From 41345b0527c69b8de85e4afafb92ec5f7a9b03ff Mon Sep 17 00:00:00 2001
From: Alex P <dtk077@gmail.com>
Date: Sat, 8 Nov 2025 00:43:09 +0200
Subject: [PATCH] refactor: use atomic.Pointer for thread-safe inputSource
 access

- Replace mutex-protected inputSource with atomic.Pointer for lock-free reads
- Eliminate ~100 mutex operations per second in audio packet hot path
- Add defer pattern for safer mutex unlock in enable/disable functions
- Add error logging for audio write failures
- Consolidate Makefile lint commands for brevity
---
 Makefile |  6 ++----
 audio.go | 35 ++++++++++++++++++-----------------
 main.go  |  2 +-
 3 files changed, 21 insertions(+), 22 deletions(-)

diff --git a/Makefile b/Makefile
index fc1acb7b..8c2b18ef 100644
--- a/Makefile
+++ b/Makefile
@@ -205,14 +205,12 @@ lint-go-fix: build_audio_deps
 # Run UI linting locally (mirrors GitHub workflow ui-lint.yml)
 lint-ui:
 	@echo "Running UI lint..."
-	@cd ui && npm ci
-	@cd ui && npm run lint
+	@cd ui && npm ci && npm run lint
 
 # Run UI linting with auto-fix
 lint-ui-fix:
 	@echo "Running UI lint with auto-fix..."
-	@cd ui && npm ci
-	@cd ui && npm run lint:fix
+	@cd ui && npm ci && npm run lint:fix
 
 # Legacy alias for UI linting (for backward compatibility)
 ui-lint: lint-ui
diff --git a/audio.go b/audio.go
index 374a98b7..348dda04 100644
--- a/audio.go
+++ b/audio.go
@@ -14,7 +14,7 @@ import (
 var (
 	audioMutex         sync.Mutex
 	outputSource       audio.AudioSource
-	inputSource        audio.AudioSource
+	inputSource        atomic.Pointer[audio.AudioSource]
 	outputRelay        *audio.OutputRelay
 	inputRelay         *audio.InputRelay
 	audioInitialized   bool
@@ -63,13 +63,15 @@ func startAudio() error {
 
 	// Start input audio if not running, USB audio enabled, and input enabled
 	ensureConfigLoaded()
-	if inputSource == nil && audioInputEnabled.Load() && config.UsbDevices != nil && config.UsbDevices.Audio {
+	if inputSource.Load() == nil && audioInputEnabled.Load() && config.UsbDevices != nil && config.UsbDevices.Audio {
 		alsaPlaybackDevice := "hw:1,0" // USB speakers
 
 		// Create CGO audio source
-		inputSource = audio.NewCgoInputSource(alsaPlaybackDevice)
+		newInputSource := audio.NewCgoInputSource(alsaPlaybackDevice)
+		var audioSrc audio.AudioSource = newInputSource
+		inputSource.Store(&audioSrc)
 
-		inputRelay = audio.NewInputRelay(inputSource)
+		inputRelay = audio.NewInputRelay(newInputSource)
 		if err := inputRelay.Start(); err != nil {
 			audioLogger.Error().Err(err).Msg("Failed to start input relay")
 		}
@@ -96,9 +98,9 @@ func stopInputLocked() {
 		inputRelay.Stop()
 		inputRelay = nil
 	}
-	if inputSource != nil {
-		inputSource.Disconnect()
-		inputSource = nil
+	if source := inputSource.Load(); source != nil {
+		(*source).Disconnect()
+		inputSource.Store(nil)
 	}
 }
 
@@ -169,8 +171,8 @@ func SetAudioOutputEnabled(enabled bool) error {
 		}
 	} else {
 		audioMutex.Lock()
+		defer audioMutex.Unlock()
 		stopOutputLocked()
-		audioMutex.Unlock()
 	}
 
 	return nil
@@ -188,8 +190,8 @@ func SetAudioInputEnabled(enabled bool) error {
 		}
 	} else {
 		audioMutex.Lock()
+		defer audioMutex.Unlock()
 		stopInputLocked()
-		audioMutex.Unlock()
 	}
 
 	return nil
@@ -238,23 +240,22 @@ func handleInputTrackForSession(track *webrtc.TrackRemote) {
 			continue // Drop frame but keep reading
 		}
 
-		// Get source in single mutex operation (hot path optimization)
-		audioMutex.Lock()
-		source := inputSource
-		audioMutex.Unlock()
+		// Get source atomically (hot path optimization)
+		source := inputSource.Load()
 
 		if source == nil {
 			continue // No relay, drop frame but keep reading
 		}
 
-		if !source.IsConnected() {
-			if err := source.Connect(); err != nil {
+		if !(*source).IsConnected() {
+			if err := (*source).Connect(); err != nil {
 				continue
 			}
 		}
 
-		if err := source.WriteMessage(0, opusData); err != nil {
-			source.Disconnect()
+		if err := (*source).WriteMessage(0, opusData); err != nil {
+			(*source).Disconnect()
+			audioLogger.Warn().Err(err).Str("track_id", myTrackID).Msg("failed to write audio message")
 		}
 	}
 }
diff --git a/main.go b/main.go
index 4df1a746..5ccd78d9 100644
--- a/main.go
+++ b/main.go
@@ -133,7 +133,7 @@ func Main() {
 	signal.Notify(sigs, syscall.SIGINT, syscall.SIGTERM)
 	<-sigs
 
-	logger.Info().Msg("JetKVM Shutting Down")
+	logger.Log().Msg("JetKVM Shutting Down")
 
 	stopAudio()