+++ /dev/null
-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.Arrays;
-
-import org.apache.lucene.store.IndexOutput;
-
-
-/**
- * Implements the skip list writer for the default posting list format
- * that stores positions and payloads.
- *
- */
-class DefaultSkipListWriter extends MultiLevelSkipListWriter {
- private int[] lastSkipDoc;
- private int[] lastSkipPayloadLength;
- private long[] lastSkipFreqPointer;
- private long[] lastSkipProxPointer;
-
- private IndexOutput freqOutput;
- private IndexOutput proxOutput;
-
- private int curDoc;
- private boolean curStorePayloads;
- private int curPayloadLength;
- private long curFreqPointer;
- private long curProxPointer;
-
- DefaultSkipListWriter(int skipInterval, int numberOfSkipLevels, int docCount, IndexOutput freqOutput, IndexOutput proxOutput) {
- super(skipInterval, numberOfSkipLevels, docCount);
- this.freqOutput = freqOutput;
- this.proxOutput = proxOutput;
-
- lastSkipDoc = new int[numberOfSkipLevels];
- lastSkipPayloadLength = new int[numberOfSkipLevels];
- lastSkipFreqPointer = new long[numberOfSkipLevels];
- lastSkipProxPointer = new long[numberOfSkipLevels];
- }
-
- void setFreqOutput(IndexOutput freqOutput) {
- this.freqOutput = freqOutput;
- }
-
- void setProxOutput(IndexOutput proxOutput) {
- this.proxOutput = proxOutput;
- }
-
- /**
- * Sets the values for the current skip data.
- */
- void setSkipData(int doc, boolean storePayloads, int payloadLength) {
- this.curDoc = doc;
- this.curStorePayloads = storePayloads;
- this.curPayloadLength = payloadLength;
- this.curFreqPointer = freqOutput.getFilePointer();
- if (proxOutput != null)
- this.curProxPointer = proxOutput.getFilePointer();
- }
-
- @Override
- protected void resetSkip() {
- super.resetSkip();
- Arrays.fill(lastSkipDoc, 0);
- Arrays.fill(lastSkipPayloadLength, -1); // we don't have to write the first length in the skip list
- Arrays.fill(lastSkipFreqPointer, freqOutput.getFilePointer());
- if (proxOutput != null)
- Arrays.fill(lastSkipProxPointer, proxOutput.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
- 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 * 2);
- } 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 * 2 + 1);
- skipBuffer.writeVInt(curPayloadLength);
- lastSkipPayloadLength[level] = curPayloadLength;
- }
- } else {
- // current field does not store payloads
- skipBuffer.writeVInt(curDoc - lastSkipDoc[level]);
- }
- skipBuffer.writeVInt((int) (curFreqPointer - lastSkipFreqPointer[level]));
- skipBuffer.writeVInt((int) (curProxPointer - lastSkipProxPointer[level]));
-
- lastSkipDoc[level] = curDoc;
- //System.out.println("write doc at level " + level + ": " + curDoc);
-
- lastSkipFreqPointer[level] = curFreqPointer;
- lastSkipProxPointer[level] = curProxPointer;
- }
-
-}
fnp / pylucene.git / blobdiff