockLines,
                      int deltaNumLines,
                      BlockEncoder blockEncoder)

Method Detail

createBlockHeaderSerializer

protected BlockHeader.Serializer createBlockHeaderSerializer()

createBlockLineSerializer

protected BlockLine.Serializer createBlockLineSerializer()

createDeltaBaseTermStateSerializer

protected DeltaBaseTermStateSerializer createDeltaBaseTermStateSerializer()

addLine

protected void addLine(BytesRef term,
                       BlockTermState blockTermState,
                       IndexDictionary.Builder dictionaryBuilder)
                throws IOException

Adds a new BlockLine term for the current field.

This method determines whether the new term is part of the current block, or if it is part of the next block. In the latter case, a new block is started (including one or more of the lastly added lines), the current block is written to the block file, and the current block key is added to the IndexDictionary.Builder.

Parameters:

term - The block line term. The BytesRef instance is used directly, the caller is responsible to make a deep copy if needed. This is required because we keep a list of block lines until we decide to write the current block, and each line must have a different term instance.

blockTermState - Block line details.

dictionaryBuilder - to which the block keys are added.

Throws:

IOException

finishLastBlock

protected void finishLastBlock(IndexDictionary.Builder dictionaryBuilder)
                        throws IOException

This method is called when there is no more term for the field. It writes the remaining lines added with addLine(org.apache.lucene.util.BytesRef, org.apache.lucene.codecs.BlockTermState, org.apache.lucene.codecs.uniformsplit.IndexDictionary.Builder) as the last block of the field and resets this BlockWriter state. Then this BlockWriter can be used for another field.

Throws:

IOException

splitAndWriteBlock

protected void splitAndWriteBlock(IndexDictionary.Builder dictionaryBuilder)
                           throws IOException

Defines the new block start according to targetNumBlockLines and deltaNumLines. The new block is started (including one or more of the lastly added lines), the current block is written to the block file, and the current block key is added to the IndexDictionary.Builder.

Throws:

IOException

writeBlock

protected void writeBlock(List<BlockLine> blockLines,
                          IndexDictionary.Builder dictionaryBuilder)
                   throws IOException

Writes a block and adds its block key to the dictionary builder.

Throws:

IOException

updateFieldMetadata

protected void updateFieldMetadata(long blockStartFP)

updates the field metadata after all lines were written for the block.

writeBlockLine

protected void writeBlockLine(boolean isIncrementalEncodingSeed,
                              BlockLine line,
                              BlockLine previousLine)
                       throws IOException

Throws:

IOException

addBlockKey

protected void addBlockKey(List<BlockLine> blockLines,
                           IndexDictionary.Builder dictionaryBuilder)
                    throws IOException

Adds a new block key with its corresponding block file pointer to the IndexDictionary.Builder . The block key is the MDP (see TermBytes) of the block first term.

Throws:

IOException