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package org.apache.lucene.index;
/*
* 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.
*/
import java.io.IOException;
/** A {@link CompositeReader} which reads multiple indexes, appending
* their content. It can be used to create a view on several
* sub-readers (like {@link DirectoryReader}) and execute searches on it.
*
* For efficiency, in this API documents are often referred to via
* document numbers, non-negative integers which each name a unique
* document in the index. These document numbers are ephemeral -- they may change
* as documents are added to and deleted from an index. Clients should thus not
* rely on a given document having the same number between sessions.
*
*
NOTE: {@link
* IndexReader} instances are completely thread
* safe, meaning multiple threads can call any of its methods,
* concurrently. If your application requires external
* synchronization, you should not synchronize on the
* IndexReader instance; use your own
* (non-Lucene) objects instead.
*/
public class MultiReader extends BaseCompositeReader {
private final boolean closeSubReaders;
/**
* Construct a MultiReader aggregating the named set of (sub)readers.
*
Note that all subreaders are closed if this Multireader is closed.
* @param subReaders set of (sub)readers
*/
public MultiReader(IndexReader... subReaders) {
this(subReaders, true);
}
/**
* Construct a MultiReader aggregating the named set of (sub)readers.
* @param subReaders set of (sub)readers; this array will be cloned.
* @param closeSubReaders indicates whether the subreaders should be closed
* when this MultiReader is closed
*/
public MultiReader(IndexReader[] subReaders, boolean closeSubReaders) {
super(subReaders.clone());
this.closeSubReaders = closeSubReaders;
if (!closeSubReaders) {
for (int i = 0; i < subReaders.length; i++) {
subReaders[i].incRef();
}
}
}
@Override
protected synchronized void doClose() throws IOException {
IOException ioe = null;
for (final IndexReader r : getSequentialSubReaders()) {
try {
if (closeSubReaders) {
r.close();
} else {
r.decRef();
}
} catch (IOException e) {
if (ioe == null) ioe = e;
}
}
// throw the first exception
if (ioe != null) throw ioe;
}
}