Added sender types, support for dropping receivers, converting to dyn-types, revised tests.

embassy-sync/src/watch.rs

@@ -1,4 +1,4 @@
-//! A synchronization primitive for passing the latest value to **multiple** tasks.
+//! A synchronization primitive for passing the latest value to **multiple** receivers.
 
 use core::cell::RefCell;
 use core::future::poll_fn;
@@ -10,22 +10,17 @@ use crate::blocking_mutex::raw::RawMutex;
 use crate::blocking_mutex::Mutex;
 use crate::waitqueue::MultiWakerRegistration;
 
-/// A `Watch` is a single-slot signaling primitive, which can awake `N` up to separate [`Receiver`]s.
+/// The `Watch` is a single-slot signaling primitive that allows multiple receivers to concurrently await
+/// changes to the value. Unlike a [`Signal`](crate::signal::Signal), `Watch` supports multiple receivers,
+/// and unlike a [`PubSubChannel`](crate::pubsub::PubSubChannel), `Watch` immediately overwrites the previous
+/// value when a new one is sent, without waiting for all receivers to read the previous value.
 ///
-/// Similar to a [`Signal`](crate::signal::Signal), except `Watch` allows for multiple tasks to
+/// This makes `Watch` particularly useful when a single task updates a value or "state", and multiple other tasks
-/// `.await` the latest value, and all receive it.
+/// need to be notified about changes to this value asynchronously. Receivers may "lose" stale values, as they are
+/// always provided with the latest value.
 ///
-/// This is similar to a [`PubSubChannel`](crate::pubsub::PubSubChannel) with a buffer size of 1, except
+/// Typically, `Watch` instances are declared as `static`, and a [`Sender`] and [`Receiver`]
-/// "sending" to it (calling [`Watch::write`]) will immediately overwrite the previous value instead
+/// (or [`DynSender`] and/or [`DynReceiver`]) are obtained and passed to the relevant parts of the program.
-/// of waiting for the receivers to pop the previous value.
-///
-/// `Watch` is useful when a single task is responsible for updating a value or "state", which multiple other
-/// tasks are interested in getting notified about changes to the latest value of. It is therefore fine for
-/// [`Receiver`]s to "lose" stale values.
-///
-/// Anyone with a reference to the Watch can update or peek the value. Watches are generally declared
-/// as `static`s and then borrowed as required to either [`Watch::peek`] the value or obtain a [`Receiver`]
-/// with [`Watch::receiver`] which has async methods.
 /// ```
 ///
 /// use futures_executor::block_on;
@@ -36,18 +31,18 @@ use crate::waitqueue::MultiWakerRegistration;
 ///
 /// static WATCH: Watch<CriticalSectionRawMutex, u8, 2> = Watch::new();
 ///
-/// // Obtain Receivers
+/// // Obtain receivers and sender
 /// let mut rcv0 = WATCH.receiver().unwrap();
-/// let mut rcv1 = WATCH.receiver().unwrap();
+/// let mut rcv1 = WATCH.dyn_receiver().unwrap();
-/// assert!(WATCH.receiver().is_err());
+/// let mut snd = WATCH.sender();
 ///
+/// // No more receivers, and no update
+/// assert!(WATCH.receiver().is_err());
 /// assert_eq!(rcv1.try_changed(), None);
 ///
-/// WATCH.write(10);
+/// snd.send(10);
-/// assert_eq!(WATCH.try_peek(), Some(10));
 ///     
-///     
+/// // Receive the new value (async or try)
-/// // Receive the new value
 /// assert_eq!(rcv0.changed().await, 10);
 /// assert_eq!(rcv1.try_changed(), Some(10));
 ///     
@@ -55,13 +50,14 @@ use crate::waitqueue::MultiWakerRegistration;
 /// assert_eq!(rcv0.try_changed(), None);
 /// assert_eq!(rcv1.try_changed(), None);
 ///
-/// WATCH.write(20);
+/// snd.send(20);
 ///
-/// // Defference `between` peek `get`.
+/// // Peek does not mark the value as seen
 /// assert_eq!(rcv0.peek().await, 20);
-/// assert_eq!(rcv1.get().await, 20);
-///
 /// assert_eq!(rcv0.try_changed(), Some(20));
+///
+/// // Get marks the value as seen
+/// assert_eq!(rcv1.get().await, 20);
 /// assert_eq!(rcv1.try_changed(), None);
 ///
 /// };
@@ -80,30 +76,57 @@ struct WatchState<const N: usize, T: Clone> {
 
