1 files changed, 48 insertions, 0 deletions
diff --git a/tokio/src/sync/loom.rs b/tokio/src/sync/loom.rs
new file mode 100644
index 00000000..1b5a5c9d
--- /dev/null
+++ b/tokio/src/sync/loom.rs
@@ -0,0 +1,48 @@
+#[cfg(not(all(test, loom)))]
+mod imp {
+    pub(crate) mod future {
+        pub(crate) use crate::sync::task::AtomicWaker;
+    }
+
+    pub(crate) mod sync {
+        pub(crate) use std::sync::atomic;
+        pub(crate) use std::sync::Arc;
+
+        use std::cell::UnsafeCell;
+
+        pub(crate) struct CausalCell<T>(UnsafeCell<T>);
+
+        impl<T> CausalCell<T> {
+            pub(crate) fn new(data: T) -> CausalCell<T> {
+                CausalCell(UnsafeCell::new(data))
+            }
+
+            pub(crate) fn with<F, R>(&self, f: F) -> R
+            where
+                F: FnOnce(*const T) -> R,
+            {
+                f(self.0.get())
+            }
+
+            pub(crate) fn with_mut<F, R>(&self, f: F) -> R
+            where
+                F: FnOnce(*mut T) -> R,
+            {
+                f(self.0.get())
+            }
+        }
+    }
+
+    pub(crate) mod thread {
+        pub(crate) fn yield_now() {
+            ::std::sync::atomic::spin_loop_hint();
+        }
+    }
+}
+
+#[cfg(all(test, loom))]
+mod imp {
+    pub(crate) use loom::*;
+}
+
+pub(crate) use self::imp::*;