Package org.apache.lucene.codecs.uniformsplit

# Class IntersectBlockReader

java.lang.Object
org.apache.lucene.index.TermsEnum
org.apache.lucene.index.BaseTermsEnum
org.apache.lucene.codecs.uniformsplit.BlockReader
org.apache.lucene.codecs.uniformsplit.IntersectBlockReader

All Implemented Interfaces:
  `Accountable`, `BytesRefIterator`

Direct Known Subclasses:
  `STIntersectBlockReader`

public class IntersectBlockReader extends BlockReader
The "intersect" `TermsEnum` response to `UniformSplitTerms.intersect(CompiledAutomaton, BytesRef)`, intersecting the terms with an automaton.

By design of the UniformSplit block keys, it is less efficient than `org.apache.lucene.backward_codecs.lucene40.blocktree.IntersectTermsEnum` for `FuzzyQuery` (-37%). It is slightly slower for `WildcardQuery` (-5%) and slightly faster for `PrefixQuery` (+5%).

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

- ## Nested Class Summary

  Nested Classes
  Modifier and Type
  Class
  Description
  `protected class`
  `IntersectBlockReader.AutomatonNextTermCalculator`
  This is mostly a copy of AutomatonTermsEnum.
  `protected static enum`
  `IntersectBlockReader.BlockIteration`
  Block iteration order.

  ## Nested classes/interfaces inherited from class org.apache.lucene.index.TermsEnum

  `TermsEnum.SeekStatus`

- ## Field Summary

  Fields
  Modifier and Type
  Field
  Description
  `protected IntersectBlockReader.BlockIteration`
  `blockIteration`
  Block iteration order determined when scanning the terms in the current block.
  `protected final ByteRunnable`
  `byteRunnable`
  `protected final BytesRef`
  `commonSuffix`
  `protected final boolean`
  `finite`
  `protected final int`
  `minTermLength`
  `protected final IntersectBlockReader.AutomatonNextTermCalculator`
  `nextStringCalculator`
  `protected final int`
  `NUM_CONSECUTIVELY_REJECTED_TERMS_THRESHOLD`
  Threshold that controls when to attempt to jump to a block away.
  `protected int`
  `numConsecutivelyRejectedTerms`
  Counter of the number of consecutively rejected terms.
  `protected int`
  `numMatchedBytes`
  Number of bytes accepted by the automaton when validating the current term.
  `protected BytesRef`
  `seekTerm`
  Set this when our current mode is seeking to this term.
  `protected int[]`
  `states`
  Automaton states reached when validating the current term, from 0 to `numMatchedBytes` - 1.
  `protected final TransitionAccessor`
  `transitionAccessor`

  ### Fields inherited from class org.apache.lucene.codecs.uniformsplit.BlockReader

  `blockDecoder, blockFirstLineStart, blockHeader, blockHeaderReader, blockInput, blockLine, blockLineReader, blockReadBuffer, blockStartFP, dictionaryBrowser, dictionaryBrowserSupplier, fieldMetadata, forcedTerm, lineIndexInBlock, postingsReader, scratchBlockBytes, scratchBlockLine, scratchTermState, termState, termStateForced, termStateSerializer, termStatesReadBuffer`

  ### Fields inherited from class org.apache.lucene.index.TermsEnum

  `EMPTY`

  ### Fields inherited from interface org.apache.lucene.util.Accountable

  `NULL_ACCOUNTABLE`

- ## Constructor Summary

  Constructors
  Modifier
  Constructor
  Description
  `protected`
  `IntersectBlockReader(CompiledAutomaton compiled, BytesRef startTerm, IndexDictionary.BrowserSupplier dictionaryBrowserSupplier, IndexInput blockInput, PostingsReaderBase postingsReader, FieldMetadata fieldMetadata, BlockDecoder blockDecoder)`

- ## Method Summary

  Modifier and Type
  Method
  Description
  `protected boolean`
  `endsWithCommonSuffix(byte[] termBytes, int termLength)`
  Indicates whether the given term ends with the automaton common suffix.
  `protected int`
  `getMinTermLength()`
  Computes the minimal length of the terms accepted by the automaton.
  `BytesRef`
  `next()`
  `protected boolean`
  `nextBlock()`
  Opens the next block.
  `protected BytesRef`
  `nextTermInBlockMatching()`
  Finds the next block line that matches (accepted by the automaton), or null when at end of block.
  `TermsEnum.SeekStatus`
  `seekCeil(BytesRef text)`
  `void`
  `seekExact(long ord)`
  Not supported.
  `boolean`
  `seekExact(BytesRef text)`
  `void`
  `seekExact(BytesRef term, TermState state)`
  Positions this `BlockReader` without re-seeking the term dictionary.
  `protected boolean`
  `seekFirstBlock()`

  ### Methods inherited from class org.apache.lucene.codecs.uniformsplit.BlockReader

  `clearTermState, compareToMiddleAndJump, createBlockHeaderSerializer, createBlockLineSerializer, createDeltaBaseTermStateSerializer, decodeBlockBytesIfNeeded, docFreq, getOrCreateDictionaryBrowser, impacts, initializeBlockReadLazily, initializeHeader, isBeyondLastTerm, isCurrentTerm, newCorruptIndexException, nextTerm, ord, postings, ramBytesUsed, readHeader, readLineInBlock, readTermState, readTermStateIfNotRead, seekInBlock, seekInBlock, term, termState, totalTermFreq`

  ### Methods inherited from class org.apache.lucene.index.BaseTermsEnum

  `attributes, prepareSeekExact`

  ### Methods inherited from class org.apache.lucene.index.TermsEnum

  `postings`

  ### Methods inherited from class java.lang.Object

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

  ### Methods inherited from interface org.apache.lucene.util.Accountable

  `getChildResources`

- ## Field Details

  - ### NUM_CONSECUTIVELY_REJECTED_TERMS_THRESHOLD

    protected final int NUM_CONSECUTIVELY_REJECTED_TERMS_THRESHOLD
    Threshold that controls when to attempt to jump to a block away.

