From 1bb0938ff60e5ec7b59a41bf7f6c50d77639a0f2 Mon Sep 17 00:00:00 2001
From: Jonas Platte <jplatte+git@posteo.de>
Date: Thu, 11 Jul 2024 22:19:41 +0200
Subject: [PATCH] Switch from criterion to divan

---
 eyeball/Cargo.toml           |  4 +-
 eyeball/benches/set_a_lot.rs | 77 +++++++++++++++---------------------
 2 files changed, 34 insertions(+), 47 deletions(-)

diff --git a/eyeball/Cargo.toml b/eyeball/Cargo.toml
index a3f3ac0..0b609c9 100644
--- a/eyeball/Cargo.toml
+++ b/eyeball/Cargo.toml
@@ -22,7 +22,7 @@ tokio = { workspace = true, optional = true }
 tokio-util = { version = "0.7.8", optional = true }
 
 # for benchmarking
-criterion = { version = "0.5.1", optional = true }
+divan = { version = "0.1.14", optional = true }
 
 [dev-dependencies]
 futures-util.workspace = true
@@ -32,7 +32,7 @@ tokio = { workspace = true, features = ["macros", "rt"] }
 [features]
 async-lock = ["dep:readlock-tokio", "dep:tokio", "dep:tokio-util"]
 
-__bench = ["dep:criterion", "dep:tokio", "tokio?/rt-multi-thread"]
+__bench = ["dep:divan", "dep:tokio", "tokio?/rt-multi-thread"]
 
 [[bench]]
 name = "set_a_lot"
diff --git a/eyeball/benches/set_a_lot.rs b/eyeball/benches/set_a_lot.rs
index e15d84d..4631381 100644
--- a/eyeball/benches/set_a_lot.rs
+++ b/eyeball/benches/set_a_lot.rs
@@ -1,72 +1,59 @@
 #![allow(missing_docs)]
 
-use criterion::{black_box, criterion_group, criterion_main, BatchSize, Bencher, Criterion};
+use divan::{black_box, main, Bencher};
 
 use eyeball::Observable;
 use tokio::task::JoinSet;
 
-fn baseline(b: &mut Bencher<'_>) {
-    let mut x = Box::new([0; 256]);
-    b.iter(|| {
+#[divan::bench]
+fn baseline(b: Bencher<'_, '_>) {
+    b.with_inputs(|| Box::new([0; 256])).bench_refs(|x| {
         for i in 1..=256 {
-            black_box(&x);
-            x = black_box(Box::new([i; 256]));
+            *x = black_box(Box::new([i; 256]));
         }
     });
 }
 
-fn no_subscribers(b: &mut Bencher<'_>) {
-    let mut ob = Observable::new(Box::new([0; 256]));
-    b.iter(|| {
+#[divan::bench]
+fn no_subscribers(b: Bencher<'_, '_>) {
+    b.with_inputs(|| Observable::new(Box::new([0; 256]))).bench_refs(|ob| {
         for i in 1..=256 {
-            black_box(&*ob);
-            Observable::set(&mut ob, black_box(Box::new([i; 256])));
+            Observable::set(ob, black_box(Box::new([i; 256])));
         }
     });
 }
 
-#[tokio::main]
-async fn n_subscribers(n: usize, b: &mut Bencher<'_>) {
-    b.iter_batched(
-        || {
-            let ob = Observable::new(Box::new([0; 256]));
-            let mut join_set = JoinSet::new();
-            for _ in 0..n {
-                let mut subscriber = Observable::subscribe(&ob);
+#[divan::bench(args = [1, 2, 4, 16, 64])]
+fn n_subscribers(b: Bencher<'_, '_>, n: usize) {
+    b.with_inputs(|| {
+        let tokio_rt = tokio::runtime::Builder::new_multi_thread()
+            .enable_all()
+            .build()
+            .expect("Failed to build tokio runtime");
+
+        let ob = Observable::new(Box::new([0; 256]));
+        let mut join_set = JoinSet::new();
+        for _ in 0..n {
+            let mut subscriber = Observable::subscribe(&ob);
+            tokio_rt.block_on(async {
                 join_set.spawn(async move {
                     while let Some(value) = subscriber.next().await {
                         black_box(&value);
                     }
                 });
-            }
-            (ob, join_set)
-        },
-        |(mut ob, mut join_set)| {
+            });
+        }
+        (tokio_rt, ob, join_set)
+    })
+    .bench_values(|(tokio_rt, mut ob, mut join_set)| {
+        tokio_rt.block_on(async move {
             for i in 1..=256 {
                 Observable::set(&mut ob, black_box(Box::new([i; 256])));
             }
             drop(ob);
-            tokio::task::block_in_place(|| {
-                let tokio_handle = tokio::runtime::Handle::current();
-                tokio_handle.block_on(async move {
-                    // wait for all tasks to finish
-                    while join_set.join_next().await.is_some() {}
-                });
-            });
-        },
-        BatchSize::LargeInput,
-    );
-}
 
-fn set_a_lot(c: &mut Criterion) {
-    c.bench_function("baseline", baseline);
-    c.bench_function("no_subscribers", no_subscribers);
-    c.bench_function("one_subscriber", |b| n_subscribers(1, b));
-    c.bench_function("two_subscribers", |b| n_subscribers(2, b));
-    c.bench_function("four_subscribers", |b| n_subscribers(4, b));
-    c.bench_function("sixteen_subscribers", |b| n_subscribers(16, b));
-    c.bench_function("sixtyfour_subscribers", |b| n_subscribers(64, b));
+            // wait for all tasks to finish
+            while join_set.join_next().await.is_some() {}
+        });
+    });
 }
-
-criterion_group!(benches, set_a_lot);
-criterion_main!(benches);