Golang encoding-binary.ReadUvarint类(方法)实例源码

func (sr *StoredRow) ParseKey(key []byte) error {
	buf := bytes.NewBuffer(key)
	_, err := buf.ReadByte() // type
	if err != nil {
		return err
	}

	sr.docID, err = buf.ReadBytes(ByteSeparator)
	if len(sr.docID) < 2 { // 1 for min doc id length, 1 for separator
		err = fmt.Errorf("invalid doc length 0")
		return err
	}

	sr.docID = sr.docID[:len(sr.docID)-1] // trim off separator byte

	sr.docNum, err = binary.ReadUvarint(buf)
	if err != nil {
		return err
	}

	err = binary.Read(buf, binary.LittleEndian, &sr.field)
	if err != nil {
		return err
	}

	sr.arrayPositions = make([]uint64, 0)
	nextArrayPos, err := binary.ReadUvarint(buf)
	for err == nil {
		sr.arrayPositions = append(sr.arrayPositions, nextArrayPos)
		nextArrayPos, err = binary.ReadUvarint(buf)
	}

	return nil
}

func NewStoredRowK(key []byte) (*StoredRow, error) {
	rv := StoredRow{}

	buf := bytes.NewBuffer(key)
	_, err := buf.ReadByte() // type
	if err != nil {
		return nil, err
	}

	rv.doc, err = buf.ReadBytes(ByteSeparator)
	if len(rv.doc) < 2 { // 1 for min doc id length, 1 for separator
		err = fmt.Errorf("invalid doc length 0")
		return nil, err
	}

	rv.doc = rv.doc[:len(rv.doc)-1] // trim off separator byte

	err = binary.Read(buf, binary.LittleEndian, &rv.field)
	if err != nil {
		return nil, err
	}

	rv.arrayPositions = make([]uint64, 0)
	nextArrayPos, err := binary.ReadUvarint(buf)
	for err == nil {
		rv.arrayPositions = append(rv.arrayPositions, nextArrayPos)
		nextArrayPos, err = binary.ReadUvarint(buf)
	}
	return &rv, nil
}

func (p *Player) recv() {
	for {
		length, err := ReadVarint(p.conn)
		if err != nil {
			p.Game.RemovePlayer(p.Name)
			fmt.Println("Player disconnected")

			return
		}

		buf := make([]byte, length)
		io.ReadFull(p.conn, buf)
		r := bytes.NewReader(buf)

		binary.ReadUvarint(r)

		id, _ := binary.ReadUvarint(r)

		switch id {
		case 0x01:
			message := ReadString(r)
			if strings.HasPrefix(message, "/") {
				// Commands
			} else {
				WriteChatMessage(p.Game, fmt.Sprintf("<%s> %s", p.Name, message))
				fmt.Printf("<%s> %s\n", p.Name, message)
			}
		}
	}
}

func readEntry(reader *dirIndexReader, offset uint64) (*indexEntry, error) {
	seekErr := seekIndex(reader, offset)
	if seekErr != nil {
		return nil, seekErr
	}

	n, err := binary.ReadUvarint(reader.indexReader)
	if err != nil {
		return nil, err
	}

	entries := []indexEntryElement{}
	for i := uint64(0); i < n; i++ {
		docId, derr := binary.ReadUvarint(reader.indexReader)
		if derr != nil {
			return nil, derr
		}
		var freq float64
		ferr := binary.Read(reader.indexReader, binary.LittleEndian, &freq)
		if ferr != nil {
			return nil, ferr
		}
		entries = append(entries, indexEntryElement{docId, freq})
	}

	tail, terr := binary.ReadUvarint(reader.indexReader)
	if terr != nil {
		return nil, terr
	}

	return &indexEntry{entries, tail}, nil
}

// Format of a simple task:
// 2 bytes      : magic number
// 8 bytes      : id length : l
// 8 bytes      : data length : n
// 32 bytes     : target
// 32 bytes     : action
// l bytes      : id
// n bytes      : data
func UnserializeSimpleTask(data []byte) *SimpleTask {

