From 9e8de5f596ffa9036c2343ccc1e69f471a4770eb Mon Sep 17 00:00:00 2001
From: xoviat <xoviat@users.noreply.github.com>
Date: Sat, 17 Jun 2023 08:11:55 -0500
Subject: [PATCH] fut: add poll_once

---
 embassy-futures/src/block_on.rs | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/embassy-futures/src/block_on.rs b/embassy-futures/src/block_on.rs
index da90351e..77695216 100644
--- a/embassy-futures/src/block_on.rs
+++ b/embassy-futures/src/block_on.rs
@@ -31,3 +31,15 @@ pub fn block_on<F: Future>(mut fut: F) -> F::Output {
         }
     }
 }
+
+/// Poll a future once.
+pub fn poll_once<F: Future>(mut fut: F) -> Poll<F::Output> {
+    // safety: we don't move the future after this line.
+    let mut fut = unsafe { Pin::new_unchecked(&mut fut) };
+
+    let raw_waker = RawWaker::new(ptr::null(), &VTABLE);
+    let waker = unsafe { Waker::from_raw(raw_waker) };
+    let mut cx = Context::from_waker(&waker);
+
+    fut.as_mut().poll(&mut cx)
+}