Destroy the old timer when the updater period changes

diagnostic_updater/CMakeLists.txt

@@ -96,6 +96,7 @@ if(BUILD_TESTING)
   find_package(ament_cmake_pytest REQUIRED)
   ament_add_pytest_test(diagnostic_updater_test.py "test/diagnostic_updater_test.py")
   ament_add_pytest_test(test_DiagnosticStatusWrapper.py "test/test_diagnostic_status_wrapper.py")
+  ament_add_pytest_test(test_updater_period.py "test/test_updater_period.py")
   # ament_add_pytest_test(status_msg_test.py "test/status_msg_test.py")
 endif()
 

diagnostic_updater/diagnostic_updater/_diagnostic_updater.py

@@ -313,7 +313,7 @@ def period(self):
     @period.setter
     def period(self, period):
         self.__period = period
-        self.timer.reset()
+        self.node.destroy_timer(self.timer)
         self.timer = self.node.create_timer(self.__period, self.update)
 
     def force_update(self):

diagnostic_updater/test/test_updater_period.py

@@ -0,0 +1,35 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+"""Tests for the Updater period setter."""
+
+import unittest
+
+from diagnostic_updater import Updater
+
+import rclpy
+
+
+class TestUpdaterPeriod(unittest.TestCase):
+
+    def setUp(self):
+        rclpy.init()
+        self.node = rclpy.create_node('test_updater_period')
+
+    def tearDown(self):
+        self.node.destroy_node()
+        rclpy.shutdown()
+
+    def test_period_setter_replaces_timer(self):
+        updater = Updater(self.node, period=1.0)
+        self.assertEqual(len(list(self.node.timers)), 1)
+        old_timer = updater.timer
+
+        updater.period = 0.5
+
+        self.assertEqual(updater.period, 0.5)
+        # The old timer must be destroyed rather than left running next to
+        # the new one, otherwise update() gets called by both of them.
+        self.assertEqual(len(list(self.node.timers)), 1)
+        self.assertIsNot(updater.timer, old_timer)
+        self.assertEqual(updater.timer.timer_period_ns, 500000000)