1 files changed, 38 insertions, 0 deletions
diff --git a/vendor/tokio/src/task/yield_now.rs b/vendor/tokio/src/task/yield_now.rs
new file mode 100644
index 000000000..251cb931b
--- /dev/null
+++ b/vendor/tokio/src/task/yield_now.rs
@@ -0,0 +1,38 @@
+use std::future::Future;
+use std::pin::Pin;
+use std::task::{Context, Poll};
+
+cfg_rt! {
+    /// Yields execution back to the Tokio runtime.
+    ///
+    /// A task yields by awaiting on `yield_now()`, and may resume when that
+    /// future completes (with no output.) The current task will be re-added as
+    /// a pending task at the _back_ of the pending queue. Any other pending
+    /// tasks will be scheduled. No other waking is required for the task to
+    /// continue.
+    ///
+    /// See also the usage example in the [task module](index.html#yield_now).
+    #[must_use = "yield_now does nothing unless polled/`await`-ed"]
+    pub async fn yield_now() {
+        /// Yield implementation
+        struct YieldNow {
+            yielded: bool,
+        }
+
+        impl Future for YieldNow {
+            type Output = ();
+
+            fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<()> {
+                if self.yielded {
+                    return Poll::Ready(());
+                }
+
+                self.yielded = true;
+                cx.waker().wake_by_ref();
+                Poll::Pending
+            }
+        }
+
+        YieldNow { yielded: false }.await
+    }
+}