wip: broker packet refactor

broker.go

@@ -4,6 +4,8 @@ import (
 	"errors"
 	"fmt"
 	"sync"
+
+	"golang.org/x/exp/slog"
 )
 
 type BrokerRequest struct {
@@ -23,15 +25,6 @@ type Broker struct {
 	unsubCh chan BrokerClient
 }
 
-func NewBroker(bufsize int) *Broker {
-	b := &Broker{
-		subs:      make(map[string]chan Frame),
-		publishCh: make(chan BrokerRequest, 3),
-		subsCh:    make(chan BrokerClient, 3),
-		unsubCh:   make(chan BrokerClient, 3),
-	}
-	return b
-}
 
 // Start runs the broker and sends messages to the subscribers (but not the sender)
 func (b *Broker) Start() {
@@ -90,12 +83,23 @@ func (b *Broker) Unsubscribe(name string) {
 
 
 type JBroker struct {
-	subs map[string] chan CANDumpJSON // contains the channel for each subsciber
+	subs map[string] chan CANDumpEntry // contains the channel for each subsciber
 
+	logger *slog.Logger
 	lock sync.RWMutex
+	bufsize int // size of chan buffer in elements.
 }
 
-func (b *JBroker) Subscribe(name string) (ch chan CANDumpJSON, err error) {
+
+func NewBroker(bufsize int, logger *slog.Logger) *JBroker {
+	return &JBroker{
+		subs: make(map[string]chan CANDumpEntry),
+		logger: logger,
+		bufsize: bufsize,
+	}
+}
+
+func (b *JBroker) Subscribe(name string) (ch chan CANDumpEntry, err error) {
 	// get rw lock.
 	b.lock.Lock()
 	defer b.lock.Unlock()
@@ -103,36 +107,33 @@ func (b *JBroker) Subscribe(name string) (ch chan CANDumpJSON, err error) {
 	if ok {
 		return nil, errors.New("name already in use")
 	}
-	ch = make(chan CANDumpJSON, 10)
+	b.logger.Info("new subscriber", "name", name)
+	ch = make(chan CANDumpEntry, b.bufsize)
 
 	return
 }
 
 func (b *JBroker) Unsubscribe(name string) {
-	// if the channel is in use, close it, else do nothing.
+	// remove the channel from the map. We don't need to close it.
 	b.lock.Lock()
 	defer b.lock.Unlock()
-	ch, ok := b.subs[name]
-	if ok {
-		close(ch)
-	}
 	delete(b.subs, name)
 }
 
-func (b *JBroker) Publish(sender string, message CANDumpJSON) {
-	go func() {
-		b.lock.RLock()
-		defer b.lock.RUnlock()
-		for name, ch := range b.subs {
-			if name == sender {
-				continue
-			}
-			// non blocking send.
-			select {
-			case ch <- message:
-			default:
-			}
+func (b *JBroker) Publish(sender string, message CANDumpEntry) {
+	b.lock.RLock()
+	defer b.lock.RUnlock()
+	for name, ch := range b.subs {
+		if name == sender {
+			continue
 		}
+		// non blocking send.
+		select {
+		case ch <- message:
+			b.logger.Debug("sent message", "dest", name, "src", sender)
+		default:
+			b.logger.Warn("recipient buffer full", "dest", name)
+		}
+	}
 
-	}()
 }

cmd/gotelem/cli/server.go

@@ -2,6 +2,7 @@ package cli
 
 import (
 	"encoding/binary"
+	"encoding/json"
 	"fmt"
 	"net"
 	"os"
@@ -45,7 +46,7 @@ type testThing func(cCtx *cli.Context, broker *gotelem.Broker, logger *slog.Logg
 
 type service interface {
 	fmt.Stringer
-	Start(cCtx *cli.Context, broker *gotelem.Broker, logger *slog.Logger) (err error)
+	Start(cCtx *cli.Context, broker *gotelem.JBroker, logger *slog.Logger) (err error)
 	Status()
 }
 
