Rename WakerStore -> WakerRegistration.

embassy/src/util/mod.rs

@@ -2,10 +2,10 @@ mod drop_bomb;
 mod forever;
 mod portal;
 mod signal;
-mod waker_store;
+mod waker;
 
 pub use drop_bomb::*;
 pub use forever::*;
 pub use portal::*;
 pub use signal::*;
-pub use waker_store::*;
+pub use waker::*;

embassy/src/util/waker.rs

@@ -0,0 +1,38 @@
+use core::task::Context;
+use core::task::Waker;
+
+/// Utility struct to register and wake a waker.
+#[derive(Debug)]
+pub struct WakerRegistration {
+    waker: Option<Waker>,
+}
+
+impl WakerRegistration {
+    pub const fn new() -> Self {
+        Self { waker: None }
+    }
+
+    /// Register a waker. Overwrites the previous waker, if any.
+    pub fn register(&mut self, w: &Waker) {
+        match self.waker {
+            // Optimization: If both the old and new Wakers wake the same task, we can simply
+            // keep the old waker, skipping the clone. (In most executor implementations,
+            // cloning a waker is somewhat expensive, comparable to cloning an Arc).
+            Some(ref w2) if (w2.will_wake(w)) => {}
+            // In all other cases
+            // - we have no waker registered
+            // - we have a waker registered but it's for a different task.
+            // then clone the new waker and store it
+            _ => self.waker = Some(w.clone()),
+        }
+    }
+
+    /// Wake the registered waker, if any.
+    pub fn wake(&mut self) {
+        self.waker.take().map(|w| w.wake());
+    }
+
+    pub fn context(&self) -> Option<Context<'_>> {
+        self.waker.as_ref().map(|w| Context::from_waker(w))
+    }
+}

embassy/src/util/waker_store.rs

@@ -1,23 +0,0 @@
-use core::task::Waker;
-
-pub struct WakerStore {
-    waker: Option<Waker>,
-}
-
-impl WakerStore {
-    pub const fn new() -> Self {
-        Self { waker: None }
-    }
-
-    pub fn store(&mut self, w: &Waker) {
-        match self.waker {
-            Some(ref w2) if (w2.will_wake(w)) => {}
-            Some(_) => panic!("Waker overflow"),
-            None => self.waker = Some(w.clone()),
-        }
-    }
-
-    pub fn wake(&mut self) {
-        self.waker.take().map(|w| w.wake());
-    }
-}