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;
import java.util.Arrays;
import java.util.Collection;
import java.util.HashMap;
import java.util.Map;
import org.apache.lucene.document.Document;
import org.apache.lucene.document.FieldSelector;
import org.apache.lucene.index.DirectoryReader.MultiTermDocs;
import org.apache.lucene.index.DirectoryReader.MultiTermEnum;
import org.apache.lucene.index.DirectoryReader.MultiTermPositions;
import org.apache.lucene.search.DefaultSimilarity;
import org.apache.lucene.search.FieldCache; // not great (circular); used only to purge FieldCache entry on close
/** An IndexReader which reads multiple indexes, appending
* their content. */
public class MultiReader extends IndexReader implements Cloneable {
protected IndexReader[] subReaders;
private int[] starts; // 1st docno for each segment
private boolean[] decrefOnClose; // remember which subreaders to decRef on close
private Map<String,byte[]> normsCache = new HashMap<String,byte[]>();
private int maxDoc = 0;
private int numDocs = -1;
private boolean hasDeletions = false;
/**
* <p>Construct a MultiReader aggregating the named set of (sub)readers.
* Directory locking for delete, undeleteAll, and setNorm operations is
* left to the subreaders. </p>
* <p>Note that all subreaders are closed if this Multireader is closed.</p>
* @param subReaders set of (sub)readers
* @throws IOException
*/
public MultiReader(IndexReader... subReaders) {
initialize(subReaders, true);
}
/**
* <p>Construct a MultiReader aggregating the named set of (sub)readers.
* Directory locking for delete, undeleteAll, and setNorm operations is
* left to the subreaders. </p>
* @param closeSubReaders indicates whether the subreaders should be closed
* when this MultiReader is closed
* @param subReaders set of (sub)readers
* @throws IOException
*/
public MultiReader(IndexReader[] subReaders, boolean closeSubReaders) {
initialize(subReaders, closeSubReaders);
}
private void initialize(IndexReader[] subReaders, boolean closeSubReaders) {
this.subReaders = subReaders.clone();
starts = new int[subReaders.length + 1]; // build starts array
decrefOnClose = new boolean[subReaders.length];
for (int i = 0; i < subReaders.length; i++) {
starts[i] = maxDoc;
maxDoc += subReaders[i].maxDoc(); // compute maxDocs
if (!closeSubReaders) {
subReaders[i].incRef();
decrefOnClose[i] = true;
} else {
decrefOnClose[i] = false;
}
if (subReaders[i].hasDeletions())
hasDeletions = true;
}
starts[subReaders.length] = maxDoc;
}
/**
* Tries to reopen the subreaders.
* <br>
* If one or more subreaders could be re-opened (i. e. subReader.reopen()
* returned a new instance != subReader), then a new MultiReader instance
* is returned, otherwise this instance is returned.
* <p>
* A re-opened instance might share one or more subreaders with the old
* instance. Index modification operations result in undefined behavior
* when performed before the old instance is closed.
* (see {@link IndexReader#reopen()}).
* <p>
* If subreaders are shared, then the reference count of those
* readers is increased to ensure that the subreaders remain open
* until the last referring reader is closed.
*
* @throws CorruptIndexException if the index is corrupt
* @throws IOException if there is a low-level IO error
*/
@Override
public synchronized IndexReader reopen() throws CorruptIndexException, IOException {
return doReopen(false);
}
/**
* Clones the subreaders.
* (see {@link IndexReader#clone()}).
* <br>
* <p>
* If subreaders are shared, then the reference count of those
* readers is increased to ensure that the subreaders remain open
* until the last referring reader is closed.
