예제 #1
0
 /** encodes an entry (bytes+(contexts)+(payload)+weight) to the provided writer */
 protected void encode(
     ByteSequencesWriter writer,
     ByteArrayDataOutput output,
     byte[] buffer,
     BytesRef spare,
     BytesRef payload,
     Set<BytesRef> contexts,
     long weight)
     throws IOException {
   int requiredLength = spare.length + 8 + ((hasPayloads) ? 2 + payload.length : 0);
   if (hasContexts) {
     for (BytesRef ctx : contexts) {
       requiredLength += 2 + ctx.length;
     }
     requiredLength += 2; // for length of contexts
   }
   if (requiredLength >= buffer.length) {
     buffer = ArrayUtil.grow(buffer, requiredLength);
   }
   output.reset(buffer);
   output.writeBytes(spare.bytes, spare.offset, spare.length);
   if (hasContexts) {
     for (BytesRef ctx : contexts) {
       output.writeBytes(ctx.bytes, ctx.offset, ctx.length);
       output.writeShort((short) ctx.length);
     }
     output.writeShort((short) contexts.size());
   }
   if (hasPayloads) {
     output.writeBytes(payload.bytes, payload.offset, payload.length);
     output.writeShort((short) payload.length);
   }
   output.writeLong(weight);
   writer.write(buffer, 0, output.getPosition());
 }
 @Override
 protected void encode(
     ByteSequencesWriter writer,
     ByteArrayDataOutput output,
     byte[] buffer,
     BytesRef spare,
     long weight)
     throws IOException {
   if (spare.length + 5 >= buffer.length) {
     buffer = ArrayUtil.grow(buffer, spare.length + 5);
   }
   output.reset(buffer);
   output.writeBytes(spare.bytes, spare.offset, spare.length);
   output.writeByte((byte) 0); // separator: not used, just for sort order
   output.writeInt(encodeWeight(weight));
   writer.write(buffer, 0, output.getPosition());
 }
  @Override
  public void build(TermFreqIterator tfit) throws IOException {
    if (tfit instanceof TermFreqPayloadIterator) {
      throw new IllegalArgumentException("this suggester doesn't support payloads");
    }
    File tempInput =
        File.createTempFile(
            FSTCompletionLookup.class.getSimpleName(), ".input", Sort.defaultTempDir());
    File tempSorted =
        File.createTempFile(
            FSTCompletionLookup.class.getSimpleName(), ".sorted", Sort.defaultTempDir());

    Sort.ByteSequencesWriter writer = new Sort.ByteSequencesWriter(tempInput);
    Sort.ByteSequencesReader reader = null;
    ExternalRefSorter sorter = null;

    // Push floats up front before sequences to sort them. For now, assume they are non-negative.
    // If negative floats are allowed some trickery needs to be done to find their byte order.
    boolean success = false;
    try {
      byte[] buffer = new byte[0];
      ByteArrayDataOutput output = new ByteArrayDataOutput(buffer);
      BytesRef spare;
      while ((spare = tfit.next()) != null) {
        if (spare.length + 4 >= buffer.length) {
          buffer = ArrayUtil.grow(buffer, spare.length + 4);
        }

        output.reset(buffer);
        output.writeInt(encodeWeight(tfit.weight()));
        output.writeBytes(spare.bytes, spare.offset, spare.length);
        writer.write(buffer, 0, output.getPosition());
      }
      writer.close();

      // We don't know the distribution of scores and we need to bucket them, so we'll sort
      // and divide into equal buckets.
      SortInfo info = new Sort().sort(tempInput, tempSorted);
      tempInput.delete();
      FSTCompletionBuilder builder =
          new FSTCompletionBuilder(
              buckets, sorter = new ExternalRefSorter(new Sort()), sharedTailLength);

      final int inputLines = info.lines;
      reader = new Sort.ByteSequencesReader(tempSorted);
      long line = 0;
      int previousBucket = 0;
      int previousScore = 0;
      ByteArrayDataInput input = new ByteArrayDataInput();
      BytesRef tmp1 = new BytesRef();
      BytesRef tmp2 = new BytesRef();
      while (reader.read(tmp1)) {
        input.reset(tmp1.bytes);
        int currentScore = input.readInt();

        int bucket;
        if (line > 0 && currentScore == previousScore) {
          bucket = previousBucket;
        } else {
          bucket = (int) (line * buckets / inputLines);
        }
        previousScore = currentScore;
        previousBucket = bucket;

        // Only append the input, discard the weight.
        tmp2.bytes = tmp1.bytes;
        tmp2.offset = input.getPosition();
        tmp2.length = tmp1.length - input.getPosition();
        builder.add(tmp2, bucket);

        line++;
      }

      // The two FSTCompletions share the same automaton.
      this.higherWeightsCompletion = builder.build();
      this.normalCompletion =
          new FSTCompletion(higherWeightsCompletion.getFST(), false, exactMatchFirst);

      success = true;
    } finally {
      if (success) IOUtils.close(reader, writer, sorter);
      else IOUtils.closeWhileHandlingException(reader, writer, sorter);

      tempInput.delete();
      tempSorted.delete();
    }
  }