Change signal routing for increased consistency (#2277)

sanic/blueprints.py

@@ -400,8 +400,9 @@ class Blueprint(BaseSanic):
         for future in self._future_signals:
             if (self, future) in app._future_registry:
                 continue
-            future.condition.update({"blueprint": self.name})
+            future.condition.update({"__blueprint__": self.name})
-            app._apply_signal(future)
+            # Force exclusive to be False
+            app._apply_signal(tuple((*future[:-1], False)))
 
         self.routes += [route for route in routes if isinstance(route, Route)]
         self.websocket_routes += [
@@ -426,7 +427,7 @@ class Blueprint(BaseSanic):
 
     async def dispatch(self, *args, **kwargs):
         condition = kwargs.pop("condition", {})
-        condition.update({"blueprint": self.name})
+        condition.update({"__blueprint__": self.name})
         kwargs["condition"] = condition
         await asyncio.gather(
             *[app.dispatch(*args, **kwargs) for app in self.apps]

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):

sanic/models/futures.py

@@ -62,6 +62,7 @@ class FutureSignal(NamedTuple):
     handler: SignalHandler
     event: str
     condition: Optional[Dict[str, str]]
+    exclusive: bool
 
 
 class FutureRegistry(set):

sanic/signals.py

@@ -4,7 +4,7 @@ import asyncio
 
 from enum import Enum
 from inspect import isawaitable
-from typing import Any, Dict, List, Optional, Tuple, Union
+from typing import Any, Dict, List, Optional, Tuple, Union, cast
 
 from sanic_routing import BaseRouter, Route, RouteGroup  # type: ignore
 from sanic_routing.exceptions import NotFound  # type: ignore
@@ -142,12 +142,21 @@ class SignalRouter(BaseRouter):
         if context:
             params.update(context)
 
+        signals = group.routes
         if not reverse:
-            handlers = handlers[::-1]
+            signals = signals[::-1]
         try:
-            for handler in handlers:
+            for signal in signals:
-                if condition is None or condition == handler.__requirements__:
+                params.pop("__trigger__", None)
-                    maybe_coroutine = handler(**params)
+                if (
+                    (condition is None and signal.ctx.exclusive is False)
+                    or (
+                        condition is None
+                        and not signal.handler.__requirements__
+                    )
+                    or (condition == signal.handler.__requirements__)
+                ) and (signal.ctx.trigger or event == signal.ctx.definition):
+                    maybe_coroutine = signal.handler(**params)
                     if isawaitable(maybe_coroutine):
                         retval = await maybe_coroutine
                         if retval:
@@ -190,23 +199,36 @@ class SignalRouter(BaseRouter):
         handler: SignalHandler,
         event: str,
         condition: Optional[Dict[str, Any]] = None,
+        exclusive: bool = True,
     ) -> Signal:
+        event_definition = event
         parts = self._build_event_parts(event)
         if parts[2].startswith("<"):
             name = ".".join([*parts[:-1], "*"])
+            trigger = self._clean_trigger(parts[2])
         else:
             name = event
+            trigger = ""
+
+        if not trigger:
+            event = ".".join([*parts[:2], "<__trigger__>"])
 
         handler.__requirements__ = condition  # type: ignore
+        handler.__trigger__ = trigger  # type: ignore
 
-        return super().add(
+        signal = super().add(
             event,
             handler,
-            requirements=condition,
             name=name,
             append=True,
         )  # type: ignore
 
+        signal.ctx.exclusive = exclusive
+        signal.ctx.trigger = trigger
+        signal.ctx.definition = event_definition
+
+        return cast(Signal, signal)
+
     def finalize(self, do_compile: bool = True, do_optimize: bool = False):
         self.add(_blank, "sanic.__signal__.__init__")
 
@@ -238,3 +260,9 @@ class SignalRouter(BaseRouter):
                 "Cannot declare reserved signal event: %s" % event
             )
         return parts
+
+    def _clean_trigger(self, trigger: str) -> str:
+        trigger = trigger[1:-1]
+        if ":" in trigger:
+            trigger, _ = trigger.split(":")
+        return trigger

tests/test_signals.py

@@ -145,6 +145,23 @@ async def test_dispatch_signal_triggers_with_requirements(app):
     assert counter == 1
 
 
+@pytest.mark.asyncio
+async def test_dispatch_signal_triggers_with_requirements_exclusive(app):
+    counter = 0
+
+    @app.signal("foo.bar.baz", condition={"one": "two"}, exclusive=False)
+    def sync_signal(*_):
+        nonlocal counter
+        counter += 1
+
+    app.signal_router.finalize()
+
+    await app.dispatch("foo.bar.baz")
+    assert counter == 1
+    await app.dispatch("foo.bar.baz", condition={"one": "two"})
+    assert counter == 2
+
+
 @pytest.mark.asyncio
 async def test_dispatch_signal_triggers_with_context(app):
     counter = 0
@@ -204,6 +221,24 @@ async def test_dispatch_signal_triggers_on_bp(app):
     assert bp_counter == 2
 
 
+@pytest.mark.asyncio
+async def test_dispatch_signal_triggers_on_bp_alone(app):
+    bp = Blueprint("bp")
+
+    bp_counter = 0
+
+    @bp.signal("foo.bar.baz")
+    def bp_signal():
+        nonlocal bp_counter
+        bp_counter += 1
+
+    app.blueprint(bp)
+    app.signal_router.finalize()
+    await app.dispatch("foo.bar.baz")
+    await bp.dispatch("foo.bar.baz")
+    assert bp_counter == 2
+
+
 @pytest.mark.asyncio
 async def test_dispatch_signal_triggers_event(app):
     app_counter = 0