	// Magic number 01
	if data[0] != 0 || data[1] != 1 {
		return nil
	}

	// ID Length
	idLength, err := binary.ReadUvarint(bytes.NewBuffer(data[2:10]))
	if err != nil {
		return nil
	}

	// Data Length
	length, err := binary.ReadUvarint(bytes.NewBuffer(data[10:18]))
	if err != nil {
		return nil
	}

	// Target
	target := string(data[18:50])

	// Action
	action := string(data[50:82])

	// ID
	readId := string(data[82 : 82+idLength])

	// Data
	readData := data[82+idLength : 82+idLength+length]

	return NewSimpleTask(readId, target, action, readData)
}

func (bin *mBinaryProto) readUvarint(reader io.Reader) (uint64, error) {
	if br, ok := reader.(io.ByteReader); ok {
		return binary.ReadUvarint(br)
	}
	br := newByteReader(reader, bin.readBuffer)
	return binary.ReadUvarint(br)
}

func ReadHandshake(r *bytes.Reader) Handshake {
	handshake := Handshake{}
	handshake.Version, _ = binary.ReadUvarint(r)
	handshake.Address = ReadString(r)
	binary.Read(r, binary.BigEndian, &handshake.Port)
	handshake.State, _ = binary.ReadUvarint(r)

	return handshake
}

func readMsgDial(r io.ByteReader) (*msgDial, error) {
	id, err := binary.ReadUvarint(r)
	if err != nil {
		return nil, err
	}
	seqno, err := binary.ReadUvarint(r)
	if err != nil {
		return nil, err
	}
	return &msgDial{ID: chainID(id), SeqNo: SeqNo(seqno)}, nil
}

func ReadDHCPOptions(payload []byte) ([]DHCPOption, error) {
	magicCookieStart := 236
	magicCookieEnd := 240

	if len(payload) < magicCookieEnd {
		return []DHCPOption{}, PayloadError
	}

	magicCookie := []byte{byte(99), byte(130), byte(83), byte(99)}

	if !bytes.Equal(payload[magicCookieStart:magicCookieEnd], magicCookie) {
		return []DHCPOption{}, errors.New("Cannot find magic cookie")
	}

	opts := []DHCPOption{}

	pR := bytes.NewReader(payload[magicCookieEnd:])
	// End Loop when only 255 end DHCP option is left
	for {
		buf := make([]byte, 1)
		if _, err := pR.Read(buf); err != nil {
			return []DHCPOption{}, err
		}

		// break if the end is reached
		if bytes.Equal(buf, []byte{byte(255)}) {
			break
		}

		code, err := binary.ReadUvarint(bytes.NewReader(buf))
		if err != nil {
			return []DHCPOption{}, err
		}

		buf = make([]byte, 1)
		if _, err := pR.Read(buf); err != nil {
			return []DHCPOption{}, err
		}
		size, err := binary.ReadUvarint(bytes.NewReader(buf))
		if err != nil {
			return []DHCPOption{}, err
		}

		buf = make([]byte, size)
		if _, err := pR.Read(buf); err != nil {
			return []DHCPOption{}, err
		}

		opts = append(opts, DHCPOption{code, buf, size})

	}

	return opts, nil
}

func (r *restartRange) next() (err error) {
	if r.cached && len(r.cache) > r.pos {
		r.kv = r.cache[r.pos]
		r.pos++
		return
	}

	if r.buf.Len() == 0 {
		return io.EOF
	}

	var nkey []byte

	// Read header
	var shared, nonShared, valueLen uint64
	shared, err = binary.ReadUvarint(r.buf)
	if err != nil || shared > uint64(len(r.kv.key)) {
		goto corrupt
	}
	nonShared, err = binary.ReadUvarint(r.buf)
	if err != nil {
		goto corrupt
	}
	valueLen, err = binary.ReadUvarint(r.buf)
	if err != nil {
		goto corrupt
	}
	if nonShared+valueLen > uint64(r.buf.Len()) {
		goto corrupt
	}

