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""" |
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Enarksh |
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Copyright 2013-2016 Set Based IT Consultancy |
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Licence MIT |
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""" |
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import os |
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import signal |
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import pwd |
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import zmq |
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import enarksh |
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from enarksh.event.Event import Event |
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from enarksh.event.EventActor import EventActor |
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from enarksh.event.EventController import EventController |
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from enarksh.message.ExitMessage import ExitMessage |
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from enarksh.message.MessageController import MessageController |
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from enarksh.spawner.JobHandler import JobHandler |
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from enarksh.spawner.event_handler.EventQueueEmptyEventHandler import EventQueueEmptyEventHandler |
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from enarksh.spawner.event_handler.ExitMessageEventHandler import ExitMessageEventHandler |
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from enarksh.spawner.event_handler.SIGCHLDEventHandler import SIGCHLDEventHandler |
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from enarksh.spawner.event_handler.SpawnJobMessageEventHandler import SpawnJobMessageEventHandler |
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from enarksh.spawner.message.SpawnJobMessage import SpawnJobMessage |
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class Spawner(EventActor): |
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""" |
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The spawner. |
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""" |
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# ------------------------------------------------------------------------------------------------------------------ |
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instance = None |
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""" |
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The instance of this class. |
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:type: None|enarksh.spawner.Spawner.Spawner |
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""" |
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# ------------------------------------------------------------------------------------------------------------------ |
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def __init__(self): |
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""" |
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Object constructor. |
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""" |
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EventActor.__init__(self) |
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Spawner.instance = self |
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self._event_controller = EventController() |
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""" |
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The event controller. |
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:type: enarksh.event.EventController.EventController |
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""" |
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self._message_controller = MessageController() |
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""" |
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The message controller. |
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:type: enarksh.message.MessageController.MessageController |
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""" |
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self._job_handlers = {} |
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""" |
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The job handlers. A dictionary from PID to the job handler for the process (of the job). |
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:type: dict[int,enarksh.spawner.JobHandler.JobHandler] |
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""" |
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self._sigchld_event = Event(self) |
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""" |
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Event for SIGCHLD has been received. |
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:type: enarksh.event.Event.Event |
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""" |
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self._zmq_incoming_message_event = Event(self) |
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""" |
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Event for a ZMQ message is available. |
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:type: enarksh.event.Event.Event |
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""" |
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# ------------------------------------------------------------------------------------------------------------------ |
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@property |
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def sigchld_event(self): |
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""" |
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Returns the event for SIGCHLD has been received. |
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:rtype: enarksh.event.Event.Event |
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""" |
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return self._sigchld_event |
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# ------------------------------------------------------------------------------------------------------------------ |
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@property |
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def job_handlers(self): |
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""" |
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Returns the job handlers for the currently running processes. |
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:rtype: dict[int,enarksh.spawner.JobHandler.JobHandler] |
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""" |
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return self._job_handlers |
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# ------------------------------------------------------------------------------------------------------------------ |
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@property |
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def zmq_incoming_message_event(self): |
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""" |
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Returns the event for a ZMQ message is available. |
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:rtype: enarksh.event.Event.Event |
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""" |
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return self._zmq_incoming_message_event |
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# ------------------------------------------------------------------------------------------------------------------ |
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def add_job_handler(self, job_handler): |
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""" |
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Adds a job handler to this spawner. |
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:param enarksh.spawner.JobHandler.JobHandler job_handler: The job handler. |
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""" |
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self._job_handlers[job_handler.pid] = job_handler |
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# ------------------------------------------------------------------------------------------------------------------ |
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def remove_job_handler(self, pid): |
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""" |
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Removes a job handler to this spawner. |
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:param int pid: The (original) PID of the process that the jon handlers was handling. |
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""" |
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self._job_handlers[pid].destroy() |
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del self._job_handlers[pid] |
