public int write(long offset, ByteBuff src) {
    return internalTransfer(offset, src, WRITER);
  }
Transfers bytes from the given source {@link ByteBuff} into this buffer array
@param offset start offset of this big logical array.
@param src    the source ByteBuff. Notice that its position will be advanced.
@return number of bytes write
hbase-common/src/main/java/org/apache/hadoop/hbase/util/ByteBufferArray.java