Merge branch 'main' of https://github.com/embassy-rs/embassy into fix_main

9 files changed, 544 insertions, 49 deletions

diff --git a/embassy-sync/src/channel.rs b/embassy-sync/src/channel.rs
index 18be462cb..55ac5fb66 100644
--- a/embassy-sync/src/channel.rs
+++ b/embassy-sync/src/channel.rs
@@ -42,7 +42,7 @@ where
     M: RawMutex,
 {
     fn clone(&self) -> Self {
-        Sender { channel: self.channel }
+        *self
     }
 }
 
@@ -81,7 +81,7 @@ pub struct DynamicSender<'ch, T> {
 
 impl<'ch, T> Clone for DynamicSender<'ch, T> {
     fn clone(&self) -> Self {
-        DynamicSender { channel: self.channel }
+        *self
     }
 }
 
@@ -135,7 +135,7 @@ where
     M: RawMutex,
 {
     fn clone(&self) -> Self {
-        Receiver { channel: self.channel }
+        *self
     }
 }
 
@@ -152,6 +152,13 @@ where
         self.channel.receive()
     }
 
+    /// Is a value ready to be received in the channel
+    ///
+    /// See [`Channel::ready_to_receive()`].
+    pub fn ready_to_receive(&self) -> ReceiveReadyFuture<'_, M, T, N> {
+        self.channel.ready_to_receive()
+    }
+
     /// Attempt to immediately receive the next value.
     ///
     /// See [`Channel::try_receive()`]
@@ -181,7 +188,7 @@ pub struct DynamicReceiver<'ch, T> {
 
 impl<'ch, T> Clone for DynamicReceiver<'ch, T> {
     fn clone(&self) -> Self {
-        DynamicReceiver { channel: self.channel }
+        *self
     }
 }
 
@@ -246,6 +253,26 @@ where
     }
 }
 
+/// Future returned by [`Channel::ready_to_receive`] and  [`Receiver::ready_to_receive`].
+#[must_use = "futures do nothing unless you `.await` or poll them"]
+pub struct ReceiveReadyFuture<'ch, M, T, const N: usize>
+where
+    M: RawMutex,
+{
+    channel: &'ch Channel<M, T, N>,
+}
+
+impl<'ch, M, T, const N: usize> Future for ReceiveReadyFuture<'ch, M, T, N>
+where
+    M: RawMutex,
+{
+    type Output = ();
+
+    fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<()> {
+        self.channel.poll_ready_to_receive(cx)
+    }
+}
+
 /// Future returned by [`DynamicReceiver::receive`].
 #[must_use = "futures do nothing unless you `.await` or poll them"]
 pub struct DynamicReceiveFuture<'ch, T> {
@@ -450,6 +477,10 @@ impl<T, const N: usize> ChannelState<T, N> {
         }
     }
 
+    fn clear(&mut self) {
+        self.queue.clear();
+    }
+
     fn len(&self) -> usize {
         self.queue.len()
     }
@@ -577,6 +608,14 @@ where
         ReceiveFuture { channel: self }
     }
 
+    /// Is a value ready to be received in the channel
+    ///
+    /// If there are no messages in the channel's buffer, this method will
+    /// wait until there is at least one
+    pub fn ready_to_receive(&self) -> ReceiveReadyFuture<'_, M, T, N> {
+        ReceiveReadyFuture { channel: self }
+    }
+
     /// Attempt to immediately receive a message.
     ///
     /// This method will either receive a message from the channel immediately or return an error
@@ -585,6 +624,23 @@ where
         self.lock(|c| c.try_receive())
     }
 
