/*
    * 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.hadoop.hbase;
  
  import java.io.EOFException;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.OutputStream;
  import java.nio.ByteBuffer;
  import java.util.ArrayList;
  import java.util.List;
  
  import org.apache.hadoop.hbase.KeyValue.Type;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.io.util.StreamUtils;
  import org.apache.hadoop.hbase.util.ByteBufferUtils;
  import org.apache.hadoop.hbase.util.Bytes;
  import org.apache.hadoop.hbase.util.IterableUtils;
  import org.apache.hadoop.hbase.util.SimpleMutableByteRange;
  import org.apache.hadoop.io.IOUtils;
  import org.apache.hadoop.io.WritableUtils;
  
  import com.google.common.base.Function;
  import com.google.common.collect.Lists;
  
  /**
   * static convenience methods for dealing with KeyValues and collections of KeyValues
   */
  @InterfaceAudience.Private
  public class KeyValueUtil {
  
    /**************** length *********************/
  
    /**
     * Returns number of bytes this cell would have been used if serialized as in {@link KeyValue}
     * @param cell
     * @return the length
     */
    public static int length(final Cell cell) {
      return length(cell.getRowLength(), cell.getFamilyLength(), cell.getQualifierLength(),
          cell.getValueLength(), cell.getTagsLength(), true);
    }
  
    private static int length(short rlen, byte flen, int qlen, int vlen, int tlen, boolean withTags) {
      if (withTags) {
        return (int) (KeyValue.getKeyValueDataStructureSize(rlen, flen, qlen, vlen, tlen));
      }
      return (int) (KeyValue.getKeyValueDataStructureSize(rlen, flen, qlen, vlen));
    }
  
    /**
     * Returns number of bytes this cell's key part would have been used if serialized as in
     * {@link KeyValue}. Key includes rowkey, family, qualifier, timestamp and type.
     * @param cell
     * @return the key length
     */
    public static int keyLength(final Cell cell) {
      return keyLength(cell.getRowLength(), cell.getFamilyLength(), cell.getQualifierLength());
    }
  
    private static int keyLength(short rlen, byte flen, int qlen) {
      return (int) KeyValue.getKeyDataStructureSize(rlen, flen, qlen);
    }
  
    public static int lengthWithMvccVersion(final KeyValue kv, final boolean includeMvccVersion) {
      int length = kv.getLength();
      if (includeMvccVersion) {
        length += WritableUtils.getVIntSize(kv.getMvccVersion());
      }
      return length;
    }
  
    public static int totalLengthWithMvccVersion(final Iterable<? extends KeyValue> kvs,
        final boolean includeMvccVersion) {
      int length = 0;
      for (KeyValue kv : IterableUtils.nullSafe(kvs)) {
        length += lengthWithMvccVersion(kv, includeMvccVersion);
      }
      return length;
    }
  
  
    /**************** copy key only *********************/
 
   public static KeyValue copyToNewKeyValue(final Cell cell) {
     byte[] bytes = copyToNewByteArray(cell);
     KeyValue kvCell = new KeyValue(bytes, 0, bytes.length);
     kvCell.setSequenceId(cell.getMvccVersion());
     return kvCell;
   }
 
   /**
    * The position will be set to the beginning of the new ByteBuffer
    * @param cell
    * @return the Bytebuffer containing the key part of the cell
    */
   public static ByteBuffer copyKeyToNewByteBuffer(final Cell cell) {
     byte[] bytes = new byte[keyLength(cell)];
     appendKeyTo(cell, bytes, 0);
     ByteBuffer buffer = ByteBuffer.wrap(bytes);
     return buffer;
   }
 
   public static byte[] copyToNewByteArray(final Cell cell) {
     int v1Length = length(cell);
     byte[] backingBytes = new byte[v1Length];
     appendToByteArray(cell, backingBytes, 0);
     return backingBytes;
   }
 
   public static int appendKeyTo(final Cell cell, final byte[] output,
       final int offset) {
     int nextOffset = offset;
     nextOffset = Bytes.putShort(output, nextOffset, cell.getRowLength());
     nextOffset = CellUtil.copyRowTo(cell, output, nextOffset);
     nextOffset = Bytes.putByte(output, nextOffset, cell.getFamilyLength());
     nextOffset = CellUtil.copyFamilyTo(cell, output, nextOffset);
     nextOffset = CellUtil.copyQualifierTo(cell, output, nextOffset);
     nextOffset = Bytes.putLong(output, nextOffset, cell.getTimestamp());
     nextOffset = Bytes.putByte(output, nextOffset, cell.getTypeByte());
     return nextOffset;
   }
 
