org.apache.lucene.search
Class CachingWrapperFilter

java.lang.Object
  org.apache.lucene.search.Filter
      org.apache.lucene.search.CachingWrapperFilter

All Implemented Interfaces:

Serializable

public class CachingWrapperFilter
extends Filter

Wraps another filter's result and caches it. The purpose is to allow filters to simply filter, and then wrap with this class to add caching.

NOTE: if you wrap this filter as a query (eg, using ConstantScoreQuery), you'll likely want to enforce deletions (using either CachingWrapperFilter.DeletesMode.RECACHE or CachingWrapperFilter.DeletesMode.DYNAMIC).

See Also:

Serialized Form

Nested Class Summary

static class

CachingWrapperFilter.DeletesMode Expert: Specifies how new deletions against a reopened reader should be handled.

Field Summary

protected org.apache.lucene.search.CachingWrapperFilter.FilterCache<DocIdSet>

cache

Constructor Summary

CachingWrapperFilter(Filter filter)
New deletes are ignored by default, which gives higher cache hit rate on reopened readers.

CachingWrapperFilter(Filter filter, CachingWrapperFilter.DeletesMode deletesMode)
Expert: by default, the cached filter will be shared across reopened segments that only had changes to their deletions.

Method Summary

protected DocIdSet	docIdSetToCache(DocIdSet docIdSet, IndexReader reader) Provide the DocIdSet to be cached, using the DocIdSet provided by the wrapped Filter.
boolean	equals(Object o)
DocIdSet	getDocIdSet(IndexReader reader) Creates a DocIdSet enumerating the documents that should be permitted in search results.
int	hashCode()
String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

cache

protected final org.apache.lucene.search.CachingWrapperFilter.FilterCache<DocIdSet> cache

Constructor Detail

CachingWrapperFilter

public CachingWrapperFilter(Filter filter)

New deletes are ignored by default, which gives higher cache hit rate on reopened readers. Most of the time this is safe, because the filter will be AND'd with a Query that fully enforces deletions. If instead you need this filter to always enforce deletions, pass either CachingWrapperFilter.DeletesMode.RECACHE or CachingWrapperFilter.DeletesMode.DYNAMIC.

Parameters:

filter - Filter to cache results of

CachingWrapperFilter

public CachingWrapperFilter(Filter filter,
                            CachingWrapperFilter.DeletesMode deletesMode)

Expert: by default, the cached filter will be shared across reopened segments that only had changes to their deletions.

Parameters:

filter - Filter to cache results of

deletesMode - See CachingWrapperFilter.DeletesMode

Method Detail

docIdSetToCache

protected DocIdSet docIdSetToCache(DocIdSet docIdSet,
                                   IndexReader reader)
                            throws IOException

Provide the DocIdSet to be cached, using the DocIdSet provided by the wrapped Filter.

This implementation returns the given DocIdSet, if DocIdSet.isCacheable() returns true, else it copies the DocIdSetIterator into an FixedBitSet.

Throws:

IOException

getDocIdSet

public DocIdSet getDocIdSet(IndexReader reader)
                     throws IOException

Description copied from class: Filter

Creates a DocIdSet enumerating the documents that should be permitted in search results. NOTE: null can be returned if no documents are accepted by this Filter.

Note: This method will be called once per segment in the index during searching. The returned DocIdSet must refer to document IDs for that segment, not for the top-level reader.

Specified by:

getDocIdSet in class Filter

Parameters:

reader - a IndexReader instance opened on the index currently searched on. Note, it is likely that the provided reader does not represent the whole underlying index i.e. if the index has more than one segment the given reader only represents a single segment.

Returns:

a DocIdSet that provides the documents which should be permitted or prohibited in search results. NOTE: null can be returned if no documents will be accepted by this Filter.

Throws:

IOException

See Also:

DocIdBitSet

toString

public String toString()

Overrides:

toString in class Object

equals

public boolean equals(Object o)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object