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 org.apache.lucene.store.IndexOutput;
import org.apache.lucene.store.Directory;
import org.apache.lucene.util.UnicodeUtil;
/** This stores a monotonically increasing set of <Term, TermInfo> pairs in a
Directory. A TermInfos can be written once, in order. */
final class TermInfosWriter {
/** The file format version, a negative number. */
public static final int FORMAT = -3;
// Changed strings to true utf8 with length-in-bytes not
// length-in-chars
public static final int FORMAT_VERSION_UTF8_LENGTH_IN_BYTES = -4;
// NOTE: always change this if you switch to a new format!
public static final int FORMAT_CURRENT = FORMAT_VERSION_UTF8_LENGTH_IN_BYTES;
private FieldInfos fieldInfos;
private IndexOutput output;
private TermInfo lastTi = new TermInfo();
private long size;
// TODO: the default values for these two parameters should be settable from
// IndexWriter. However, once that's done, folks will start setting them to
// ridiculous values and complaining that things don't work well, as with
// mergeFactor. So, let's wait until a number of folks find that alternate
// values work better. Note that both of these values are stored in the
// segment, so that it's safe to change these w/o rebuilding all indexes.
/** Expert: The fraction of terms in the "dictionary" which should be stored
* in RAM. Smaller values use more memory, but make searching slightly
* faster, while larger values use less memory and make searching slightly
* slower. Searching is typically not dominated by dictionary lookup, so
* tweaking this is rarely useful.*/
int indexInterval = 128;
/** Expert: The fraction of {@link TermDocs} entries stored in skip tables,
* used to accelerate {@link TermDocs#skipTo(int)}. Larger values result in
* smaller indexes, greater acceleration, but fewer accelerable cases, while
* smaller values result in bigger indexes, less acceleration and more
* accelerable cases. More detailed experiments would be useful here. */
int skipInterval = 16;
/** Expert: The maximum number of skip levels. Smaller values result in
* slightly smaller indexes, but slower skipping in big posting lists.
*/
int maxSkipLevels = 10;
private long lastIndexPointer;
private boolean isIndex;
private byte[] lastTermBytes = new byte[10];
private int lastTermBytesLength = 0;
private int lastFieldNumber = -1;
private TermInfosWriter other;
private UnicodeUtil.UTF8Result utf8Result = new UnicodeUtil.UTF8Result();
TermInfosWriter(Directory directory, String segment, FieldInfos fis,
int interval)
throws IOException {
initialize(directory, segment, fis, interval, false);
other = new TermInfosWriter(directory, segment, fis, interval, true);
other.other = this;
}
private TermInfosWriter(Directory directory, String segment, FieldInfos fis,
int interval, boolean isIndex) throws IOException {
initialize(directory, segment, fis, interval, isIndex);
}
private void initialize(Directory directory, String segment, FieldInfos fis,
int interval, boolean isi) throws IOException {
indexInterval = interval;
fieldInfos = fis;
isIndex = isi;
output = directory.createOutput(segment + (isIndex ? ".tii" : ".tis"));
output.writeInt(FORMAT_CURRENT); // write format
output.writeLong(0); // leave space for size
output.writeInt(indexInterval); // write indexInterval
output.writeInt(skipInterval); // write skipInterval
output.writeInt(maxSkipLevels); // write maxSkipLevels
assert initUTF16Results();
}
void add(Term term, TermInfo ti) throws IOException {
UnicodeUtil.UTF16toUTF8(term.text, 0, term.text.length(), utf8Result);
add(fieldInfos.fieldNumber(term.field), utf8Result.result, utf8Result.length, ti);
}
// Currently used only by assert statements
UnicodeUtil.UTF16Result utf16Result1;
UnicodeUtil.UTF16Result utf16Result2;
// Currently used only by assert statements
private boolean initUTF16Results() {
utf16Result1 = new UnicodeUtil.UTF16Result();
utf16Result2 = new UnicodeUtil.UTF16Result();
return true;
}
// Currently used only by assert statement
private int compareToLastTerm(int fieldNumber, byte[] termBytes, int termBytesLength) {
if (lastFieldNumber != fieldNumber) {
final int cmp = fieldInfos.fieldName(lastFieldNumber).compareTo(fieldInfos.fieldName(fieldNumber));
// If there is a field named "" (empty string) then we
// will get 0 on this comparison, yet, it's "OK". But
// it's not OK if two different field numbers map to
// the same name.