 /// A trait representing the 'inner' behavior of the `Watch`.
 pub trait WatchBehavior<T: Clone> {
+    /// Sends a new value to the `Watch`.
+    fn send(&self, val: T);
+
+    /// Clears the value of the `Watch`.
+    fn clear(&self);
+
     /// Poll the `Watch` for the current value, **without** making it as seen.
-    fn inner_poll_peek(&self, cx: &mut Context<'_>) -> Poll<T>;
+    fn poll_peek(&self, cx: &mut Context<'_>) -> Poll<T>;
 
     /// Tries to peek the value of the `Watch`, **without** marking it as seen.
-    fn inner_try_peek(&self) -> Option<T>;
+    fn try_peek(&self) -> Option<T>;
 
     /// Poll the `Watch` for the current value, making it as seen.
-    fn inner_poll_get(&self, id: &mut u64, cx: &mut Context<'_>) -> Poll<T>;
+    fn poll_get(&self, id: &mut u64, cx: &mut Context<'_>) -> Poll<T>;
 
     /// Tries to get the value of the `Watch`, marking it as seen.
-    fn inner_try_get(&self, id: &mut u64) -> Option<T>;
+    fn try_get(&self, id: &mut u64) -> Option<T>;
 
     /// Poll the `Watch` for a changed value, marking it as seen.
-    fn inner_poll_changed(&self, id: &mut u64, cx: &mut Context<'_>) -> Poll<T>;
+    fn poll_changed(&self, id: &mut u64, cx: &mut Context<'_>) -> Poll<T>;
 
     /// Tries to retrieve the value of the `Watch` if it has changed, marking it as seen.
-    fn inner_try_changed(&self, id: &mut u64) -> Option<T>;
+    fn try_changed(&self, id: &mut u64) -> Option<T>;
 
     /// Checks if the `Watch` is been initialized with a value.
-    fn inner_contains_value(&self) -> bool;
+    fn contains_value(&self) -> bool;
+
+    /// Used when a receiver is dropped to decrement the receiver count.
+    ///
+    /// ## This method should not be called by the user.
+    fn drop_receiver(&self);
 }
 
 impl<M: RawMutex, T: Clone, const N: usize> WatchBehavior<T> for Watch<M, T, N> {
-    fn inner_poll_peek(&self, cx: &mut Context<'_>) -> Poll<T> {
+    fn send(&self, val: T) {
+        self.mutex.lock(|state| {
+            let mut s = state.borrow_mut();
+            s.data = Some(val);
+            s.current_id += 1;
+            s.wakers.wake();
+        })
+    }
+
+    fn clear(&self) {
+        self.mutex.lock(|state| {
+            let mut s = state.borrow_mut();
+            s.data = None;
+        })
+    }
+
+    fn poll_peek(&self, cx: &mut Context<'_>) -> Poll<T> {
         self.mutex.lock(|state| {
             let mut s = state.borrow_mut();
             match &s.data {
@@ -116,11 +139,11 @@ impl<M: RawMutex, T: Clone, const N: usize> WatchBehavior<T> for Watch<M, T, N>
         })
     }
 
-    fn inner_try_peek(&self) -> Option<T> {
+    fn try_peek(&self) -> Option<T> {
         self.mutex.lock(|state| state.borrow().data.clone())
     }
 
-    fn inner_poll_get(&self, id: &mut u64, cx: &mut Context<'_>) -> Poll<T> {
+    fn poll_get(&self, id: &mut u64, cx: &mut Context<'_>) -> Poll<T> {
         self.mutex.lock(|state| {
             let mut s = state.borrow_mut();
             match &s.data {
@@ -136,7 +159,7 @@ impl<M: RawMutex, T: Clone, const N: usize> WatchBehavior<T> for Watch<M, T, N>
         })
     }
 