+    /// Returns the maximum number of elements the channel can hold.
+    pub const fn capacity(&self) -> usize {
+        N
+    }
+
+    /// Returns the free capacity of the channel.
+    ///
+    /// This is equivalent to `capacity() - len()`
+    pub fn free_capacity(&self) -> usize {
+        N - self.len()
+    }
+
+    /// Clears all elements in the channel.
+    pub fn clear(&self) {
+        self.lock(|c| c.clear());
+    }
+
     /// Returns the number of elements currently in the channel.
     pub fn len(&self) -> usize {
         self.lock(|c| c.len())
diff --git a/embassy-sync/src/mutex.rs b/embassy-sync/src/mutex.rs
index 72459d660..8c3a3af9f 100644
--- a/embassy-sync/src/mutex.rs
+++ b/embassy-sync/src/mutex.rs
@@ -5,6 +5,7 @@ use core::cell::{RefCell, UnsafeCell};
 use core::future::poll_fn;
 use core::ops::{Deref, DerefMut};
 use core::task::Poll;
+use core::{fmt, mem};
 
 use crate::blocking_mutex::raw::RawMutex;
 use crate::blocking_mutex::Mutex as BlockingMutex;
@@ -128,12 +129,49 @@ where
     }
 }
 
+impl<M: RawMutex, T> From<T> for Mutex<M, T> {
+    fn from(from: T) -> Self {
+        Self::new(from)
+    }
+}
+
+impl<M, T> Default for Mutex<M, T>
+where
+    M: RawMutex,
+    T: ?Sized + Default,
+{
+    fn default() -> Self {
+        Self::new(Default::default())
+    }
+}
+
+impl<M, T> fmt::Debug for Mutex<M, T>
+where
+    M: RawMutex,
+    T: ?Sized + fmt::Debug,
+{
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let mut d = f.debug_struct("Mutex");
+        match self.try_lock() {
+            Ok(value) => {
+                d.field("inner", &&*value);
+            }
+            Err(TryLockError) => {
+                d.field("inner", &format_args!("<locked>"));
+            }
+        }
+
+        d.finish_non_exhaustive()
+    }
+}
+
 /// Async mutex guard.
 ///
 /// Owning an instance of this type indicates having
 /// successfully locked the mutex, and grants access to the contents.
 ///
 /// Dropping it unlocks the mutex.
+#[clippy::has_significant_drop]
 pub struct MutexGuard<'a, M, T>
 where
     M: RawMutex,
@@ -142,6 +180,25 @@ where
     mutex: &'a Mutex<M, T>,
 }
 
