higher frame rate, PL meter

main.go

@@ -1,3 +1,6 @@
+//go:build linux
+// +build linux
+
 // netmon – dual-interface network dashboard (curses)
 // WTFPL – 2025-05-16  sneak@sneak.berlin
 package main
@@ -34,6 +37,8 @@ var (
 			"console.aws.amazon.com,console.cloud.google.com,"+
 			"fast.com,cloudflare.com,datavi.be",
 		"comma-separated reachability hosts")
+
+	logFile = flag.String("logfile", "/tmp/rtnetmon.log", "path to log file")
 )
 
 /*────────────────── constants ──────────────────*/
@@ -44,7 +49,14 @@ const (
 	packetLossPings  = 20
 	packetLossPeriod = 5 * time.Second
 	statsHistory     = 300
-	screenRefresh    = 500 * time.Millisecond
+	screenRefresh    = 500 * time.Millisecond // Still used as backup refresh rate
+
+	// Unicode characters for the meter
+	greenDot      = '🟢' // Unicode green circle
+	redDot        = '🔴' // Unicode red circle
+	emptyDot      = '⚪' // Unicode white circle
+	meterWidth    = 6   // Fixed width of the meter
+	maxMeterValue = 10  // Maximum value for the meter
 )
 
 /*────────────────── runtime struct ─────────────*/
@@ -58,6 +70,7 @@ type InterfaceStatus struct {
 	DroppedCount               int
 	LastDrop, LastPing         time.Time
 	SpinFrame                  int
+	MeterValue                 int // Current value for the packet loss meter
 	mu                         sync.RWMutex
 }
 
@@ -200,7 +213,21 @@ func tcpDuration(iface, hp string) time.Duration {
 
 var spins = []rune{'|', '/', '-', '\\'}
 
-func (st *InterfaceStatus) spin() { st.SpinFrame = (st.SpinFrame + 1) % len(spins) }
+// Update to add a channel for signaling UI updates
+var uiUpdateChan = make(chan struct{}, 100) // Buffered channel to avoid blocking
+
+// Advances the spinner frame and signals a UI update
+// This is called only when packets are successfully received,
+// so the spinner only moves when there's actual network activity
+func (st *InterfaceStatus) spin() {
+	st.SpinFrame = (st.SpinFrame + 1) % len(spins)
+	// Signal UI update after spinner changes
+	select {
+	case uiUpdateChan <- struct{}{}:
+	default:
+		// Non-blocking send - if channel is full, just continue
+	}
+}
 
 /*────────────────── screen helpers ─────────────*/
 
@@ -257,9 +284,16 @@ func drawIface(scr tcell.Screen, y, w int, st *InterfaceStatus) int {
 	st.mu.RLock()
 	header := fmt.Sprintf("%s: %s —   %s", st.Name, st.Label, st.IPInfo)
 	spin := spins[st.SpinFrame]
+	meterValue := st.MeterValue
 	st.mu.RUnlock()
+
+	// Create the meter - fixed width of 6 characters
+	meter := createMeter(meterValue, meterWidth)
+
 	put(scr, 0, y+1, "== ", cDefault)
-	put(scr, 3, y+1, string(spin)+" "+header, style)
+	put(scr, 3, y+1, string(spin)+" ", cDefault)
+	put(scr, 5, y+1, meter+" ", cDefault)        // Add the meter after the spinner
+	put(scr, 5+meterWidth+1, y+1, header, style) // Move the header after the meter
 	put(scr, 0, y+2, hline(w), cDefault)
 	y += 4
 
@@ -356,16 +390,51 @@ func drawIface(scr tcell.Screen, y, w int, st *InterfaceStatus) int {
 	return y
 }
 
+// Create a visual meter using green and red dots
+func createMeter(value, width int) string {
+	if value > maxMeterValue {
+		value = maxMeterValue
+	}
+	if value < 0 {
+		value = 0
+	}
+
+	// Calculate how many dots of each color to show
+	redDots := value
+	if redDots > width {
+		redDots = width
+	}
+	greenDots := width - redDots
+
+	// Build the meter string
+	var b strings.Builder
+
+	// Add red dots for unreplied packets
+	for i := 0; i < redDots; i++ {
+		b.WriteRune(redDot)
+	}
+
+	// Add green dots for available capacity
+	for i := 0; i < greenDots; i++ {
+		b.WriteRune(greenDot)
+	}
+
+	return b.String()
+}
+
 /*────────────────── goroutine loops ─────────────*/
 