 
   /**************** copy key and value *********************/
 
   public static int appendToByteArray(final Cell cell, final byte[] output, final int offset) {
     // TODO when cell instance of KV we can bypass all steps and just do backing single array
     // copy(?)
     int pos = offset;
     pos = Bytes.putInt(output, pos, keyLength(cell));
     pos = Bytes.putInt(output, pos, cell.getValueLength());
     pos = appendKeyTo(cell, output, pos);
     pos = CellUtil.copyValueTo(cell, output, pos);
     if ((cell.getTagsLength() > 0)) {
       pos = Bytes.putAsShort(output, pos, cell.getTagsLength());
       pos = CellUtil.copyTagTo(cell, output, pos);
     }
     return pos;
   }
 
   /**
    * The position will be set to the beginning of the new ByteBuffer
    * @param cell
    * @return the ByteBuffer containing the cell
    */
   public static ByteBuffer copyToNewByteBuffer(final Cell cell) {
     byte[] bytes = new byte[length(cell)];
     appendToByteArray(cell, bytes, 0);
     ByteBuffer buffer = ByteBuffer.wrap(bytes);
     return buffer;
   }
 
   public static void appendToByteBuffer(final ByteBuffer bb, final KeyValue kv,
       final boolean includeMvccVersion) {
     // keep pushing the limit out. assume enough capacity
     bb.limit(bb.position() + kv.getLength());
     bb.put(kv.getBuffer(), kv.getOffset(), kv.getLength());
     if (includeMvccVersion) {
       int numMvccVersionBytes = WritableUtils.getVIntSize(kv.getMvccVersion());
       ByteBufferUtils.extendLimit(bb, numMvccVersionBytes);
       ByteBufferUtils.writeVLong(bb, kv.getMvccVersion());
     }
   }
 
 
   /**************** iterating *******************************/
 
   /**
    * Creates a new KeyValue object positioned in the supplied ByteBuffer and sets the ByteBuffer's
    * position to the start of the next KeyValue. Does not allocate a new array or copy data.
    * @param bb
    * @param includesMvccVersion
    * @param includesTags
    */
   public static KeyValue nextShallowCopy(final ByteBuffer bb, final boolean includesMvccVersion,
       boolean includesTags) {
     if (bb.isDirect()) {
       throw new IllegalArgumentException("only supports heap buffers");
     }
     if (bb.remaining() < 1) {
       return null;
     }
     KeyValue keyValue = null;
     int underlyingArrayOffset = bb.arrayOffset() + bb.position();
     int keyLength = bb.getInt();
     int valueLength = bb.getInt();
     ByteBufferUtils.skip(bb, keyLength + valueLength);
     int tagsLength = 0;
     if (includesTags) {
       // Read short as unsigned, high byte first
       tagsLength = ((bb.get() & 0xff) << 8) ^ (bb.get() & 0xff);
       ByteBufferUtils.skip(bb, tagsLength);
     }
     int kvLength = (int) KeyValue.getKeyValueDataStructureSize(keyLength, valueLength, tagsLength);
     keyValue = new KeyValue(bb.array(), underlyingArrayOffset, kvLength);
     if (includesMvccVersion) {
       long mvccVersion = ByteBufferUtils.readVLong(bb);
       keyValue.setSequenceId(mvccVersion);
     }
     return keyValue;
   }
 
 
   /*************** next/previous **********************************/
 
   /**
    * Append single byte 0x00 to the end of the input row key
    */
   public static KeyValue createFirstKeyInNextRow(final Cell in){
     byte[] nextRow = new byte[in.getRowLength() + 1];
     System.arraycopy(in.getRowArray(), in.getRowOffset(), nextRow, 0, in.getRowLength());
     nextRow[nextRow.length - 1] = 0;//maybe not necessary
     return createFirstOnRow(nextRow);
   }
 
