python/aqmp: add .empty() method to EventListener

Synchronous clients may want to know if they're about to block waiting
for an event or not. A method such as this is necessary to implement a
compatible interface for the old QEMUMonitorProtocol using the new async
internals.

Signed-off-by: John Snow <[email protected]>
Reviewed-by: Hanna Reitz <[email protected]>
Reviewed-by: Paolo Bonzini <[email protected]>
Message-id: [email protected]
Signed-off-by: John Snow <[email protected]>

Author: jnsnow

python/qemu/aqmp/events.py

@@ -556,6 +556,12 @@ async def get(self) -> Message:
         """
         return await self._queue.get()
 
+    def empty(self) -> bool:
+        """
+        Return `True` if there are no pending events.
+        """
+        return self._queue.empty()
+
     def clear(self) -> None:
         """
         Clear this listener of all pending events.