-    fn inner_try_get(&self, id: &mut u64) -> Option<T> {
+    fn try_get(&self, id: &mut u64) -> Option<T> {
         self.mutex.lock(|state| {
             let s = state.borrow();
             *id = s.current_id;
@@ -144,7 +167,7 @@ impl<M: RawMutex, T: Clone, const N: usize> WatchBehavior<T> for Watch<M, T, N>
         })
     }
 
-    fn inner_poll_changed(&self, id: &mut u64, cx: &mut Context<'_>) -> Poll<T> {
+    fn poll_changed(&self, id: &mut u64, cx: &mut Context<'_>) -> Poll<T> {
         self.mutex.lock(|state| {
             let mut s = state.borrow_mut();
             match (&s.data, s.current_id > *id) {
@@ -160,7 +183,7 @@ impl<M: RawMutex, T: Clone, const N: usize> WatchBehavior<T> for Watch<M, T, N>
         })
     }
 
-    fn inner_try_changed(&self, id: &mut u64) -> Option<T> {
+    fn try_changed(&self, id: &mut u64) -> Option<T> {
         self.mutex.lock(|state| {
             let s = state.borrow();
             match s.current_id > *id {
@@ -173,9 +196,16 @@ impl<M: RawMutex, T: Clone, const N: usize> WatchBehavior<T> for Watch<M, T, N>
         })
     }
 
-    fn inner_contains_value(&self) -> bool {
+    fn contains_value(&self) -> bool {
         self.mutex.lock(|state| state.borrow().data.is_some())
     }
+
+    fn drop_receiver(&self) {
+        self.mutex.lock(|state| {
+            let mut s = state.borrow_mut();
+            s.receiver_count -= 1;
+        })
+    }
 }
 
 #[derive(Debug)]
@@ -198,14 +228,14 @@ impl<'a, M: RawMutex, T: Clone, const N: usize> Watch<M, T, N> {
         }
     }
 
-    /// Write a new value to the `Watch`.
+    /// Create a new [`Receiver`] for the `Watch`.
-    pub fn write(&self, val: T) {
+    pub fn sender(&self) -> Sender<'_, M, T, N> {
-        self.mutex.lock(|state| {
+        Sender(Snd::new(self))
-            let mut s = state.borrow_mut();
+    }
-            s.data = Some(val);
+
-            s.current_id += 1;
+    /// Create a new [`DynReceiver`] for the `Watch`.
-            s.wakers.wake();
+    pub fn dyn_sender(&self) -> DynSender<'_, T> {
-        })
+        DynSender(Snd::new(self))
     }
 
     /// Create a new [`Receiver`] for the `Watch`.
@@ -214,7 +244,7 @@ impl<'a, M: RawMutex, T: Clone, const N: usize> Watch<M, T, N> {
             let mut s = state.borrow_mut();
             if s.receiver_count < N {
                 s.receiver_count += 1;
-                Ok(Receiver(Rcv::new(self)))
+                Ok(Receiver(Rcv::new(self, 0)))
             } else {
                 Err(Error::MaximumReceiversReached)
             }
@@ -227,29 +257,121 @@ impl<'a, M: RawMutex, T: Clone, const N: usize> Watch<M, T, N> {
             let mut s = state.borrow_mut();
             if s.receiver_count < N {
                 s.receiver_count += 1;
-                Ok(DynReceiver(Rcv::new(self)))
+                Ok(DynReceiver(Rcv::new(self, 0)))
             } else {
                 Err(Error::MaximumReceiversReached)
             }
         })
     }
+}
+
+/// A receiver can `.await` a change in the `Watch` value.
+pub struct Snd<'a, T: Clone, W: WatchBehavior<T> + ?Sized> {
+    watch: &'a W,
+    _phantom: PhantomData<T>,
+}
+
+impl<'a, T: Clone, W: WatchBehavior<T> + ?Sized> Clone for Snd<'a, T, W> {
+    fn clone(&self) -> Self {
+        Self {
+            watch: self.watch,
+            _phantom: PhantomData,
+        }
+    }
+}
+
+impl<'a, T: Clone, W: WatchBehavior<T> + ?Sized> Snd<'a, T, W> {
+    /// Creates a new `Receiver` with a reference to the `Watch`.
+    fn new(watch: &'a W) -> Self {
+        Self {
+            watch,
+            _phantom: PhantomData,
+        }
+    }
+
+    /// Sends a new value to the `Watch`.
+    pub fn send(&self, val: T) {
+        self.watch.send(val)
+    }
+
+    /// Clears the value of the `Watch`.
+    /// This will cause calls to [`Rcv::get`] and [`Rcv::peek`] to be pending.
+    pub fn clear(&self) {
+        self.watch.clear()
+    }
 
