fixup! various

- Expand module docstring a bit
- Remove outdated comment
- Correct setting annotation (copy-paste error)
- Clarify get_producer docstring (since it caches)
- Annotate infinite loop as NoReturn

openedx_events/event_bus/__init__.py

@@ -1,6 +1,8 @@
 """
 Classes and utility functions for the event bus.
 
+This module includes the entry points for the producer and consumer.
+
 API:
 
 - ``get_producer`` returns an ``EventBusProducer`` singleton that should be used for sending all events
@@ -42,7 +44,6 @@ def _try_load(*, setting_name: str, args: tuple, kwargs: dict, expected_class: t
     constructor_path = getattr(settings, setting_name, None)
     if constructor_path is None:
         warnings.warn(f"Event Bus setting {setting_name} is missing; component will be inactive.", UserWarning)
-        # No warning is called for if event-bus is not configured-for at *all*
         return default
 
     try:
@@ -100,12 +101,12 @@ def send(
 #   called. The format of the string is a dotted path to an attribute in a module, e.g.
 #   ``some.module.path.EventBusImplementation``. This producer will be managed as a singleton
 #   by openedx_events. If setting is not supplied or the callable raises an exception or does not return
-#   an instance of EventBusConsumer, calls to the consumer will be ignored with a warning at startup.
+#   an instance of EventBusProducer, calls to the producer will be ignored with a warning at startup.
 
 @lru_cache  # will just be one cache entry, in practice
 def get_producer() -> EventBusProducer:
     """
-    Create the producer implementation, as configured.
+    Create or retrieve the producer implementation, as configured.
 
     If misconfigured, returns a fake implementation that can be called but does nothing.
     """
@@ -121,7 +122,7 @@ class EventBusConsumer(ABC):
     """
 
     @abstractmethod
-    def consume_indefinitely(self):
+    def consume_indefinitely(self) -> NoReturn:
         """
         Consume events from a topic in an infinite loop.
 
@@ -134,7 +135,7 @@ class NoEventBusConsumer(EventBusConsumer):
     Stub implementation to "load" when no implementation is properly configured.
     """
 
-    def consume_indefinitely(self):
+    def consume_indefinitely(self) -> NoReturn:
         """Do nothing."""