@Override
  public void write(ByteBuff srcBuffer, long offset) throws IOException {
    bufferArray.write(offset, srcBuffer);
  }
Transfers data from the given byte buffer to file
@param srcBuffer the given byte buffer from which bytes are to be read
@param offset    The offset in the file where the first byte to be written
hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/bucket/FileMmapIOEngine.java