    This counter is 0 when entering a block. It is incremented each time a term is rejected by the automaton. When the counter is greater than or equal to this threshold, then we compute the next term accepted by the automaton, with `IntersectBlockReader.AutomatonNextTermCalculator`, and we jump to a block away if the next term accepted is greater than the immediate next term in the block.

    A low value, for example 1, improves the performance of automatons requiring many jumps, for example `FuzzyQuery` and most `WildcardQuery`. A higher value improves the performance of automatons with less or no jump, for example `PrefixQuery`. A threshold of 4 seems to be a good balance.

    See Also:
      - Constant Field Values

  - ### transitionAccessor

    protected final TransitionAccessor transitionAccessor

  - ### byteRunnable

    protected final ByteRunnable byteRunnable

  - ### finite

    protected final boolean finite

  - ### commonSuffix

    protected final BytesRef commonSuffix

  - ### minTermLength

    protected final int minTermLength

  - ### nextStringCalculator

    protected final IntersectBlockReader.AutomatonNextTermCalculator nextStringCalculator

  - ### seekTerm

    protected BytesRef seekTerm
    Set this when our current mode is seeking to this term. Set to null after.

  - ### numMatchedBytes

    protected int numMatchedBytes
    Number of bytes accepted by the automaton when validating the current term.

  - ### states

    protected int[] states
    Automaton states reached when validating the current term, from 0 to `numMatchedBytes` - 1.

  - ### blockIteration

    protected IntersectBlockReader.BlockIteration blockIteration
    Block iteration order determined when scanning the terms in the current block.

  - ### numConsecutivelyRejectedTerms

    protected int numConsecutivelyRejectedTerms
    Counter of the number of consecutively rejected terms. Depending on `NUM_CONSECUTIVELY_REJECTED_TERMS_THRESHOLD`, this may trigger a jump to a block away.

- ## Constructor Details

  - ### IntersectBlockReader

    protected IntersectBlockReader(CompiledAutomaton compiled, BytesRef startTerm, IndexDictionary.BrowserSupplier dictionaryBrowserSupplier, IndexInput blockInput, PostingsReaderBase postingsReader, FieldMetadata fieldMetadata, BlockDecoder blockDecoder) throws IOException
    Throws:
      `IOException`

- ## Method Details

  - ### getMinTermLength

    protected int getMinTermLength()
    Computes the minimal length of the terms accepted by the automaton. This speeds up the term scanning for automatons accepting a finite language.

  - ### next

    public BytesRef next() throws IOException
    Specified by:
      `next` in interface `BytesRefIterator`
    Overrides:
      `next` in class `BlockReader`
    Throws:
      `IOException`

  - ### seekFirstBlock

    protected boolean seekFirstBlock() throws IOException
    Throws:
      `IOException`

  - ### nextTermInBlockMatching

    protected BytesRef nextTermInBlockMatching() throws IOException
    Finds the next block line that matches (accepted by the automaton), or null when at end of block.
    Returns:
      The next term in the current block that is accepted by the automaton; or null if none.
    Throws:
      `IOException`

  - ### endsWithCommonSuffix

    protected boolean endsWithCommonSuffix(byte[] termBytes, int termLength)
    Indicates whether the given term ends with the automaton common suffix. This allows to quickly skip terms that the automaton would reject eventually.

  - ### nextBlock

    protected boolean nextBlock() throws IOException
    Opens the next block. Depending on the `blockIteration` order, it may be the very next block, or a block away that may contain `seekTerm`.
    Returns:
      true if the next block is opened; false if there is no blocks anymore and the iteration is over.
    Throws:
      `IOException`

  - ### seekExact

    public boolean seekExact(BytesRef text)
    Overrides:
      `seekExact` in class `BlockReader`

  - ### seekExact

    public void seekExact(long ord)
    Description copied from class: `BlockReader`
    Not supported.
    Overrides:
      `seekExact` in class `BlockReader`

  - ### seekExact

    public void seekExact(BytesRef term, TermState state)
    Description copied from class: `BlockReader`
    Positions this `BlockReader` without re-seeking the term dictionary.

    The block containing the term is not read by this method. It will be read lazily only if needed, for example if `BlockReader.next()` is called. Calling `BlockReader.postings(org.apache.lucene.index.PostingsEnum, int)` after this method does require the block to be read.

    Overrides:
      `seekExact` in class `BlockReader`

  - ### seekCeil

    public TermsEnum.SeekStatus seekCeil(BytesRef text)
    Overrides:
      `seekCeil` in class `BlockReader`