     /// Tries to retrieve the value of the `Watch`.
     pub fn try_peek(&self) -> Option<T> {
-        self.inner_try_peek()
+        self.watch.try_peek()
     }
 
     /// Returns true if the `Watch` contains a value.
     pub fn contains_value(&self) -> bool {
-        self.inner_contains_value()
+        self.watch.contains_value()
     }
+}
 
-    /// Clears the value of the `Watch`. This will cause calls to [`Rcv::get`] and [`Rcv::peek`] to be pending.
+/// A sender of a `Watch` channel.
-    pub fn clear(&self) {
+///
-        self.mutex.lock(|state| {
+/// For a simpler type definition, consider [`DynSender`] at the expense of
-            let mut s = state.borrow_mut();
+/// some runtime performance due to dynamic dispatch.
-            s.data = None;
+pub struct Sender<'a, M: RawMutex, T: Clone, const N: usize>(Snd<'a, T, Watch<M, T, N>>);
-        })
+
+impl<'a, M: RawMutex, T: Clone, const N: usize> Clone for Sender<'a, M, T, N> {
+    fn clone(&self) -> Self {
+        Self(self.0.clone())
+    }
+}
+
+impl<'a, M: RawMutex, T: Clone, const N: usize> Sender<'a, M, T, N> {
+    /// Converts the `Sender` into a [`DynSender`].
+    pub fn as_dyn(self) -> DynSender<'a, T> {
+        DynSender(Snd::new(self.watch))
+    }
+}
+
+impl<'a, M: RawMutex, T: Clone, const N: usize> Into<DynSender<'a, T>> for Sender<'a, M, T, N> {
+    fn into(self) -> DynSender<'a, T> {
+        self.as_dyn()
+    }
+}
+
+impl<'a, M: RawMutex, T: Clone, const N: usize> Deref for Sender<'a, M, T, N> {
+    type Target = Snd<'a, T, Watch<M, T, N>>;
+
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+
+impl<'a, M: RawMutex, T: Clone, const N: usize> DerefMut for Sender<'a, M, T, N> {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        &mut self.0
+    }
+}
+
+/// A sender which holds a **dynamic** reference to a `Watch` channel.
+///
+/// This is an alternative to [`Sender`] with a simpler type definition,
+pub struct DynSender<'a, T: Clone>(Snd<'a, T, dyn WatchBehavior<T> + 'a>);
+
+impl<'a, T: Clone> Clone for DynSender<'a, T> {
+    fn clone(&self) -> Self {
+        Self(self.0.clone())
+    }
+}
+
+impl<'a, T: Clone> Deref for DynSender<'a, T> {
+    type Target = Snd<'a, T, dyn WatchBehavior<T> + 'a>;
+
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+
+impl<'a, T: Clone> DerefMut for DynSender<'a, T> {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        &mut self.0
     }
 }
 
@@ -262,59 +384,83 @@ pub struct Rcv<'a, T: Clone, W: WatchBehavior<T> + ?Sized> {
 
 impl<'a, T: Clone, W: WatchBehavior<T> + ?Sized> Rcv<'a, T, W> {
     /// Creates a new `Receiver` with a reference to the `Watch`.
-    fn new(watch: &'a W) -> Self {
+    fn new(watch: &'a W, at_id: u64) -> Self {
         Self {
             watch,
-            at_id: 0,
+            at_id,
             _phantom: PhantomData,
         }
     }
 
