package org.apache.lucene.codecs.blockterms;
/*
* 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.io.FileOutputStream; // for toDot
import java.io.OutputStreamWriter; // for toDot
import java.io.Writer; // for toDot
import java.util.HashMap;
import org.apache.lucene.codecs.CodecUtil;
import org.apache.lucene.index.CorruptIndexException;
import org.apache.lucene.index.FieldInfo;
import org.apache.lucene.index.FieldInfos;
import org.apache.lucene.index.IndexFileNames;
import org.apache.lucene.store.Directory;
import org.apache.lucene.store.IOContext;
import org.apache.lucene.store.IndexInput;
import org.apache.lucene.util.BytesRef;
import org.apache.lucene.util.IntsRef;
import org.apache.lucene.util.fst.Builder;
import org.apache.lucene.util.fst.BytesRefFSTEnum;
import org.apache.lucene.util.fst.FST;
import org.apache.lucene.util.fst.PositiveIntOutputs;
import org.apache.lucene.util.fst.Util; // for toDot
/** See {@link VariableGapTermsIndexWriter}
*
* @lucene.experimental */
public class VariableGapTermsIndexReader extends TermsIndexReaderBase {
private final PositiveIntOutputs fstOutputs = PositiveIntOutputs.getSingleton(true);
private int indexDivisor;
// Closed if indexLoaded is true:
private IndexInput in;
private volatile boolean indexLoaded;
final HashMap<FieldInfo,FieldIndexData> fields = new HashMap<FieldInfo,FieldIndexData>();
// start of the field info data
protected long dirOffset;
final String segment;
public VariableGapTermsIndexReader(Directory dir, FieldInfos fieldInfos, String segment, int indexDivisor, String segmentSuffix, IOContext context)
throws IOException {
in = dir.openInput(IndexFileNames.segmentFileName(segment, segmentSuffix, VariableGapTermsIndexWriter.TERMS_INDEX_EXTENSION), new IOContext(context, true));
this.segment = segment;
boolean success = false;
assert indexDivisor == -1 || indexDivisor > 0;
try {
readHeader(in);
this.indexDivisor = indexDivisor;
seekDir(in, dirOffset);
// Read directory
final int numFields = in.readVInt();
if (numFields < 0) {
throw new CorruptIndexException("invalid numFields: " + numFields + " (resource=" + in + ")");
}
for(int i=0;i<numFields;i++) {
final int field = in.readVInt();
final long indexStart = in.readVLong();
final FieldInfo fieldInfo = fieldInfos.fieldInfo(field);
FieldIndexData previous = fields.put(fieldInfo, new FieldIndexData(fieldInfo, indexStart));
if (previous != null) {
throw new CorruptIndexException("duplicate field: " + fieldInfo.name + " (resource=" + in + ")");
}
}
success = true;
} finally {
if (indexDivisor > 0) {
in.close();
in = null;
if (success) {
indexLoaded = true;
}
}
}
}
@Override
public int getDivisor() {
return indexDivisor;
}
protected void readHeader(IndexInput input) throws IOException {
CodecUtil.checkHeader(input, VariableGapTermsIndexWriter.CODEC_NAME,
VariableGapTermsIndexWriter.VERSION_START, VariableGapTermsIndexWriter.VERSION_START);
dirOffset = input.readLong();
}
private static class IndexEnum extends FieldIndexEnum {
private final BytesRefFSTEnum<Long> fstEnum;
private BytesRefFSTEnum.InputOutput<Long> current;
public IndexEnum(FST<Long> fst) {
fstEnum = new BytesRefFSTEnum<Long>(fst);
}
@Override
public BytesRef term() {
if (current == null) {
return null;
} else {
return current.input;
}
}
@Override
public long seek(BytesRef target) throws IOException {
//System.out.println("VGR: seek field=" + fieldInfo.name + " target=" + target);
current = fstEnum.seekFloor(target);
//System.out.println(" got input=" + current.input + " output=" + current.output);
return current.output;
}
@Override
public long next() throws IOException {
//System.out.println("VGR: next field=" + fieldInfo.name);
current = fstEnum.next();
if (current == null) {
//System.out.println(" eof");
return -1;
} else {
return current.output;
}
}
@Override
public long ord() {
throw new UnsupportedOperationException();
}
@Override
public long seek(long ord) {
throw new UnsupportedOperationException();
}
}
@Override
public boolean supportsOrd() {
return false;
}
private final class FieldIndexData {
private final long indexStart;
// Set only if terms index is loaded:
private volatile FST<Long> fst;
public FieldIndexData(FieldInfo fieldInfo, long indexStart) throws IOException {
this.indexStart = indexStart;
if (indexDivisor > 0) {
loadTermsIndex();
}
}
private void loadTermsIndex() throws IOException {
if (fst == null) {
IndexInput clone = in.clone();
clone.seek(indexStart);
fst = new FST<Long>(clone, fstOutputs);
clone.close();
/*
final String dotFileName = segment + "_" + fieldInfo.name + ".dot";
Writer w = new OutputStreamWriter(new FileOutputStream(dotFileName));
Util.toDot(fst, w, false, false);
System.out.println("FST INDEX: SAVED to " + dotFileName);
w.close();
*/
if (indexDivisor > 1) {
// subsample
final IntsRef scratchIntsRef = new IntsRef();
final PositiveIntOutputs outputs = PositiveIntOutputs.getSingleton(true);
final Builder<Long> builder = new Builder<Long>(FST.INPUT_TYPE.BYTE1, outputs);
final BytesRefFSTEnum<Long> fstEnum = new BytesRefFSTEnum<Long>(fst);
BytesRefFSTEnum.InputOutput<Long> result;
int count = indexDivisor;
while((result = fstEnum.next()) != null) {
if (count == indexDivisor) {
builder.add(Util.toIntsRef(result.input, scratchIntsRef), result.output);
count = 0;
}
count++;
}
fst = builder.finish();
}
}
}
}
@Override
public FieldIndexEnum getFieldEnum(FieldInfo fieldInfo) {
final FieldIndexData fieldData = fields.get(fieldInfo);
if (fieldData.fst == null) {
return null;
} else {
return new IndexEnum(fieldData.fst);
}
}
@Override
public void close() throws IOException {
if (in != null && !indexLoaded) {
in.close();
}
}
protected void seekDir(IndexInput input, long dirOffset) throws IOException {
input.seek(dirOffset);
}
}