*/
@Override
public synchronized Object clone() {
try {
return doReopen(true);
} catch (Exception ex) {
throw new RuntimeException(ex);
}
}
/**
* If clone is true then we clone each of the subreaders
* @param doClone
* @return New IndexReader, or same one (this) if
* reopen/clone is not necessary
* @throws CorruptIndexException
* @throws IOException
*/
protected IndexReader doReopen(boolean doClone) throws CorruptIndexException, IOException {
ensureOpen();
boolean reopened = false;
IndexReader[] newSubReaders = new IndexReader[subReaders.length];
boolean success = false;
try {
for (int i = 0; i < subReaders.length; i++) {
if (doClone)
newSubReaders[i] = (IndexReader) subReaders[i].clone();
else
newSubReaders[i] = subReaders[i].reopen();
// if at least one of the subreaders was updated we remember that
// and return a new MultiReader
if (newSubReaders[i] != subReaders[i]) {
reopened = true;
}
}
success = true;
} finally {
if (!success && reopened) {
for (int i = 0; i < newSubReaders.length; i++) {
if (newSubReaders[i] != subReaders[i]) {
try {
newSubReaders[i].close();
} catch (IOException ignore) {
// keep going - we want to clean up as much as possible
}
}
}
}
}
if (reopened) {
boolean[] newDecrefOnClose = new boolean[subReaders.length];
for (int i = 0; i < subReaders.length; i++) {
if (newSubReaders[i] == subReaders[i]) {
newSubReaders[i].incRef();
newDecrefOnClose[i] = true;
}
}
MultiReader mr = new MultiReader(newSubReaders);
mr.decrefOnClose = newDecrefOnClose;
return mr;
} else {
return this;
}
}
@Override
public TermFreqVector[] getTermFreqVectors(int n) throws IOException {
ensureOpen();
int i = readerIndex(n); // find segment num
return subReaders[i].getTermFreqVectors(n - starts[i]); // dispatch to segment
}
@Override
public TermFreqVector getTermFreqVector(int n, String field)
throws IOException {
ensureOpen();
int i = readerIndex(n); // find segment num
return subReaders[i].getTermFreqVector(n - starts[i], field);
}
@Override
public void getTermFreqVector(int docNumber, String field, TermVectorMapper mapper) throws IOException {
ensureOpen();
int i = readerIndex(docNumber); // find segment num
subReaders[i].getTermFreqVector(docNumber - starts[i], field, mapper);
}
@Override
public void getTermFreqVector(int docNumber, TermVectorMapper mapper) throws IOException {
ensureOpen();
int i = readerIndex(docNumber); // find segment num
subReaders[i].getTermFreqVector(docNumber - starts[i], mapper);
}
@Override
public boolean isOptimized() {
return false;
}
@Override
public int numDocs() {
// Don't call ensureOpen() here (it could affect performance)
// NOTE: multiple threads may wind up init'ing
// numDocs... but that's harmless
if (numDocs == -1) { // check cache
int n = 0; // cache miss--recompute
for (int i = 0; i < subReaders.length; i++)
n += subReaders[i].numDocs(); // sum from readers
numDocs = n;
}
return numDocs;
}
@Override
public int maxDoc() {
// Don't call ensureOpen() here (it could affect performance)
return maxDoc;
}
// inherit javadoc
@Override
public Document document(int n, FieldSelector fieldSelector) throws CorruptIndexException, IOException {
ensureOpen();
int i = readerIndex(n); // find segment num
return subReaders[i].document(n - starts[i], fieldSelector); // dispatch to segment reader
}
@Override
public boolean isDeleted(int n) {
// Don't call ensureOpen() here (it could affect performance)
int i = readerIndex(n); // find segment num
return subReaders[i].isDeleted(n - starts[i]); // dispatch to segment reader
}
@Override
public boolean hasDeletions() {
// Don't call ensureOpen() here (it could affect performance)
return hasDeletions;
}
@Override
protected void doDelete(int n) throws CorruptIndexException, IOException {
numDocs = -1; // invalidate cache
int i = readerIndex(n); // find segment num
subReaders[i].deleteDocument(n - starts[i]); // dispatch to segment reader