-    /// Returns the current value of the `Watch` if it is initialized, **without** marking it as seen.
+    /// Returns the current value of the `Watch` once it is initialized, **without** marking it as seen.
+    ///
+    /// **Note**: Futures do nothing unless you `.await` or poll them.
     pub async fn peek(&self) -> T {
-        poll_fn(|cx| self.watch.inner_poll_peek(cx)).await
+        poll_fn(|cx| self.watch.poll_peek(cx)).await
     }
 
     /// Tries to peek the current value of the `Watch` without waiting, and **without** marking it as seen.
     pub fn try_peek(&self) -> Option<T> {
-        self.watch.inner_try_peek()
+        self.watch.try_peek()
     }
 
-    /// Returns the current value of the `Watch` if it is initialized, marking it as seen.
+    /// Returns the current value of the `Watch` once it is initialized, marking it as seen.
+    ///
+    /// **Note**: Futures do nothing unless you `.await` or poll them.
     pub async fn get(&mut self) -> T {
-        poll_fn(|cx| self.watch.inner_poll_get(&mut self.at_id, cx)).await
+        poll_fn(|cx| self.watch.poll_get(&mut self.at_id, cx)).await
     }
 
     /// Tries to get the current value of the `Watch` without waiting, marking it as seen.
     pub fn try_get(&mut self) -> Option<T> {
-        self.watch.inner_try_get(&mut self.at_id)
+        self.watch.try_get(&mut self.at_id)
     }
 
     /// Waits for the `Watch` to change and returns the new value, marking it as seen.
+    ///
+    /// **Note**: Futures do nothing unless you `.await` or poll them.
     pub async fn changed(&mut self) -> T {
-        poll_fn(|cx| self.watch.inner_poll_changed(&mut self.at_id, cx)).await
+        poll_fn(|cx| self.watch.poll_changed(&mut self.at_id, cx)).await
     }
 
     /// Tries to get the new value of the watch without waiting, marking it as seen.
     pub fn try_changed(&mut self) -> Option<T> {
-        self.watch.inner_try_changed(&mut self.at_id)
+        self.watch.try_changed(&mut self.at_id)
     }
 
     /// Checks if the `Watch` contains a value. If this returns true,
     /// then awaiting [`Rcv::get`] and [`Rcv::peek`] will return immediately.
     pub fn contains_value(&self) -> bool {
-        self.watch.inner_contains_value()
+        self.watch.contains_value()
+    }
+}
+
+impl<'a, T: Clone, W: WatchBehavior<T> + ?Sized> Drop for Rcv<'a, T, W> {
+    fn drop(&mut self) {
+        self.watch.drop_receiver();
     }
 }
 
 /// A receiver of a `Watch` channel.
 pub struct Receiver<'a, M: RawMutex, T: Clone, const N: usize>(Rcv<'a, T, Watch<M, T, N>>);
 
-/// A receiver which holds a **reference** to a `Watch` channel.
+impl<'a, M: RawMutex, T: Clone, const N: usize> Receiver<'a, M, T, N> {
-///
+    /// Converts the `Receiver` into a [`DynReceiver`].
-/// This is an alternative to [`Receiver`] with a simpler type definition, at the expense of
+    pub fn as_dyn(self) -> DynReceiver<'a, T> {
-/// some runtime performance due to dynamic dispatch.
+        // We need to increment the receiver count since the original
-pub struct DynReceiver<'a, T: Clone>(Rcv<'a, T, dyn WatchBehavior<T> + 'a>);
+        // receiver is being dropped, which decrements the count.
+        self.watch.mutex.lock(|state| {
+            state.borrow_mut().receiver_count += 1;
+        });
+        DynReceiver(Rcv::new(self.0.watch, self.at_id))
+    }
+}
+
+impl<'a, M: RawMutex, T: Clone, const N: usize> Into<DynReceiver<'a, T>> for Receiver<'a, M, T, N> {
+    fn into(self) -> DynReceiver<'a, T> {
+        self.as_dyn()
+    }
+}
 
 impl<'a, M: RawMutex, T: Clone, const N: usize> Deref for Receiver<'a, M, T, N> {
     type Target = Rcv<'a, T, Watch<M, T, N>>;
@@ -330,6 +476,12 @@ impl<'a, M: RawMutex, T: Clone, const N: usize> DerefMut for Receiver<'a, M, T,
     }
 }
 