 func reachLoop(ctx context.Context, st *InterfaceStatus, hosts []string) {
+	logf("Starting reachability monitoring for %s with %d hosts", st.Name, len(hosts))
 	tk := time.NewTicker(time.Second)
 	defer tk.Stop()
 	for {
 		select {
 		case <-ctx.Done():
+			logf("Stopping reachability monitoring for %s", st.Name)
 			return
 		case <-tk.C:
+			// logf("Checking reachability for %s", st.Name) // Too verbose
 			var wg sync.WaitGroup
 			res := make(map[string]bool, len(hosts))
 			mu := sync.Mutex{}
@@ -375,6 +444,11 @@ func reachLoop(ctx context.Context, st *InterfaceStatus, hosts []string) {
 					defer wg.Done()
 					st.mu.Lock()
 					st.TotalICMPReq++
+					// Increase meter value when a packet is sent
+					st.MeterValue++
+					if st.MeterValue > maxMeterValue {
+						st.MeterValue = maxMeterValue
+					}
 					st.mu.Unlock()
 
 					ok := pingOnce(st.Name, host)
@@ -385,18 +459,41 @@ func reachLoop(ctx context.Context, st *InterfaceStatus, hosts []string) {
 					st.mu.Lock()
 					if ok {
 						st.TotalICMPRep++
+						// Decrease meter value when a packet is successfully received
+						st.MeterValue--
+						if st.MeterValue < 0 {
+							st.MeterValue = 0
+						}
+						// Only update spinner when packets are successfully received
 						st.spin()
 					} else {
 						st.DroppedCount++
 						st.LastDrop = time.Now()
+						// For failed pings, we don't decrease the meter value
+						// Trigger UI update on ping failure
+						select {
+						case uiUpdateChan <- struct{}{}:
+						default:
+						}
 					}
 					st.mu.Unlock()
 				}(h)
 			}
 			wg.Wait()
+
+			// Check if reachability status changed
+			statusChanged := false
 			st.mu.Lock()
+			for host, newStatus := range res {
+				if oldStatus, ok := st.Reachable[host]; !ok || oldStatus != newStatus {
+					statusChanged = true
+					break
+				}
+			}
+
 			st.Reachable = res
 			st.LastPing = time.Now()
+
 			// Reset DroppedCount if all hosts are reachable
 			allReachable := true
 			for _, ok := range res {
@@ -407,19 +504,34 @@ func reachLoop(ctx context.Context, st *InterfaceStatus, hosts []string) {
 			}
 			if allReachable {
 				st.DroppedCount = 0
+				// If all hosts are reachable, gradually decay the meter value
+				if st.MeterValue > 0 {
+					st.MeterValue--
+				}
 			}
 			st.mu.Unlock()
+
+			// Always trigger UI update when reachability status changes
+			if statusChanged {
+				select {
+				case uiUpdateChan <- struct{}{}:
+				default:
+				}
+			}
 		}
 	}
 }
 func lossLoop(ctx context.Context, st *InterfaceStatus, hosts []string) {
+	logf("Starting packet loss monitoring for %s with %d hosts", st.Name, len(hosts))
 	tk := time.NewTicker(packetLossPeriod)
 	defer tk.Stop()
 	for {
 		select {
 		case <-ctx.Done():
+			logf("Stopping packet loss monitoring for %s", st.Name)
 			return
 		case <-tk.C:
+			// logf("Checking packet loss for %s", st.Name) // Too verbose
 			var wg sync.WaitGroup
 			res := make(map[string]float64, len(hosts))
 			mu := sync.Mutex{}
@@ -430,42 +542,103 @@ func lossLoop(ctx context.Context, st *InterfaceStatus, hosts []string) {
 					lp := lossPercent(st.Name, host)
 					mu.Lock()
 					res[host] = lp
-					if lp == 0 {
-						st.spin()
-					}
 					mu.Unlock()
+
+					st.mu.Lock()
+					if lp == 0 {
+						// Only update spinner when there's 0% packet loss (successful receipt)
+						st.spin()
+					} else {
+						// Trigger UI update on packet loss
+						select {
+						case uiUpdateChan <- struct{}{}:
+						default:
+						}
+					}
+					st.mu.Unlock()
 				}(h)
 			}
 			wg.Wait()
+
+			// Check if loss status changed
+			statusChanged := false
 			st.mu.Lock()
+			for host, newLoss := range res {
+				if oldLoss, ok := st.Loss[host]; !ok || math.Abs(oldLoss-newLoss) > 0.01 {
+					statusChanged = true
+					break
+				}
+			}
+
 			for k, v := range res {
 				st.Loss[k] = v
 			}
 			st.mu.Unlock()
+
+			// Always trigger UI update when loss status changes
+			if statusChanged {
+				select {
+				case uiUpdateChan <- struct{}{}:
+				default:
+				}
+			}
 		}
 	}
 }
 func tcpLoop(ctx context.Context, st *InterfaceStatus, hosts []string) {
+	logf("Starting TCP monitoring for %s with %d hosts", st.Name, len(hosts))
 	tk := time.NewTicker(time.Second)
 	defer tk.Stop()
 	for {
 		select {
 		case <-ctx.Done():
+			logf("Stopping TCP monitoring for %s", st.Name)
 			return
 		case <-tk.C:
+			// logf("Checking TCP for %s", st.Name) // Too verbose
+			statusChanged := false
+
 			for _, hp := range hosts {
 				ms := float64(tcpDuration(st.Name, hp).Milliseconds())
 				st.mu.Lock()
-				if ms < float64(tcpTimeout.Milliseconds()) {
+
-					st.spin()
+				// Check if TCP latency significantly changed
-				}
 				hist := st.TCP[hp]
+				if len(hist) > 0 {
+					lastMs := hist[len(hist)-1]
+					if math.Abs(lastMs-ms) > 20 { // 20ms threshold for significant change
+						statusChanged = true
+					}
+				} else {
+					// First measurement
+					statusChanged = true
+				}
+
+				if ms < float64(tcpTimeout.Milliseconds()) {
+					// Only update spinner on successful TCP connections
+					st.spin()
+				} else {
+					// Trigger UI update on TCP timeout
+					select {
+					case uiUpdateChan <- struct{}{}:
+					default:
+					}
+				}
+
 				if len(hist) >= statsHistory {
 					hist = hist[1:]
 				}
 				st.TCP[hp] = append(hist, ms)
 				st.mu.Unlock()
 			}
+
+			// Always trigger UI update when TCP status changes significantly
+			if statusChanged {
+				select {
+				case uiUpdateChan <- struct{}{}:
+				default:
+				}
+			}
 		}
 	}
 }
@@ -473,26 +646,54 @@ func tcpLoop(ctx context.Context, st *InterfaceStatus, hosts []string) {
 /*────────────────── UI loop ─────────────────────*/
 
