1 files changed, 26 insertions, 0 deletions
diff --git a/third_party/rust/tokio/src/util/sync_wrapper.rs b/third_party/rust/tokio/src/util/sync_wrapper.rs
new file mode 100644
index 0000000000..5ffc8f96b1
--- /dev/null
+++ b/third_party/rust/tokio/src/util/sync_wrapper.rs
@@ -0,0 +1,26 @@
+//! This module contains a type that can make `Send + !Sync` types `Sync` by
+//! disallowing all immutable access to the value.
+//!
+//! A similar primitive is provided in the `sync_wrapper` crate.
+
+pub(crate) struct SyncWrapper<T> {
+    value: T,
+}
+
+// safety: The SyncWrapper being send allows you to send the inner value across
+// thread boundaries.
+unsafe impl<T: Send> Send for SyncWrapper<T> {}
+
+// safety: An immutable reference to a SyncWrapper is useless, so moving such an
+// immutable reference across threads is safe.
+unsafe impl<T> Sync for SyncWrapper<T> {}
+
+impl<T> SyncWrapper<T> {
+    pub(crate) fn new(value: T) -> Self {
+        Self { value }
+    }
+
+    pub(crate) fn into_inner(self) -> T {
+        self.value
+    }
+}