/*
* JBoss, Home of Professional Open Source
* Copyright 2011 Red Hat Inc. and/or its affiliates and other contributors
* as indicated by the @authors tag. All rights reserved.
* See the copyright.txt in the distribution for a
* full listing of individual contributors.
*
* This copyrighted material is made available to anyone wishing to use,
* modify, copy, or redistribute it subject to the terms and conditions
* of the GNU Lesser General Public License, v. 2.1.
* This program is distributed in the hope that it will be useful, but WITHOUT A
* WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
* PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.
* You should have received a copy of the GNU Lesser General Public License,
* v.2.1 along with this distribution; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
* MA 02110-1301, USA.
*/
package org.hibernate.search.query.fieldcache.impl;
import java.io.IOException;
import org.apache.lucene.index.IndexReader;
/**
* Using as composition in implementations of {@link org.hibernate.search.query.collector.FieldCacheCollector},
* so that we can reuse different loading strategies in different kinds
* of Collectors.
*
* @author Sanne Grinovero <sanne@hibernate.org> (C) 2011 Red Hat Inc.
* @see org.hibernate.search.query.collector.BigArrayFieldCacheCollectorImpl
* @see org.hibernate.search.query.collector.MapFieldCacheCollectorImpl
*/
public interface FieldLoadingStrategy {
/**
* A new IndexReader is opened - implementations usually need this to
* load the next array of cached data.
*
* @param reader the {@code IndexReader} for which to load the new cache values
* @throws java.io.IOException in case an error occurs reading the cache values from the index
*/
public void loadNewCacheValues(IndexReader reader) throws IOException;
/**
* The collector wants to pick a specific element from the cache.
* Only at this point we convert primitives into an object if needed.
*
* @param relativeDocId the doc id relative to the current reader
* @return the cached field value for the document with the relative id {@code relativeDocId}.
*/
public Object collect(int relativeDocId);
}