perf: inline functions in the audio hot path

Author: roderickvd

playback/src/audio_backend/alsa.rs

@@ -452,6 +452,7 @@ impl Sink for AlsaSink {
 }
 
 impl SinkAsBytes for AlsaSink {
+    #[inline]
     fn write_bytes(&mut self, data: &[u8]) -> SinkResult<()> {
         let mut start_index = 0;
         let data_len = data.len();

playback/src/audio_backend/gstreamer.rs

@@ -171,6 +171,7 @@ impl Drop for GstreamerSink {
 }
 
 impl SinkAsBytes for GstreamerSink {
+    #[inline]
     fn write_bytes(&mut self, data: &[u8]) -> SinkResult<()> {
         if let Some(async_error) = &*self.async_error.lock() {
             return Err(SinkError::OnWrite(async_error.to_string()));

playback/src/audio_backend/mod.rs

@@ -46,6 +46,7 @@ fn mk_sink<S: Sink + Open + 'static>(device: Option<String>, format: AudioFormat
 // reuse code for various backends
 macro_rules! sink_as_bytes {
     () => {
+        #[inline]
         fn write(&mut self, packet: AudioPacket, converter: &mut Converter) -> SinkResult<()> {
             use crate::convert::i24;
             use zerocopy::IntoBytes;

playback/src/audio_backend/pipe.rs

@@ -96,6 +96,7 @@ impl Sink for StdoutSink {
 }
 
 impl SinkAsBytes for StdoutSink {
+    #[inline]
     fn write_bytes(&mut self, data: &[u8]) -> SinkResult<()> {
         self.output
             .as_deref_mut()

playback/src/audio_backend/pulseaudio.rs

@@ -137,6 +137,7 @@ impl Sink for PulseAudioSink {
 }
 
 impl SinkAsBytes for PulseAudioSink {
+    #[inline]
     fn write_bytes(&mut self, data: &[u8]) -> SinkResult<()> {
         let sink = self.sink.as_mut().ok_or(PulseError::NotConnected)?;
 

playback/src/audio_backend/subprocess.rs

@@ -139,6 +139,7 @@ impl Sink for SubprocessSink {
 }
 
 impl SinkAsBytes for SubprocessSink {
+    #[inline]
     fn write_bytes(&mut self, data: &[u8]) -> SinkResult<()> {
         // We get one attempted restart per write.
         // We don't want to get stuck in a restart loop.

playback/src/convert.rs

@@ -42,7 +42,6 @@ impl Converter {
     const SHIFT_S24: u8 = 23; // 24-bit: 2^23 = 8388608  
     const SHIFT_S32: u8 = 31; // 32-bit: 2^31 = 2147483648
 
-
     /// Additional bit shifts needed to scale from 16-bit to higher bit depths.
     /// These are the differences between the base shift amounts above.
     const SHIFT_16_TO_24: u8 = Self::SHIFT_S24 - Self::SHIFT_S16; // 23 - 15 = 8
@@ -52,12 +51,12 @@ impl Converter {
     const SCALE_S24: f64 = (1_u64 << Self::SHIFT_S24) as f64;
 
     /// Scale audio samples with optimal dithering strategy for Spotify's 16-bit source material.
-    /// 
+    ///
     /// Since Spotify audio is always 16-bit depth, this function:
     /// 1. When dithering: applies noise at 16-bit level, preserves fractional precision,
     ///    then scales to target format and rounds once at the end
     /// 2. When not dithering: scales directly from normalized float to target format
-    /// 
+    ///
     /// The `shift` parameter specifies how many extra bits to shift beyond
     /// the base 16-bit scaling (0 for 16-bit, 8 for 24-bit, 16 for 32-bit).
     #[inline]
@@ -85,11 +84,11 @@ impl Converter {
     #[inline]
     pub fn clamping_scale_s24(&mut self, sample: f64) -> f64 {
         let int_value = self.scale(sample, Self::SHIFT_16_TO_24);
-        
+
         // In two's complement, there are more negative than positive values.
         let min = -Self::SCALE_S24;
         let max = Self::SCALE_S24 - 1.0;
-        
+
         int_value.clamp(min, max)
     }
 

playback/src/decoder/mod.rs

@@ -36,20 +36,23 @@ pub enum AudioPacket {
 }
 
 impl AudioPacket {
+    #[inline]
     pub fn samples(&self) -> AudioPacketResult<&[f64]> {
         match self {
             AudioPacket::Samples(s) => Ok(s),
             AudioPacket::Raw(_) => Err(AudioPacketError::Raw),
         }
     }
 
+    #[inline]
     pub fn raw(&self) -> AudioPacketResult<&[u8]> {
         match self {
             AudioPacket::Raw(d) => Ok(d),
             AudioPacket::Samples(_) => Err(AudioPacketError::Samples),
         }
     }
 
+    #[inline]
     pub fn is_empty(&self) -> bool {
         match self {
             AudioPacket::Samples(s) => s.is_empty(),

playback/src/decoder/symphonia_decoder.rs

@@ -131,6 +131,7 @@ impl SymphoniaDecoder {
         }
     }
 
+    #[inline]
     fn ts_to_ms(&self, ts: u64) -> u32 {
         match self.decoder.codec_params().time_base {
             Some(time_base) => {

playback/src/mixer/mod.rs

@@ -25,6 +25,7 @@ pub trait VolumeGetter {
 }
 
 impl VolumeGetter for NoOpVolume {
+    #[inline]
     fn attenuation_factor(&self) -> f64 {
         1.0
     }