   /**
    * Increment the row bytes and clear the other fields
    */
   public static KeyValue createFirstKeyInIncrementedRow(final Cell in){
     byte[] thisRow = new SimpleMutableByteRange(in.getRowArray(), in.getRowOffset(),
         in.getRowLength()).deepCopyToNewArray();
     byte[] nextRow = Bytes.unsignedCopyAndIncrement(thisRow);
     return createFirstOnRow(nextRow);
   }
 
   /**
    * Decrement the timestamp.  For tests (currently wasteful)
    *
    * Remember timestamps are sorted reverse chronologically.
    * @param in
    * @return previous key
    */
   public static KeyValue previousKey(final KeyValue in) {
     return createFirstOnRow(CellUtil.cloneRow(in), CellUtil.cloneFamily(in),
       CellUtil.cloneQualifier(in), in.getTimestamp() - 1);
   }
 
 
   /**
    * Create a KeyValue for the specified row, family and qualifier that would be
    * larger than or equal to all other possible KeyValues that have the same
    * row, family, qualifier. Used for reseeking. Should NEVER be returned to a client.
    *
    * @param row
    *          row key
    * @param roffset
    *         row offset
    * @param rlength
    *         row length
    * @param family
    *         family name
    * @param foffset
    *         family offset
    * @param flength
    *         family length
    * @param qualifier
    *        column qualifier
    * @param qoffset
    *        qualifier offset
    * @param qlength
    *        qualifier length
    * @return Last possible key on passed row, family, qualifier.
    */
   public static KeyValue createLastOnRow(final byte[] row, final int roffset, final int rlength,
       final byte[] family, final int foffset, final int flength, final byte[] qualifier,
       final int qoffset, final int qlength) {
     return new KeyValue(row, roffset, rlength, family, foffset, flength, qualifier, qoffset,
         qlength, HConstants.OLDEST_TIMESTAMP, Type.Minimum, null, 0, 0);
   }
   
   /**
    * Creates a keyValue for the specified keyvalue larger than or equal to all other possible
    * KeyValues that have the same row, family, qualifer.  Used for reseeking
    * @param kv
    * @return KeyValue
    */
   public static KeyValue createLastOnRow(Cell kv) {
     return createLastOnRow(kv.getRowArray(), kv.getRowOffset(), kv.getRowLength(), null, 0, 0,
         null, 0, 0);
   }
 
   /**
    * Similar to
    * {@link #createLastOnRow(byte[], int, int, byte[], int, int, byte[], int, int)}
    * but creates the last key on the row/column of this KV (the value part of
    * the returned KV is always empty). Used in creating "fake keys" for the
    * multi-column Bloom filter optimization to skip the row/column we already
    * know is not in the file. Not to be returned to clients.
    * 
    * @param kv - cell
    * @return the last key on the row/column of the given key-value pair
    */
   public static KeyValue createLastOnRowCol(Cell kv) {
     return new KeyValue(kv.getRowArray(), kv.getRowOffset(), kv.getRowLength(),
         kv.getFamilyArray(), kv.getFamilyOffset(), kv.getFamilyLength(), kv.getQualifierArray(),
         kv.getQualifierOffset(), kv.getQualifierLength(), HConstants.OLDEST_TIMESTAMP,
         Type.Minimum, null, 0, 0);
   }
 
   /**
    * Creates the first KV with the row/family/qualifier of this KV and the given
    * timestamp. Uses the "maximum" KV type that guarantees that the new KV is
    * the lowest possible for this combination of row, family, qualifier, and
    * timestamp. This KV's own timestamp is ignored. While this function copies
    * the value from this KV, it is normally used on key-only KVs.
    * 
    * @param kv - cell
    * @param ts
    */
   public static KeyValue createFirstOnRowColTS(Cell kv, long ts) {
     return new KeyValue(kv.getRowArray(), kv.getRowOffset(), kv.getRowLength(),
         kv.getFamilyArray(), kv.getFamilyOffset(), kv.getFamilyLength(), kv.getQualifierArray(),
         kv.getQualifierOffset(), kv.getQualifierLength(), ts, Type.Maximum, kv.getValueArray(),
         kv.getValueOffset(), kv.getValueLength());
   }
   
   /**
    * Create a KeyValue that is smaller than all other possible KeyValues
    * for the given row. That is any (valid) KeyValue on 'row' would sort
    * _after_ the result.
    *
    * @param row - row key (arbitrary byte array)
    * @return First possible KeyValue on passed <code>row</code>
    */
   public static KeyValue createFirstOnRow(final byte [] row, int roffset, short rlength) {
     return new KeyValue(row, roffset, rlength,
         null, 0, 0, null, 0, 0, HConstants.LATEST_TIMESTAMP, Type.Maximum, null, 0, 0);
   }
   
