Merge pull request #3393 from sourcebox/sync-additions

embassy-sync: add clear, len, is_empty and is_full functions to zerocopy_channel

embassy-sync/CHANGELOG.md

@@ -8,6 +8,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ## Unreleased
 
 - Add LazyLock sync primitive.
+- Add `clear`, `len`, `is_empty` and `is_full` functions to `zerocopy_channel`.
 
 ## 0.6.0 - 2024-05-29
 

embassy-sync/src/zerocopy_channel.rs

@@ -53,7 +53,7 @@ impl<'a, M: RawMutex, T> Channel<'a, M, T> {
             buf: buf.as_mut_ptr(),
             phantom: PhantomData,
             state: Mutex::new(RefCell::new(State {
-                len,
+                capacity: len,
                 front: 0,
                 back: 0,
                 full: false,
@@ -70,6 +70,28 @@ impl<'a, M: RawMutex, T> Channel<'a, M, T> {
     pub fn split(&mut self) -> (Sender<'_, M, T>, Receiver<'_, M, T>) {
         (Sender { channel: self }, Receiver { channel: self })
     }
+
+    /// Clears all elements in the channel.
+    pub fn clear(&mut self) {
+        self.state.lock(|s| {
+            s.borrow_mut().clear();
+        });
+    }
+
+    /// Returns the number of elements currently in the channel.
+    pub fn len(&self) -> usize {
+        self.state.lock(|s| s.borrow().len())
+    }
+
+    /// Returns whether the channel is empty.
+    pub fn is_empty(&self) -> bool {
+        self.state.lock(|s| s.borrow().is_empty())
+    }
+
+    /// Returns whether the channel is full.
+    pub fn is_full(&self) -> bool {
+        self.state.lock(|s| s.borrow().is_full())
+    }
 }
 
 /// Send-only access to a [`Channel`].
@@ -130,6 +152,28 @@ impl<'a, M: RawMutex, T> Sender<'a, M, T> {
     pub fn send_done(&mut self) {
         self.channel.state.lock(|s| s.borrow_mut().push_done())
     }
+
+    /// Clears all elements in the channel.
+    pub fn clear(&mut self) {
+        self.channel.state.lock(|s| {
+            s.borrow_mut().clear();
+        });
+    }
+
+    /// Returns the number of elements currently in the channel.
+    pub fn len(&self) -> usize {
+        self.channel.state.lock(|s| s.borrow().len())
+    }
+
+    /// Returns whether the channel is empty.
+    pub fn is_empty(&self) -> bool {
+        self.channel.state.lock(|s| s.borrow().is_empty())
+    }
+
+    /// Returns whether the channel is full.
+    pub fn is_full(&self) -> bool {
+        self.channel.state.lock(|s| s.borrow().is_full())
+    }
 }
 
 /// Receive-only access to a [`Channel`].
@@ -190,10 +234,33 @@ impl<'a, M: RawMutex, T> Receiver<'a, M, T> {
     pub fn receive_done(&mut self) {
         self.channel.state.lock(|s| s.borrow_mut().pop_done())
     }
+
+    /// Clears all elements in the channel.
+    pub fn clear(&mut self) {
+        self.channel.state.lock(|s| {
+            s.borrow_mut().clear();
+        });
+    }
+
+    /// Returns the number of elements currently in the channel.
+    pub fn len(&self) -> usize {
+        self.channel.state.lock(|s| s.borrow().len())
+    }
+
+    /// Returns whether the channel is empty.
+    pub fn is_empty(&self) -> bool {
+        self.channel.state.lock(|s| s.borrow().is_empty())
+    }
+
+    /// Returns whether the channel is full.
+    pub fn is_full(&self) -> bool {
+        self.channel.state.lock(|s| s.borrow().is_full())
+    }
 }
 
 struct State {
-    len: usize,
+    /// Maximum number of elements the channel can hold.
+    capacity: usize,
 
     /// Front index. Always 0..=(N-1)
     front: usize,
@@ -210,13 +277,31 @@ struct State {
 
 impl State {
     fn increment(&self, i: usize) -> usize {
-        if i + 1 == self.len {
+        if i + 1 == self.capacity {
             0
         } else {
             i + 1
         }
     }
 
+    fn clear(&mut self) {
+        self.front = 0;
+        self.back = 0;
+        self.full = false;
+    }
+
+    fn len(&self) -> usize {
+        if !self.full {
+            if self.back >= self.front {
+                self.back - self.front
+            } else {
+                self.capacity + self.back - self.front
+            }
+        } else {
+            self.capacity
+        }
+    }
+
     fn is_full(&self) -> bool {
         self.full
     }