+/// A receiver which holds a **dynamic** reference to a `Watch` channel.
+///
+/// This is an alternative to [`Receiver`] with a simpler type definition, at the expense of
+/// some runtime performance due to dynamic dispatch.
+pub struct DynReceiver<'a, T: Clone>(Rcv<'a, T, dyn WatchBehavior<T> + 'a>);
+
 impl<'a, T: Clone> Deref for DynReceiver<'a, T> {
     type Target = Rcv<'a, T, dyn WatchBehavior<T> + 'a>;
 
@@ -348,167 +500,242 @@ impl<'a, T: Clone> DerefMut for DynReceiver<'a, T> {
 mod tests {
     use futures_executor::block_on;
 
-    use super::*;
+    use super::Watch;
     use crate::blocking_mutex::raw::CriticalSectionRawMutex;
 
     #[test]
-    fn multiple_writes() {
+    fn multiple_sends() {
         let f = async {
-            static WATCH: Watch<CriticalSectionRawMutex, u8, 2> = Watch::new();
+            static WATCH: Watch<CriticalSectionRawMutex, u8, 1> = Watch::new();
 
-            // Obtain Receivers
+            // Obtain receiver and sender
-            let mut rcv0 = WATCH.receiver().unwrap();
+            let mut rcv = WATCH.receiver().unwrap();
-            let mut rcv1 = WATCH.dyn_receiver().unwrap();
+            let snd = WATCH.sender();
 
-            WATCH.write(10);
+            // Not initialized
+            assert_eq!(rcv.try_changed(), None);
 
             // Receive the new value
-            assert_eq!(rcv0.changed().await, 10);
+            snd.send(10);
-            assert_eq!(rcv1.changed().await, 10);
+            assert_eq!(rcv.changed().await, 10);
+
+            // Receive another value
+            snd.send(20);
+            assert_eq!(rcv.try_changed(), Some(20));
 
             // No update
-            assert_eq!(rcv0.try_changed(), None);
+            assert_eq!(rcv.try_changed(), None);
-            assert_eq!(rcv1.try_changed(), None);
-
-            WATCH.write(20);
-
-            assert_eq!(rcv0.changed().await, 20);
-            assert_eq!(rcv1.changed().await, 20);
         };
         block_on(f);
     }
 
     #[test]
-    fn max_receivers() {
+    fn receive_after_create() {
         let f = async {
-            static WATCH: Watch<CriticalSectionRawMutex, u8, 2> = Watch::new();
+            static WATCH: Watch<CriticalSectionRawMutex, u8, 1> = Watch::new();
 
-            // Obtain Receivers
+            // Obtain sender and send value
-            let _ = WATCH.receiver().unwrap();
+            let snd = WATCH.sender();
-            let _ = WATCH.receiver().unwrap();
+            snd.send(10);
-            assert!(WATCH.receiver().is_err());
+
+            // Obtain receiver and receive value
+            let mut rcv = WATCH.receiver().unwrap();
+            assert_eq!(rcv.try_changed(), Some(10));
         };
         block_on(f);
     }
 
     #[test]
-    fn receive_initial() {
+    fn max_receivers_drop() {
         let f = async {
             static WATCH: Watch<CriticalSectionRawMutex, u8, 2> = Watch::new();
 
