feat(audio): improve socket handling and validation performance

- Add retry logic for socket file removal and listener creation
- Optimize message writing by combining header and data writes
- Move socket paths from temp dir to /var/run
- Refactor OPUS parameter lookup to use map for better readability
- Simplify validation functions for better performance in hotpaths

internal/audio/core_validation.go

@@ -72,23 +72,12 @@ func ValidateZeroCopyFrame(frame *ZeroCopyAudioFrame) error {
 }
 
 // ValidateBufferSize validates buffer size parameters with enhanced boundary checks
-// Optimized to use AudioConfigCache for frequently accessed values
+// Optimized for minimal overhead in hotpath
 func ValidateBufferSize(size int) error {
 	if size <= 0 {
 		return fmt.Errorf("%w: buffer size %d must be positive", ErrInvalidBufferSize, size)
 	}
-
-	// Fast path: Check against cached max frame size
-	cache := Config
-	maxFrameSize := cache.MaxAudioFrameSize
-
-	// Most common case: validating a buffer that's sized for audio frames
-	if maxFrameSize > 0 && size <= maxFrameSize {
-		return nil
-	}
-
-	// Use SocketMaxBuffer as the upper limit for general buffer validation
-	// This allows for socket buffers while still preventing extremely large allocations
+	// Single boundary check using pre-cached value
 	if size > Config.SocketMaxBuffer {
 		return fmt.Errorf("%w: buffer size %d exceeds maximum %d",
 			ErrInvalidBufferSize, size, Config.SocketMaxBuffer)
@@ -219,91 +208,42 @@ func ValidateOutputIPCConfig(sampleRate, channels, frameSize int) error {
 }
 
 // ValidateSampleRate validates audio sample rate values
-// Optimized to use AudioConfigCache for frequently accessed values
+// Optimized for minimal overhead in hotpath
 func ValidateSampleRate(sampleRate int) error {
 	if sampleRate <= 0 {
 		return fmt.Errorf("%w: sample rate %d must be positive", ErrInvalidSampleRate, sampleRate)
 	}
-
-	// Fast path: Check against cached sample rate first
-	cache := Config
-	cachedRate := cache.SampleRate
-
-	// Most common case: validating against the current sample rate
-	if sampleRate == cachedRate {
-		return nil
-	}
-
-	// Slower path: check against all valid rates
-	validRates := Config.ValidSampleRates
-	for _, rate := range validRates {
+	// Direct validation against valid rates
+	for _, rate := range Config.ValidSampleRates {
 		if sampleRate == rate {
 			return nil
 		}
 	}
-	return fmt.Errorf("%w: sample rate %d not in supported rates %v",
-		ErrInvalidSampleRate, sampleRate, validRates)
+	return fmt.Errorf("%w: sample rate %d not in valid rates %v",
+		ErrInvalidSampleRate, sampleRate, Config.ValidSampleRates)
 }
 
 // ValidateChannelCount validates audio channel count
-// Optimized to use AudioConfigCache for frequently accessed values
+// Optimized for minimal overhead in hotpath
 func ValidateChannelCount(channels int) error {
 	if channels <= 0 {
 		return fmt.Errorf("%w: channel count %d must be positive", ErrInvalidChannels, channels)
 	}
-
-	// Fast path: Check against cached channels first
-	cache := Config
-	cachedChannels := cache.Channels
-
-	// Most common case: validating against the current channel count
-	if channels == cachedChannels {
-		return nil
-	}
-
-	// Fast path: Check against cached max channels
-	cachedMaxChannels := cache.MaxChannels
-	if cachedMaxChannels > 0 && channels <= cachedMaxChannels {
-		return nil
-	}
-
-	// Slow path: Use current config values
-	updatedMaxChannels := cache.MaxChannels
-	if channels > updatedMaxChannels {
+	// Direct boundary check
+	if channels > Config.MaxChannels {
 		return fmt.Errorf("%w: channel count %d exceeds maximum %d",
-			ErrInvalidChannels, channels, updatedMaxChannels)
+			ErrInvalidChannels, channels, Config.MaxChannels)
 	}
 	return nil
 }
 
 // ValidateBitrate validates audio bitrate values (expects kbps)
-// Optimized to use AudioConfigCache for frequently accessed values
+// Optimized for minimal overhead in hotpath
 func ValidateBitrate(bitrate int) error {
 	if bitrate <= 0 {
 		return fmt.Errorf("%w: bitrate %d must be positive", ErrInvalidBitrate, bitrate)
 	}
-
-	// Fast path: Check against cached bitrate values
-	cache := Config
-	minBitrate := cache.MinOpusBitrate
-	maxBitrate := cache.MaxOpusBitrate
-
-	// If we have valid cached values, use them
-	if minBitrate > 0 && maxBitrate > 0 {
-		// Convert kbps to bps for comparison with config limits
-		bitrateInBps := bitrate * 1000
-		if bitrateInBps < minBitrate {
-			return fmt.Errorf("%w: bitrate %d kbps (%d bps) below minimum %d bps",
-				ErrInvalidBitrate, bitrate, bitrateInBps, minBitrate)
-		}
-		if bitrateInBps > maxBitrate {
-			return fmt.Errorf("%w: bitrate %d kbps (%d bps) exceeds maximum %d bps",
-				ErrInvalidBitrate, bitrate, bitrateInBps, maxBitrate)
-		}
-		return nil
-	}
-
-	// Convert kbps to bps for comparison with config limits
+	// Direct boundary check with single conversion
 	bitrateInBps := bitrate * 1000
 	if bitrateInBps < Config.MinOpusBitrate {
 		return fmt.Errorf("%w: bitrate %d kbps (%d bps) below minimum %d bps",

