Merge pull request #363 from b-ma/perf/param-array-vec

Perf - use `ArrayVec` instead of `Vec` for internal `AudioParam` buffer

Author: orottier

src/param.rs

@@ -2,7 +2,9 @@
 use std::any::Any;
 use std::slice::{Iter, IterMut};
 use std::sync::atomic::{AtomicBool, Ordering};
-use std::sync::Arc;
+use std::sync::{Arc, OnceLock};
+
+use arrayvec::ArrayVec;
 
 use crate::context::AudioContextRegistration;
 use crate::node::{
@@ -11,8 +13,6 @@ use crate::node::{
 use crate::render::{AudioParamValues, AudioProcessor, AudioRenderQuantum, RenderScope};
 use crate::{AtomicF32, RENDER_QUANTUM_SIZE};
 
-use std::sync::OnceLock;
-
 /// For SetTargetAtTime event, that theoretically cannot end, if the diff between
 /// the current value and the target is below this threshold, the value is set
 /// to target value and the event is considered ended.
@@ -620,7 +620,7 @@ pub(crate) struct AudioParamProcessor {
     shared_parts: Arc<AudioParamShared>,
     event_timeline: AudioParamEventTimeline,
     last_event: Option<AudioParamEvent>,
-    buffer: Vec<f32>,
+    buffer: ArrayVec<f32, RENDER_QUANTUM_SIZE>,
 }
 
 impl AudioProcessor for AudioParamProcessor {
@@ -670,11 +670,11 @@ impl AudioProcessor for AudioParamProcessor {
 }
 
 impl AudioParamProcessor {
-    // warning: tick in called directly in the unit tests so everything important
-    // for the tests should be done here
+    // Warning: compute_intrinsic_values in called directly in the unit tests so
+    // everything important for the tests should be done here
+    // The returned value is only used in tests
     fn compute_intrinsic_values(&mut self, block_time: f64, dt: f64, count: usize) -> &[f32] {
         self.compute_buffer(block_time, dt, count);
-
         self.buffer.as_slice()
     }
 
@@ -1088,7 +1088,14 @@ impl AudioParamProcessor {
             match some_event {
                 None => {
                     if is_a_rate {
-                        self.buffer.resize(count, self.intrinsic_value);
+                        // @note - we use `count` rather then `buffer.remaining_capacity`
+                        // to correctly unit tests where `count` is lower than RENDER_QUANTUM_SIZE
+                        //
+                        // @todo(perf) - consider using try_extend_from_slice
+                        // which internally uses ptr::copy_nonoverlapping
+                        for _ in self.buffer.len()..count {
+                            self.buffer.push(self.intrinsic_value);
+                        }
                     }
                     break;
                 }
@@ -1614,7 +1621,7 @@ pub(crate) fn audio_param_pair(
         shared_parts,
         event_timeline: AudioParamEventTimeline::new(),
         last_event: None,
-        buffer: Vec::with_capacity(RENDER_QUANTUM_SIZE),
+        buffer: ArrayVec::new(),
     };
 
     (param, processor)