content: /*
   * 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.
   */
  package org.apache.asterix.column.bytes.encoder;
  
  import org.apache.commons.lang3.mutable.Mutable;
  import org.apache.hyracks.api.exceptions.HyracksDataException;
  import org.apache.hyracks.data.std.api.IValueReference;
  import org.apache.hyracks.data.std.primitive.VoidPointable;
  import org.apache.hyracks.data.std.util.ArrayBackedValueStorage;
  import org.apache.hyracks.storage.am.lsm.btree.column.api.IColumnWriteMultiPageOp;
  import org.apache.hyracks.util.string.UTF8StringUtil;
  import org.apache.parquet.bytes.BytesInput;
  import org.apache.parquet.column.values.deltastrings.DeltaByteArrayWriter;
  
  /**
   * Re-implementation of {@link DeltaByteArrayWriter}
   */
  public class ParquetDeltaByteArrayWriter extends AbstractParquetValuesWriter {
      public static final int REQUIRED_TEMPORARY_BUFFERS =
              ParquetDeltaBinaryPackingValuesWriterForInteger.REQUIRED_TEMPORARY_BUFFERS
                      + ParquetDeltaLengthByteArrayValuesWriter.REQUIRED_TEMPORARY_BUFFERS;
  
      private static final IValueReference EMPTY_VALUE;
      private final ParquetDeltaBinaryPackingValuesWriterForInteger prefixLengthWriter;
      private final ParquetDeltaLengthByteArrayValuesWriter suffixWriter;
      private final VoidPointable suffix;
      private final ArrayBackedValueStorage previous = new ArrayBackedValueStorage();
  
      static {
          VoidPointable emptyPointable = new VoidPointable();
          emptyPointable.set(new byte[0], 0, 0);
          EMPTY_VALUE = emptyPointable;
      }
  
      public ParquetDeltaByteArrayWriter(Mutable<IColumnWriteMultiPageOp> multiPageOpRef) {
          this.prefixLengthWriter = new ParquetDeltaBinaryPackingValuesWriterForInteger(multiPageOpRef);
          this.suffixWriter = new ParquetDeltaLengthByteArrayValuesWriter(multiPageOpRef);
          suffix = new VoidPointable();
          suffix.set(EMPTY_VALUE);
      }
  
      @Override
      public BytesInput getBytes() {
          BytesInput prefixBytes = prefixLengthWriter.getBytes();
          BytesInput prefixLength = BytesInput.fromUnsignedVarInt((int) prefixBytes.size());
          BytesInput suffixBytes = suffixWriter.getBytes();
          return BytesInput.concat(prefixLength, prefixBytes, suffixBytes);
      }
  
      @Override
      public void reset() throws HyracksDataException {
          prefixLengthWriter.reset();
          suffixWriter.reset();
          previous.reset();
          suffix.set(EMPTY_VALUE);
      }
  
      @Override
      public void close() {
          prefixLengthWriter.close();
          suffixWriter.close();
          previous.reset();
          suffix.set(EMPTY_VALUE);
      }
  
      @Override
      public int getEstimatedSize() {
          return prefixLengthWriter.getEstimatedSize() + suffixWriter.getEstimatedSize();
      }
  
      @Override
      public int getAllocatedSize() {
          return prefixLengthWriter.getAllocatedSize() + suffixWriter.getAllocatedSize();
      }
  
      @Override
      public void writeBytes(IValueReference value, boolean skipLengthBytes) {
          byte[] bytes = value.getByteArray();
          int start = value.getStartOffset();
          int length = value.getLength();
          if (skipLengthBytes) {
              // Length bytes are skipped so the prefix encoding works properly (e.g., "123", "1234")
              // the prefix "123" is a common substring between the two; however, their lengths are not
              int lengthBytes = UTF8StringUtil.getNumBytesToStoreLength(bytes, start);
              start += lengthBytes;
              length -= lengthBytes;
          }
          writeBytes(bytes, start, length);
      }
  
      private void writeBytes(byte[] bytes, int offset, int length) {
          final byte[] prevBytes = previous.getByteArray();
          final int prevOffset = previous.getStartOffset();
          final int minLength = Math.min(length, previous.getLength());
          // find the number of matching prefix bytes between this value and the previous one
          int i;
          for (i = 0; (i < minLength) && (bytes[i + offset] == prevBytes[i + prevOffset]); i++);
          prefixLengthWriter.writeInteger(i);
          suffix.set(bytes, offset + i, length - i);
          suffixWriter.writeBytes(suffix, false);
          // We store as bytes could be evicted from the buffer cache
          previous.set(bytes, offset, length);
      }
  }
  