Spawner.__install_signal_handlers() - Code Metrics - Inspection of "Code and comment enhancements." - SetBased/py-enarksh - Measure and Improve Code Quality continuously with Scrutinizer

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by P.R.

created 2016-10-20 07:40 UTC

Spawner.__install_signal_handlers() A

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Tests	0
CRAP Score	2

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cc	1
dl	0
loc	6
ccs	0
cts	2
cp	0
crap	2
rs	9.4285
c	0
b	0
f	0

"""
Enarksh

Copyright 2013-2016 Set Based IT Consultancy

Licence MIT
"""
import os
import pwd
import signal

import zmq

import enarksh
from enarksh.event.Event import Event
from enarksh.event.EventActor import EventActor
from enarksh.event.EventController import EventController
from enarksh.message.ExitMessage import ExitMessage
from enarksh.message.MessageController import MessageController
from enarksh.spawner.JobHandler import JobHandler
from enarksh.spawner.event_handler.EventQueueEmptyEventHandler import EventQueueEmptyEventHandler
from enarksh.spawner.event_handler.ExitMessageEventHandler import ExitMessageEventHandler
from enarksh.spawner.event_handler.SIGCHLDEventHandler import SIGCHLDEventHandler
from enarksh.spawner.event_handler.SpawnJobMessageEventHandler import SpawnJobMessageEventHandler
from enarksh.spawner.message.SpawnJobMessage import SpawnJobMessage


class Spawner(EventActor):
    """
    The spawner.
    """
    # ------------------------------------------------------------------------------------------------------------------
    instance = None
    """
    The instance of this class.

    :type: None|enarksh.spawner.Spawner.Spawner
    """

    # ------------------------------------------------------------------------------------------------------------------
    def __init__(self):
        """
        Object constructor.
        """
        Spawner.instance = self

        self.__event_controller = EventController()
        """
        The event controller.

        :type: enarksh.event.EventController.EventController
        """

        EventActor.__init__(self)

        self.__message_controller = MessageController()
        """
        The message controller.

        :type: enarksh.message.MessageController.MessageController
        """

        self.__job_handlers = {}
        """
        The job handlers. A dictionary from PID to the job handler for the process (of the job).

        :type: dict[int,enarksh.spawner.JobHandler.JobHandler]
        """

        self.__sigchld_event = Event(self)
        """
        Event for SIGCHLD has been received.

        :type: enarksh.event.Event.Event
        """

        self.__zmq_incoming_message_event = Event(self)
        """
        Event for a ZMQ message is available.

        :type: enarksh.event.Event.Event
        """

    # ------------------------------------------------------------------------------------------------------------------
    @property
    def sigchld_event(self):
        """
        Returns the event for SIGCHLD has been received.

        :rtype: enarksh.event.Event.Event
        """
        return self.__sigchld_event

    # ------------------------------------------------------------------------------------------------------------------
    @property
    def job_handlers(self):
        """
        Returns the job handlers for the currently running processes.

        :rtype: dict[int,enarksh.spawner.JobHandler.JobHandler]
        """
        return self.__job_handlers

    # ------------------------------------------------------------------------------------------------------------------
    @property
    def zmq_incoming_message_event(self):
        """
        Returns the event for a ZMQ message is available.

        :rtype: enarksh.event.Event.Event
        """
        return self.__zmq_incoming_message_event

    # ------------------------------------------------------------------------------------------------------------------
    def add_job_handler(self, job_handler):
        """
        Adds a job handler to this spawner.

        :param enarksh.spawner.JobHandler.JobHandler job_handler: The job handler.
        """
        self.__job_handlers[job_handler.pid] = job_handler

    # ------------------------------------------------------------------------------------------------------------------
    def remove_job_handler(self, pid):
        """
        Removes a job handler to this spawner.

        :param int pid: The (original) PID of the process that the jon handlers was handling.
        """
        del self.__job_handlers[pid]

    # ------------------------------------------------------------------------------------------------------------------
    @staticmethod
    def sigchld_handler(*_):
        """
        Static method for SIGCHLD. Set a flag that a child has exited.
        """
        Spawner.instance.sigchld_event.fire()

    # ------------------------------------------------------------------------------------------------------------------
    def __install_signal_handlers(self):
        """
        Install signal handlers for SIGCHLD and SIGHUP.
        """
        # Install signal handler for child has exited.
        signal.signal(signal.SIGCHLD, self.sigchld_handler)

    # ------------------------------------------------------------------------------------------------------------------
    @staticmethod
    def __set_unprivileged_user():
        """
        Set the real and effective user and group to an unprivileged user.
        """
        _, _, uid, gid, _, _, _ = pwd.getpwnam('enarksh')

        os.setresgid(gid, gid, 0)
        os.setresuid(uid, uid, 0)

    # ------------------------------------------------------------------------------------------------------------------
    def __startup(self):
        """
        Performs the necessary actions for starting the spawner daemon.
        """
        # Log stop of the spawner.
        print('Start spawner')

        # Set the effective user and group to an unprivileged user and group.
        self.__set_unprivileged_user()

        # Install signal handlers.
        self.__install_signal_handlers()

        # Read all user names under which the controller is allowed to start jobs.
        JobHandler.read_allowed_users()

    # ------------------------------------------------------------------------------------------------------------------
    @staticmethod
    def __shutdown():
        """
        Performs the necessary actions for stopping the spawner.
        """
        # Log stop of the spawner.
        print('Stop spawner')

