chore: add vendor dependencies for kauma build

vendor/once_cell/tests/it/race_once_box.rs

@@ -0,0 +1,145 @@
+#[cfg(feature = "std")]
+use std::sync::Barrier;
+use std::sync::{
+    atomic::{AtomicUsize, Ordering::SeqCst},
+    Arc,
+};
+
+use once_cell::race::OnceBox;
+
+#[derive(Default)]
+struct Heap {
+    total: Arc<AtomicUsize>,
+}
+
+#[derive(Debug)]
+struct Pebble<T> {
+    val: T,
+    total: Arc<AtomicUsize>,
+}
+
+impl<T> Drop for Pebble<T> {
+    fn drop(&mut self) {
+        self.total.fetch_sub(1, SeqCst);
+    }
+}
+
+impl Heap {
+    fn total(&self) -> usize {
+        self.total.load(SeqCst)
+    }
+    fn new_pebble<T>(&self, val: T) -> Pebble<T> {
+        self.total.fetch_add(1, SeqCst);
+        Pebble { val, total: Arc::clone(&self.total) }
+    }
+}
+
+#[cfg(feature = "std")]
+#[test]
+fn once_box_smoke_test() {
+    use std::thread::scope;
+
+    let heap = Heap::default();
+    let global_cnt = AtomicUsize::new(0);
+    let cell = OnceBox::new();
+    let b = Barrier::new(128);
+    scope(|s| {
+        for _ in 0..128 {
+            s.spawn(|| {
+                let local_cnt = AtomicUsize::new(0);
+                cell.get_or_init(|| {
+                    global_cnt.fetch_add(1, SeqCst);
+                    local_cnt.fetch_add(1, SeqCst);
+                    b.wait();
+                    Box::new(heap.new_pebble(()))
+                });
+                assert_eq!(local_cnt.load(SeqCst), 1);
+
+                cell.get_or_init(|| {
+                    global_cnt.fetch_add(1, SeqCst);
+                    local_cnt.fetch_add(1, SeqCst);
+                    Box::new(heap.new_pebble(()))
+                });
+                assert_eq!(local_cnt.load(SeqCst), 1);
+            });
+        }
+    });
+    assert!(cell.get().is_some());
+    assert!(global_cnt.load(SeqCst) > 10);
+
+    assert_eq!(heap.total(), 1);
+    drop(cell);
+    assert_eq!(heap.total(), 0);
+}
+
+#[test]
+fn once_box_set() {
+    let heap = Heap::default();
+    let cell = OnceBox::new();
+    assert!(cell.get().is_none());
+
+    assert!(cell.set(Box::new(heap.new_pebble("hello"))).is_ok());
+    assert_eq!(cell.get().unwrap().val, "hello");
+    assert_eq!(heap.total(), 1);
+
+    assert!(cell.set(Box::new(heap.new_pebble("world"))).is_err());
+    assert_eq!(cell.get().unwrap().val, "hello");
+    assert_eq!(heap.total(), 1);
+
+    drop(cell);
+    assert_eq!(heap.total(), 0);
+}
+
+#[cfg(feature = "std")]
+#[test]
+fn once_box_first_wins() {
+    use std::thread::scope;
+
+    let cell = OnceBox::new();
+    let val1 = 92;
+    let val2 = 62;
+
+    let b1 = Barrier::new(2);
+    let b2 = Barrier::new(2);
+    let b3 = Barrier::new(2);
+    scope(|s| {
+        s.spawn(|| {
+            let r1 = cell.get_or_init(|| {
+                b1.wait();
+                b2.wait();
+                Box::new(val1)
+            });
+            assert_eq!(*r1, val1);
+            b3.wait();
+        });
+        b1.wait();
+        s.spawn(|| {
+            let r2 = cell.get_or_init(|| {
+                b2.wait();
+                b3.wait();
+                Box::new(val2)
+            });
+            assert_eq!(*r2, val1);
+        });
+    });
+
+    assert_eq!(cell.get(), Some(&val1));
+}
+
+#[test]
+fn once_box_reentrant() {
+    let cell = OnceBox::new();
+    let res = cell.get_or_init(|| {
+        cell.get_or_init(|| Box::new("hello".to_string()));
+        Box::new("world".to_string())
+    });
+    assert_eq!(res, "hello");
+}
+
+#[test]
+fn once_box_default() {
+    struct Foo;
+
+    let cell: OnceBox<Foo> = Default::default();
+    assert!(cell.get().is_none());
+}