add iterate method to journald worker

Author: arcan1s

README.md

@@ -31,7 +31,18 @@ Library functions to monitor state of systemd spawned units
         time.sleep(60)
     ```
 
-2. Get unit properties
+2. Single-thread realtime monitoring
+
+    ```python
+    from systemd_monitor.journald_worker import JournaldWorker
+
+    worker = JournaldWorker()
+
+    for unit, state in worker.run_iterate():
+        print("Update received for unit {}".format(unit))
+    ```
+
+3. Get unit properties
 
     ```python
     from systemd_monitor.systemd_dbus_adapter import SystemdDBusAdapter

src/systemd_monitor/journald_worker.py

@@ -80,7 +80,8 @@ def __load_states(self):
         '''
         initial services load
         '''
-        self.__states = self.__systemd.get_all()
+        with self.__lock:
+            self.__states = self.__systemd.get_all()
 
     def run(self):
         '''
@@ -112,6 +113,37 @@ def run(self):
                 self.__status = False
             time.sleep(60)
 
+    def run_iterate(self):
+        '''
+        run thread and return states right in time
+        '''
+        self.__load_states()
+        while self.__should_run:
+            try:
+                for line in self.__get_journal():
+                    self.__status = True
+                    # exit on no actions
+                    if not self.__should_run:
+                        break
+                    # parse line
+                    if isinstance(line, bytes):
+                        line = line.decode('utf8')
+                    data = json.loads(line)
+                    # check if it is unit related infomation
+                    if 'UNIT' not in data:
+                        continue
+                    # update internal storage
+                    with self.__lock:
+                        self.__states[
+                            data['UNIT']] = self.__systemd.get(
+                            data['UNIT'])
+                        self.__lst = datetime.datetime.utcnow()
+                        yield data['UNIT'], self.__states[data['UNIT']]
+            except Exception:
+                self.__logger.warning('Exception recieved', exc_info=True)
+                self.__status = False
+            time.sleep(60)
+
     def stop(self):
         '''
         stop worker

src/systemd_monitor/systemd_dbus_adapter.py

@@ -113,7 +113,7 @@ def get(self, unit):
         # type defined properties
         interface = self.__define_type(unit)
         properties.update(service.GetAll(interface))
-        return systemd_unit_state.SystemdUnit(path, **properties)
+        return systemd_unit.SystemdUnit(path, **properties)
 
     def reload_unit(self, unit, mode='replace'):
         '''