func (s *scanner) cur() byte { return s.buf[s.ipos] }

// read next byte
func (s *scanner) next() byte {
	if s.pos >= atomic.LoadInt64(&s.end) {
		return nullByte
	}
	s.ipos++

	if s.ipos > s.ifill { // internal buffer is exhausted
		s.ifill = <-s.fillReady

		s.buf[0] = s.buf[len(s.buf)-1] // copy current last item to guarantee lookback
		copy(s.buf[1:], s.nbuf[:])     // copy contents of pre-filled next buffer

	// The approach here is to write 8 byte sizes if needed without
	// adding a zip64 extra in the local header (too late anyway).
	var buf []byte
	if w.isZip64() {
		buf = make([]byte, dataDescriptor64Len)
	} else {
		buf = make([]byte, dataDescriptorLen)
	}
	b := writeBuf(buf)
	b.uint32(dataDescriptorSignature) // de-facto standard, required by OS X
	b.uint32(w.CRC32)
	if w.isZip64() {
		b.uint64(w.CompressedSize64)

	if err != nil {
		return x, buf, err
	}
	x.metaVer, buf, err = msgp.ReadUintBytes(buf)
	if err != nil {
		return x, buf, err
	}
	if x.headerVer > xlHeaderVersion {
		return x, buf, fmt.Errorf("decodeXLHeaders: Unknown xl header version %d", x.headerVer)
	}
	if x.metaVer > xlMetaVersion {
		return x, buf, fmt.Errorf("decodeXLHeaders: Unknown xl meta version %d", x.metaVer)
	}

    assertEquals(-1, empty.read());
  }

  public void testExhaust_readable() throws IOException {
    CharBuffer buf = CharBuffer.wrap(ASCII);
    assertEquals(ASCII.length(), CharStreams.exhaust(buf));
    assertEquals(0, buf.remaining());
    assertEquals(0, CharStreams.exhaust(buf));

    CharBuffer empty = CharBuffer.wrap("");
    assertEquals(0, CharStreams.exhaust(empty));

    assertEquals(-1, empty.read());
  }

  public void testExhaust_readable() throws IOException {
    CharBuffer buf = CharBuffer.wrap(ASCII);
    assertEquals(ASCII.length(), CharStreams.exhaust(buf));
    assertEquals(0, buf.remaining());
    assertEquals(0, CharStreams.exhaust(buf));

    CharBuffer empty = CharBuffer.wrap("");
    assertEquals(0, CharStreams.exhaust(empty));

	}
}

func decodeXLHeaders(buf []byte) (versions int, headerV, metaV uint8, b []byte, err error) {
	hdrVer, buf, err := msgp.ReadUint8Bytes(buf)
	if err != nil {
		return 0, 0, 0, buf, err
	}
	metaVer, buf, err := msgp.ReadUint8Bytes(buf)
	if err != nil {
		return 0, 0, 0, buf, err
	}
	if hdrVer > xlHeaderVersion {

	stat, err := f.Stat()
	if err != nil {
		buf, err = io.ReadAll(f)
		return buf, dmTime, osErrToFileErr(err)
	}
	if stat.IsDir() {
		return nil, dmTime, errFileNotFound
	}

	// Read into appropriate buffer.
	sz := stat.Size()
	if sz <= metaDataReadDefault {
		buf = metaDataPoolGet()
		buf = buf[:sz]
	} else {
		buf = make([]byte, sz)
	}

	// Read file...

            buf.append(',');
            buf.append("\"page_number\":");
            buf.append(currentPageNumber);
            buf.append(',');
            buf.append("\"record_count\":");
            buf.append(allRecordCount);
            buf.append(',');
            buf.append("\"record_count_relation\":");
            buf.append(escapeJson(allRecordCountRelation));
            buf.append(',');

	v := allTierStats{}
	var buf bytes.Buffer
	msgp.Encode(&buf, &v)

	m := v.Msgsize()
	if buf.Len() > m {
		t.Log("WARNING: TestEncodeDecodeallTierStats Msgsize() is inaccurate")
	}

	vn := allTierStats{}
	err := msgp.Decode(&buf, &vn)
	if err != nil {
		t.Error(err)
	}

	buf.Reset()
	msgp.Encode(&buf, &v)
	err = msgp.NewReader(&buf).Skip()
	if err != nil {
		t.Error(err)
	}
}

	v := BatchJobPrefix{}
	var buf bytes.Buffer
	msgp.Encode(&buf, &v)

	m := v.Msgsize()
	if buf.Len() > m {
		t.Log("WARNING: TestEncodeDecodeBatchJobPrefix Msgsize() is inaccurate")
	}

	vn := BatchJobPrefix{}
	err := msgp.Decode(&buf, &vn)
	if err != nil {
		t.Error(err)
	}

	buf.Reset()
	msgp.Encode(&buf, &v)
	err = msgp.NewReader(&buf).Skip()
	if err != nil {
		t.Error(err)
	}
}