 func uiLoop(ctx context.Context, scr tcell.Screen, a, b *InterfaceStatus, start time.Time) {
-	defer scr.Fini()
+	logf("UI loop started")
-	tk := time.NewTicker(screenRefresh)
+	defer func() {
-	defer tk.Stop()
+		logf("UI loop cleanup")
+		scr.Clear()
+		scr.ShowCursor(0, 0)
+		scr.Fini()
+		logf("Screen finalized")
+	}()
+
+	// Remove the ticker as we'll update on spinner ticks
+	// tk := time.NewTicker(screenRefresh)
+	// defer tk.Stop()
 	spin := 0
+
+	// Function to draw the screen
+	drawScreen := func() {
+		w, _ := scr.Size()
+		scr.Clear()
+		put(scr, 0, 0, hline(w), cDefault)
+		put(scr, 0, 1, fmt.Sprintf("== %c %s", spins[spin%len(spins)], time.Now().Format(time.RFC1123Z)), cDefault)
+		put(scr, 0, 2, hline(w), cDefault)
+		spin++
+		put(scr, 0, 3, "Runtime: "+time.Since(start).Round(time.Second).String(), cDefault)
+		y := 5
+		y = drawIface(scr, y, w, a)
+		_ = drawIface(scr, y, w, b)
+		scr.Show()
+	}
+
+	// Initial draw
+	drawScreen()
+
+	// Even without a ticker, ensure we update at least every second
+	// This is a backup in case there are no spinner updates
+	backupTicker := time.NewTicker(time.Second)
+	defer backupTicker.Stop()
+
 	for {
 		select {
 		case <-ctx.Done():
+			logf("Context cancelled, exiting UI loop")
 			return
-		case <-tk.C:
+		case <-uiUpdateChan:
-			w, _ := scr.Size()
+			// Update on spinner ticks (no rate limiting)
-			scr.Clear()
+			drawScreen()
-			put(scr, 0, 0, hline(w), cDefault)
+		case <-backupTicker.C:
-			put(scr, 0, 1, fmt.Sprintf("== %c %s", spins[spin%len(spins)], time.Now().Format(time.RFC1123Z)), cDefault)
+			// Fallback to ensure we update at least once per second
-			put(scr, 0, 2, hline(w), cDefault)
+			drawScreen()
-			spin++
-			put(scr, 0, 3, "Runtime: "+time.Since(start).Round(time.Second).String(), cDefault)
-			y := 5
-			y = drawIface(scr, y, w, a)
-			_ = drawIface(scr, y, w, b)
-			scr.Show()
 		}
 	}
 }
@@ -508,50 +709,92 @@ var (
 	}
 )
 