if (cmp != 0 || lastFieldNumber != -1)
return cmp;
}
UnicodeUtil.UTF8toUTF16(lastTermBytes, 0, lastTermBytesLength, utf16Result1);
UnicodeUtil.UTF8toUTF16(termBytes, 0, termBytesLength, utf16Result2);
final int len;
if (utf16Result1.length < utf16Result2.length)
len = utf16Result1.length;
else
len = utf16Result2.length;
for(int i=0;i<len;i++) {
final char ch1 = utf16Result1.result[i];
final char ch2 = utf16Result2.result[i];
if (ch1 != ch2)
return ch1-ch2;
}
return utf16Result1.length - utf16Result2.length;
}
/** Adds a new <<fieldNumber, termBytes>, TermInfo> pair to the set.
Term must be lexicographically greater than all previous Terms added.
TermInfo pointers must be positive and greater than all previous.*/
void add(int fieldNumber, byte[] termBytes, int termBytesLength, TermInfo ti)
throws IOException {
assert compareToLastTerm(fieldNumber, termBytes, termBytesLength) < 0 ||
(isIndex && termBytesLength == 0 && lastTermBytesLength == 0) :
"Terms are out of order: field=" + fieldInfos.fieldName(fieldNumber) + " (number " + fieldNumber + ")" +
" lastField=" + fieldInfos.fieldName(lastFieldNumber) + " (number " + lastFieldNumber + ")" +
" text=" + new String(termBytes, 0, termBytesLength, "UTF-8") + " lastText=" + new String(lastTermBytes, 0, lastTermBytesLength, "UTF-8");
assert ti.freqPointer >= lastTi.freqPointer: "freqPointer out of order (" + ti.freqPointer + " < " + lastTi.freqPointer + ")";
assert ti.proxPointer >= lastTi.proxPointer: "proxPointer out of order (" + ti.proxPointer + " < " + lastTi.proxPointer + ")";
if (!isIndex && size % indexInterval == 0)
other.add(lastFieldNumber, lastTermBytes, lastTermBytesLength, lastTi); // add an index term
writeTerm(fieldNumber, termBytes, termBytesLength); // write term
output.writeVInt(ti.docFreq); // write doc freq
output.writeVLong(ti.freqPointer - lastTi.freqPointer); // write pointers
output.writeVLong(ti.proxPointer - lastTi.proxPointer);
if (ti.docFreq >= skipInterval) {
output.writeVInt(ti.skipOffset);
}
if (isIndex) {
output.writeVLong(other.output.getFilePointer() - lastIndexPointer);
lastIndexPointer = other.output.getFilePointer(); // write pointer
}
lastFieldNumber = fieldNumber;
lastTi.set(ti);
size++;
}
private void writeTerm(int fieldNumber, byte[] termBytes, int termBytesLength)
throws IOException {
// TODO: UTF16toUTF8 could tell us this prefix
// Compute prefix in common with last term:
int start = 0;
final int limit = termBytesLength < lastTermBytesLength ? termBytesLength : lastTermBytesLength;
while(start < limit) {
if (termBytes[start] != lastTermBytes[start])
break;
start++;
}
final int length = termBytesLength - start;
output.writeVInt(start); // write shared prefix length
output.writeVInt(length); // write delta length
output.writeBytes(termBytes, start, length); // write delta bytes
output.writeVInt(fieldNumber); // write field num
if (lastTermBytes.length < termBytesLength) {
byte[] newArray = new byte[(int) (termBytesLength*1.5)];
System.arraycopy(lastTermBytes, 0, newArray, 0, start);
lastTermBytes = newArray;
}
System.arraycopy(termBytes, start, lastTermBytes, start, length);
lastTermBytesLength = termBytesLength;
}
/** Called to complete TermInfos creation. */
void close() throws IOException {
output.seek(4); // write size after format
output.writeLong(size);
output.close();
if (!isIndex)
other.close();
}
}