Allow RestartableCyclicTaskABC using Windows events to restart

can/broadcastmanager.py

@@ -269,9 +269,10 @@ def __init__(
         self.start()
 
     def stop(self) -> None:
-        if USE_WINDOWS_EVENTS:
-            win32event.CancelWaitableTimer(self.event.handle)
         self.stopped = True
+        if USE_WINDOWS_EVENTS:
+            # Reset and signal any pending wait by setting the timer to 0
+            win32event.SetWaitableTimer(self.event.handle, 0, 0, None, None, False)
 
     def start(self) -> None:
         self.stopped = False

test/simplecyclic_test.py

@@ -152,6 +152,41 @@ def test_stopping_perodic_tasks(self):
 
         bus.shutdown()
 
+    def test_restart_perodic_tasks(self):
+        period = 0.01
+        safe_timeout = period * 5
+
+        msg = can.Message(
+            is_extended_id=False, arbitration_id=0x123, data=[0, 1, 2, 3, 4, 5, 6, 7]
+        )
+
+        with can.ThreadSafeBus(interface="virtual", receive_own_messages=True) as bus:
+            task = bus.send_periodic(msg, period)
+            self.assertIsInstance(task, can.broadcastmanager.RestartableCyclicTaskABC)
+
+            # Test that the task is sending messages
+            sleep(safe_timeout)
+            assert not bus.queue.empty(), "messages should have been transmitted"
+
+            # Stop the task and check that messages are no longer being sent
+            bus.stop_all_periodic_tasks(remove_tasks=False)
+            sleep(safe_timeout)
+            while not bus.queue.empty():
+                bus.recv(timeout=period)
+            sleep(safe_timeout)
+            assert bus.queue.empty(), "messages should not have been transmitted"
+
+            # Restart the task and check that messages are being sent again
+            task.start()
+            sleep(safe_timeout)
+            assert not bus.queue.empty(), "messages should have been transmitted"
+
+            # Stop all tasks and wait for the thread to exit
+            bus.stop_all_periodic_tasks()
+            if isinstance(task, can.broadcastmanager.ThreadBasedCyclicSendTask):
+                # Avoids issues where the thread is still running when the bus is shutdown
+                task.thread.join(safe_timeout)
+
     @unittest.skipIf(IS_CI, "fails randomly when run on CI server")
     def test_thread_based_cyclic_send_task(self):
         bus = can.ThreadSafeBus(interface="virtual")