 
   /**
    * Creates a KeyValue that is last on the specified row id. That is,
    * every other possible KeyValue for the given row would compareTo()
    * less than the result of this call.
    * @param row row key
    * @return Last possible KeyValue on passed <code>row</code>
    */
   public static KeyValue createLastOnRow(final byte[] row) {
     return new KeyValue(row, null, null, HConstants.LATEST_TIMESTAMP, Type.Minimum);
   }
 
   /**
    * Create a KeyValue that is smaller than all other possible KeyValues
    * for the given row. That is any (valid) KeyValue on 'row' would sort
    * _after_ the result.
    *
    * @param row - row key (arbitrary byte array)
    * @return First possible KeyValue on passed <code>row</code>
    */
   public static KeyValue createFirstOnRow(final byte [] row) {
     return createFirstOnRow(row, HConstants.LATEST_TIMESTAMP);
   }
 
   /**
    * Creates a KeyValue that is smaller than all other KeyValues that
    * are older than the passed timestamp.
    * @param row - row key (arbitrary byte array)
    * @param ts - timestamp
    * @return First possible key on passed <code>row</code> and timestamp.
    */
   public static KeyValue createFirstOnRow(final byte [] row,
       final long ts) {
     return new KeyValue(row, null, null, ts, Type.Maximum);
   }
 
   /**
    * Create a KeyValue for the specified row, family and qualifier that would be
    * smaller than all other possible KeyValues that have the same row,family,qualifier.
    * Used for seeking.
    * @param row - row key (arbitrary byte array)
    * @param family - family name
    * @param qualifier - column qualifier
    * @return First possible key on passed <code>row</code>, and column.
    */
   public static KeyValue createFirstOnRow(final byte [] row, final byte [] family,
       final byte [] qualifier) {
     return new KeyValue(row, family, qualifier, HConstants.LATEST_TIMESTAMP, Type.Maximum);
   }
 
   /**
    * Create a Delete Family KeyValue for the specified row and family that would
    * be smaller than all other possible Delete Family KeyValues that have the
    * same row and family.
    * Used for seeking.
    * @param row - row key (arbitrary byte array)
    * @param family - family name
    * @return First Delete Family possible key on passed <code>row</code>.
    */
   public static KeyValue createFirstDeleteFamilyOnRow(final byte [] row,
       final byte [] family) {
     return new KeyValue(row, family, null, HConstants.LATEST_TIMESTAMP,
         Type.DeleteFamily);
   }
 
   /**
    * @param row - row key (arbitrary byte array)
    * @param f - family name
    * @param q - column qualifier
    * @param ts - timestamp
    * @return First possible key on passed <code>row</code>, column and timestamp
    */
   public static KeyValue createFirstOnRow(final byte [] row, final byte [] f,
       final byte [] q, final long ts) {
     return new KeyValue(row, f, q, ts, Type.Maximum);
   }
 
   /**
    * Create a KeyValue for the specified row, family and qualifier that would be
    * smaller than all other possible KeyValues that have the same row,
    * family, qualifier.
    * Used for seeking.
    * @param row row key
    * @param roffset row offset
    * @param rlength row length
    * @param family family name
    * @param foffset family offset
    * @param flength family length
    * @param qualifier column qualifier
    * @param qoffset qualifier offset
    * @param qlength qualifier length
    * @return First possible key on passed Row, Family, Qualifier.
    */
   public static KeyValue createFirstOnRow(final byte [] row,
       final int roffset, final int rlength, final byte [] family,
       final int foffset, final int flength, final byte [] qualifier,
       final int qoffset, final int qlength) {
     return new KeyValue(row, roffset, rlength, family,
         foffset, flength, qualifier, qoffset, qlength,
         HConstants.LATEST_TIMESTAMP, Type.Maximum, null, 0, 0);
   }
 