internal/audio/ipc_unified.go

@@ -8,6 +8,7 @@ import (
 	"net"
 	"os"
 	"path/filepath"
+	"strings"
 	"sync"
 	"sync/atomic"
 	"time"
@@ -157,15 +158,38 @@ func (s *UnifiedAudioServer) Start() error {
 		return fmt.Errorf("server already running")
 	}
 
-	// Remove existing socket file
-	if err := os.Remove(s.socketPath); err != nil && !os.IsNotExist(err) {
-		return fmt.Errorf("failed to remove existing socket: %w", err)
+	// Remove existing socket file with retry logic
+	for i := 0; i < 3; i++ {
+		if err := os.Remove(s.socketPath); err != nil && !os.IsNotExist(err) {
+			s.logger.Warn().Err(err).Int("attempt", i+1).Msg("failed to remove existing socket file, retrying")
+			time.Sleep(100 * time.Millisecond)
+			continue
+		}
+		break
+	}
+
+	// Create listener with retry on address already in use
+	var listener net.Listener
+	var err error
+	for i := 0; i < 3; i++ {
+		listener, err = net.Listen("unix", s.socketPath)
+		if err == nil {
+			break
+		}
+
+		// If address is still in use, try to remove socket file again
+		if strings.Contains(err.Error(), "address already in use") {
+			s.logger.Warn().Err(err).Int("attempt", i+1).Msg("socket address in use, attempting cleanup and retry")
+			os.Remove(s.socketPath)
+			time.Sleep(200 * time.Millisecond)
+			continue
+		}
+
+		return fmt.Errorf("failed to create unix socket: %w", err)
 	}
 
-	// Create listener
-	listener, err := net.Listen("unix", s.socketPath)
 	if err != nil {
-		return fmt.Errorf("failed to create listener: %w", err)
+		return fmt.Errorf("failed to create unix socket after retries: %w", err)
 	}
 
 	s.listener = listener
@@ -367,14 +391,18 @@ func (s *UnifiedAudioServer) SendFrame(frame []byte) error {
 func (s *UnifiedAudioServer) writeMessage(conn net.Conn, msg *UnifiedIPCMessage) error {
 	header := EncodeMessageHeader(msg.Magic, uint8(msg.Type), msg.Length, msg.Timestamp)
 
-	if _, err := conn.Write(header); err != nil {
-		return fmt.Errorf("failed to write header: %w", err)
-	}
-
-	// Write data if present
+	// Optimize: Use single write for header+data to reduce system calls
 	if msg.Length > 0 && msg.Data != nil {
-		if _, err := conn.Write(msg.Data); err != nil {
-			return fmt.Errorf("failed to write data: %w", err)
+		// Pre-allocate combined buffer to avoid copying
+		combined := make([]byte, len(header)+len(msg.Data))
+		copy(combined, header)
+		copy(combined[len(header):], msg.Data)
+		if _, err := conn.Write(combined); err != nil {
+			return fmt.Errorf("failed to write message: %w", err)
+		}
+	} else {
+		if _, err := conn.Write(header); err != nil {
+			return fmt.Errorf("failed to write header: %w", err)
 		}
 	}
 
@@ -642,9 +670,9 @@ func (c *UnifiedAudioClient) calculateAdaptiveDelay(attempt int, initialDelay, m
 
 // Helper functions for socket paths
 func getInputSocketPath() string {
-	return filepath.Join(os.TempDir(), inputSocketName)
+	return filepath.Join("/var/run", inputSocketName)
 }
 
 func getOutputSocketPath() string {
-	return filepath.Join(os.TempDir(), outputSocketName)
+	return filepath.Join("/var/run", outputSocketName)
 }

internal/audio/quality_presets.go

@@ -260,6 +260,16 @@ func GetAudioConfig() AudioConfig {
 	return currentConfig
 }
 
