build(rust): vendor rnix parser crate

third_party/crates/countme-3.0.1/examples/bench.rs

@@ -0,0 +1,69 @@
+use std::thread;
+
+use countme::{get, Count};
+
+#[derive(Default)]
+struct Foo {
+    _c: Count<Self>,
+}
+
+#[derive(Default)]
+struct Bar {
+    _c: Count<Self>,
+    _x: i32,
+}
+
+mod deeply {
+    pub(crate) mod nested {
+        pub(crate) mod module {
+            use countme::Count;
+
+            #[derive(Default)]
+            pub(crate) struct Quux {
+                _c: Count<Self>,
+            }
+        }
+    }
+}
+
+fn main() {
+    countme::enable(true);
+    let t = std::time::Instant::now();
+    let n = 5;
+    let m = 1_000_000;
+
+    let mut threads = Vec::new();
+    for _ in 0..n {
+        threads.push(thread::spawn(move || {
+            for _ in 0..m {
+                Foo::default();
+            }
+        }));
+        threads.push(thread::spawn(move || {
+            let mut xs = Vec::with_capacity(m);
+            for _ in 0..m {
+                xs.push(Bar::default())
+            }
+        }));
+        threads.push(thread::spawn(move || {
+            for _ in 0..m {
+                deeply::nested::module::Quux::default();
+            }
+        }));
+    }
+    for t in threads {
+        t.join().unwrap();
+    }
+
+    let foo = get::<Foo>();
+    assert_eq!(foo.total, m * n);
+    assert!(foo.max_live >= 1);
+    assert_eq!(foo.live, 0);
+
+    let bar = get::<Bar>();
+    assert_eq!(bar.total, m * n);
+    assert!(bar.max_live >= m);
+    assert_eq!(bar.live, 0);
+
+    println!("{:?}", t.elapsed());
+}