/*
* 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.
*/
using System;
using System.Runtime.InteropServices;
using IndexReader = Lucene.Net.Index.IndexReader;
using DocIdBitSet = Lucene.Net.Util.DocIdBitSet;
using OpenBitSetDISI = Lucene.Net.Util.OpenBitSetDISI;
namespace Lucene.Net.Search
{
/// 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.
///
[Serializable]
public class CachingWrapperFilter:Filter
{
protected internal Filter filter;
/// A transient Filter cache.
[NonSerialized]
protected internal System.Collections.IDictionary cache;
/// Filter to cache results of
///
public CachingWrapperFilter(Filter filter)
{
this.filter = filter;
}
/// Use {@link #GetDocIdSet(IndexReader)} instead.
///
[Obsolete("Use GetDocIdSet(IndexReader) instead.")]
public override System.Collections.BitArray Bits(IndexReader reader)
{
if (cache == null)
{
cache = new SupportClass.WeakHashTable();
}
System.Object cached = null;
lock (cache.SyncRoot)
{
// check cache
cached = cache[reader];
}
if (cached != null)
{
if (cached is System.Collections.BitArray)
{
return (System.Collections.BitArray) cached;
}
else if (cached is DocIdBitSet)
return ((DocIdBitSet) cached).GetBitSet();
// It would be nice to handle the DocIdSet case, but that's not really possible
}
System.Collections.BitArray bits = filter.Bits(reader);
lock (cache.SyncRoot)
{
// update cache
cache[reader] = bits;
}
return bits;
}
/// Provide the DocIdSet to be cached, using the DocIdSet provided
/// by the wrapped Filter.
/// This implementation returns the given DocIdSet.
///
protected internal virtual DocIdSet DocIdSetToCache(DocIdSet docIdSet, IndexReader reader)
{
if (docIdSet.IsCacheable())
{
return docIdSet;
}
else
{
DocIdSetIterator it = docIdSet.Iterator();
// null is allowed to be returned by iterator(),
// in this case we wrap with the empty set,
// which is cacheable.
return (it == null) ? DocIdSet.EMPTY_DOCIDSET : new OpenBitSetDISI(it, reader.MaxDoc());
}
}
public override DocIdSet GetDocIdSet(IndexReader reader)
{
if (cache == null)
{
cache = new SupportClass.WeakHashTable();
}
System.Object cached = null;
lock (cache.SyncRoot)
{
// check cache
cached = cache[reader];
}
if (cached != null)
{
if (cached is DocIdSet)
return (DocIdSet) cached;
else
return new DocIdBitSet((System.Collections.BitArray) cached);
}
DocIdSet docIdSet = DocIdSetToCache(filter.GetDocIdSet(reader), reader);
if (docIdSet != null)
{
lock (cache.SyncRoot)
{
// update cache
cache[reader] = docIdSet;
}
}
return docIdSet;
}
public override System.String ToString()
{
return "CachingWrapperFilter(" + filter + ")";
}
public override bool Equals(System.Object o)
{
if (!(o is CachingWrapperFilter))
return false;
return this.filter.Equals(((CachingWrapperFilter) o).filter);
}
public override int GetHashCode()
{
return filter.GetHashCode() ^ 0x1117BF25;
}
}
}