+impl<'a, M, T> MutexGuard<'a, M, T>
+where
+    M: RawMutex,
+    T: ?Sized,
+{
+    /// Returns a locked view over a portion of the locked data.
+    pub fn map<U>(this: Self, fun: impl FnOnce(&mut T) -> &mut U) -> MappedMutexGuard<'a, M, U> {
+        let mutex = this.mutex;
+        let value = fun(unsafe { &mut *this.mutex.inner.get() });
+        // Don't run the `drop` method for MutexGuard. The ownership of the underlying
+        // locked state is being moved to the returned MappedMutexGuard.
+        mem::forget(this);
+        MappedMutexGuard {
+            state: &mutex.state,
+            value,
+        }
+    }
+}
+
 impl<'a, M, T> Drop for MutexGuard<'a, M, T>
 where
     M: RawMutex,
@@ -180,3 +237,155 @@ where
         unsafe { &mut *(self.mutex.inner.get()) }
     }
 }
+
+impl<'a, M, T> fmt::Debug for MutexGuard<'a, M, T>
+where
+    M: RawMutex,
+    T: ?Sized + fmt::Debug,
+{
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt::Debug::fmt(&**self, f)
+    }
+}
+
+impl<'a, M, T> fmt::Display for MutexGuard<'a, M, T>
+where
+    M: RawMutex,
+    T: ?Sized + fmt::Display,
+{
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt::Display::fmt(&**self, f)
+    }
+}
+
+/// A handle to a held `Mutex` that has had a function applied to it via [`MutexGuard::map`] or
+/// [`MappedMutexGuard::map`].
+///
+/// This can be used to hold a subfield of the protected data.
+#[clippy::has_significant_drop]
+pub struct MappedMutexGuard<'a, M, T>
+where
+    M: RawMutex,
+    T: ?Sized,
+{
+    state: &'a BlockingMutex<M, RefCell<State>>,
+    value: *mut T,
+}
+
+impl<'a, M, T> MappedMutexGuard<'a, M, T>
+where
+    M: RawMutex,
+    T: ?Sized,
+{
+    /// Returns a locked view over a portion of the locked data.
+    pub fn map<U>(this: Self, fun: impl FnOnce(&mut T) -> &mut U) -> MappedMutexGuard<'a, M, U> {
+        let state = this.state;
+        let value = fun(unsafe { &mut *this.value });
+        // Don't run the `drop` method for MutexGuard. The ownership of the underlying
+        // locked state is being moved to the returned MappedMutexGuard.
+        mem::forget(this);
+        MappedMutexGuard { state, value }
+    }
+}
+
+impl<'a, M, T> Deref for MappedMutexGuard<'a, M, T>
+where
+    M: RawMutex,
+    T: ?Sized,
+{
+    type Target = T;
+    fn deref(&self) -> &Self::Target {
+        // Safety: the MutexGuard represents exclusive access to the contents
+        // of the mutex, so it's OK to get it.
+        unsafe { &*self.value }
+    }
+}
+
+impl<'a, M, T> DerefMut for MappedMutexGuard<'a, M, T>
+where
+    M: RawMutex,
+    T: ?Sized,
+{
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        // Safety: the MutexGuard represents exclusive access to the contents
+        // of the mutex, so it's OK to get it.
+        unsafe { &mut *self.value }
+    }
+}
+
+impl<'a, M, T> Drop for MappedMutexGuard<'a, M, T>
+where
+    M: RawMutex,
+    T: ?Sized,
+{
+    fn drop(&mut self) {
+        self.state.lock(|s| {
+            let mut s = unwrap!(s.try_borrow_mut());
+            s.locked = false;
+            s.waker.wake();
+        })
+    }
+}
+
+unsafe impl<M, T> Send for MappedMutexGuard<'_, M, T>
+where
+    M: RawMutex + Sync,
+    T: Send + ?Sized,
+{
+}
+
+unsafe impl<M, T> Sync for MappedMutexGuard<'_, M, T>
+where
+    M: RawMutex + Sync,
+    T: Sync + ?Sized,
+{
+}
+
+impl<'a, M, T> fmt::Debug for MappedMutexGuard<'a, M, T>
+where
+    M: RawMutex,
+    T: ?Sized + fmt::Debug,
+{
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt::Debug::fmt(&**self, f)
+    }
+}
+
+impl<'a, M, T> fmt::Display for MappedMutexGuard<'a, M, T>
+where
+    M: RawMutex,
+    T: ?Sized + fmt::Display,
+{
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt::Display::fmt(&**self, f)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::blocking_mutex::raw::NoopRawMutex;
+    use crate::mutex::{Mutex, MutexGuard};
+
+    #[futures_test::test]
+    async fn mapped_guard_releases_lock_when_dropped() {
+        let mutex: Mutex<NoopRawMutex, [i32; 2]> = Mutex::new([0, 1]);
+
+        {
+            let guard = mutex.lock().await;
+            assert_eq!(*guard, [0, 1]);
+            let mut mapped = MutexGuard::map(guard, |this| &mut this[1]);
+            assert_eq!(*mapped, 1);
+            *mapped = 2;
+        }
+
+        {
+            let guard = mutex.lock().await;
+            assert_eq!(*guard, [0, 2]);
+            let mut mapped = MutexGuard::map(guard, |this| &mut this[1]);
+            assert_eq!(*mapped, 2);
+            *mapped = 3;
+        }
+
+        assert_eq!(*mutex.lock().await, [0, 3]);
+    }
+}
diff --git a/embassy-sync/src/once_lock.rs b/embassy-sync/src/once_lock.rs
index 31cc99711..55608ba32 100644
--- a/embassy-sync/src/once_lock.rs
+++ b/embassy-sync/src/once_lock.rs
@@ -1,4 +1,4 @@
-//! Syncronization primitive for initializing a value once, allowing others to await a reference to the value.
+//! Synchronization primitive for initializing a value once, allowing others to await a reference to the value.
 
