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Lucene example source code file (NormsWriter.java)

This example Lucene source code file (NormsWriter.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Lucene tags/keywords

arraylist, fieldinfos, inverteddocendconsumer, io, ioexception, iterator, list, list, normswriter, normswriterperfield, normswriterperfield, normswriterperthread, override, override, string, util

The Lucene NormsWriter.java source code

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.Collection;
import java.util.Iterator;
import java.util.HashMap;
import java.util.Map;
import java.util.List;
import java.util.ArrayList;

import org.apache.lucene.store.IndexOutput;
import org.apache.lucene.search.Similarity;
import org.apache.lucene.util.IOUtils;

// TODO FI: norms could actually be stored as doc store

/** Writes norms.  Each thread X field accumulates the norms
 *  for the doc/fields it saw, then the flush method below
 *  merges all of these together into a single _X.nrm file.
 */

final class NormsWriter extends InvertedDocEndConsumer {

  private final byte defaultNorm = Similarity.getDefault().encodeNormValue(1.0f);
  private FieldInfos fieldInfos;
  @Override
  public InvertedDocEndConsumerPerThread addThread(DocInverterPerThread docInverterPerThread) {
    return new NormsWriterPerThread(docInverterPerThread, this);
  }

  @Override
  public void abort() {}

  // We only write the _X.nrm file at flush
  void files(Collection<String> files) {}

  @Override
  void setFieldInfos(FieldInfos fieldInfos) {
    this.fieldInfos = fieldInfos;
  }

  /** Produce _X.nrm if any document had a field with norms
   *  not disabled */
  @Override
  public void flush(Map<InvertedDocEndConsumerPerThread,Collection threadsAndFields, SegmentWriteState state) throws IOException {

    final Map<FieldInfo,List byField = new HashMap>();

    // Typically, each thread will have encountered the same
    // field.  So first we collate by field, ie, all
    // per-thread field instances that correspond to the
    // same FieldInfo
    for (final Map.Entry<InvertedDocEndConsumerPerThread,Collection entry : threadsAndFields.entrySet()) {
      final Collection<InvertedDocEndConsumerPerField> fields = entry.getValue();
      final Iterator<InvertedDocEndConsumerPerField> fieldsIt = fields.iterator();

      while (fieldsIt.hasNext()) {
        final NormsWriterPerField perField = (NormsWriterPerField) fieldsIt.next();

        if (perField.upto > 0) {
          // It has some norms
          List<NormsWriterPerField> l = byField.get(perField.fieldInfo);
          if (l == null) {
            l = new ArrayList<NormsWriterPerField>();
            byField.put(perField.fieldInfo, l);
          }
          l.add(perField);
        } else
          // Remove this field since we haven't seen it
          // since the previous flush
          fieldsIt.remove();
      }
    }

    final String normsFileName = IndexFileNames.segmentFileName(state.segmentName, IndexFileNames.NORMS_EXTENSION);
    IndexOutput normsOut = state.directory.createOutput(normsFileName);
    boolean success = false;
    try {
      normsOut.writeBytes(SegmentNorms.NORMS_HEADER, 0, SegmentNorms.NORMS_HEADER.length);

      final int numField = fieldInfos.size();

      int normCount = 0;

      for(int fieldNumber=0;fieldNumber<numField;fieldNumber++) {

        final FieldInfo fieldInfo = fieldInfos.fieldInfo(fieldNumber);

        List<NormsWriterPerField> toMerge = byField.get(fieldInfo);
        int upto = 0;
        if (toMerge != null) {

          final int numFields = toMerge.size();

          normCount++;

          final NormsWriterPerField[] fields = new NormsWriterPerField[numFields];
          int[] uptos = new int[numFields];

          for(int j=0;j<numFields;j++)
            fields[j] = toMerge.get(j);

          int numLeft = numFields;
              
          while(numLeft > 0) {

            assert uptos[0] < fields[0].docIDs.length : " uptos[0]=" + uptos[0] + " len=" + (fields[0].docIDs.length);

            int minLoc = 0;
            int minDocID = fields[0].docIDs[uptos[0]];

            for(int j=1;j<numLeft;j++) {
              final int docID = fields[j].docIDs[uptos[j]];
              if (docID < minDocID) {
                minDocID = docID;
                minLoc = j;
              }
            }

            assert minDocID < state.numDocs;

            // Fill hole
            for(;upto<minDocID;upto++)
              normsOut.writeByte(defaultNorm);

            normsOut.writeByte(fields[minLoc].norms[uptos[minLoc]]);
            (uptos[minLoc])++;
            upto++;

            if (uptos[minLoc] == fields[minLoc].upto) {
              fields[minLoc].reset();
              if (minLoc != numLeft-1) {
                fields[minLoc] = fields[numLeft-1];
                uptos[minLoc] = uptos[numLeft-1];
              }
              numLeft--;
            }
          }
          
          // Fill final hole with defaultNorm
          for(;upto<state.numDocs;upto++)
            normsOut.writeByte(defaultNorm);
        } else if (fieldInfo.isIndexed && !fieldInfo.omitNorms) {
          normCount++;
          // Fill entire field with default norm:
          for(;upto<state.numDocs;upto++)
            normsOut.writeByte(defaultNorm);
        }

        assert 4+normCount*state.numDocs == normsOut.getFilePointer() : ".nrm file size mismatch: expected=" + (4+normCount*state.numDocs) + " actual=" + normsOut.getFilePointer();
      }
      success = true;
    } finally {
      IOUtils.closeSafely(!success, normsOut);
    }
  }
}

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