bench after one

benches/bench.rs

@@ -186,6 +186,7 @@ fn criterion_benchmark(c: &mut Criterion) {
     c.bench_function("extend many too many", extend_many_too_many);
     c.bench_function("extend exact cap", extend_exact_cap);
     c.bench_function("extend too few", extend_too_few);
+    c.bench_function("extend after one", extend_after_one);
 }
 
 fn extend_many_too_many(b: &mut Bencher) {
@@ -232,5 +233,17 @@ fn extend_too_few(b: &mut Bencher) {
     );
 }
 
+fn extend_after_one(b: &mut Bencher) {
+    let mut rb = ConstGenericRingBuffer::new::<8192>();
+    rb.push(0);
+    let input = (0..4096).collect::<Vec<_>>();
+
+    b.iter_batched(
+        &|| rb.clone(),
+        |mut r| black_box(r.extend(black_box(input.as_slice()))),
+        BatchSize::LargeInput,
+    );
+}
+
 criterion_group!(benches, criterion_benchmark);
 criterion_main!(benches);

src/with_const_generics.rs

@@ -431,6 +431,7 @@ impl<T, const CAP: usize> ConstGenericRingBuffer<T, CAP> {
 
     /// # Safety
     /// ONLY USE WHEN WORKING ON A CLEARED RINGBUFFER
+    #[inline]
     unsafe fn finish_iter<const BATCH_SIZE: usize>(&mut self, mut iter: impl Iterator<Item = T>) {
         let mut index = 0;
         for i in iter.by_ref() {
@@ -457,7 +458,8 @@ impl<T, const CAP: usize> Extend<T> for ConstGenericRingBuffer<T, CAP> {
     /// NOTE: correctness (but not soundness) of extend depends on `size_hint` on iter being correct.
     #[inline]
     fn extend<A: IntoIterator<Item = T>>(&mut self, iter: A) {
-        const BATCH_SIZE: usize = 128;
+        const BATCH_SIZE: usize = 1;
+        // const BATCH_SIZE: usize = 1024;
 
         let iter = iter.into_iter();