From 0557605cb86b7de497bc3f7b915b18d49cd4de02 Mon Sep 17 00:00:00 2001
From: David Barsky <me@davidbarsky.com>
Date: Mon, 12 Aug 2024 16:00:33 -0400
Subject: [PATCH] internal: add some initial input benchmarks

---
 Cargo.toml                  |  4 ++
 benches/compare.rs          | 93 +++++++++++++++++++++++++++++++++++++
 examples/lazy-input/main.rs |  2 +
 3 files changed, 99 insertions(+)
 create mode 100644 benches/compare.rs

diff --git a/Cargo.toml b/Cargo.toml
index e9db335..d3815b1 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -34,6 +34,10 @@ rustversion = "1.0"
 test-log = { version ="0.2.11", features = ["trace"] }
 trybuild = "1.0"
 
+[[bench]]
+name = "compare"
+harness = false
+
 
 [[bench]]
 name = "incremental"
diff --git a/benches/compare.rs b/benches/compare.rs
new file mode 100644
index 0000000..ac15ac9
--- /dev/null
+++ b/benches/compare.rs
@@ -0,0 +1,93 @@
+use codspeed_criterion_compat::{criterion_group, criterion_main, BenchmarkId, Criterion};
+use salsa::Setter;
+
+#[salsa::input]
+pub struct Input {
+    pub text: String,
+}
+
+#[salsa::tracked]
+pub fn length(db: &dyn salsa::Database, 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 salsa::Database, input: InternedInput<'db>) -> usize {
+    input.text(db).len()
+}
+
+fn mutating_inputs(c: &mut Criterion) {
+    let mut group: codspeed_criterion_compat::BenchmarkGroup<
+        codspeed_criterion_compat::measurement::WallTime,
+    > = c.benchmark_group("Mutating Inputs");
+
+    let mut db = salsa::DatabaseImpl::default();
+
+    for n in &[10, 20, 30] {
+        let base_string = "hello, world!".to_owned();
+        let base_len = base_string.len();
+
+        let string = base_string.clone().repeat(*n);
+        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();
+}
+
+fn inputs(c: &mut Criterion) {
+    let mut group: codspeed_criterion_compat::BenchmarkGroup<
+        codspeed_criterion_compat::measurement::WallTime,
+    > = c.benchmark_group("Mutating Inputs");
+
+    let db = salsa::DatabaseImpl::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::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));
+    });
+
+    group.finish();
+}
+
+criterion_group!(benches, mutating_inputs, inputs);
+criterion_main!(benches);
diff --git a/examples/lazy-input/main.rs b/examples/lazy-input/main.rs
index 3b91888..792b7f3 100644
--- a/examples/lazy-input/main.rs
+++ b/examples/lazy-input/main.rs
@@ -1,3 +1,5 @@
+#![allow(unreachable_patterns)]
+// FIXME(rust-lang/rust#129031): regression in nightly
 use std::{path::PathBuf, sync::Mutex, time::Duration};
 
 use crossbeam::channel::{unbounded, Sender};