Golang femebe.Message类代码示例

func (s *Startup) FillMessage(m *femebe.Message) {
	buf := bytes.NewBuffer(make([]byte, 0, 1024))

	// Startup-message type word
	buf.Write([]byte{0x00, 0x03, 0x00, 0x00})

	for name, value := range s.Params {
		femebe.WriteCString(buf, name)
		femebe.WriteCString(buf, value)
	}

	buf.Write([]byte{'\000'})

	m.InitFromBytes(femebe.MSG_TYPE_FIRST, buf.Bytes())
}

func TestBackendKeyReading(t *testing.T) {
	buf := bytes.Buffer{}
	const PID = 1234
	const KEY = 5768
	femebe.WriteInt32(&buf, PID)
	femebe.WriteInt32(&buf, KEY)

	var m femebe.Message
	m.InitFromBytes(MSG_BACKEND_KEY_DATA_K, buf.Bytes())

	kd, err := ReadBackendKeyData(&m)
	if err != nil {
		t.Fatal()
	}

	if kd.pid != PID {
		t.Fatal()
	}

	if kd.key != KEY {
		t.Fatal()
	}
}

// Process a log message, sending it to the client.
func processLogMsg(die dieCh, lpc *logplexc.Client, msgInit msgInit,
	sr *serveRecord, exit exitFn) {
	var m femebe.Message

	for {
		// Poll request to exit
		select {
		case <-die:
			return
		default:
			break
		}

		msgInit(&m, exit)

		// Refuse to handle any log message above an arbitrary
		// size.  Furthermore, exit the worker, closing the0
		// connection, so that the client doesn't even bother
		// to wait for this process to drain the oversized
		// item and anything following it; these will be
		// dropped.  It's on the client to gracefully handle
		// the error and re-connect after this happens.
		if m.Size() > 1*MB {
			exit("client %q sent oversized log record")
		}

		payload, err := m.Force()
		if err != nil {
			exit("could not retrieve payload of message: %v",
				err)
		}

		var lr logRecord
		parseLogRecord(&lr, payload, exit)
		processLogRec(&lr, lpc, sr, exit)
	}
}

func TestStartupSerDes(t *testing.T) {
	ms, _ := newTestClientStream(t)
	var m femebe.Message
	s := Startup{Params: make(map[string]string)}

	s.Params["hello"] = "world"
	s.Params["goodbye"] = "world"
	s.Params["glory"] = "spite"

	s.FillMessage(&m)
	ms.Send(&m)

	var deserM femebe.Message
	ms.Next(&deserM)

	serBytes, _ := m.Force()
	deserBytes, _ := deserM.Force()
	if !bytes.Equal(serBytes, deserBytes) {
		t.Fatal()
	}
}

// Process the identity ('I') message, reporting the identity therein.
func processIdentMsg(msgInit msgInit, exit exitFn) string {
	var m femebe.Message

	msgInit(&m, exit)

	// Read the remote system identifier string
	if m.MsgType() != 'I' {
		exit("expected identification ('I') message, "+
			"but received %c", m.MsgType())
	}

	// hard-coded lengh limit, but it's very generous
	if m.Size() > 10*KB {
		log.Printf("oversized message string, msg size is %d",
			m.Size())
	}

	s, err := femebe.ReadCString(m.Payload())
	if err != nil {
		exit("couldn't read identification string: %v",
			err)
	}

	return s
}

// Read the version message, calling exit if this is not a supported
// version.
func processVerMsg(msgInit msgInit, exit exitFn) {
	var m femebe.Message

	msgInit(&m, exit)

	if m.MsgType() != 'V' {
		exit("expected version ('V') message, "+
			"but received %c", m.MsgType())
	}

	// hard-coded lengh limit, but it's very generous
	if m.Size() > 10*KB {
		log.Printf("oversized message string, msg size is %d",
			m.Size())
	}

	s, err := femebe.ReadCString(m.Payload())
	if err != nil {
		exit("couldn't read version string: %v", err)
	}

	if !strings.HasPrefix(s, "PG-9.2.") ||
		!strings.HasSuffix(s, "/logfebe-1") {
		exit("protocol version not supported: %s", s)
	}
}

func ReadStartupMessage(m *femebe.Message) (*Startup, error) {
	var err error

	if remainingSz := m.Size() - 4; remainingSz > 10000 {
		// Startup packets longer than this are considered
		// invalid.  Copied from the PostgreSQL source code.
		err = ErrTooBig{fmt.Errorf(
			"Rejecting oversized startup packet: got %v",
			m.Size())}
		return nil, err
	} else if remainingSz < 4 {
		// We expect all initialization messages to
		// have at least a 4-byte header
		err = ErrWrongSize{
			fmt.Errorf(
				"Expected message of at least 4 bytes; got %v",
				remainingSz)}
		return nil, err
	}

	body, err := m.Force()
	if err != nil {
		return nil, err
	}

	var b femebe.Reader
	b.InitReader(body)
	protoVer, _ := femebe.ReadInt32(&b)

	const SUPPORTED_PROTOVER = 0x00030000
	if protoVer != SUPPORTED_PROTOVER {
		err = ErrStartupVersion{
			fmt.Errorf("bad version: got %x expected %x",
				protoVer, SUPPORTED_PROTOVER)}
		return nil, err
	}

	params := make(map[string]string)
	for remaining := b.Len(); remaining > 1; {
		key, err := femebe.ReadCString(&b)
		if err != nil {
			return nil, err
		}

		val, err := femebe.ReadCString(&b)
		if err != nil {
			return nil, err
		}

		remaining -= len(key) + len(val) + 2 /* null bytes */
		params[key] = val
	}

	// Fidelity check on the startup packet, whereby the last byte
	// must be a NUL.
	if d, _ := femebe.ReadByte(&b); d != '\000' {
		return nil, ErrStartupFmt{
			errors.New("malformed startup packet")}
	}

	return &Startup{params}, nil
}