internal: add some initial input benchmarks

Cargo.toml

@@ -32,6 +32,11 @@ ordered-float = "3.0"
 rustversion = "1.0"
 test-log = "0.2.11"
 trybuild = "1.0"
+criterion = "0.5.1"
+
+[[bench]]
+name = "compare"
+harness = false
 
 [workspace]
 members = [ "components/salsa-macro-rules","components/salsa-macros"]

benches/compare.rs

@@ -0,0 +1,97 @@
+use criterion::{criterion_group, criterion_main, BenchmarkId, Criterion};
+use salsa::Setter;
+
+#[salsa::db]
+pub trait Db: salsa::Database {}
+
+#[salsa::db]
+#[derive(Default)]
+pub struct Database {
+    storage: salsa::Storage<Self>,
+}
+
+#[salsa::db]
+impl salsa::Database for Database {}
+
+#[salsa::db]
+impl Db for Database {}
+
+#[salsa::input]
+pub struct Input {
+    pub text: String,
+}
+
+#[salsa::tracked]
+pub fn length(db: &dyn Db, input: Input) -> usize {
+    input.text(db).len()
+}
+
+#[salsa::interned]
+pub struct InternedInput<'db> {
+    pub text: String,
+}
+
+#[salsa::tracked]
+pub fn interned_length<'db>(db: &'db dyn Db, input: InternedInput<'db>) -> usize {
+    input.text(db).len()
+}
+
+fn inputs(c: &mut Criterion) {
+    let mut group = c.benchmark_group("Inputs");
+    let mut db = Database::default();
+
+    group.bench_function(BenchmarkId::new("new", "InternedInput"), |b| {
+        b.iter(|| {
+            let input: InternedInput = InternedInput::new(&db, "hello, world!".to_owned());
+            interned_length(&db, input);
+        })
+    });
+
+    group.bench_function(BenchmarkId::new("amortized", "InternedInput"), |b| {
+        let input: InternedInput = InternedInput::new(&db, "hello, world!".to_owned());
+        let _ = interned_length(&db, input);
+
+        b.iter(|| interned_length(&db, input));
+    });
+
+    group.bench_function(BenchmarkId::new("new", "Input"), |b| {
+        b.iter(|| {
+            let input = Input::new(&db, "hello, world!".to_owned());
+            length(&db, input);
+        })
+    });
+
+    group.bench_function(BenchmarkId::new("amortized", "Input"), |b| {
+        let input = Input::new(&db, "hello, world!".to_owned());
+        let _ = length(&db, input);
+
+        b.iter(|| length(&db, input));
+    });
+
+    for n in &[10, 20, 30] {
+        let base_string = "hello, world!".to_owned();
+        let base_len = base_string.len();
+
+        let string = std::iter::repeat(base_string.clone())
+            .take(*n)
+            .collect::<String>();
+        let new_len = string.len();
+
+        group.bench_function(BenchmarkId::new("mutating", n), |b| {
+            b.iter(|| {
+                let input = Input::new(&db, base_string.clone());
+                let actual_len = length(&db, input);
+                assert_eq!(base_len, actual_len);
+
+                input.set_text(&mut db).to(string.clone());
+                let actual_len = length(&db, input);
+                assert_eq!(new_len, actual_len);
+            })
+        });
+    }
+
+    group.finish();
+}
+
+criterion_group!(benches, inputs);
+criterion_main!(benches);