// $Id: CachingWrapperFilter.java 20861 2010-11-08 10:16:04Z stliu $
package org.hibernate.search.filter;
import java.io.IOException;
import java.util.BitSet;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.search.DocIdSet;
import org.apache.lucene.search.Filter;
import org.hibernate.search.util.LoggerFactory;
import org.hibernate.search.util.SoftLimitMRUCache;
import org.slf4j.Logger;
/**
* A slightly different version of Lucene's original <code>CachingWrapperFilter</code> which
* uses <code>SoftReferences</code> instead of <code>WeakReferences</code> in order to cache
* the filter <code>BitSet</code>.
*
* @author Hardy Ferentschik
* @see org.apache.lucene.search.CachingWrapperFilter
* @see <a href="http://opensource.atlassian.com/projects/hibernate/browse/HSEARCH-174">HSEARCH-174</a>
*/
@SuppressWarnings("serial")
public class CachingWrapperFilter extends Filter {
private static final Logger log = LoggerFactory.make();
public static final int DEFAULT_SIZE = 5;
/**
* The cache using soft references in order to store the filter bit sets.
*/
private final SoftLimitMRUCache cache;
private final Filter filter;
/**
* @param filter Filter to cache results of
*/
public CachingWrapperFilter(Filter filter) {
this(filter, DEFAULT_SIZE);
}
/**
* @param filter Filter to cache results of
*/
public CachingWrapperFilter(Filter filter, int size) {
this.filter = filter;
log.debug( "Initialising SoftLimitMRUCache with hard ref size of {}", size );
this.cache = new SoftLimitMRUCache( size );
}
@Override
public BitSet bits(IndexReader reader) throws IOException {
throw new UnsupportedOperationException();
/* BitSet cached = (BitSet) cache.get(reader);
if (cached != null) {
return cached;
}
final BitSet bits = filter.bits(reader);
cache.put(reader, bits);
return bits; */
}
@Override
public DocIdSet getDocIdSet(IndexReader reader) throws IOException {
DocIdSet cached = (DocIdSet) cache.get( reader );
if ( cached != null ) {
return cached;
}
synchronized (cache) {
cached = (DocIdSet) cache.get( reader );
if ( cached != null ) {
return cached;
}
final DocIdSet docIdSet = filter.getDocIdSet( reader );
cache.put( reader, docIdSet );
return docIdSet;
}
}
public String toString() {
return this.getClass().getName() + "(" + filter + ")";
}
public boolean equals(Object o) {
if (!(o instanceof CachingWrapperFilter))
return false;
return this.filter.equals(((CachingWrapperFilter) o).filter);
}
public int hashCode() {
return filter.hashCode() ^ 0x1117BF25;
}
}