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fake_backend.go
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fake_backend.go
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package signalflow
import (
"bytes"
"context"
"encoding/binary"
"encoding/json"
"errors"
"fmt"
"log"
"net"
"net/http"
"net/http/httptest"
"strings"
"sync"
"time"
"github.com/gorilla/websocket"
"github.com/signalfx/signalfx-go/idtool"
"github.com/signalfx/signalfx-go/signalflow/messages"
)
var upgrader = websocket.Upgrader{} // use default options
type tsidVal struct {
TSID idtool.ID
Val float64
}
// FakeBackend is useful for testing, both internal to this package and
// externally. It supports basic messages and allows for the specification of
// metadata and data messages that map to a particular program.
type FakeBackend struct {
sync.Mutex
AccessToken string
authenticated bool
conns map[*websocket.Conn]bool
received []map[string]interface{}
metadataByTSID map[idtool.ID]*messages.MetadataProperties
dataByTSID map[idtool.ID]*float64
tsidsByProgram map[string][]idtool.ID
programErrors map[string]string
runningJobsByProgram map[string]int
cancelFuncsByHandle map[string]context.CancelFunc
server *httptest.Server
handleIdx int
}
func (f *FakeBackend) ServeHTTP(w http.ResponseWriter, r *http.Request) {
ctx, cancel := context.WithCancel(context.Background())
c, err := upgrader.Upgrade(w, r, nil)
if err != nil {
panic(err)
}
f.registerConn(c)
defer c.Close()
defer cancel()
textMsgs := make(chan string)
binMsgs := make(chan []byte)
go func() {
for {
var err error
select {
case m := <-textMsgs:
err = c.WriteMessage(websocket.TextMessage, []byte(m))
case m := <-binMsgs:
err = c.WriteMessage(websocket.BinaryMessage, m)
case <-ctx.Done():
f.unregisterConn(c)
return
}
if err != nil {
log.Printf("Could not write message: %v", err)
}
}
}()
for {
_, message, err := c.ReadMessage()
if err != nil {
log.Println("read err:", err)
break
}
var in map[string]interface{}
if err := json.Unmarshal(message, &in); err != nil {
log.Println("error unmarshalling: ", err)
}
f.received = append(f.received, in)
err = f.handleMessage(ctx, in, textMsgs, binMsgs)
if err != nil {
log.Printf("Error handling fake backend message, closing connection: %v", err)
return
}
}
}
func (f *FakeBackend) registerConn(conn *websocket.Conn) {
f.Lock()
f.conns[conn] = true
f.Unlock()
}
func (f *FakeBackend) unregisterConn(conn *websocket.Conn) {
f.Lock()
delete(f.conns, conn)
f.Unlock()
}
func (f *FakeBackend) handleMessage(ctx context.Context, message map[string]interface{}, textMsgs chan<- string, binMsgs chan<- []byte) error {
f.Lock()
defer f.Unlock()
typ, ok := message["type"].(string)
if !ok {
textMsgs <- `{"type": "error"}`
return nil
}
switch typ {
case "authenticate":
token, _ := message["token"].(string)
if f.AccessToken == "" || token == f.AccessToken {
textMsgs <- `{"type": "authenticated"}`
f.authenticated = true
} else {
textMsgs <- `{"type": "error", "message": "Invalid auth token"}`
return errors.New("bad auth token")
}
case "stop":
if cancel := f.cancelFuncsByHandle[message["handle"].(string)]; cancel != nil {
cancel()
}
case "execute":
if !f.authenticated {
return errors.New("not authenticated")
}
program, _ := message["program"].(string)
ch, _ := message["channel"].(string)
if errMsg := f.programErrors[program]; errMsg != "" {
textMsgs <- fmt.Sprintf(`{"type": "error", "message": "%s", "channel": "%s"}`, errMsg, ch)
}
programTSIDs := f.tsidsByProgram[program]
handle := fmt.Sprintf("handle-%d", f.handleIdx)
f.handleIdx++
execCtx, cancel := context.WithCancel(ctx)
f.cancelFuncsByHandle[handle] = cancel
log.Printf("Executing SignalFlow program %s with tsids %v and handle %s", program, programTSIDs, handle)
f.runningJobsByProgram[program]++
var resolutionMs int
for _, tsid := range programTSIDs {
if md := f.metadataByTSID[tsid]; md != nil {
if md.ResolutionMS > resolutionMs {
resolutionMs = md.ResolutionMS
}
}
}
messageResMs, _ := message["resolution"].(float64)
if messageResMs != 0.0 {
resolutionMs = int(messageResMs)
}
if resolutionMs == 0 {
resolutionMs = 1000
}
textMsgs <- fmt.Sprintf(`{"type": "control-message", "channel": "%s", "event": "STREAM_START"}`, ch)
textMsgs <- fmt.Sprintf(`{"type": "control-message", "channel": "%s", "event": "JOB_START", "handle": "%s"}`, ch, handle)
textMsgs <- fmt.Sprintf(`{"type": "message", "channel": "%s", "logicalTimestampMs": 1464736034000, "message": {"contents": {"resolutionMs" : %d}, "messageCode": "JOB_RUNNING_RESOLUTION", "timestampMs": 1464736033000}}`, ch, int64(resolutionMs))
for _, tsid := range programTSIDs {
if md := f.metadataByTSID[tsid]; md != nil {
propJSON, err := json.Marshal(md)
if err != nil {
log.Printf("Error serializing metadata to json: %v", err)
continue
}
textMsgs <- fmt.Sprintf(`{"type": "metadata", "tsId": "%s", "channel": "%s", "properties": %s}`, tsid, ch, propJSON)
}
}
// Send data periodically until the connection is closed.
