Make thread based cyclic task more accurate

christiansandberg · christiansandberg · commit df8030d08c8c · 2017-02-13T10:09:07.000+01:00
diff --git a/can/broadcastmanager.py b/can/broadcastmanager.py
@@ -93,7 +93,8 @@ class ThreadBasedCyclicSendManager(object):
 
     def __init__(self, send):
         """
-        :param send: A callable function to transmit one :class:`can.Message`.
+        :param send:
+            A callable function to transmit one :class:`can.Message`.
         """
         self.send = send
         self.scheduler = sched.scheduler(time.time, time.sleep)
@@ -102,23 +103,25 @@ def __init__(self, send):
     def add_task(self, task):
         """Add task to be transmitted periodically.
 
-        :param can.broadcastmanager.SimpleCyclicSendTask: Task to schedule
+        :param can.broadcastmanager.ThreadBasedCyclicSendTask task:
+            Task to schedule
         """
-        self._schedule_task(task, 0)
+        self._schedule_task(task)
         if self.thread is None or not self.thread.is_alive():
             self.thread = threading.Thread(target=self.scheduler.run)
             self.thread.daemon = True
             self.thread.start()
 
-    def _schedule_task(self, task, delay):
-        self.scheduler.enter(delay, task.message.arbitration_id,
-                             self._transmit, (task, ))
+    def _schedule_task(self, task):
+        self.scheduler.enterabs(task.next_time, task.message.arbitration_id,
+                                self._transmit, (task, ))
 
     def _transmit(self, task):
         if not task.stopped and (task.end_time is None or
                                  time.time() <= task.end_time):
-            self._schedule_task(task, task.period)
             self.send(task.message)
+            task.next_time += task.period
+            self._schedule_task(task)
 
 
 class ThreadBasedCyclicSendTask(ModifiableCyclicTaskABC,
@@ -132,6 +135,7 @@ def __init__(self, bus, message, period, duration=None):
             bus.cyclic_manager = ThreadBasedCyclicSendManager(bus.send)
         self.bus = bus
         self.stopped = False
+        self.next_time = time.time()
         self.end_time = time.time() + duration if duration else None
         self.start()
 
diff --git a/test/simplecyclic_test.py b/test/simplecyclic_test.py
@@ -18,7 +18,7 @@ def test_cycle_time(self):
         print(size)
         # About 100 messages should have been transmitted. Some overhead will
         # make it less though
-        self.assertTrue(75 < size < 110)
+        self.assertTrue(90 < size < 110)
         last_msg = bus.recv()
         self.assertEqual(last_msg, msg)
 
