@Override
  public void mark(int readLimit) {
    if (in.markSupported()) {
      super.mark(readLimit);
      mMarkedTailOffset = mTailOffset;
    }
  }
InputStream that returns all bytes from another stream, then appends the specified 'tail' bytes.
fbcore/src/main/java/com/facebook/common/streams/TailAppendingInputStream.java