 use core::cell::Cell;
 use core::future::poll_fn;
@@ -13,7 +13,7 @@ use core::task::Poll;
 ///
 /// **Note**: this implementation uses a busy loop to poll the value,
 /// which is not as efficient as registering a dedicated `Waker`.
-/// However, the if the usecase for is to initialize a static variable
+/// However, if the usecase for it is to initialize a static variable
 /// relatively early in the program life cycle, it should be fine.
 ///
 /// # Example
@@ -78,7 +78,7 @@ impl<T> OnceLock<T> {
     /// Set the underlying value. If the value is already set, this will return an error with the given value.
     pub fn init(&self, value: T) -> Result<(), T> {
         // Critical section is required to ensure that the value is
-        // not simultaniously initialized elsewhere at the same time.
+        // not simultaneously initialized elsewhere at the same time.
         critical_section::with(|_| {
             // If the value is not set, set it and return Ok.
             if !self.init.load(Ordering::Relaxed) {
@@ -99,7 +99,7 @@ impl<T> OnceLock<T> {
         F: FnOnce() -> T,
     {
         // Critical section is required to ensure that the value is
-        // not simultaniously initialized elsewhere at the same time.
+        // not simultaneously initialized elsewhere at the same time.
         critical_section::with(|_| {
             // If the value is not set, set it.
             if !self.init.load(Ordering::Relaxed) {
diff --git a/embassy-sync/src/pipe.rs b/embassy-sync/src/pipe.rs
index 42fe8ebd0..cd5b8ed75 100644
--- a/embassy-sync/src/pipe.rs
+++ b/embassy-sync/src/pipe.rs
@@ -25,7 +25,7 @@ where
     M: RawMutex,
 {
     fn clone(&self) -> Self {
-        Writer { pipe: self.pipe }
+        *self
     }
 }
 
diff --git a/embassy-sync/src/priority_channel.rs b/embassy-sync/src/priority_channel.rs
index e77678c24..24c6c5a7f 100644
--- a/embassy-sync/src/priority_channel.rs
+++ b/embassy-sync/src/priority_channel.rs
@@ -33,7 +33,7 @@ where
     M: RawMutex,
 {
     fn clone(&self) -> Self {
-        Sender { channel: self.channel }
+        *self
     }
 }
 
@@ -101,7 +101,7 @@ where
     M: RawMutex,
 {
     fn clone(&self) -> Self {
-        Receiver { channel: self.channel }
+        *self
     }
 }
 
@@ -314,6 +314,22 @@ where
             Poll::Pending
         }
     }
+
+    fn clear(&mut self) {
+        self.queue.clear();
+    }
+
+    fn len(&self) -> usize {
+        self.queue.len()
+    }
+
+    fn is_empty(&self) -> bool {
+        self.queue.is_empty()
+    }
+
+    fn is_full(&self) -> bool {
+        self.queue.len() == self.queue.capacity()
+    }
 }
 
 /// A bounded channel for communicating between asynchronous tasks
@@ -323,7 +339,7 @@ where
 /// buffer is full, attempts to `send` new messages will wait until a message is
 /// received from the channel.
 ///
-/// Sent data may be reordered based on their priorty within the channel.
+/// Sent data may be reordered based on their priority within the channel.
 /// For example, in a [`Max`](heapless::binary_heap::Max) [`PriorityChannel`]
 /// containing `u32`'s, data sent in the following order `[1, 2, 3]` will be received as `[3, 2, 1]`.
 pub struct PriorityChannel<M, T, K, const N: usize>
@@ -433,6 +449,38 @@ where
     pub fn try_receive(&self) -> Result<T, TryReceiveError> {
         self.lock(|c| c.try_receive())
     }
+
+    /// Returns the maximum number of elements the channel can hold.
+    pub const fn capacity(&self) -> usize {
+        N
+    }
+
+    /// Returns the free capacity of the channel.
+    ///
+    /// This is equivalent to `capacity() - len()`
+    pub fn free_capacity(&self) -> usize {
+        N - self.len()
+    }
+
+    /// Clears all elements in the channel.
+    pub fn clear(&self) {
+        self.lock(|c| c.clear());
+    }
+
+    /// Returns the number of elements currently in the channel.
+    pub fn len(&self) -> usize {
+        self.lock(|c| c.len())
+    }
+
+    /// Returns whether the channel is empty.
+    pub fn is_empty(&self) -> bool {
+        self.lock(|c| c.is_empty())
+    }
+
+    /// Returns whether the channel is full.
+    pub fn is_full(&self) -> bool {
+        self.lock(|c| c.is_full())
+    }
 }
 