@@ -68,12 +69,11 @@ func serve(cCtx *cli.Context) error {
 	logger := slog.New(slog.NewTextHandler(os.Stderr))
 
 	slog.SetDefault(logger)
-	broker := gotelem.NewBroker(3)
+	broker := gotelem.NewBroker(3, logger.WithGroup("broker"))
 
 	done := make(chan struct{})
 	// start the can listener
 
-	go broker.Start()
 
 
 	wg := sync.WaitGroup{}
@@ -176,27 +176,31 @@ func (c *CanLoggerService) Status() {
 }
 
 
-func (c *CanLoggerService)  Start(cCtx *cli.Context, broker *gotelem.Broker, l *slog.Logger) (err error) {
-	rxCh := broker.Subscribe("candump")
+func (c *CanLoggerService)  Start(cCtx *cli.Context, broker *gotelem.JBroker, l *slog.Logger) (err error) {
+	rxCh, err := broker.Subscribe("candump")
+	if err != nil {
+		return err
+	}
 	t := time.Now()
 	fname := fmt.Sprintf("candump_%d-%02d-%02dT%02d.%02d.%02d.txt",
 		t.Year(), t.Month(), t.Day(), t.Hour(), t.Minute(), t.Second())
 	
 	l.Info("logging to file", "filename", fname)
 
-	cw, err := gotelem.OpenCanWriter(fname)
+	f, err := os.Create(fname)
 	if err != nil {
 		l.Error("error opening file", "filename", fname, "err", err)
 		return
 	}
+	enc := json.NewEncoder(f)
 
 	for {
 		select {
 		case msg := <-rxCh:
 
-			cw.Send(&msg)
+			enc.Encode(msg)
 		case <-cCtx.Done():
-			cw.Close()
+			f.Close()
 			return
 		}
 	}
@@ -216,18 +220,21 @@ func (x *XBeeService) Status() {
 }
 
 
-func (x *XBeeService) Start(cCtx *cli.Context, broker *gotelem.Broker, logger *slog.Logger) (err error) {
+func (x *XBeeService) Start(cCtx *cli.Context, broker *gotelem.JBroker, logger *slog.Logger) (err error) {
 	if cCtx.String("xbee") == "" {
 		logger.Info("not using xbee")
 		return
 	}
-	transport, err := xbee.ParseDeviceString(cCtx.String("device"))
+	transport, err := xbee.ParseDeviceString(cCtx.String("xbee"))
 	if err != nil {
 		logger.Error("failed to open xbee string", "err", err)
 		return
 	}
 	logger.Info("using xbee device", "transport", transport)
-	rxCh := broker.Subscribe("xbee")
+	rxCh, err := broker.Subscribe("xbee")
+	if err != nil {
+		logger.Error("failed to subscribe to broker", "err", err)
+	}
 
 	x.session, err = xbee.NewSession(transport, logger.With("device", transport.Type()))
 	if err != nil {
@@ -245,8 +252,7 @@ func (x *XBeeService) Start(cCtx *cli.Context, broker *gotelem.Broker, logger *s
 			logger.Info("got msg", "msg", msg)
 			buf := make([]byte, 0)
 
-			buf = binary.BigEndian.AppendUint32(buf, msg.Id)
-			buf = append(buf, msg.Data...)
+			// FIXME: implement serialzation over xbee.
 
 			_, err := x.session.Write(buf)
 			if err != nil {

cmd/skylabify/skylabify.go

@@ -92,7 +92,7 @@ func run(ctx *cli.Context) (err error) {
 
 		segments := strings.Split(dumpLine, " ")
 
-		var cd gotelem.CANDumpJSON
+		var cd gotelem.CANDumpEntry
 		// this is cursed but easiest way to get a float from a string.
 		fmt.Sscanf(segments[0], "(%g)", &cd.Timestamp)
 

skylab_logger.go

@@ -12,7 +12,7 @@ import (
 // CanWriter
 type CanWriter struct {
 	output  *os.File
-	cd      CANDumpJSON
+	cd      CANDumpEntry
 	jsonBuf []byte
 }
 
@@ -51,7 +51,7 @@ func OpenCanWriter(name string) (*CanWriter, error) {
 	return cw, nil
 }
 
-type CANDumpJSON struct {
+type CANDumpEntry struct {
 	Timestamp float64       `json:"ts"`
 	Id        uint64        `json:"id"`
 	Data      skylab.Packet `json:"data"`