Add method to check if a type is currently being dispatched

Signed-off-by: Mathias L. Baumann <[email protected]>

Author: Marenz

RELEASE_NOTES.md

@@ -21,4 +21,7 @@ This release introduces a more flexible and powerful mechanism for managing disp
 
 * A new feature "merge strategy" (`MergeByType`, `MergeByTypeTarget`) has been added to the `Dispatcher.new_running_state_event_receiver` method. Using it, you can automatically merge consecutive and overlapping dispatch start/stop events of the same type. E.g. dispatch `A` starting at 10:10 and ending at 10:30 and dispatch `B` starts at 10:30 until 11:00, with the feature enabled this would in total trigger one start event, one reconfigure event at 10:30 and one stop event at 11:00.
 * The SDK dependency was widened to allow versions up to (excluding) v1.0.0-rc1600.
-* Actor management with dispatches has been simplified. Calling `Dispatcher.start_dispatching(dispatch_type, actor_factory, merge_strategy)` will begin managing your actor for the given type and merge strategy. All you need provide is an actor factory. To stop dispatching for your type, call `Dispatcher.stop_dispatching(dispatch_type)`.
+* Actor management with dispatches has been simplified:
+    * `Dispatcher.start_dispatching(dispatch_type, actor_factory, merge_strategy)` to manage your actor for the given type and merge strategy. All you need provide is an actor factory.
+    * `Dispatcher.stop_dispatching(dispatch_type)` to stop dispatching for the given type.
+    * `Dispatcher.is_dispatching(dispatch_type)` to check if dispatching is active for the given type.

src/frequenz/dispatch/_dispatcher.py

@@ -221,6 +221,17 @@ def cancel(self, msg: str | None = None) -> None:
         for instance in self._actor_dispatchers.values():
             instance.cancel()
 
+    def is_dispatching(self, dispatch_type: str) -> bool:
+        """Check if the dispatcher is managing actors for a given dispatch type.
+
+        Args:
+            dispatch_type: The type of the dispatch to check.
+
+        Returns:
+            True if the dispatcher is managing actors for the given dispatch type.
+        """
+        return dispatch_type in self._actor_dispatchers
+
     async def start_dispatching(
         self,
         dispatch_type: str,