api: add event channel overflow event

src/events.rs

@@ -71,16 +71,13 @@ impl EventEmitter {
     /// [`try_recv`]: Self::try_recv
     pub async fn recv(&self) -> Option<Event> {
         let mut lock = self.0.lock().await;
-        loop {
-            match lock.recv().await {
-                Err(async_broadcast::RecvError::Overflowed(_)) => {
-                    // Some events have been lost,
-                    // but the channel is not closed.
-                    continue;
-                }
-                Err(async_broadcast::RecvError::Closed) => return None,
-                Ok(event) => return Some(event),
-            }
+        match lock.recv().await {
+            Err(async_broadcast::RecvError::Overflowed(n)) => Some(Event {
+                id: 0,
+                typ: EventType::EventChannelOverflow { n },
+            }),
+            Err(async_broadcast::RecvError::Closed) => None,
+            Ok(event) => Some(event),
         }
     }
 
@@ -96,17 +93,18 @@ impl EventEmitter {
         // to avoid blocking
         // in case there is a concurrent call to `recv`.
         let mut lock = self.0.try_lock()?;
-        loop {
-            match lock.try_recv() {
-                Err(async_broadcast::TryRecvError::Overflowed(_)) => {
-                    // Some events have been lost,
-                    // but the channel is not closed.
-                    continue;
-                }
-                res @ (Err(async_broadcast::TryRecvError::Empty)
-                | Err(async_broadcast::TryRecvError::Closed)
-                | Ok(_)) => return Ok(res?),
+        match lock.try_recv() {
+            Err(async_broadcast::TryRecvError::Overflowed(n)) => {
+                // Some events have been lost,
+                // but the channel is not closed.
+                Ok(Event {
+                    id: 0,
+                    typ: EventType::EventChannelOverflow { n },
+                })
             }
+            res @ (Err(async_broadcast::TryRecvError::Empty)
+            | Err(async_broadcast::TryRecvError::Closed)
+            | Ok(_)) => Ok(res?),
         }
     }
 }

src/events/payload.rs

@@ -315,4 +315,10 @@ pub enum EventType {
     /// Event for using in tests, e.g. as a fence between normally generated events.
     #[cfg(test)]
     Test,
+
+    /// Inform than some events have been skipped due to event channel overflow.
+    EventChannelOverflow {
+        /// Number of events skipped.
+        n: u64,
+    },
 }