Change signal routing for increased consistency (#2277)

sanic/mixins/signals.py

@@ -21,6 +21,7 @@ class SignalMixin(metaclass=SanicMeta):
         *,
         apply: bool = True,
         condition: Dict[str, Any] = None,
+        exclusive: bool = True,
     ) -> Callable[[SignalHandler], SignalHandler]:
         """
         For creating a signal handler, used similar to a route handler:
@@ -33,17 +34,22 @@ class SignalMixin(metaclass=SanicMeta):
 
         :param event: Representation of the event in ``one.two.three`` form
         :type event: str
-        :param apply: For lazy evaluation, defaults to True
+        :param apply: For lazy evaluation, defaults to ``True``
         :type apply: bool, optional
         :param condition: For use with the ``condition`` argument in dispatch
-            filtering, defaults to None
+            filtering, defaults to ``None``
+        :param exclusive: When ``True``, the signal can only be dispatched
+            when the condition has been met. When ``False``, the signal can
+            be dispatched either with or without it. *THIS IS INAPPLICABLE TO
+            BLUEPRINT SIGNALS. THEY ARE ALWAYS NON-EXCLUSIVE*, defaults
+            to ``True``
         :type condition: Dict[str, Any], optional
         """
         event_value = str(event.value) if isinstance(event, Enum) else event
 
         def decorator(handler: SignalHandler):
             future_signal = FutureSignal(
-                handler, event_value, HashableDict(condition or {})
+                handler, event_value, HashableDict(condition or {}), exclusive
             )
             self._future_signals.add(future_signal)
 
@@ -59,6 +65,7 @@ class SignalMixin(metaclass=SanicMeta):
         handler: Optional[Callable[..., Any]],
         event: str,
         condition: Dict[str, Any] = None,
+        exclusive: bool = True,
     ):
         if not handler:
 
@@ -66,7 +73,9 @@ class SignalMixin(metaclass=SanicMeta):
                 ...
 
             handler = noop
-        self.signal(event=event, condition=condition)(handler)
+        self.signal(event=event, condition=condition, exclusive=exclusive)(
+            handler
+        )
         return handler
 
     def event(self, event: str):