core: remove loop.signal in favor of chan, change usage

core/src/trezor/loop.py

@@ -220,53 +220,6 @@ class wait(Syscall):
         pause(task, self.msg_iface)
 
 
-_NO_VALUE = object()
-
-
-class signal(Syscall):
-    """
-    Pause current task, and let other running task to resume it later with a
-    result value or an exception.
-
-    Example:
-
-    >>> # in task #1:
-    >>> signal = loop.signal()
-    >>> result = await signal
-    >>> print('awaited result:', result)
-    >>> # in task #2:
-    >>> signal.send('hello from task #2')
-    >>> # prints in the next iteration of the event loop
-    """
-
-    def __init__(self) -> None:
-        self.reset()
-
-    def reset(self) -> None:
-        self.value = _NO_VALUE
-        self.task = None  # type: Optional[Task]
-
-    def handle(self, task: Task) -> None:
-        self.task = task
-        self._deliver()
-
-    def send(self, value: Any) -> None:
-        self.value = value
-        self._deliver()
-
-    def _deliver(self) -> None:
-        if self.task is not None and self.value is not _NO_VALUE:
-            schedule(self.task, self.value)
-            self.reset()
-
-    def __iter__(self) -> Task:  # type: ignore
-        try:
-            return (yield self)
-        except:  # noqa: E722
-            self.task = None
-            raise
-
-
 _type_gen = type((lambda: (yield))())
 
 

core/src/trezor/ui/__init__.py

@@ -200,12 +200,12 @@ class Layout(Control):
     async def __iter__(self) -> ResultValue:
         value = None
         try:
-            if workflow.layout_signal.task is not None:
-                workflow.layout_signal.send(LayoutCancelled())
+            if workflow.layout_signal.takers:
+                await workflow.layout_signal.put(LayoutCancelled())
             workflow.onlayoutstart(self)
             while True:
                 layout_tasks = self.create_tasks()
-                await loop.spawn(workflow.layout_signal, *layout_tasks)
+                await loop.spawn(workflow.layout_signal.take, *layout_tasks)
         except Result as result:
             value = result.value
         finally:

core/src/trezor/workflow.py

@@ -6,7 +6,7 @@ if False:
 
 workflows = []  # type: List[loop.Task]
 layouts = []  # type: List[ui.Layout]
-layout_signal = loop.signal()
+layout_signal = loop.chan()
 default = None  # type: Optional[loop.Task]
 default_layout = None  # type: Optional[Callable[[], loop.Task]]