+// Simplified OPUS parameter lookup table
+var opusParams = map[AudioQuality]struct {
+	complexity, vbr, signalType, bandwidth, dtx int
+}{
+	AudioQualityLow:    {Config.AudioQualityLowOpusComplexity, Config.AudioQualityLowOpusVBR, Config.AudioQualityLowOpusSignalType, Config.AudioQualityLowOpusBandwidth, Config.AudioQualityLowOpusDTX},
+	AudioQualityMedium: {Config.AudioQualityMediumOpusComplexity, Config.AudioQualityMediumOpusVBR, Config.AudioQualityMediumOpusSignalType, Config.AudioQualityMediumOpusBandwidth, Config.AudioQualityMediumOpusDTX},
+	AudioQualityHigh:   {Config.AudioQualityHighOpusComplexity, Config.AudioQualityHighOpusVBR, Config.AudioQualityHighOpusSignalType, Config.AudioQualityHighOpusBandwidth, Config.AudioQualityHighOpusDTX},
+	AudioQualityUltra:  {Config.AudioQualityUltraOpusComplexity, Config.AudioQualityUltraOpusVBR, Config.AudioQualityUltraOpusSignalType, Config.AudioQualityUltraOpusBandwidth, Config.AudioQualityUltraOpusDTX},
+}
+
 // SetMicrophoneQuality updates the current microphone quality configuration
 func SetMicrophoneQuality(quality AudioQuality) {
 	// Validate audio quality parameter
@@ -274,40 +284,11 @@ func SetMicrophoneQuality(quality AudioQuality) {
 	if config, exists := presets[quality]; exists {
 		currentMicrophoneConfig = config
 
-		// Get OPUS parameters for the selected quality
-		var complexity, vbr, signalType, bandwidth, dtx int
-		switch quality {
-		case AudioQualityLow:
-			complexity = Config.AudioQualityLowOpusComplexity
-			vbr = Config.AudioQualityLowOpusVBR
-			signalType = Config.AudioQualityLowOpusSignalType
-			bandwidth = Config.AudioQualityLowOpusBandwidth
-			dtx = Config.AudioQualityLowOpusDTX
-		case AudioQualityMedium:
-			complexity = Config.AudioQualityMediumOpusComplexity
-			vbr = Config.AudioQualityMediumOpusVBR
-			signalType = Config.AudioQualityMediumOpusSignalType
-			bandwidth = Config.AudioQualityMediumOpusBandwidth
-			dtx = Config.AudioQualityMediumOpusDTX
-		case AudioQualityHigh:
-			complexity = Config.AudioQualityHighOpusComplexity
-			vbr = Config.AudioQualityHighOpusVBR
-			signalType = Config.AudioQualityHighOpusSignalType
-			bandwidth = Config.AudioQualityHighOpusBandwidth
-			dtx = Config.AudioQualityHighOpusDTX
-		case AudioQualityUltra:
-			complexity = Config.AudioQualityUltraOpusComplexity
-			vbr = Config.AudioQualityUltraOpusVBR
-			signalType = Config.AudioQualityUltraOpusSignalType
-			bandwidth = Config.AudioQualityUltraOpusBandwidth
-			dtx = Config.AudioQualityUltraOpusDTX
-		default:
-			// Use medium quality as fallback
-			complexity = Config.AudioQualityMediumOpusComplexity
-			vbr = Config.AudioQualityMediumOpusVBR
-			signalType = Config.AudioQualityMediumOpusSignalType
-			bandwidth = Config.AudioQualityMediumOpusBandwidth
-			dtx = Config.AudioQualityMediumOpusDTX
+		// Get OPUS parameters using lookup table
+		params, exists := opusParams[quality]
+		if !exists {
+			// Fallback to medium quality
+			params = opusParams[AudioQualityMedium]
 		}
 
 		// Update audio input subprocess configuration dynamically without restart
@@ -315,7 +296,7 @@ func SetMicrophoneQuality(quality AudioQuality) {
 
 		// Set new OPUS configuration for future restarts
 		if supervisor := GetAudioInputSupervisor(); supervisor != nil {
-			supervisor.SetOpusConfig(config.Bitrate*1000, complexity, vbr, signalType, bandwidth, dtx)
+			supervisor.SetOpusConfig(config.Bitrate*1000, params.complexity, params.vbr, params.signalType, params.bandwidth, params.dtx)
 
 			// Check if microphone is active but IPC control is broken
 			inputManager := getAudioInputManager()
@@ -336,11 +317,11 @@ func SetMicrophoneQuality(quality AudioQuality) {
 					Channels:   config.Channels,
 					FrameSize:  int(config.FrameSize.Milliseconds() * int64(config.SampleRate) / 1000), // Convert ms to samples
 					Bitrate:    config.Bitrate * 1000,                                                  // Convert kbps to bps
-					Complexity: complexity,
-					VBR:        vbr,
-					SignalType: signalType,
-					Bandwidth:  bandwidth,
-					DTX:        dtx,
+					Complexity: params.complexity,
+					VBR:        params.vbr,
+					SignalType: params.signalType,
+					Bandwidth:  params.bandwidth,
+					DTX:        params.dtx,
 				}
 
 				if err := supervisor.SendOpusConfig(opusConfig); err != nil {