Review

finding-12

/mubench/checkouts/lucene/1918/build/src/java/org/apache/lucene/index/DirectoryReader.java

DirectoryReader(Directory, SegmentInfos, SegmentReader[], int[], Map, boolean, boolean, int)

class DirectoryReader {
  /** This constructor is only used for {@link #reopen()} */
  DirectoryReader(Directory directory, SegmentInfos infos, SegmentReader[] oldReaders, int[] oldStarts,
                  Map oldNormsCache, boolean readOnly, boolean doClone, int termInfosIndexDivisor) throws IOException {
    this.directory = directory;
    this.readOnly = readOnly;
    this.segmentInfos = infos;
    this.termInfosIndexDivisor = termInfosIndexDivisor;
    if (!readOnly) {
      // We assume that this segments_N was previously
      // properly sync'd:
      synced.addAll(infos.files(directory, true));
    }
    // we put the old SegmentReaders in a map, that allows us
    // to lookup a reader using its segment name
    Map segmentReaders = new HashMap();
    if (oldReaders != null) {
      // create a Map SegmentName->SegmentReader
      for (int i = 0; i < oldReaders.length; i++) {
        segmentReaders.put(oldReaders[i].getSegmentName(), new Integer(i));
      }
    }
    
    SegmentReader[] newReaders = new SegmentReader[infos.size()];
    
    // remember which readers are shared between the old and the re-opened
    // DirectoryReader - we have to incRef those readers
    boolean[] readerShared = new boolean[infos.size()];
    
    for (int i = infos.size() - 1; i>=0; i--) {
      // find SegmentReader for this segment
      Integer oldReaderIndex = (Integer) segmentReaders.get(infos.info(i).name);
      if (oldReaderIndex == null) {
        // this is a new segment, no old SegmentReader can be reused
        newReaders[i] = null;
      } else {
        // there is an old reader for this segment - we'll try to reopen it
        newReaders[i] = oldReaders[oldReaderIndex.intValue()];
      }
      boolean success = false;
      try {
        SegmentReader newReader;
        if (newReaders[i] == null || infos.info(i).getUseCompoundFile() != newReaders[i].getSegmentInfo().getUseCompoundFile()) {
          // We should never see a totally new segment during cloning
          assert !doClone;
          // this is a new reader; in case we hit an exception we can close it safely
          newReader = SegmentReader.get(readOnly, infos.info(i), termInfosIndexDivisor);
        } else {
          newReader = newReaders[i].reopenSegment(infos.info(i), doClone, readOnly);
        }
        if (newReader == newReaders[i]) {
          // this reader will be shared between the old and the new one,
          // so we must incRef it
          readerShared[i] = true;
          newReader.incRef();
        } else {
          readerShared[i] = false;
          newReaders[i] = newReader;
        }
        success = true;
      } finally {
        if (!success) {
          for (i++; i < infos.size(); i++) {
            if (newReaders[i] != null) {
              try {
                if (!readerShared[i]) {
                  // this is a new subReader that is not used by the old one,
                  // we can close it
                  newReaders[i].close();
                } else {
                  // this subReader is also used by the old reader, so instead
                  // closing we must decRef it
                  newReaders[i].decRef();
                }
              } catch (IOException ignore) {
                // keep going - we want to clean up as much as possible
              }
            }
          }
        }
      }
    }    
    
    // initialize the readers to calculate maxDoc before we try to reuse the old normsCache
    initialize(newReaders);
    
    // try to copy unchanged norms from the old normsCache to the new one
    if (oldNormsCache != null) {
      Iterator it = oldNormsCache.entrySet().iterator();
      while (it.hasNext()) {
        Map.Entry entry = (Map.Entry) it.next();
        String field = (String) entry.getKey();
        if (!hasNorms(field)) {
          continue;
        }
        byte[] oldBytes = (byte[]) entry.getValue();
        byte[] bytes = new byte[maxDoc()];
        for (int i = 0; i < subReaders.length; i++) {
          Integer oldReaderIndex = ((Integer) segmentReaders.get(subReaders[i].getSegmentName()));
          // this SegmentReader was not re-opened, we can copy all of its norms 
          if (oldReaderIndex != null &&
               (oldReaders[oldReaderIndex.intValue()] == subReaders[i] 
                 || oldReaders[oldReaderIndex.intValue()].norms.get(field) == subReaders[i].norms.get(field))) {
            // we don't have to synchronize here: either this constructor is called from a SegmentReader,
            // in which case no old norms cache is present, or it is called from MultiReader.reopen(),
            // which is synchronized
            System.arraycopy(oldBytes, oldStarts[oldReaderIndex.intValue()], bytes, starts[i], starts[i+1] - starts[i]);
          } else {
            subReaders[i].norms(field, bytes, starts[i]);
          }
        }
        normsCache.put(field, bytes);      // update cache
      }
    }
  }
}