+// Simple logging function
+func logf(format string, v ...interface{}) {
+	if logFile == nil || *logFile == "" {
+		return
+	}
+	f, err := os.OpenFile(*logFile, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
+	if err != nil {
+		return // silently fail if we can't log
+	}
+	defer f.Close()
+	fmt.Fprintf(f, time.Now().Format("2006-01-02 15:04:05.000 ")+format+"\n", v...)
+}
+
 func main() {
 	flag.Parse()
+	logf("Starting rtnetmon")
 	reachHosts = strings.Split(*hostCSV, ",")
+	logf("Monitoring interfaces %s and %s", *ifaceA, *ifaceB)
+
+	// Initialize UI update channel
+	uiUpdateChan = make(chan struct{}, 100)
+	logf("UI update channel initialized with buffer size 100")
 
 	newStatus := func(name, label string) *InterfaceStatus {
+		logf("Initializing status for interface %s", name)
 		return &InterfaceStatus{
-			Name:      name,
+			Name:       name,
-			Label:     label,
+			Label:      label,
-			IPInfo:    fetchIPInfo(name),
+			IPInfo:     fetchIPInfo(name),
-			Reachable: map[string]bool{},
+			Reachable:  map[string]bool{},
-			Loss:      map[string]float64{},
+			Loss:       map[string]float64{},
-			TCP:       map[string][]float64{},
+			TCP:        map[string][]float64{},
+			MeterValue: 0, // Initialize meter value to 0
 		}
 	}
 	a, b := newStatus(*ifaceA, *labelA), newStatus(*ifaceB, *labelB)
 
+	logf("Initializing screen")
 	scr, err := tcell.NewScreen()
 	if err != nil {
+		logf("Error creating screen: %v", err)
 		panic(err)
 	}
 	if err = scr.Init(); err != nil {
+		logf("Error initializing screen: %v", err)
 		panic(err)
 	}
+	logf("Screen initialized")
 
 	ctx, cancel := context.WithCancel(context.Background())
 	defer cancel()
 
 	sig := make(chan os.Signal, 1)
 	signal.Notify(sig, os.Interrupt, syscall.SIGTERM)
-	go func() { <-sig; cancel() }()
-
 	go func() {
+		s := <-sig
+		logf("Signal received: %v", s)
+		cancel()
+	}()
+
+	// Event polling loop with logging
+	go func() {
+		logf("Starting keyboard event loop")
 		for {
 			if ev := scr.PollEvent(); ev != nil {
+				logf("Event received: %T", ev)
 				if ke, ok := ev.(*tcell.EventKey); ok {
+					logf("Key event: %v, rune: %c", ke.Key(), ke.Rune())
 					if ke.Key() == tcell.KeyCtrlC || ke.Rune() == 'q' {
+						logf("Quit key detected")
 						cancel()
 						return
 					}
 				}
+
+				// Trigger UI update on any event
+				select {
+				case uiUpdateChan <- struct{}{}:
+				default:
+				}
 			}
 		}
 	}()
 
+	// Start monitoring goroutines
+	logf("Starting monitoring goroutines")
 	go reachLoop(ctx, a, reachHosts)
 	go reachLoop(ctx, b, reachHosts)
 	go lossLoop(ctx, a, packetLossHosts)
@@ -559,7 +802,9 @@ func main() {
 	go tcpLoop(ctx, a, tcpTestHosts)
 	go tcpLoop(ctx, b, tcpTestHosts)
 
+	logf("Starting UI loop")
 	uiLoop(ctx, scr, a, b, time.Now())
+	logf("UI loop exited, program ending")
 }
 
 /*────────────────── Extra packet-loss hosts ─────