zephyr: sync: channel: Fully dynamically allocated

Implement `unbounded` that is able to dynamically allocate the
underlying Zephyr queue.  This is useful in cases where none of the
queue access happens from userspace.

Signed-off-by: David Brown <[email protected]>

Author: d3zd3z

zephyr/src/sync/channel.rs

@@ -28,8 +28,11 @@ mod counter;
 // simply Box the message, leak it out of the box, and give it to Zephyr, and then on receipt, wrap
 // it back into a Box, and give it to the recipient.
 
-/// Create a multi-producer multi-consumer channel of unbounded capacity.  The messages are
-/// allocated individually as "Box", and the queue is managed by the underlying Zephyr queue.
+/// Create a multi-producer multi-consumer channel of unbounded capacity, using an existing Queue
+/// object.
+///
+/// The messages are allocated individually as "Box", and the queue is managed by the underlying
+/// Zephyr queue.
 pub fn unbounded_from<T>(queue: Queue) -> (Sender<T>, Receiver<T>) {
     let (s, r) = counter::new(queue);
     let s = Sender {
@@ -43,6 +46,18 @@ pub fn unbounded_from<T>(queue: Queue) -> (Sender<T>, Receiver<T>) {
     (s, r)
 }
 
+/// Create a multi-producer multi-consumer channel of unbounded capacity.
+///
+/// The messages are allocated individually as "Box".  The underlying Zephyr queue will be
+/// dynamically allocated.
+///
+/// **Note**: Currently Drop is not propertly supported on Zephyr.  If all senders are dropped, any
+/// receivers will likely be blocked forever.  Any data that has been queued and not received will
+/// be leaked when all receivers have been droped.
+pub fn unbounded<T>() -> (Sender<T>, Receiver<T>) {
+    unbounded_from(Queue::new().unwrap())
+}
+
 /// The underlying type for Messages through Zephyr's [`Queue`].
 ///
 /// This wrapper is used internally to wrap user messages through the queue.  It is not useful in