up

internal/cat/cat.go

@@ -57,6 +57,7 @@ type RigState struct {
 // Manager owns the active backend and runs the polling loop.
 type Manager struct {
 	mu      sync.RWMutex
+	startMu sync.Mutex // serializes Start/Stop so concurrent calls can't leak a poller
 	state   RigState
 	emit    func(RigState)
 	backend Backend
@@ -115,7 +116,13 @@ func (m *Manager) State() RigState {
 // state.Error rather than returned, so the UI can keep retrying via the
 // poll loop on next reconnect attempt.
 func (m *Manager) Start(b Backend) {
-	m.Stop()
+	// Serialize the whole stop-old-then-start-new sequence. Two concurrent
+	// Start (or Start+Stop) calls could otherwise interleave and leave the
+	// previous poll goroutine alive — two pollers then fight, e.g. flipping
+	// OmniRig Rig1/Rig2 endlessly when the user reselects a rig.
+	m.startMu.Lock()
+	defer m.startMu.Unlock()
+	m.stopLocked()
 	m.mu.Lock()
 	m.stopCh = make(chan struct{})
 	m.doneCh = make(chan struct{})
@@ -134,6 +141,18 @@ func (m *Manager) Start(b Backend) {
 
 // Stop signals the CAT goroutine to disconnect and waits for it to exit.
 func (m *Manager) Stop() {
+	m.startMu.Lock()
+	defer m.startMu.Unlock()
+	m.stopLocked()
+	m.mu.Lock()
+	m.state = RigState{Enabled: false}
+	m.mu.Unlock()
+	m.emitState()
+}
+
+// stopLocked tears down any running poller and blocks until it exits. The
+// caller must hold startMu so it can't race a concurrent Start.
+func (m *Manager) stopLocked() {
 	m.mu.Lock()
 	stop := m.stopCh
 	done := m.doneCh
@@ -148,10 +167,6 @@ func (m *Manager) Stop() {
 	if done != nil {
 		<-done
 	}
-	m.mu.Lock()
-	m.state = RigState{Enabled: false}
-	m.mu.Unlock()
-	m.emitState()
 }
 
 // SetFrequency dispatches a SetFreq call to the CAT goroutine.