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.ArrayList;
import java.util.Comparator;
import java.util.List;
import org.apache.lucene.util.BitUtil;
import org.apache.lucene.util.BytesRef;
import org.apache.lucene.util.PagedBytes.PagedBytesDataInput;
import org.apache.lucene.util.PagedBytes.PagedBytesDataOutput;
import org.apache.lucene.util.PagedBytes;
import org.apache.lucene.util.packed.GrowableWriter;
import org.apache.lucene.util.packed.PackedInts;
/**
* This stores a monotonically increasing set of <Term, TermInfo> pairs in an
* index segment. Pairs are accessed either by Term or by ordinal position the
* set. The Terms and TermInfo are actually serialized and stored into a byte
* array and pointers to the position of each are stored in a int array.
*/
class TermInfosReaderIndex implements TermInfoReaderIndexInterface{
private static final int MAX_PAGE_BITS = 18; // 256 KB block
private Term[] fields;
private int totalIndexInterval;
private Comparator<BytesRef> comparator = BytesRef.getUTF8SortedAsUTF16Comparator();
private final PagedBytesDataInput dataInput;
private final PackedInts.Reader indexToDataOffset;
private final int indexSize;
private final int skipInterval;
/**
* Loads the segment information at segment load time.
*
* @param indexEnum
* the term enum.
* @param indexDivisor
* the index divisor.
* @param tiiFileLength
* the size of the tii file, used to approximate the size of the
* buffer.
* @param totalIndexInterval
* the total index interval.
*/
TermInfosReaderIndex(SegmentTermEnum indexEnum, int indexDivisor, long tiiFileLength, int totalIndexInterval) throws IOException {
this.totalIndexInterval = totalIndexInterval;
indexSize = 1 + ((int) indexEnum.size - 1) / indexDivisor;
skipInterval = indexEnum.skipInterval;
// this is only an inital size, it will be GCed once the build is complete
long initialSize = (long) (tiiFileLength * 1.5) / indexDivisor;
PagedBytes dataPagedBytes = new PagedBytes(estimatePageBits(initialSize));
PagedBytesDataOutput dataOutput = dataPagedBytes.getDataOutput();
GrowableWriter indexToTerms = new GrowableWriter(4, indexSize, false);
String currentField = null;
List<String> fieldStrs = new ArrayList<String>();
int fieldCounter = -1;
for (int i = 0; indexEnum.next(); i++) {
Term term = indexEnum.term();
if (currentField != term.field) {
currentField = term.field;
fieldStrs.add(currentField);
fieldCounter++;
}
TermInfo termInfo = indexEnum.termInfo();
indexToTerms.set(i, dataOutput.getPosition());
dataOutput.writeVInt(fieldCounter);
dataOutput.writeString(term.text());
dataOutput.writeVInt(termInfo.docFreq);
if (termInfo.docFreq >= skipInterval) {
dataOutput.writeVInt(termInfo.skipOffset);
}
dataOutput.writeVLong(termInfo.freqPointer);
dataOutput.writeVLong(termInfo.proxPointer);
dataOutput.writeVLong(indexEnum.indexPointer);
for (int j = 1; j < indexDivisor; j++) {
if (!indexEnum.next()) {
break;
}
}
}
fields = new Term[fieldStrs.size()];
for (int i = 0; i < fields.length; i++) {
fields[i] = new Term(fieldStrs.get(i));
}
dataPagedBytes.freeze(true);
dataInput = dataPagedBytes.getDataInput();
indexToDataOffset = indexToTerms.getMutable();
}
private static int estimatePageBits(long estSize) {
return Math.max(Math.min(64 - BitUtil.nlz(estSize), MAX_PAGE_BITS), 4);
}
public void seekEnum(SegmentTermEnum enumerator, int indexOffset) throws IOException {
PagedBytesDataInput input = (PagedBytesDataInput) dataInput.clone();
input.setPosition(indexToDataOffset.get(indexOffset));
// read the term
int fieldId = input.readVInt();
Term field = fields[fieldId];
Term term = field.createTerm(input.readString());
// read the terminfo
TermInfo termInfo = new TermInfo();
termInfo.docFreq = input.readVInt();
if (termInfo.docFreq >= skipInterval) {
termInfo.skipOffset = input.readVInt();
} else {
termInfo.skipOffset = 0;
}
termInfo.freqPointer = input.readVLong();
termInfo.proxPointer = input.readVLong();
long pointer = input.readVLong();
// perform the seek
enumerator.seek(pointer, ((long) indexOffset * totalIndexInterval) - 1, term, termInfo);
}
/**
* Binary search for the given term.
*
* @param term
* the term to locate.
* @throws IOException
*/
public int getIndexOffset(Term term, BytesRef termBytesRef) throws IOException {
int lo = 0;
int hi = indexSize - 1;
PagedBytesDataInput input = (PagedBytesDataInput) dataInput.clone();
BytesRef scratch = new BytesRef();
while (hi >= lo) {
int mid = (lo + hi) >>> 1;
int delta = compareTo(term, termBytesRef, mid, input, scratch);
if (delta < 0)
hi = mid - 1;
else if (delta > 0)
lo = mid + 1;
else
return mid;
}
return hi;
}
/**
* Gets the term at the given position. For testing.
*
* @param termIndex
* the position to read the term from the index.
* @return the term.
* @throws IOException
*/
Term getTerm(int termIndex) throws IOException {
PagedBytesDataInput input = (PagedBytesDataInput) dataInput.clone();
input.setPosition(indexToDataOffset.get(termIndex));
// read the term
int fieldId = input.readVInt();
Term field = fields[fieldId];
return field.createTerm(input.readString());
}
/**
* Returns the number of terms.
*
* @return int.
*/
public int length() {
return indexSize;
}
/**
* The compares the given term against the term in the index specified by the
* term index. ie It returns negative N when term is less than index term;
*
* @param term
* the given term.
* @param termIndex
* the index of the of term to compare.
* @return int.
* @throws IOException
*/
public int compareTo(Term term, BytesRef termBytesRef, int termIndex) throws IOException {
return compareTo(term, termBytesRef, termIndex, (PagedBytesDataInput) dataInput.clone(), new BytesRef());
}
/**
* Compare the fields of the terms first, and if not equals return from
* compare. If equal compare terms.
*
* @param term
* the term to compare.
* @param termIndex
* the position of the term in the input to compare
* @param input
* the input buffer.
* @return int.
* @throws IOException
*/
private int compareTo(Term term, BytesRef termBytesRef, int termIndex, PagedBytesDataInput input, BytesRef reuse) throws IOException {
// if term field does not equal mid's field index, then compare fields
// else if they are equal, compare term's string values...
int c = compareField(term, termIndex, input);
if (c == 0) {
reuse.length = input.readVInt();
reuse.grow(reuse.length);
input.readBytes(reuse.bytes, 0, reuse.length);
return comparator.compare(termBytesRef, reuse);
}
return c;
}
/**
* Compares the fields before checking the text of the terms.
*
* @param term
* the given term.
* @param termIndex
* the term that exists in the data block.
* @param input
* the data block.
* @return int.
* @throws IOException
*/
private int compareField(Term term, int termIndex, PagedBytesDataInput input) throws IOException {
input.setPosition(indexToDataOffset.get(termIndex));
return term.field.compareTo(fields[input.readVInt()].field);
}
}