-            // Obtain Receivers
+            // Try to create 3 receivers (only 2 can exist at once)
+            let rcv0 = WATCH.receiver();
+            let rcv1 = WATCH.receiver();
+            let rcv2 = WATCH.receiver();
+
+            // Ensure the first two are successful and the third is not
+            assert!(rcv0.is_ok());
+            assert!(rcv1.is_ok());
+            assert!(rcv2.is_err());
+
+            // Drop the first receiver
+            drop(rcv0);
+
+            // Create another receiver and ensure it is successful
+            let rcv3 = WATCH.receiver();
+            assert!(rcv3.is_ok());
+        };
+        block_on(f);
+    }
+
+    #[test]
+    fn multiple_receivers() {
+        let f = async {
+            static WATCH: Watch<CriticalSectionRawMutex, u8, 2> = Watch::new();
+
+            // Obtain receivers and sender
             let mut rcv0 = WATCH.receiver().unwrap();
             let mut rcv1 = WATCH.receiver().unwrap();
+            let snd = WATCH.sender();
 
-            assert_eq!(rcv0.contains_value(), false);
+            // No update for both
-
             assert_eq!(rcv0.try_changed(), None);
             assert_eq!(rcv1.try_changed(), None);
 
-            WATCH.write(0);
+            // Send a new value
-
+            snd.send(0);
-            assert_eq!(rcv0.contains_value(), true);
 
+            // Both receivers receive the new value
             assert_eq!(rcv0.try_changed(), Some(0));
             assert_eq!(rcv1.try_changed(), Some(0));
         };
         block_on(f);
     }
 
+    #[test]
+    fn clone_senders() {
+        let f = async {
+            // Obtain different ways to send
+            static WATCH: Watch<CriticalSectionRawMutex, u8, 1> = Watch::new();
+            let snd0 = WATCH.sender();
+            let snd1 = snd0.clone();
+
+            // Obtain Receiver
+            let mut rcv = WATCH.receiver().unwrap().as_dyn();
+
+            // Send a value from first sender
+            snd0.send(10);
+            assert_eq!(rcv.try_changed(), Some(10));
+
+            // Send a value from second sender
+            snd1.send(20);
+            assert_eq!(rcv.try_changed(), Some(20));
+        };
+        block_on(f);
+    }
+
     #[test]
     fn peek_get_changed() {
         let f = async {
             static WATCH: Watch<CriticalSectionRawMutex, u8, 2> = Watch::new();
 
-            // Obtain Receivers
+            // Obtain receiver and sender
-            let mut rcv0 = WATCH.receiver().unwrap();
+            let mut rcv = WATCH.receiver().unwrap();
+            let snd = WATCH.sender();
 
-            WATCH.write(10);
+            // Send a value
+            snd.send(10);
 
             // Ensure peek does not mark as seen
-            assert_eq!(rcv0.peek().await, 10);
+            assert_eq!(rcv.peek().await, 10);
-            assert_eq!(rcv0.try_changed(), Some(10));
+            assert_eq!(rcv.try_changed(), Some(10));
-            assert_eq!(rcv0.try_changed(), None);
+            assert_eq!(rcv.try_changed(), None);
-            assert_eq!(rcv0.peek().await, 10);
+            assert_eq!(rcv.try_peek(), Some(10));
 
-            WATCH.write(20);
+            // Send a value
+            snd.send(20);
 
             // Ensure get does mark as seen
-            assert_eq!(rcv0.get().await, 20);
+            assert_eq!(rcv.get().await, 20);
-            assert_eq!(rcv0.try_changed(), None);
+            assert_eq!(rcv.try_changed(), None);
-            assert_eq!(rcv0.try_get(), Some(20));
+            assert_eq!(rcv.try_get(), Some(20));
         };
         block_on(f);
     }
 
     #[test]
-    fn count_ids() {
+    fn use_dynamics() {
         let f = async {
             static WATCH: Watch<CriticalSectionRawMutex, u8, 2> = Watch::new();
 
-            // Obtain Receivers
+            // Obtain receiver and sender
-            let mut rcv0 = WATCH.receiver().unwrap();
+            let mut dyn_rcv = WATCH.dyn_receiver().unwrap();
-            let mut rcv1 = WATCH.receiver().unwrap();
+            let dyn_snd = WATCH.dyn_sender();
 
-            let get_id = || WATCH.mutex.lock(|state| state.borrow().current_id);
+            // Send a value
+            dyn_snd.send(10);
 
