feat(benches): add a criterion bench for triangulation functions (#207)

* add files for a new bench#

* add new example vtk file

* add benchmarks

* replace quad example file to have more cells

* Revert "replace quad example file to have more cells"

This reverts commit d65c70f.

* better preallocs

.gitignore

@@ -21,6 +21,7 @@ Cargo.lock
 *.vtk
 !/assets/*.vtk
 !/examples/shape.vtk
+!/examples/quads.vtk
 
 # ignore coverage-related files
 *.profraw
@@ -36,4 +37,4 @@ perf.data.old
 # ignore bench result directories
 /fixed
 /grid
-/thread
+/thread

benches/Cargo.toml

@@ -81,3 +81,8 @@ harness = false
 name = "grisubal_grid_size"
 path = "benches/grisubal/grid_size.rs"
 harness = false
+
+[[bench]]
+name = "triangulate_quads"
+path = "benches/triangulate/quads.rs"
+harness = false

benches/benches/triangulate/quads.rs

@@ -0,0 +1,93 @@
+// ------ IMPORTS
+
+use criterion::{black_box, criterion_group, criterion_main, Criterion};
+use honeycomb::prelude::{
+    triangulation::{earclip_cell, fan_cell, TriangulateError},
+    CMap2, CMapBuilder, DartIdentifier, Orbit2, OrbitPolicy,
+};
+use honeycomb_benches::FloatType;
+
+// ------ CONTENT
+
+const PATH: &str = "../examples/quads.vtk";
+
+fn fan_bench() -> Result<(), TriangulateError> {
+    let mut map: CMap2<FloatType> = CMapBuilder::default().vtk_file(PATH).build().unwrap();
+
+    // prealloc darts
+    let faces = map.fetch_faces().identifiers.clone();
+    let n_darts_per_face: Vec<_> = faces
+        .iter()
+        .map(|id| (Orbit2::new(&map, OrbitPolicy::Face, *id as DartIdentifier).count() - 3) * 2)
+        .collect();
+    let n_tot: usize = n_darts_per_face.iter().sum();
+    let tmp = map.add_free_darts(n_tot) as usize;
+    // the prefix sum gives an offset that corresponds to the starting index of each slice, minus
+    // the location of the allocated dart block (given by `tmp`)
+    // end of the slice is deduced using these values and the number of darts the current seg needs
+    let prefix_sum = n_darts_per_face.iter().scan(0, |state, &n_d| {
+        *state += n_d;
+        Some(*state - n_d) // we want an offset, not the actual sum
+    });
+    #[allow(clippy::cast_possible_truncation)]
+    let dart_slices: Vec<Vec<DartIdentifier>> = n_darts_per_face
+        .iter()
+        .zip(prefix_sum)
+        .map(|(n_d, start)| {
+            ((tmp + start) as DartIdentifier..(tmp + start + n_d) as DartIdentifier)
+                .collect::<Vec<_>>()
+        })
+        .collect();
+
+    for (face_id, new_darts) in faces.iter().zip(dart_slices.iter()) {
+        fan_cell(&mut map, *face_id, new_darts)?
+    }
+
+    Ok(())
+}
+
+fn earclip_bench() -> Result<(), TriangulateError> {
+    let mut map: CMap2<FloatType> = CMapBuilder::default().vtk_file(PATH).build().unwrap();
+
+    // prealloc darts
+    let faces = map.fetch_faces().identifiers.clone();
+    let n_darts_per_face: Vec<_> = faces
+        .iter()
+        .map(|id| (Orbit2::new(&map, OrbitPolicy::Face, *id as DartIdentifier).count() - 3) * 2)
+        .collect();
+    let n_tot: usize = n_darts_per_face.iter().sum();
+    let tmp = map.add_free_darts(n_tot) as usize;
+    // the prefix sum gives an offset that corresponds to the starting index of each slice, minus
+    // the location of the allocated dart block (given by `tmp`)
+    // end of the slice is deduced using these values and the number of darts the current seg needs
+    let prefix_sum = n_darts_per_face.iter().scan(0, |state, &n_d| {
+        *state += n_d;
+        Some(*state - n_d) // we want an offset, not the actual sum
+    });
+    #[allow(clippy::cast_possible_truncation)]
+    let dart_slices: Vec<Vec<DartIdentifier>> = n_darts_per_face
+        .iter()
+        .zip(prefix_sum)
+        .map(|(n_d, start)| {
+            ((tmp + start) as DartIdentifier..(tmp + start + n_d) as DartIdentifier)
+                .collect::<Vec<_>>()
+        })
+        .collect();
+
+    for (face_id, new_darts) in faces.iter().zip(dart_slices.iter()) {
+        earclip_cell(&mut map, *face_id, new_darts)?
+    }
+
+    Ok(())
+}
+
+pub fn criterion_benchmark(c: &mut Criterion) {
+    let mut group = c.benchmark_group("triangulation");
+
+    group.bench_function("fan", |b| b.iter(|| black_box(fan_bench())));
+    group.bench_function("earclip", |b| b.iter(|| black_box(earclip_bench())));
+    group.finish();
+}
+
+criterion_group!(benches, criterion_benchmark);
+criterion_main!(benches);