hasDeletions = true;
}
@Override
protected void doUndeleteAll() throws CorruptIndexException, IOException {
for (int i = 0; i < subReaders.length; i++)
subReaders[i].undeleteAll();
hasDeletions = false;
numDocs = -1; // invalidate cache
}
private int readerIndex(int n) { // find reader for doc n:
return DirectoryReader.readerIndex(n, this.starts, this.subReaders.length);
}
@Override
public boolean hasNorms(String field) throws IOException {
ensureOpen();
for (int i = 0; i < subReaders.length; i++) {
if (subReaders[i].hasNorms(field)) return true;
}
return false;
}
@Override
public synchronized byte[] norms(String field) throws IOException {
ensureOpen();
byte[] bytes = normsCache.get(field);
if (bytes != null)
return bytes; // cache hit
if (!hasNorms(field))
return null;
bytes = new byte[maxDoc()];
for (int i = 0; i < subReaders.length; i++)
subReaders[i].norms(field, bytes, starts[i]);
normsCache.put(field, bytes); // update cache
return bytes;
}
@Override
public synchronized void norms(String field, byte[] result, int offset)
throws IOException {
ensureOpen();
byte[] bytes = normsCache.get(field);
for (int i = 0; i < subReaders.length; i++) // read from segments
subReaders[i].norms(field, result, offset + starts[i]);
if (bytes==null && !hasNorms(field)) {
Arrays.fill(result, offset, result.length, DefaultSimilarity.encodeNorm(1.0f));
} else if (bytes != null) { // cache hit
System.arraycopy(bytes, 0, result, offset, maxDoc());
} else {
for (int i = 0; i < subReaders.length; i++) { // read from segments
subReaders[i].norms(field, result, offset + starts[i]);
}
}
}
@Override
protected void doSetNorm(int n, String field, byte value)
throws CorruptIndexException, IOException {
synchronized (normsCache) {
normsCache.remove(field); // clear cache
}
int i = readerIndex(n); // find segment num
subReaders[i].setNorm(n-starts[i], field, value); // dispatch
}
@Override
public TermEnum terms() throws IOException {
ensureOpen();
return new MultiTermEnum(this, subReaders, starts, null);
}
@Override
public TermEnum terms(Term term) throws IOException {
ensureOpen();
return new MultiTermEnum(this, subReaders, starts, term);
}
@Override
public int docFreq(Term t) throws IOException {
ensureOpen();
int total = 0; // sum freqs in segments
for (int i = 0; i < subReaders.length; i++)
total += subReaders[i].docFreq(t);
return total;
}
@Override
public TermDocs termDocs() throws IOException {
ensureOpen();
return new MultiTermDocs(this, subReaders, starts);
}
@Override
public TermPositions termPositions() throws IOException {
ensureOpen();
return new MultiTermPositions(this, subReaders, starts);
}
@Override
protected void doCommit(Map<String,String> commitUserData) throws IOException {
for (int i = 0; i < subReaders.length; i++)
subReaders[i].commit(commitUserData);
}
@Override
protected synchronized void doClose() throws IOException {
for (int i = 0; i < subReaders.length; i++) {
if (decrefOnClose[i]) {
subReaders[i].decRef();
} else {
subReaders[i].close();
}
}
// NOTE: only needed in case someone had asked for
// FieldCache for top-level reader (which is generally
// not a good idea):
FieldCache.DEFAULT.purge(this);
}
@Override
public Collection<String> getFieldNames (IndexReader.FieldOption fieldNames) {
ensureOpen();
return DirectoryReader.getFieldNames(fieldNames, this.subReaders);
}
/**
* Checks recursively if all subreaders are up to date.
*/
@Override
public boolean isCurrent() throws CorruptIndexException, IOException {
for (int i = 0; i < subReaders.length; i++) {
if (!subReaders[i].isCurrent()) {
return false;
}
}
// all subreaders are up to date
return true;
}
/** Not implemented.
* @throws UnsupportedOperationException
*/
@Override
public long getVersion() {
throw new UnsupportedOperationException("MultiReader does not support this method.");
}
@Override
public IndexReader[] getSequentialSubReaders() {
return subReaders;
}
}