   /**
    * Create a KeyValue for the specified row, family and qualifier that would be
    * smaller than all other possible KeyValues that have the same row,
    * family, qualifier.
    * Used for seeking.
    *
    * @param buffer the buffer to use for the new <code>KeyValue</code> object
    * @param row the value key
    * @param family family name
    * @param qualifier column qualifier
    *
    * @return First possible key on passed Row, Family, Qualifier.
    *
    * @throws IllegalArgumentException The resulting <code>KeyValue</code> object would be larger
    * than the provided buffer or than <code>Integer.MAX_VALUE</code>
    */
   public static KeyValue createFirstOnRow(byte [] buffer, final byte [] row,
       final byte [] family, final byte [] qualifier)
           throws IllegalArgumentException {
     return createFirstOnRow(buffer, 0, row, 0, row.length,
         family, 0, family.length,
         qualifier, 0, qualifier.length);
   }
 
   /**
    * Create a KeyValue for the specified row, family and qualifier that would be
    * smaller than all other possible KeyValues that have the same row,
    * family, qualifier.
    * Used for seeking.
    *
    * @param buffer the buffer to use for the new <code>KeyValue</code> object
    * @param boffset buffer offset
    * @param row the value key
    * @param roffset row offset
    * @param rlength row length
    * @param family family name
    * @param foffset family offset
    * @param flength family length
    * @param qualifier column qualifier
    * @param qoffset qualifier offset
    * @param qlength qualifier length
    *
    * @return First possible key on passed Row, Family, Qualifier.
    *
    * @throws IllegalArgumentException The resulting <code>KeyValue</code> object would be larger
    * than the provided buffer or than <code>Integer.MAX_VALUE</code>
    */
   public static KeyValue createFirstOnRow(byte[] buffer, final int boffset, final byte[] row,
       final int roffset, final int rlength, final byte[] family, final int foffset,
       final int flength, final byte[] qualifier, final int qoffset, final int qlength)
       throws IllegalArgumentException {
 
     long lLength = KeyValue.getKeyValueDataStructureSize(rlength, flength, qlength, 0);
 
     if (lLength > Integer.MAX_VALUE) {
       throw new IllegalArgumentException("KeyValue length " + lLength + " > " + Integer.MAX_VALUE);
     }
     int iLength = (int) lLength;
     if (buffer.length - boffset < iLength) {
       throw new IllegalArgumentException("Buffer size " + (buffer.length - boffset) + " < "
           + iLength);
     }
 
     int len = KeyValue.writeByteArray(buffer, boffset, row, roffset, rlength, family, foffset,
         flength, qualifier, qoffset, qlength, HConstants.LATEST_TIMESTAMP, KeyValue.Type.Maximum,
         null, 0, 0, null);
     return new KeyValue(buffer, boffset, len);
   }
 
   /**
    * Creates the first KV with the row/family/qualifier of this KV and the
    * given timestamp. Uses the "maximum" KV type that guarantees that the new
    * KV is the lowest possible for this combination of row, family, qualifier,
    * and timestamp. This KV's own timestamp is ignored. While this function
    * copies the value from this KV, it is normally used on key-only KVs.
    */
   public static KeyValue createFirstOnRowColTS(KeyValue kv, long ts) {
     return new KeyValue(
         kv.getRowArray(), kv.getRowOffset(), kv.getRowLength(),
         kv.getFamilyArray(), kv.getFamilyOffset(), kv.getFamilyLength(),
         kv.getQualifierArray(), kv.getQualifierOffset(), kv.getQualifierLength(),
         ts, Type.Maximum, kv.getValueArray(), kv.getValueOffset(), kv.getValueLength());
   }
 
   /*************** misc **********************************/
   /**
    * @param cell
    * @return <code>cell</code> if it is an instance of {@link KeyValue} else we will return a
    * new {@link KeyValue} instance made from <code>cell</code>
    * @deprecated without any replacement.
    */
   @Deprecated
   public static KeyValue ensureKeyValue(final Cell cell) {
     if (cell == null) return null;
     return cell instanceof KeyValue? (KeyValue)cell: copyToNewKeyValue(cell);
   }
 