	if r.cached && r.pos > 0 {
		r.cache = append(r.cache, r.kv)
	}

	// Read content
	nkey = r.buf.Next(int(nonShared))
	if shared == 0 {
		r.kv.key = nkey
	} else {
		pkey := r.kv.key[:shared]
		key := make([]byte, shared+nonShared)
		copy(key, pkey)
		copy(key[shared:], nkey)
		r.kv.key = key
	}
	r.kv.value = r.buf.Next(int(valueLen))
	r.pos++
	return

corrupt:
	return errors.ErrCorrupt("bad entry in block")
}

func (conn *conn) readHeader() (uint64, uint64, error) {
	seq, err := binary.ReadUvarint(conn.buf)
	if err != nil {
		return 0, 0, err
	}

	size, err := binary.ReadUvarint(conn.buf)
	if err != nil {
		return 0, 0, err
	}

	return seq, size, nil
}

func readUint64(r Reader) uint64 {
	x, err := binary.ReadUvarint(r)
	if err != nil {
		log.Fatal(err)
	}
	return x
}

func decodeUint(buf *bytes.Reader) (uint32, error) {
	v, err := binary.ReadUvarint(buf)
	if v > 0xffffffff {
		return 0, errors.New("Something wrong, this number looks too big")
	}
	return uint32(v), err
}

// NewStreamReader returns a reader that will decode the supplied data stream.
//
// This is compatible content from the NewStreamWriter function.
//
// When you are done with the Reader, use Close to release resources.
func NewStreamReader(in io.Reader) (Reader, error) {
	f := &streamReader{
		ready:        make(chan *rblock, 8), // Read up to 8 blocks ahead
		closeReader:  make(chan struct{}, 0),
		readerClosed: make(chan struct{}, 0),
		curBlock:     0,
	}
	br := bufio.NewReader(in)
	format, err := binary.ReadUvarint(br)
	if err != nil {
		return nil, err
	}

	switch format {
	case 2:
		err = f.readFormat2(br)
		if err != nil {
			return nil, err
		}
	default:
		return nil, ErrUnknownFormat
	}

	go f.streamReader(br)

	return f, nil
}

// NewSeekRead returns a reader that will decode the supplied index and data stream.
//
// This is compatible content from the NewWriter function.
//
// No blocks will be kept in memory, but the block data input must be seekable.
// The function will decode the index before returning.
//
// When you are done with the Reader, use Close to release resources.
func NewSeekReader(index io.Reader, blocks io.ReadSeeker) (IndexedReader, error) {
	f := &reader{streamReader: streamReader{
		ready:        make(chan *rblock, 8), // Read up to 8 blocks ahead
		closeReader:  make(chan struct{}, 0),
		readerClosed: make(chan struct{}, 0),
		curBlock:     0,
		maxLength:    8, // We have 8 blocks readahead.
	}}
	idx := bufio.NewReader(index)
	format, err := binary.ReadUvarint(idx)
	if err != nil {
		return nil, err
	}

	switch format {
	case 1:
		err = f.readFormat1(idx)
	default:
		err = ErrUnknownFormat
	}

	go f.seekReader(blocks)

	return f, err
}

// Read a message from io.ByteReader by first reading a varint size,
// and then reading and decoding the message object.
// If buf is not big enough a new buffer will be allocated to replace buf.
func ReadMessage(buf *[]byte, r ByteReadReader, msg proto.Message) error {
	size, err := binary.ReadUvarint(r)
	if err != nil {
		return err
	}
	if cap(*buf) < int(size) {
		*buf = make([]byte, size)
	}
	b := (*buf)[:size]
	read := uint64(0)

