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.io.Reader;
import org.apache.lucene.util.LuceneTestCase;
import org.apache.lucene.analysis.Analyzer;
import org.apache.lucene.analysis.LowerCaseTokenizer;
import org.apache.lucene.analysis.Token;
import org.apache.lucene.analysis.TokenFilter;
import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.document.Document;
import org.apache.lucene.document.Field;
import org.apache.lucene.document.Field.Index;
import org.apache.lucene.document.Field.Store;
import org.apache.lucene.store.IndexInput;
import org.apache.lucene.store.RAMDirectory;
/**
* This testcase tests whether multi-level skipping is being used
* to reduce I/O while skipping through posting lists.
*
* Skipping in general is already covered by several other
* testcases.
*
*/
public class TestMultiLevelSkipList extends LuceneTestCase {
public void testSimpleSkip() throws IOException {
RAMDirectory dir = new RAMDirectory();
IndexWriter writer = new IndexWriter(dir, new PayloadAnalyzer(), true,
IndexWriter.MaxFieldLength.LIMITED);
Term term = new Term("test", "a");
for (int i = 0; i < 5000; i++) {
Document d1 = new Document();
d1.add(new Field(term.field(), term.text(), Store.NO, Index.ANALYZED));
writer.addDocument(d1);
}
writer.flush();
writer.optimize();
writer.close();
IndexReader reader = IndexReader.open(dir);
SegmentTermPositions tp = (SegmentTermPositions) reader.termPositions();
tp.freqStream = new CountingStream(tp.freqStream);
for (int i = 0; i < 2; i++) {
counter = 0;
tp.seek(term);
checkSkipTo(tp, 14, 185); // no skips
checkSkipTo(tp, 17, 190); // one skip on level 0
checkSkipTo(tp, 287, 200); // one skip on level 1, two on level 0
// this test would fail if we had only one skip level,
// because than more bytes would be read from the freqStream
checkSkipTo(tp, 4800, 250);// one skip on level 2
}
}
public void checkSkipTo(TermPositions tp, int target, int maxCounter) throws IOException {
tp.skipTo(target);
if (maxCounter < counter) {
fail("Too many bytes read: " + counter);
}
assertEquals("Wrong document " + tp.doc() + " after skipTo target " + target, target, tp.doc());
assertEquals("Frequency is not 1: " + tp.freq(), 1,tp.freq());
tp.nextPosition();
byte[] b = new byte[1];
tp.getPayload(b, 0);
assertEquals("Wrong payload for the target " + target + ": " + b[0], (byte) target, b[0]);
}
private static class PayloadAnalyzer extends Analyzer {
public TokenStream tokenStream(String fieldName, Reader reader) {
return new PayloadFilter(new LowerCaseTokenizer(reader));
}
}
private static class PayloadFilter extends TokenFilter {
static int count = 0;
protected PayloadFilter(TokenStream input) {
super(input);
}
public Token next(final Token reusableToken) throws IOException {
assert reusableToken != null;
Token nextToken = input.next(reusableToken);
if (nextToken != null) {
nextToken.setPayload(new Payload(new byte[] { (byte) count++ }));
}
return nextToken;
}
}
private int counter = 0;
// Simply extends IndexInput in a way that we are able to count the number
// of bytes read
class CountingStream extends IndexInput {
private IndexInput input;
CountingStream(IndexInput input) {
this.input = input;
}
public byte readByte() throws IOException {
TestMultiLevelSkipList.this.counter++;
return this.input.readByte();
}
public void readBytes(byte[] b, int offset, int len) throws IOException {
TestMultiLevelSkipList.this.counter += len;
this.input.readBytes(b, offset, len);
}
public void close() throws IOException {
this.input.close();
}
public long getFilePointer() {
return this.input.getFilePointer();
}
public void seek(long pos) throws IOException {
this.input.seek(pos);
}
public long length() {
return this.input.length();
}
public Object clone() {
return new CountingStream((IndexInput) this.input.clone());
}
}
}