   /**
    * @param cell
    * @return <code>cell</code> if it is an object of class {@link KeyValue} else we will return a
    * new {@link KeyValue} instance made from <code>cell</code> Note: Even if the cell is an object
    * of any of the subclass of {@link KeyValue}, we will create a new {@link KeyValue} object
    * wrapping same buffer. This API should be used only with MR based tools which expect the type
    * to be exactly KeyValue. That is the reason for doing this way.
    *
    * @deprecated without any replacement.
    */
   @Deprecated
   public static KeyValue ensureKeyValueTypeForMR(final Cell cell) {
     if (cell == null) return null;
     if (cell instanceof KeyValue) {
       if (cell.getClass().getName().equals(KeyValue.class.getName())) {
         return (KeyValue) cell;
       }
       // Cell is an Object of any of the sub classes of KeyValue. Make a new KeyValue wrapping the
       // same byte[]
       KeyValue kv = (KeyValue) cell;
       KeyValue newKv = new KeyValue(kv.bytes, kv.offset, kv.length);
       newKv.setSequenceId(kv.getSequenceId());
       return newKv;
     }
     return copyToNewKeyValue(cell);
   }
 
   @Deprecated
   public static List<KeyValue> ensureKeyValues(List<Cell> cells) {
     List<KeyValue> lazyList = Lists.transform(cells, new Function<Cell, KeyValue>() {
       @Override
       public KeyValue apply(Cell arg0) {
         return KeyValueUtil.ensureKeyValue(arg0);
       }
     });
     return new ArrayList<KeyValue>(lazyList);
   }
 
   /**
    * Create a KeyValue reading from the raw InputStream. Named
    * <code>iscreate</code> so doesn't clash with the <code>create(DataInput)</code> method
    * added in 2.0
    *
    * @param in
    * @param withTags
    *          whether the keyvalue should include tags are not
    * @return Created KeyValue OR if we find a length of zero, we will return
    *         null which can be useful marking a stream as done.
    * @throws IOException
    */
   public static KeyValue iscreate(final InputStream in, boolean withTags) throws IOException {
     byte[] intBytes = new byte[Bytes.SIZEOF_INT];
     int bytesRead = 0;
     while (bytesRead < intBytes.length) {
       int n = in.read(intBytes, bytesRead, intBytes.length - bytesRead);
       if (n < 0) {
         if (bytesRead == 0) {
           throw new EOFException();
         }
         throw new IOException("Failed read of int, read " + bytesRead + " bytes");
       }
       bytesRead += n;
     }
     // TODO: perhaps some sanity check is needed here.
     byte[] bytes = new byte[Bytes.toInt(intBytes)];
     IOUtils.readFully(in, bytes, 0, bytes.length);
     if (withTags) {
       return new KeyValue(bytes, 0, bytes.length);
     } else {
       return new NoTagsKeyValue(bytes, 0, bytes.length);
     }
   }
 
   public static void oswrite(final Cell cell, final OutputStream out, final boolean withTags)
       throws IOException {
     if (cell instanceof KeyValue) {
       KeyValue.oswrite((KeyValue) cell, out, withTags);
     } else {
       short rlen = cell.getRowLength();
       byte flen = cell.getFamilyLength();
       int qlen = cell.getQualifierLength();
       int vlen = cell.getValueLength();
       int tlen = cell.getTagsLength();
 
       // write total length
       StreamUtils.writeInt(out, length(rlen, flen, qlen, vlen, tlen, withTags));
       // write key length
       StreamUtils.writeInt(out, keyLength(rlen, flen, qlen));
       // write value length
       StreamUtils.writeInt(out, vlen);
       // Write rowkey - 2 bytes rk length followed by rowkey bytes
       StreamUtils.writeShort(out, rlen);
       out.write(cell.getRowArray(), cell.getRowOffset(), rlen);
       // Write cf - 1 byte of cf length followed by the family bytes
       out.write(flen);
       out.write(cell.getFamilyArray(), cell.getFamilyOffset(), flen);
       // write qualifier
       out.write(cell.getQualifierArray(), cell.getQualifierOffset(), qlen);
       // write timestamp
       StreamUtils.writeLong(out, cell.getTimestamp());
       // write the type
       out.write(cell.getTypeByte());
       // write value
       out.write(cell.getValueArray(), cell.getValueOffset(), vlen);
       // write tags if we have to
       if (withTags && tlen > 0) {
         // 2 bytes tags length followed by tags bytes
         // tags length is serialized with 2 bytes only(short way) even if the type is int. As this
         // is non -ve numbers, we save the sign bit. See HBASE-11437
         out.write((byte) (0xff & (tlen >> 8)));
         out.write((byte) (0xff & tlen));
         out.write(cell.getTagsArray(), cell.getTagsOffset(), tlen);
       }
     }
   }
 }