/
binary.go
185 lines (159 loc) · 3.92 KB
/
binary.go
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package messages
import (
"bytes"
"compress/gzip"
"encoding/binary"
"errors"
"fmt"
"io"
"math"
"github.com/signalfx/signalfx-go/idtool"
)
type DataPayload struct {
Type ValType
TSID idtool.ID
Val [8]byte
}
// Value returns the numeric value as an interface{}.
func (dp *DataPayload) Value() interface{} {
switch dp.Type {
case ValTypeLong:
return dp.Int64()
case ValTypeDouble:
return dp.Float64()
case ValTypeInt:
return dp.Int32()
default:
return nil
}
}
func (dp *DataPayload) Int64() int64 {
n := binary.BigEndian.Uint64(dp.Val[:])
return int64(n)
}
func (dp *DataPayload) Float64() float64 {
bits := binary.BigEndian.Uint64(dp.Val[:])
return math.Float64frombits(bits)
}
func (dp *DataPayload) Int32() int32 {
var n int32
_ = binary.Read(bytes.NewBuffer(dp.Val[:]), binary.BigEndian, &n)
return n
}
// DataMessage is a set of datapoints that share a common timestamp
type DataMessage struct {
BaseMessage
BaseChannelMessage
TimestampedMessage
Payloads []DataPayload
}
func (dm *DataMessage) String() string {
pls := make([]map[string]interface{}, 0)
for _, pl := range dm.Payloads {
pls = append(pls, map[string]interface{}{
"type": pl.Type,
"tsid": pl.TSID,
"value": pl.Value(),
})
}
return fmt.Sprintf("%v", map[string]interface{}{
"channel": dm.Channel(),
"timestamp": dm.Timestamp(),
"payloads": pls,
})
}
type DataMessageHeader struct {
TimestampMillis uint64
ElementCount uint32
}
type ValType uint8
const (
ValTypeLong ValType = 1
ValTypeDouble ValType = 2
ValTypeInt ValType = 3
)
func (vt ValType) String() string {
switch vt {
case ValTypeLong:
return "long"
case ValTypeDouble:
return "double"
case ValTypeInt:
return "int32"
}
return "Unknown"
}
// BinaryMessageHeader represents the first 20 bytes of every binary websocket
// message from the backend.
// https://developers.signalfx.com/signalflow_analytics/rest_api_messages/stream_messages_specification.html#_binary_encoding_of_websocket_messages
type BinaryMessageHeader struct {
Version uint8
MessageType uint8
Flags uint8
Reserved uint8
Channel [16]byte
}
const (
compressed uint8 = 1 << iota
jsonEncoded = 1 << iota
)
func parseBinaryHeader(msg []byte) (string, bool /* isCompressed */, bool /* isJSON */, []byte /* rest of message */, error) {
if len(msg) <= 20 {
return "", false, false, nil, fmt.Errorf("expected SignalFlow message of at least 21 bytes, got %d bytes", len(msg))
}
r := bytes.NewReader(msg[:20])
var header BinaryMessageHeader
err := binary.Read(r, binary.BigEndian, &header)
if err != nil {
return "", false, false, nil, err
}
isCompressed := header.Flags&compressed != 0
isJSON := header.Flags&jsonEncoded != 0
return string(header.Channel[:bytes.IndexByte(header.Channel[:], 0)]), isCompressed, isJSON, msg[20:], err
}
func parseBinaryMessage(msg []byte) (Message, error) {
channel, isCompressed, isJSON, rest, err := parseBinaryHeader(msg)
if err != nil {
return nil, err
}
if isCompressed {
reader, err := gzip.NewReader(bytes.NewReader(rest))
if err != nil {
return nil, err
}
rest, err = io.ReadAll(reader)
if err != nil {
return nil, err
}
}
if isJSON {
return nil, errors.New("cannot handle json binary message")
}
r := bytes.NewReader(rest[:12])
var header DataMessageHeader
err = binary.Read(r, binary.BigEndian, &header)
if err != nil {
return nil, err
}
var payloads []DataPayload
for i := 0; i < int(header.ElementCount); i++ {
r := bytes.NewReader(rest[12+17*i : 12+17*(i+1)])
var payload DataPayload
if err := binary.Read(r, binary.BigEndian, &payload); err != nil {
return nil, err
}
payloads = append(payloads, payload)
}
return &DataMessage{
BaseMessage: BaseMessage{
Typ: DataType,
},
BaseChannelMessage: BaseChannelMessage{
Chan: channel,
},
TimestampedMessage: TimestampedMessage{
TimestampMillis: header.TimestampMillis,
},
Payloads: payloads,
}, nil
}