-            WATCH.write(10);
+            // Ensure the dynamic receiver receives the value
-
+            assert_eq!(dyn_rcv.try_changed(), Some(10));
-            assert_eq!(rcv0.changed().await, 10);
+            assert_eq!(dyn_rcv.try_changed(), None);
-            assert_eq!(rcv1.changed().await, 10);
-
-            assert_eq!(rcv0.try_changed(), None);
-            assert_eq!(rcv1.try_changed(), None);
-
-            WATCH.write(20);
-            WATCH.write(20);
-            WATCH.write(20);
-
-            assert_eq!(rcv0.changed().await, 20);
-            assert_eq!(rcv1.changed().await, 20);
-
-            assert_eq!(rcv0.try_changed(), None);
-            assert_eq!(rcv1.try_changed(), None);
-
-            assert_eq!(get_id(), 4);
         };
         block_on(f);
     }
 
     #[test]
-    fn peek_still_await() {
+    fn convert_to_dyn() {
         let f = async {
             static WATCH: Watch<CriticalSectionRawMutex, u8, 2> = Watch::new();
 
-            // Obtain Receivers
+            // Obtain receiver and sender
-            let mut rcv0 = WATCH.receiver().unwrap();
+            let rcv = WATCH.receiver().unwrap();
-            let mut rcv1 = WATCH.receiver().unwrap();
+            let snd = WATCH.sender();
 
-            WATCH.write(10);
+            // Convert to dynamic
+            let mut dyn_rcv = rcv.as_dyn();
+            let dyn_snd = snd.as_dyn();
 
-            assert_eq!(rcv0.peek().await, 10);
+            // Send a value
-            assert_eq!(rcv1.try_peek(), Some(10));
+            dyn_snd.send(10);
 
-            assert_eq!(rcv0.changed().await, 10);
+            // Ensure the dynamic receiver receives the value
-            assert_eq!(rcv1.changed().await, 10);
+            assert_eq!(dyn_rcv.try_changed(), Some(10));
+            assert_eq!(dyn_rcv.try_changed(), None);
         };
         block_on(f);
     }
 
     #[test]
-    fn peek_with_static() {
+    fn dynamic_receiver_count() {
         let f = async {
             static WATCH: Watch<CriticalSectionRawMutex, u8, 2> = Watch::new();
 
-            // Obtain Receivers
+            // Obtain receiver and sender
-            let rcv0 = WATCH.receiver().unwrap();
+            let rcv0 = WATCH.receiver();
-            let rcv1 = WATCH.receiver().unwrap();
+            let rcv1 = WATCH.receiver();
+            let rcv2 = WATCH.receiver();
 
-            WATCH.write(20);
+            // Ensure the first two are successful and the third is not
+            assert!(rcv0.is_ok());
+            assert!(rcv1.is_ok());
+            assert!(rcv2.is_err());
 
-            assert_eq!(rcv0.peek().await, 20);
+            // Convert to dynamic
-            assert_eq!(rcv1.peek().await, 20);
+            let dyn_rcv0 = rcv0.unwrap().as_dyn();
-            assert_eq!(WATCH.try_peek(), Some(20));
+
+            // Drop the (now dynamic) receiver
+            drop(dyn_rcv0);
+
+            // Create another receiver and ensure it is successful
+            let rcv3 = WATCH.receiver();
+            let rcv4 = WATCH.receiver();
+            assert!(rcv3.is_ok());
+            assert!(rcv4.is_err());
+        };
+        block_on(f);
+    }
+
+    #[test]
+    fn contains_value() {
+        let f = async {
+            static WATCH: Watch<CriticalSectionRawMutex, u8, 2> = Watch::new();
+
+            // Obtain receiver and sender
+            let rcv = WATCH.receiver().unwrap();
+            let snd = WATCH.sender();
+
+            // check if the watch contains a value
+            assert_eq!(rcv.contains_value(), false);
+            assert_eq!(snd.contains_value(), false);
+
+            // Send a value
+            snd.send(10);
+
+            // check if the watch contains a value
+            assert_eq!(rcv.contains_value(), true);
+            assert_eq!(snd.contains_value(), true);
         };
         block_on(f);
     }