 /// Implements the DynamicChannel to allow creating types that are unaware of the queue size with the
diff --git a/embassy-sync/src/pubsub/mod.rs b/embassy-sync/src/pubsub/mod.rs
index 6afd54af5..66c9b0017 100644
--- a/embassy-sync/src/pubsub/mod.rs
+++ b/embassy-sync/src/pubsub/mod.rs
@@ -160,9 +160,41 @@ impl<M: RawMutex, T: Clone, const CAP: usize, const SUBS: usize, const PUBS: usi
     pub fn dyn_immediate_publisher(&self) -> DynImmediatePublisher<T> {
         DynImmediatePublisher(ImmediatePub::new(self))
     }
+
+    /// Returns the maximum number of elements the channel can hold.
+    pub const fn capacity(&self) -> usize {
+        CAP
+    }
+
+    /// Returns the free capacity of the channel.
+    ///
+    /// This is equivalent to `capacity() - len()`
+    pub fn free_capacity(&self) -> usize {
+        CAP - self.len()
+    }
+
+    /// Clears all elements in the channel.
+    pub fn clear(&self) {
+        self.inner.lock(|inner| inner.borrow_mut().clear());
+    }
+
+    /// Returns the number of elements currently in the channel.
+    pub fn len(&self) -> usize {
+        self.inner.lock(|inner| inner.borrow().len())
+    }
+
+    /// Returns whether the channel is empty.
+    pub fn is_empty(&self) -> bool {
+        self.inner.lock(|inner| inner.borrow().is_empty())
+    }
+
+    /// Returns whether the channel is full.
+    pub fn is_full(&self) -> bool {
+        self.inner.lock(|inner| inner.borrow().is_full())
+    }
 }
 
-impl<M: RawMutex, T: Clone, const CAP: usize, const SUBS: usize, const PUBS: usize> PubSubBehavior<T>
+impl<M: RawMutex, T: Clone, const CAP: usize, const SUBS: usize, const PUBS: usize> SealedPubSubBehavior<T>
     for PubSubChannel<M, T, CAP, SUBS, PUBS>
 {
     fn get_message_with_context(&self, next_message_id: &mut u64, cx: Option<&mut Context<'_>>) -> Poll<WaitResult<T>> {
@@ -221,13 +253,6 @@ impl<M: RawMutex, T: Clone, const CAP: usize, const SUBS: usize, const PUBS: usi
         })
     }
 
-    fn space(&self) -> usize {
-        self.inner.lock(|s| {
-            let s = s.borrow();
-            s.queue.capacity() - s.queue.len()
-        })
-    }
-
     fn unregister_subscriber(&self, subscriber_next_message_id: u64) {
         self.inner.lock(|s| {
             let mut s = s.borrow_mut();
@@ -241,6 +266,30 @@ impl<M: RawMutex, T: Clone, const CAP: usize, const SUBS: usize, const PUBS: usi
             s.unregister_publisher()
         })
     }
+
+    fn capacity(&self) -> usize {
+        self.capacity()
+    }
+
+    fn free_capacity(&self) -> usize {
+        self.free_capacity()
+    }
+
+    fn clear(&self) {
+        self.clear();
+    }
+
+    fn len(&self) -> usize {
+        self.len()
+    }
+
+    fn is_empty(&self) -> bool {
+        self.is_empty()
+    }
+
+    fn is_full(&self) -> bool {
+        self.is_full()
+    }
 }
 