	for read != size {
		n, err := r.Read(b[read:])
		if err == io.EOF {
			return fmt.Errorf("unexpected EOF, expected %d more bytes", size)
		}
		if err != nil {
			return err
		}
		read += uint64(n)
	}
	err = proto.Unmarshal(b, msg)
	if err != nil {
		return err
	}
	return nil
}

func (c *baseConn) recvProto(m proto.Message,
	uncompressedSize uint32, decompressor decompressFunc) error {
	size, err := binary.ReadUvarint(c.r)
	if err != nil {
		return err
	}
	if size == 0 {
		return nil
	}
	if c.r.Buffered() >= int(size) {
		// Parse proto directly from the buffered data.
		data, err := c.r.Peek(int(size))
		if err != nil {
			return err
		}
		if err := decompressor(data, uncompressedSize, m); err != nil {
			return err
		}
		// TODO(pmattis): This is a hack to advance the bufio pointer by
		// reading into the same slice that bufio.Reader.Peek
		// returned. In Go 1.5 we'll be able to use
		// bufio.Reader.Discard.
		_, err = io.ReadFull(c.r, data)
		return err
	}

	data := make([]byte, size)
	if _, err := io.ReadFull(c.r, data); err != nil {
		return err
	}
	return decompressor(data, uncompressedSize, m)
}

func ReadNextToken(rw io.ReadWriter) (string, error) {
	br := &byteReader{rw}
	length, err := binary.ReadUvarint(br)
	if err != nil {
		return "", err
	}

	if length > 64*1024 {
		err := delimWrite(rw, []byte("messages over 64k are not allowed"))
		if err != nil {
			return "", err
		}
		return "", ErrTooLarge
	}

	buf := make([]byte, length)
	_, err = io.ReadFull(rw, buf)
	if err != nil {
		return "", err
	}

	if len(buf) == 0 || buf[length-1] != '\n' {
		return "", errors.New("message did not have trailing newline")
	}

	// slice off the trailing newline
	buf = buf[:length-1]

	return string(buf), nil
}

func (t *Transport) decodeArrayish(r reader, val reflect.Value) error {
	usize, err := binary.ReadUvarint(r)
	if err != nil {
		return err
	}
	size := int(usize)

	// Special cases: []byte, string
	isByteArr := val.Kind() == reflect.Array && val.Type().Elem().Kind() == reflect.Uint8
	isString := val.Kind() == reflect.String
	if isByteArr || isString {
		raw := make([]byte, size)
		if _, err := io.ReadFull(r, raw); err != nil {
			return err
		}
		switch {
		case isString:
			val.SetString(string(raw))
		case isByteArr:
			val.SetBytes(raw)
		}
		return nil
	}

	slice := reflect.MakeSlice(val.Type(), size, size)
	for i := 0; i < size; i++ {
		if err := t.decodeValue(r, slice.Index(i)); err != nil {
			return err
		}
	}
	val.Set(slice)
	return nil
}

func NewLevelDbDatastore(dbDir string) (Datastore, error) {
	opts := levigo.NewOptions()
	opts.SetCache(levigo.NewLRUCache(ONE_GIGABYTE))
	opts.SetCreateIfMissing(true)
	opts.SetBlockSize(TWO_FIFTY_SIX_KILOBYTES)
	filter := levigo.NewBloomFilter(BLOOM_FILTER_BITS_PER_KEY)
	opts.SetFilterPolicy(filter)
	db, err := levigo.Open(dbDir, opts)
	if err != nil {
		return nil, err
	}

	ro := levigo.NewReadOptions()

	lastIdBytes, err2 := db.Get(ro, NEXT_ID_KEY)
	if err2 != nil {
		return nil, err2
	}

	lastId := uint64(0)
	if lastIdBytes != nil {
		lastId, err2 = binary.ReadUvarint(bytes.NewBuffer(lastIdBytes))
		if err2 != nil {
			return nil, err2
		}
	}

	wo := levigo.NewWriteOptions()

	return &LevelDbDatastore{db: db, lastIdUsed: lastId, readOptions: ro, writeOptions: wo}, nil
}