can.Notifier enhancements (#266)

* prepended an underscore to private fields/methdos of can.Notifier

* added add_listener and remove_listener to can.Notifier. closes #265

* added tests for can.Notifier.add_listener() and remove_listener()

* added tests for can.Notifier.add_listener() and remove_listener()

* fix an import problem that was cuased by pervious merge

* attempt fixing Sqlite tests

Author: felixdivo

can/notifier.py

@@ -2,7 +2,7 @@
 # coding: utf-8
 
 """
-This module contains the implementation of `can.Notifier`.
+This module contains the implementation of :class:`~can.Notifier`.
 """
 
 import threading
@@ -18,7 +18,7 @@ def __init__(self, bus, listeners, timeout=None):
         list of listeners.
 
         :param bus: The :ref:`bus` to listen too.
-        :param listeners: An iterable of :class:`~can.Listeners`
+        :param listeners: An iterable of :class:`~can.Listener`s
         :param timeout: An optional maximum number of seconds to wait for any message.
         """
         self.listeners = listeners
@@ -28,23 +28,25 @@ def __init__(self, bus, listeners, timeout=None):
         # exception raised in thread
         self.exception = None
 
-        self.running = threading.Event()
-        self.running.set()
+        self._running = threading.Event()
+        self._running.set()
 
-        self._reader = threading.Thread(target=self.rx_thread, name="can.notifier")
+        self._reader = threading.Thread(target=self._rx_thread,
+                                        name='can.notifier for bus "{}"'.format(self.bus.channel_info))
         self._reader.daemon = True
         self._reader.start()
 
     def stop(self):
         """Stop notifying Listeners when new :class:`~can.Message` objects arrive
-         and call :meth:`~can.Listener.stop` on each Listener."""
-        self.running.clear()
+        and call :meth:`~can.Listener.stop` on each Listener.
+        """
+        self._running.clear()
         if self.timeout is not None:
             self._reader.join(self.timeout + 0.1)
 
-    def rx_thread(self):
+    def _rx_thread(self):
         try:
-            while self.running.is_set():
+            while self._running.is_set():
                 msg = self.bus.recv(self.timeout)
                 if msg is not None:
                     for callback in self.listeners:
@@ -55,3 +57,24 @@ def rx_thread(self):
         finally:
             for listener in self.listeners:
                 listener.stop()
+
+    def add_listener(self, listener):
+        """Add new Listener to the notification list. 
+        If it is already present, it will be called two times
+        each time a message arrives.
+
+        :param listener: a :class:`~can.Listener` object to be added to
+                         the list to be notified
+        """
+        self.listeners.append(listener)
+
+    def remove_listener(self, listener):
+        """Remove a listener from the notification list. This method
+        trows an exception if the given listener is not part of the
+        stored listeners.
+
+        :param listener: a :class:`~can.Listener` object to be removed from
+                         the list to be notified
+        :raises ValueError: if `listener` was never added to this notifier
+        """
+        self.listeners.remove(listener)

test/back2back_test.py

@@ -13,9 +13,12 @@
 
 import can
 
+from .data.example_data import generate_message
+
 from .config import *
 from .data.example_data import generate_message
 
+
 BITRATE = 500000
 TIMEOUT = 0.1
 

test/listener_test.py

@@ -73,6 +73,22 @@ def testBasicListenerCanBeAddedToNotifier(self):
         notifier = can.Notifier(self.bus, [a_listener], 0.1)
         notifier.stop()
         self.assertIn(a_listener, notifier.listeners)
+    
+    def testAddListenerToNotifier(self):
+        a_listener = can.Listener()
+        notifier = can.Notifier(self.bus, [], 0.1)
+        notifier.stop()
+        self.assertNotIn(a_listener, notifier.listeners)
+        notifier.add_listener(a_listener)
+        self.assertIn(a_listener, notifier.listeners)
+
+    def testRemoveListenerFromNotifier(self):
+        a_listener = can.Listener()
+        notifier = can.Notifier(self.bus, [a_listener], 0.1)
+        notifier.stop()
+        self.assertIn(a_listener, notifier.listeners)
+        notifier.remove_listener(a_listener)
+        self.assertNotIn(a_listener, notifier.listeners)
 
     def testPlayerTypeResolution(self):
         def test_filetype_to_instance(extension, klass):

test/logformats_test.py

@@ -166,7 +166,7 @@ class TestSqliteDatabaseFormat(unittest.TestCase):
 
     def test_writer_and_reader(self):
         _test_writer_and_reader(self, can.SqliteWriter, can.SqliteReader,
-                                sleep_time=can.SqliteWriter.MAX_TIME_BETWEEN_WRITES,
+                                sleep_time=can.SqliteWriter.MAX_TIME_BETWEEN_WRITES + 0.5,
                                 check_comments=False)
 
     def testSQLWriterWritesToSameFile(self):