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# ------------------------------------------------------------------------------------------------------------------ |
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@staticmethod |
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def sigchld_handler(*_): |
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""" |
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Static method for SIGCHLD. Set a flag that a child has exited. |
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""" |
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Spawner.instance.sigchld_event.fire() |
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# ------------------------------------------------------------------------------------------------------------------ |
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def _install_signal_handlers(self): |
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""" |
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Install signal handlers for SIGCHLD and SIGHUP. |
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""" |
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# Install signal handler for child has exited. |
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signal.signal(signal.SIGCHLD, self.sigchld_handler) |
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# ------------------------------------------------------------------------------------------------------------------ |
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@staticmethod |
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def _set_unprivileged_user(): |
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""" |
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Set the real and effective user and group to an unprivileged user. |
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""" |
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_, _, uid, gid, _, _, _ = pwd.getpwnam('enarksh') |
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os.setresgid(gid, gid, 0) |
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os.setresuid(uid, uid, 0) |
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# ------------------------------------------------------------------------------------------------------------------ |
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def _startup(self): |
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""" |
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Performs the necessary actions for starting the spawner daemon. |
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""" |
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# Log stop of the spawner. |
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print('Start spawner') |
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# Set the effective user and group to an unprivileged user and group. |
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self._set_unprivileged_user() |
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# Install signal handlers. |
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self._install_signal_handlers() |
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# Read all user names under which the controller is allowed to start jobs. |
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JobHandler.read_allowed_users() |
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# ------------------------------------------------------------------------------------------------------------------ |
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@staticmethod |
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def _shutdown(): |
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""" |
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Performs the necessary actions for stopping the spawner. |
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""" |
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# Log stop of the spawner. |
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print('Stop spawner') |
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# ------------------------------------------------------------------------------------------------------------------ |
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def _register_sockets(self): |
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""" |
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Registers ZMQ sockets for communication with other processes in Enarksh. |
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""" |
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# Register socket for receiving asynchronous incoming messages. |
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self._message_controller.register_end_point('pull', zmq.PULL, enarksh.SPAWNER_PULL_END_POINT) |
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# Register socket for sending asynchronous messages to the controller. |
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self._message_controller.register_end_point('controller', zmq.PUSH, enarksh.CONTROLLER_PULL_END_POINT) |
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# Register socket for sending asynchronous messages to the logger. |
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self._message_controller.register_end_point('logger', zmq.PUSH, enarksh.LOGGER_PULL_END_POINT) |
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# ------------------------------------------------------------------------------------------------------------------ |
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def _register_message_types(self): |
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""" |
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Registers all message type that the spawner handles at the message controller. |
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""" |
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self._message_controller.register_message_type(ExitMessage.MESSAGE_TYPE) |
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self._message_controller.register_message_type(SpawnJobMessage.MESSAGE_TYPE) |
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# ------------------------------------------------------------------------------------------------------------------ |
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def _register_events_handlers(self): |
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""" |
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Registers all event handlers at the event controller. |
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""" |
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EventQueueEmptyEventHandler.init() |
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# Register message received event handlers. |
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self._message_controller.register_listener(ExitMessage.MESSAGE_TYPE, ExitMessageEventHandler.handle) |
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self._message_controller.register_listener(SpawnJobMessage.MESSAGE_TYPE, |
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SpawnJobMessageEventHandler.handle, |
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self) |
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# Register other event handlers. |
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self._sigchld_event.register_listener(SIGCHLDEventHandler.handle, self) |
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self._zmq_incoming_message_event.register_listener(self._message_controller.receive_message) |
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self._event_controller.event_queue_empty.register_listener(EventQueueEmptyEventHandler.handle, self) |
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# ------------------------------------------------------------------------------------------------------------------ |
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def main(self): |
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""" |
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The main function of the job spawner. |
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""" |
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self._startup() |
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self._register_sockets() |
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self._register_message_types() |
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self._register_events_handlers() |
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self._message_controller.no_barking(3) |
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self._event_controller.loop() |
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self._shutdown() |
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# ---------------------------------------------------------------------------------------------------------------------- |
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