Add basic benchmarks (#31)

Cargo.toml

@@ -18,4 +18,12 @@ exclude = ["/.*"]
 parking = "2.0.0"
 
 [dev-dependencies]
+criterion = "0.3.4"
 waker-fn = "1"
+
+[[bench]]
+name = "bench"
+harness = false
+
+[lib]
+bench = false

benches/bench.rs

@@ -0,0 +1,26 @@
+use criterion::{criterion_group, criterion_main, Criterion};
+use event_listener::Event;
+
+const COUNT: usize = 8000;
+
+fn bench_events(c: &mut Criterion) {
+    c.bench_function("notify_and_wait", |b| {
+        let ev = Event::new();
+        b.iter(|| {
+            let mut handles = Vec::with_capacity(COUNT);
+
+            for _ in 0..COUNT {
+                handles.push(ev.listen());
+            }
+
+            ev.notify(COUNT);
+
+            for handle in handles {
+                handle.wait();
+            }
+        });
+    });
+}
+
+criterion_group!(benches, bench_events);
+criterion_main!(benches);