Refactor DirectoryMonitor managing code to a mixin

lib/tfw/mixins/__init__.py

@@ -4,3 +4,4 @@
 from .supervisor_mixin import SupervisorMixin
 from .callback_mixin import CallbackMixin
 from .observer_mixin import ObserverMixin
+from .monitor_manager_mixin import MonitorManagerMixin

lib/tfw/mixins/monitor_manager_mixin.py

@@ -0,0 +1,27 @@
+# Copyright (C) 2018 Avatao.com Innovative Learning Kft.
+# All Rights Reserved. See LICENSE file for details.
+
+from tfw.config.logs import logging
+
+LOG = logging.getLogger(__name__)
+
+
+class MonitorManagerMixin:
+    def __init__(self, monitor_type, directory):
+        self._monitor_type = monitor_type
+        self._monitor = None
+        self._monitored_directory = directory
+        self.reload_monitor()
+
+    @property
+    def monitor(self):
+        return self._monitor
+
+    def reload_monitor(self):
+        if self._monitor:
+            try:
+                self._monitor.stop()
+            except KeyError:
+                LOG.debug('Working directory was removed – ignoring...')
+        self._monitor = self._monitor_type(self._monitored_directory)
+        self._monitor.watch()   # This runs on a separate thread