| package org.apache.lucene.codecs.sep; |
| |
| /* |
| * 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 org.apache.lucene.store.IndexOutput; |
| import org.apache.lucene.codecs.MultiLevelSkipListWriter; |
| import org.apache.lucene.index.FieldInfo.IndexOptions; |
| |
| // TODO: -- skip data should somehow be more local to the |
| // particular stream (doc, freq, pos, payload) |
| |
| /** |
| * Implements the skip list writer for the default posting list format |
| * that stores positions and payloads. |
| * |
| * @lucene.experimental |
| */ |
| class SepSkipListWriter extends MultiLevelSkipListWriter { |
| private int[] lastSkipDoc; |
| private int[] lastSkipPayloadLength; |
| private long[] lastSkipPayloadPointer; |
| |
| private IntIndexOutput.Index[] docIndex; |
| private IntIndexOutput.Index[] freqIndex; |
| private IntIndexOutput.Index[] posIndex; |
| |
| private IntIndexOutput freqOutput; |
| // TODO: -- private again |
| IntIndexOutput posOutput; |
| // TODO: -- private again |
| IndexOutput payloadOutput; |
| |
| private int curDoc; |
| private boolean curStorePayloads; |
| private int curPayloadLength; |
| private long curPayloadPointer; |
| |
| SepSkipListWriter(int skipInterval, int numberOfSkipLevels, int docCount, |
| IntIndexOutput freqOutput, |
| IntIndexOutput docOutput, |
| IntIndexOutput posOutput, |
| IndexOutput payloadOutput) |
| throws IOException { |
| super(skipInterval, numberOfSkipLevels, docCount); |
| |
| this.freqOutput = freqOutput; |
| this.posOutput = posOutput; |
| this.payloadOutput = payloadOutput; |
| |
| lastSkipDoc = new int[numberOfSkipLevels]; |
| lastSkipPayloadLength = new int[numberOfSkipLevels]; |
| // TODO: -- also cutover normal IndexOutput to use getIndex()? |
| lastSkipPayloadPointer = new long[numberOfSkipLevels]; |
| |
| freqIndex = new IntIndexOutput.Index[numberOfSkipLevels]; |
| docIndex = new IntIndexOutput.Index[numberOfSkipLevels]; |
| posIndex = new IntIndexOutput.Index[numberOfSkipLevels]; |
| |
| for(int i=0;i<numberOfSkipLevels;i++) { |
| if (freqOutput != null) { |
| freqIndex[i] = freqOutput.index(); |
| } |
| docIndex[i] = docOutput.index(); |
| if (posOutput != null) { |
| posIndex[i] = posOutput.index(); |
| } |
| } |
| } |
| |
| IndexOptions indexOptions; |
| |
| void setIndexOptions(IndexOptions v) { |
| indexOptions = v; |
| } |
| |
| void setPosOutput(IntIndexOutput posOutput) throws IOException { |
| this.posOutput = posOutput; |
| for(int i=0;i<numberOfSkipLevels;i++) { |
| posIndex[i] = posOutput.index(); |
| } |
| } |
| |
| void setPayloadOutput(IndexOutput payloadOutput) { |
| this.payloadOutput = payloadOutput; |
| } |
| |
| /** |
| * Sets the values for the current skip data. |
| */ |
| // Called @ every index interval (every 128th (by default) |
| // doc) |
| void setSkipData(int doc, boolean storePayloads, int payloadLength) { |
| this.curDoc = doc; |
| this.curStorePayloads = storePayloads; |
| this.curPayloadLength = payloadLength; |
| if (payloadOutput != null) { |
| this.curPayloadPointer = payloadOutput.getFilePointer(); |
| } |
| } |
| |
| // Called @ start of new term |
| protected void resetSkip(IntIndexOutput.Index topDocIndex, IntIndexOutput.Index topFreqIndex, IntIndexOutput.Index topPosIndex) |
| throws IOException { |
| super.resetSkip(); |
| |
| Arrays.fill(lastSkipDoc, 0); |
| Arrays.fill(lastSkipPayloadLength, -1); // we don't have to write the first length in the skip list |
| for(int i=0;i<numberOfSkipLevels;i++) { |
| docIndex[i].copyFrom(topDocIndex, true); |
| if (freqOutput != null) { |
| freqIndex[i].copyFrom(topFreqIndex, true); |
| } |
| if (posOutput != null) { |
| posIndex[i].copyFrom(topPosIndex, true); |
| } |
| } |
| if (payloadOutput != null) { |
| Arrays.fill(lastSkipPayloadPointer, payloadOutput.getFilePointer()); |
| } |
| } |
| |
| @Override |
| protected void writeSkipData(int level, IndexOutput skipBuffer) throws IOException { |
| // To efficiently store payloads in the posting lists we do not store the length of |
| // every payload. Instead we omit the length for a payload if the previous payload had |
| // the same length. |
| // However, in order to support skipping the payload length at every skip point must be known. |
| // So we use the same length encoding that we use for the posting lists for the skip data as well: |
| // Case 1: current field does not store payloads |
| // SkipDatum --> DocSkip, FreqSkip, ProxSkip |
| // DocSkip,FreqSkip,ProxSkip --> VInt |
| // DocSkip records the document number before every SkipInterval th document in TermFreqs. |
| // Document numbers are represented as differences from the previous value in the sequence. |
| // Case 2: current field stores payloads |
| // SkipDatum --> DocSkip, PayloadLength?, FreqSkip,ProxSkip |
| // DocSkip,FreqSkip,ProxSkip --> VInt |
| // PayloadLength --> VInt |
| // In this case DocSkip/2 is the difference between |
| // the current and the previous value. If DocSkip |
| // is odd, then a PayloadLength encoded as VInt follows, |
| // if DocSkip is even, then it is assumed that the |
| // current payload length equals the length at the previous |
| // skip point |
| |
| assert indexOptions == IndexOptions.DOCS_AND_FREQS_AND_POSITIONS || !curStorePayloads; |
| |
| if (curStorePayloads) { |
| int delta = curDoc - lastSkipDoc[level]; |
| if (curPayloadLength == lastSkipPayloadLength[level]) { |
| // the current payload length equals the length at the previous skip point, |
| // so we don't store the length again |
| skipBuffer.writeVInt(delta << 1); |
| } else { |
| // the payload length is different from the previous one. We shift the DocSkip, |
| // set the lowest bit and store the current payload length as VInt. |
| skipBuffer.writeVInt(delta << 1 | 1); |
| skipBuffer.writeVInt(curPayloadLength); |
| lastSkipPayloadLength[level] = curPayloadLength; |
| } |
| } else { |
| // current field does not store payloads |
| skipBuffer.writeVInt(curDoc - lastSkipDoc[level]); |
| } |
| |
| if (indexOptions != IndexOptions.DOCS_ONLY) { |
| freqIndex[level].mark(); |
| freqIndex[level].write(skipBuffer, false); |
| } |
| docIndex[level].mark(); |
| docIndex[level].write(skipBuffer, false); |
| if (indexOptions == IndexOptions.DOCS_AND_FREQS_AND_POSITIONS) { |
| posIndex[level].mark(); |
| posIndex[level].write(skipBuffer, false); |
| if (curStorePayloads) { |
| skipBuffer.writeVInt((int) (curPayloadPointer - lastSkipPayloadPointer[level])); |
| } |
| } |
| |
| lastSkipDoc[level] = curDoc; |
| lastSkipPayloadPointer[level] = curPayloadPointer; |
| } |
| } |