+++ /dev/null
-/*
- * Created on 25-Jan-2006
- */
-package org.apache.lucene.xmlparser.builders;
-
-import java.util.Map.Entry;
-
-import org.apache.lucene.search.CachingWrapperFilter;
-import org.apache.lucene.search.Filter;
-import org.apache.lucene.search.Query;
-import org.apache.lucene.search.QueryWrapperFilter;
-import org.apache.lucene.xmlparser.DOMUtils;
-import org.apache.lucene.xmlparser.FilterBuilder;
-import org.apache.lucene.xmlparser.FilterBuilderFactory;
-import org.apache.lucene.xmlparser.ParserException;
-import org.apache.lucene.xmlparser.QueryBuilder;
-import org.apache.lucene.xmlparser.QueryBuilderFactory;
-import org.w3c.dom.Element;
-/**
- * Licensed to the Apache Software Foundation (ASF) under one or more
- * contributor license agreements. See the NOTICE file distributed with
- * this work for additional information regarding copyright ownership.
- * The ASF licenses this file to You under the Apache License, Version 2.0
- * (the "License"); you may not use this file except in compliance with
- * the License. You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-/**
- * Filters are cached in an LRU Cache keyed on the contained query or filter object. Using this will
- * speed up overall performance for repeated uses of the same expensive query/filter. The sorts of
- * queries/filters likely to benefit from caching need not necessarily be complex - e.g. simple
- * TermQuerys with a large DF (document frequency) can be expensive on large indexes.
- * A good example of this might be a term query on a field with only 2 possible values -
- * "true" or "false". In a large index, querying or filtering on this field requires reading
- * millions of document ids from disk which can more usefully be cached as a filter bitset.
- *
- * For Queries/Filters to be cached and reused the object must implement hashcode and
- * equals methods correctly so that duplicate queries/filters can be detected in the cache.
- *
- * The CoreParser.maxNumCachedFilters property can be used to control the size of the LRU
- * Cache established during the construction of CoreParser instances.
- *
- */
-public class CachedFilterBuilder implements FilterBuilder {
-
- private QueryBuilderFactory queryFactory;
- private FilterBuilderFactory filterFactory;
-
- private LRUCache<Object,Filter> filterCache = null;
-
- private int cacheSize;
-
- public CachedFilterBuilder(QueryBuilderFactory queryFactory,
- FilterBuilderFactory filterFactory,int cacheSize)
- {
- this.queryFactory=queryFactory;
- this.filterFactory=filterFactory;
- this.cacheSize=cacheSize;
- }
-
- public synchronized Filter getFilter(Element e) throws ParserException
- {
-
- Element childElement = DOMUtils.getFirstChildOrFail(e);
-
- if (filterCache == null)
- {
- filterCache = new LRUCache<Object,Filter>(cacheSize);
- }
-
- // Test to see if child Element is a query or filter that needs to be
- // cached
- QueryBuilder qb = queryFactory.getQueryBuilder(childElement.getNodeName());
- Object cacheKey = null;
- Query q = null;
- Filter f = null;
- if (qb != null)
- {
- q = qb.getQuery(childElement);
- cacheKey = q;
- } else
- {
- f = filterFactory.getFilter(childElement);
- cacheKey = f;
- }
- Filter cachedFilter = filterCache.get(cacheKey);
- if (cachedFilter != null)
- {
- return cachedFilter; // cache hit
- }
-
- //cache miss
- if (qb != null)
- {
- cachedFilter = new QueryWrapperFilter(q);
- } else
- {
- cachedFilter = new CachingWrapperFilter(f);
- }
-
- filterCache.put(cacheKey, cachedFilter);
- return cachedFilter;
- }
-
- static class LRUCache<K,V> extends java.util.LinkedHashMap<K,V>
- {
- public LRUCache(int maxsize)
- {
- super(maxsize * 4 / 3 + 1, 0.75f, true);
- this.maxsize = maxsize;
- }
-
- protected int maxsize;
-
- @Override
- protected boolean removeEldestEntry(Entry<K,V> eldest)
- {
- return size() > maxsize;
- }
-
- }
-
-}