 /// Internal state for the PubSub channel
@@ -366,6 +415,22 @@ impl<T: Clone, const CAP: usize, const SUBS: usize, const PUBS: usize> PubSubSta
     fn unregister_publisher(&mut self) {
         self.publisher_count -= 1;
     }
+
+    fn clear(&mut self) {
+        self.queue.clear();
+    }
+
+    fn len(&self) -> usize {
+        self.queue.len()
+    }
+
+    fn is_empty(&self) -> bool {
+        self.queue.is_empty()
+    }
+
+    fn is_full(&self) -> bool {
+        self.queue.is_full()
+    }
 }
 
 /// Error type for the [PubSubChannel]
@@ -382,10 +447,10 @@ pub enum Error {
 
 /// 'Middle level' behaviour of the pubsub channel.
 /// This trait is used so that Sub and Pub can be generic over the channel.
-pub trait PubSubBehavior<T> {
+trait SealedPubSubBehavior<T> {
     /// Try to get a message from the queue with the given message id.
     ///
-    /// If the message is not yet present and a context is given, then its waker is registered in the subsriber wakers.
+    /// If the message is not yet present and a context is given, then its waker is registered in the subscriber wakers.
     fn get_message_with_context(&self, next_message_id: &mut u64, cx: Option<&mut Context<'_>>) -> Poll<WaitResult<T>>;
 
     /// Get the amount of messages that are between the given the next_message_id and the most recent message.
@@ -400,8 +465,25 @@ pub trait PubSubBehavior<T> {
     /// Publish a message immediately
     fn publish_immediate(&self, message: T);
 
-    /// The amount of messages that can still be published without having to wait or without having to lag the subscribers
-    fn space(&self) -> usize;
+    /// Returns the maximum number of elements the channel can hold.
+    fn capacity(&self) -> usize;
+
+    /// Returns the free capacity of the channel.
+    ///
+    /// This is equivalent to `capacity() - len()`
+    fn free_capacity(&self) -> usize;
+
+    /// Clears all elements in the channel.
+    fn clear(&self);
+
+    /// Returns the number of elements currently in the channel.
+    fn len(&self) -> usize;
+
+    /// Returns whether the channel is empty.
+    fn is_empty(&self) -> bool;
+
+    /// Returns whether the channel is full.
+    fn is_full(&self) -> bool;
 
     /// Let the channel know that a subscriber has dropped
     fn unregister_subscriber(&self, subscriber_next_message_id: u64);
@@ -410,6 +492,13 @@ pub trait PubSubBehavior<T> {
     fn unregister_publisher(&self);
 }
 
+/// 'Middle level' behaviour of the pubsub channel.
+/// This trait is used so that Sub and Pub can be generic over the channel.
+#[allow(private_bounds)]
+pub trait PubSubBehavior<T>: SealedPubSubBehavior<T> {}
+
+impl<T, C: SealedPubSubBehavior<T>> PubSubBehavior<T> for C {}
+
 /// The result of the subscriber wait procedure
 #[derive(Debug, Clone, PartialEq, Eq)]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
@@ -542,6 +631,7 @@ mod tests {
         assert_eq!(pub0.try_publish(0), Ok(()));
         assert_eq!(pub0.try_publish(0), Ok(()));
         assert_eq!(pub0.try_publish(0), Ok(()));
+        assert!(pub0.is_full());
         assert_eq!(pub0.try_publish(0), Err(0));
 
         drop(sub0);
@@ -574,32 +664,42 @@ mod tests {
     }
 
     #[futures_test::test]
-    async fn correct_space() {
+    async fn correct_len() {
         let channel = PubSubChannel::<NoopRawMutex, u32, 4, 4, 4>::new();
 
         let mut sub0 = channel.subscriber().unwrap();
         let mut sub1 = channel.subscriber().unwrap();
         let pub0 = channel.publisher().unwrap();
 
-        assert_eq!(pub0.space(), 4);
+        assert!(sub0.is_empty());
+        assert!(sub1.is_empty());
+        assert!(pub0.is_empty());
+        assert_eq!(pub0.free_capacity(), 4);
+        assert_eq!(pub0.len(), 0);
 
         pub0.publish(42).await;
 