go func() {
t := time.NewTicker(time.Duration(resolutionMs) * time.Millisecond)
for {
select {
case <-execCtx.Done():
f.Lock()
f.runningJobsByProgram[program]--
f.Unlock()
return
case <-t.C:
f.Lock()
valsWithTSID := []tsidVal{}
for _, tsid := range programTSIDs {
if data := f.dataByTSID[tsid]; data != nil {
valsWithTSID = append(valsWithTSID, tsidVal{TSID: tsid, Val: *data})
}
}
binMsgs <- makeDataMessage(ch, valsWithTSID)
f.Unlock()
}
}
}()
}
return nil
}
func makeDataMessage(channel string, valsWithTSID []tsidVal) []byte {
var ch [16]byte
copy(ch[:], channel)
header := messages.BinaryMessageHeader{
Version: 1,
MessageType: 5,
Flags: 0,
Reserved: 0,
Channel: ch,
}
w := new(bytes.Buffer)
binary.Write(w, binary.BigEndian, &header)
dataHeader := messages.DataMessageHeader{
TimestampMillis: uint64(time.Now().Unix() * 1000),
ElementCount: uint32(len(valsWithTSID)),
}
binary.Write(w, binary.BigEndian, &dataHeader)
for i := range valsWithTSID {
var valBytes [8]byte
buf := new(bytes.Buffer)
binary.Write(buf, binary.BigEndian, valsWithTSID[i].Val)
copy(valBytes[:], buf.Bytes())
payload := messages.DataPayload{
Type: messages.ValTypeDouble,
TSID: valsWithTSID[i].TSID,
Val: valBytes,
}
binary.Write(w, binary.BigEndian, &payload)
}
return w.Bytes()
}
func (f *FakeBackend) Start() {
f.metadataByTSID = map[idtool.ID]*messages.MetadataProperties{}
f.dataByTSID = map[idtool.ID]*float64{}
f.tsidsByProgram = map[string][]idtool.ID{}
f.programErrors = map[string]string{}
f.runningJobsByProgram = map[string]int{}
f.cancelFuncsByHandle = map[string]context.CancelFunc{}
f.conns = map[*websocket.Conn]bool{}
f.server = httptest.NewServer(f)
}
func (f *FakeBackend) Stop() {
f.KillExistingConnections()
f.server.Close()
}
func (f *FakeBackend) Restart() {
l, err := net.Listen("tcp", f.server.Listener.Addr().String())
if err != nil {
panic("Could not relisten: " + err.Error())
}
f.server = httptest.NewUnstartedServer(f)
f.server.Listener = l
f.server.Start()
}
func (f *FakeBackend) Client() (*Client, error) {
return NewClient(StreamURL(f.URL()), AccessToken(f.AccessToken))
}
func (f *FakeBackend) AddProgramError(program string, errorMsg string) {
f.Lock()
f.programErrors[program] = errorMsg
f.Unlock()
}
func (f *FakeBackend) AddProgramTSIDs(program string, tsids []idtool.ID) {
f.Lock()
f.tsidsByProgram[program] = tsids
f.Unlock()
}
func (f *FakeBackend) AddTSIDMetadata(tsid idtool.ID, props *messages.MetadataProperties) {
f.Lock()
f.metadataByTSID[tsid] = props
f.Unlock()
}
func (f *FakeBackend) SetTSIDFloatData(tsid idtool.ID, val float64) {
f.Lock()
f.dataByTSID[tsid] = &val
f.Unlock()
}
func (f *FakeBackend) RemoveTSIDData(tsid idtool.ID) {
f.Lock()
delete(f.dataByTSID, tsid)
f.Unlock()
}
func (f *FakeBackend) URL() string {
return strings.Replace(f.server.URL, "http", "ws", 1)
}
func (f *FakeBackend) KillExistingConnections() {
f.Lock()
for conn := range f.conns {
conn.Close()
}
f.Unlock()
}
// RunningJobsForProgram returns how many currently executing jobs there are
// for a particular program text.
func (f *FakeBackend) RunningJobsForProgram(program string) int {
f.Lock()
defer f.Unlock()
return f.runningJobsByProgram[program]
}
func NewRunningFakeBackend() *FakeBackend {
f := &FakeBackend{
AccessToken: "abcd",
}
f.Start()
return f
}