org.apache.lucene.index

Class SlowCompositeReaderWrapper

java.lang.Object

org.apache.lucene.index.IndexReader

org.apache.lucene.index.AtomicReader

org.apache.lucene.index.SlowCompositeReaderWrapper

All Implemented Interfaces:

Closeable

public final class SlowCompositeReaderWrapper
extends AtomicReader

This class forces a composite reader (eg a MultiReader or DirectoryReader) to emulate an atomic reader. This requires implementing the postings APIs on-the-fly, using the static methods in MultiFields, MultiDocValues, by stepping through the sub-readers to merge fields/terms, appending docs, etc.

NOTE: this class almost always results in a performance hit. If this is important to your use case, you'll get better performance by gathering the sub readers using IndexReader.getContext() to get the atomic leaves and then operate per-AtomicReader, instead of using this class.

Nested Class Summary

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

IndexReader.ReaderClosedListener

Constructor Summary

Constructors

Constructor and Description
SlowCompositeReaderWrapper(CompositeReader reader) Sole constructor, wrapping the provided CompositeReader.

Method Summary

Methods

Modifier and Type	Method and Description
protected void	doClose() Implements close.
void	document(int docID, StoredFieldVisitor visitor) Expert: visits the fields of a stored document, for custom processing/loading of each field.
DocValues	docValues(String field) Returns DocValues for this field.
Fields	fields() Returns Fields for this reader.
Object	getCombinedCoreAndDeletesKey() Expert: Returns a key for this IndexReader that also includes deletions, so FieldCache/CachingWrapperFilter can find it again.
Object	getCoreCacheKey() Expert: Returns a key for this IndexReader, so FieldCache/CachingWrapperFilter can find it again.
FieldInfos	getFieldInfos() Get the FieldInfos describing all fields in this reader.
Bits	getLiveDocs() Returns the Bits representing live (not deleted) docs.
Fields	getTermVectors(int docID) Retrieve term vectors for this document, or null if term vectors were not indexed.
boolean	hasDeletions() Returns true if any documents have been deleted
int	maxDoc() Returns one greater than the largest possible document number.
DocValues	normValues(String field) Returns DocValues for this field's normalization values.
int	numDocs() Returns the number of documents in this index.
String	toString()
static AtomicReader	wrap(IndexReader reader) This method is sugar for getting an AtomicReader from an IndexReader of any kind.

Methods inherited from class org.apache.lucene.index.AtomicReader

docFreq, getContext, hasNorms, termDocsEnum, termPositionsEnum, terms, totalTermFreq

Methods inherited from class org.apache.lucene.index.IndexReader

addReaderClosedListener, close, decRef, document, document, ensureOpen, equals, getRefCount, getTermVector, hashCode, incRef, leaves, numDeletedDocs, open, open, open, open, open, registerParentReader, removeReaderClosedListener, tryIncRef

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

SlowCompositeReaderWrapper

public SlowCompositeReaderWrapper(CompositeReader reader)
                           throws IOException

Sole constructor, wrapping the provided CompositeReader.

Throws:

IOException

Method Detail

wrap

public static AtomicReader wrap(IndexReader reader)
                         throws IOException

This method is sugar for getting an AtomicReader from an IndexReader of any kind. If the reader is already atomic, it is returned unchanged, otherwise wrapped by this class.

Throws:

IOException

toString

public String toString()

Overrides:

toString in class Object

fields

public Fields fields()

Description copied from class: AtomicReader

Returns Fields for this reader. This method may return null if the reader has no postings.

Specified by:

fields in class AtomicReader

docValues

public DocValues docValues(String field)
                    throws IOException

Description copied from class: AtomicReader

Returns DocValues for this field. This method may return null if the reader has no per-document values stored.

Specified by:

docValues in class AtomicReader

Throws:

IOException

normValues

public DocValues normValues(String field)
                     throws IOException

Description copied from class: AtomicReader

Returns DocValues for this field's normalization values. This method may return null if the field has no norms.

Specified by:

normValues in class AtomicReader

Throws:

IOException

getTermVectors

public Fields getTermVectors(int docID)
                      throws IOException

Description copied from class: IndexReader

Retrieve term vectors for this document, or null if term vectors were not indexed. The returned Fields instance acts like a single-document inverted index (the docID will be 0).

Specified by:

getTermVectors in class IndexReader

Throws:

IOException

numDocs

public int numDocs()

Description copied from class: IndexReader

Returns the number of documents in this index.

Specified by:

numDocs in class IndexReader

maxDoc

public int maxDoc()

Description copied from class: IndexReader

Returns one greater than the largest possible document number. This may be used to, e.g., determine how big to allocate an array which will have an element for every document number in an index.

Specified by:

maxDoc in class IndexReader

document

public void document(int docID,
            StoredFieldVisitor visitor)
              throws IOException

Description copied from class: IndexReader

Expert: visits the fields of a stored document, for custom processing/loading of each field. If you simply want to load all fields, use IndexReader.document(int). If you want to load a subset, use DocumentStoredFieldVisitor.

Specified by:

document in class IndexReader

Throws:

IOException

getLiveDocs

public Bits getLiveDocs()

Description copied from class: AtomicReader

Returns the Bits representing live (not deleted) docs. A set bit indicates the doc ID has not been deleted. If this method returns null it means there are no deleted documents (all documents are live). The returned instance has been safely published for use by multiple threads without additional synchronization.

Specified by:

getLiveDocs in class AtomicReader

getFieldInfos

public FieldInfos getFieldInfos()

Description copied from class: AtomicReader

Get the FieldInfos describing all fields in this reader.

Specified by:

getFieldInfos in class AtomicReader

hasDeletions

public boolean hasDeletions()

Description copied from class: IndexReader

Returns true if any documents have been deleted

Specified by:

hasDeletions in class IndexReader

getCoreCacheKey

public Object getCoreCacheKey()

Description copied from class: IndexReader

Expert: Returns a key for this IndexReader, so FieldCache/CachingWrapperFilter can find it again. This key must not have equals()/hashCode() methods, so "equals" means "identical".

Overrides:

getCoreCacheKey in class IndexReader

getCombinedCoreAndDeletesKey

public Object getCombinedCoreAndDeletesKey()

Description copied from class: IndexReader

Expert: Returns a key for this IndexReader that also includes deletions, so FieldCache/CachingWrapperFilter can find it again. This key must not have equals()/hashCode() methods, so "equals" means "identical".

Overrides:

getCombinedCoreAndDeletesKey in class IndexReader

doClose

protected void doClose()
                throws IOException

Description copied from class: IndexReader

Implements close.

Specified by:

doClose in class IndexReader

Throws:

IOException