-        assert_eq!(pub0.space(), 3);
+        assert_eq!(pub0.free_capacity(), 3);
+        assert_eq!(pub0.len(), 1);
 
         pub0.publish(42).await;
 
-        assert_eq!(pub0.space(), 2);
+        assert_eq!(pub0.free_capacity(), 2);
+        assert_eq!(pub0.len(), 2);
 
         sub0.next_message().await;
         sub0.next_message().await;
 
-        assert_eq!(pub0.space(), 2);
+        assert_eq!(pub0.free_capacity(), 2);
+        assert_eq!(pub0.len(), 2);
 
         sub1.next_message().await;
-        assert_eq!(pub0.space(), 3);
+        assert_eq!(pub0.free_capacity(), 3);
+        assert_eq!(pub0.len(), 1);
+
         sub1.next_message().await;
-        assert_eq!(pub0.space(), 4);
+        assert_eq!(pub0.free_capacity(), 4);
+        assert_eq!(pub0.len(), 0);
     }
 
     #[futures_test::test]
@@ -610,29 +710,29 @@ mod tests {
         let mut sub0 = channel.subscriber().unwrap();
         let mut sub1 = channel.subscriber().unwrap();
 
-        assert_eq!(4, pub0.space());
+        assert_eq!(4, pub0.free_capacity());
 
         pub0.publish(1).await;
         pub0.publish(2).await;
 
-        assert_eq!(2, channel.space());
+        assert_eq!(2, channel.free_capacity());
 
         assert_eq!(1, sub0.try_next_message_pure().unwrap());
         assert_eq!(2, sub0.try_next_message_pure().unwrap());
 
-        assert_eq!(2, channel.space());
+        assert_eq!(2, channel.free_capacity());
 
         drop(sub0);
 
-        assert_eq!(2, channel.space());
+        assert_eq!(2, channel.free_capacity());
 
         assert_eq!(1, sub1.try_next_message_pure().unwrap());
 
-        assert_eq!(3, channel.space());
+        assert_eq!(3, channel.free_capacity());
 
         drop(sub1);
 
-        assert_eq!(4, channel.space());
+        assert_eq!(4, channel.free_capacity());
     }
 
     struct CloneCallCounter(usize);
diff --git a/embassy-sync/src/pubsub/publisher.rs b/embassy-sync/src/pubsub/publisher.rs
index e1edc9eb9..e66b3b1db 100644
--- a/embassy-sync/src/pubsub/publisher.rs
+++ b/embassy-sync/src/pubsub/publisher.rs
@@ -43,12 +43,36 @@ impl<'a, PSB: PubSubBehavior<T> + ?Sized, T: Clone> Pub<'a, PSB, T> {
         self.channel.publish_with_context(message, None)
     }
 
-    /// The amount of messages that can still be published without having to wait or without having to lag the subscribers
+    /// Returns the maximum number of elements the ***channel*** can hold.
+    pub fn capacity(&self) -> usize {
+        self.channel.capacity()
+    }
+
+    /// Returns the free capacity of the ***channel***.
     ///
-    /// *Note: In the time between checking this and a publish action, other publishers may have had time to publish something.
-    /// So checking doesn't give any guarantees.*
-    pub fn space(&self) -> usize {
-        self.channel.space()
+    /// This is equivalent to `capacity() - len()`
+    pub fn free_capacity(&self) -> usize {
+        self.channel.free_capacity()
+    }
+
+    /// Clears all elements in the ***channel***.
+    pub fn clear(&self) {
+        self.channel.clear();
+    }
+
+    /// Returns the number of elements currently in the ***channel***.
+    pub fn len(&self) -> usize {
+        self.channel.len()
+    }
+
+    /// Returns whether the ***channel*** is empty.
+    pub fn is_empty(&self) -> bool {
+        self.channel.is_empty()
+    }
+
+    /// Returns whether the ***channel*** is full.
+    pub fn is_full(&self) -> bool {
+        self.channel.is_full()
     }
 }
 
@@ -124,12 +148,36 @@ impl<'a, PSB: PubSubBehavior<T> + ?Sized, T: Clone> ImmediatePub<'a, PSB, T> {
         self.channel.publish_with_context(message, None)
     }
 
-    /// The amount of messages that can still be published without having to wait or without having to lag the subscribers
+    /// Returns the maximum number of elements the ***channel*** can hold.
+    pub fn capacity(&self) -> usize {
+        self.channel.capacity()
+    }
+
+    /// Returns the free capacity of the ***channel***.
     ///
-    /// *Note: In the time between checking this and a publish action, other publishers may have had time to publish something.
-    /// So checking doesn't give any guarantees.*
-    pub fn space(&self) -> usize {
-        self.channel.space()
+    /// This is equivalent to `capacity() - len()`
+    pub fn free_capacity(&self) -> usize {
+        self.channel.free_capacity()
+    }
+
+    /// Clears all elements in the ***channel***.
+    pub fn clear(&self) {
+        self.channel.clear();
+    }
+
+    /// Returns the number of elements currently in the ***channel***.
+    pub fn len(&self) -> usize {
+        self.channel.len()
+    }
+
+    /// Returns whether the ***channel*** is empty.
+    pub fn is_empty(&self) -> bool {
+        self.channel.is_empty()
+    }
+
+    /// Returns whether the ***channel*** is full.
+    pub fn is_full(&self) -> bool {
+        self.channel.is_full()
     }
 }
 
diff --git a/embassy-sync/src/pubsub/subscriber.rs b/embassy-sync/src/pubsub/subscriber.rs
index f420a75f0..6ad660cb3 100644
--- a/embassy-sync/src/pubsub/subscriber.rs
+++ b/embassy-sync/src/pubsub/subscriber.rs
@@ -65,10 +65,44 @@ impl<'a, PSB: PubSubBehavior<T> + ?Sized, T: Clone> Sub<'a, PSB, T> {
         }
     }
 
-    /// The amount of messages this subscriber hasn't received yet
+    /// The amount of messages this subscriber hasn't received yet. This is like [Self::len] but specifically
+    /// for this subscriber.
     pub fn available(&self) -> u64 {
         self.channel.available(self.next_message_id)
     }
+
+    /// Returns the maximum number of elements the ***channel*** can hold.
+    pub fn capacity(&self) -> usize {
+        self.channel.capacity()
+    }
+
+    /// Returns the free capacity of the ***channel***.
+    ///
+    /// This is equivalent to `capacity() - len()`
+    pub fn free_capacity(&self) -> usize {
+        self.channel.free_capacity()
+    }
+
+    /// Clears all elements in the ***channel***.
+    pub fn clear(&self) {
+        self.channel.clear();
+    }
+
+    /// Returns the number of elements currently in the ***channel***.
+    /// See [Self::available] for how many messages are available for this subscriber.
+    pub fn len(&self) -> usize {
+        self.channel.len()
+    }
+
+    /// Returns whether the ***channel*** is empty.
+    pub fn is_empty(&self) -> bool {
+        self.channel.is_empty()
+    }
+
+    /// Returns whether the ***channel*** is full.
+    pub fn is_full(&self) -> bool {
+        self.channel.is_full()
+    }
 }
 
 impl<'a, PSB: PubSubBehavior<T> + ?Sized, T: Clone> Drop for Sub<'a, PSB, T> {
diff --git a/embassy-sync/src/waitqueue/multi_waker.rs b/embassy-sync/src/waitqueue/multi_waker.rs
index 824d192da..0e520bf40 100644
--- a/embassy-sync/src/waitqueue/multi_waker.rs
+++ b/embassy-sync/src/waitqueue/multi_waker.rs
@@ -14,7 +14,7 @@ impl<const N: usize> MultiWakerRegistration<N> {
     }
 
     /// Register a waker. If the buffer is full the function returns it in the error
-    pub fn register<'a>(&mut self, w: &'a Waker) {
+    pub fn register(&mut self, w: &Waker) {
         // If we already have some waker that wakes the same task as `w`, do nothing.
         // This avoids cloning wakers, and avoids unnecessary mass-wakes.
         for w2 in &self.wakers {