    # ------------------------------------------------------------------------------------------------------------------
    def __register_sockets(self):
        """
        Registers ZMQ sockets for communication with other processes in Enarksh.
        """
        # Register socket for receiving asynchronous incoming messages.
        self.__message_controller.register_end_point('pull', zmq.PULL, enarksh.SPAWNER_PULL_END_POINT)

        # Register socket for sending asynchronous messages to the controller.
        self.__message_controller.register_end_point('controller', zmq.PUSH, enarksh.CONTROLLER_PULL_END_POINT)

        # Register socket for sending asynchronous messages to the logger.
        self.__message_controller.register_end_point('logger', zmq.PUSH, enarksh.LOGGER_PULL_END_POINT)

    # ------------------------------------------------------------------------------------------------------------------
    def __register_message_types(self):
        """
        Registers all message type that the spawner handles at the message controller.
        """
        self.__message_controller.register_message_type(ExitMessage.MESSAGE_TYPE)
        self.__message_controller.register_message_type(SpawnJobMessage.MESSAGE_TYPE)

    # ------------------------------------------------------------------------------------------------------------------
    def __register_events_handlers(self):
        """
        Registers all event handlers at the event controller.
        """
        EventQueueEmptyEventHandler.init()

        # Register message received event handlers.
        self.__message_controller.register_listener(ExitMessage.MESSAGE_TYPE, ExitMessageEventHandler.handle)
        self.__message_controller.register_listener(SpawnJobMessage.MESSAGE_TYPE,
                                                    SpawnJobMessageEventHandler.handle,
                                                    self)
        # Register other event handlers.
        self.__sigchld_event.register_listener(SIGCHLDEventHandler.handle, self)
        self.__zmq_incoming_message_event.register_listener(self.__message_controller.receive_message)
        self.__event_controller.event_queue_empty.register_listener(EventQueueEmptyEventHandler.handle, self)

    # ------------------------------------------------------------------------------------------------------------------
    def main(self):
        """
        The main function of the job spawner.
        """
        self.__startup()

        self.__register_sockets()

        self.__register_message_types()

        self.__register_events_handlers()

        self.__message_controller.no_barking(3)

        self.__event_controller.loop()

        self.__shutdown()

# ----------------------------------------------------------------------------------------------------------------------


1			"""
2			Enarksh
3
4			Copyright 2013-2016 Set Based IT Consultancy
5
6			Licence MIT
7			"""
8			import os
9			import pwd
10			import signal
11
12			import zmq
13
14			import enarksh
15			from enarksh.event.Event import Event
16			from enarksh.event.EventActor import EventActor
17			from enarksh.event.EventController import EventController
18			from enarksh.message.ExitMessage import ExitMessage
19			from enarksh.message.MessageController import MessageController
20			from enarksh.spawner.JobHandler import JobHandler
21			from enarksh.spawner.event_handler.EventQueueEmptyEventHandler import EventQueueEmptyEventHandler
22			from enarksh.spawner.event_handler.ExitMessageEventHandler import ExitMessageEventHandler
23			from enarksh.spawner.event_handler.SIGCHLDEventHandler import SIGCHLDEventHandler
24			from enarksh.spawner.event_handler.SpawnJobMessageEventHandler import SpawnJobMessageEventHandler
25			from enarksh.spawner.message.SpawnJobMessage import SpawnJobMessage
26
27
28			class Spawner(EventActor):
29			"""
30			The spawner.
31			"""
32			# ------------------------------------------------------------------------------------------------------------------
33			instance = None
34			"""
35			The instance of this class.
36
37			:type: None\|enarksh.spawner.Spawner.Spawner
38			"""
39
40			# ------------------------------------------------------------------------------------------------------------------
41			def __init__(self):
42			"""
43			Object constructor.
44			"""
45			Spawner.instance = self
46
47			self.__event_controller = EventController()
48			"""
49			The event controller.
50
51			:type: enarksh.event.EventController.EventController
52			"""
53
54			EventActor.__init__(self)
55
56			self.__message_controller = MessageController()
57			"""
58			The message controller.
59
60			:type: enarksh.message.MessageController.MessageController
61			"""
62
63			self.__job_handlers = {}
64			"""
65			The job handlers. A dictionary from PID to the job handler for the process (of the job).
66
67			:type: dict[int,enarksh.spawner.JobHandler.JobHandler]
68			"""
69
70			self.__sigchld_event = Event(self)
71			"""
72			Event for SIGCHLD has been received.
73
74			:type: enarksh.event.Event.Event
75			"""
76
77			self.__zmq_incoming_message_event = Event(self)
78			"""
79			Event for a ZMQ message is available.
80
81			:type: enarksh.event.Event.Event
82			"""
83
84			# ------------------------------------------------------------------------------------------------------------------
85			@property
86			def sigchld_event(self):
87			"""
88			Returns the event for SIGCHLD has been received.
89
90			:rtype: enarksh.event.Event.Event
91			"""
92			return self.__sigchld_event
93
94			# ------------------------------------------------------------------------------------------------------------------
95			@property
96			def job_handlers(self):
97			"""
98			Returns the job handlers for the currently running processes.
99
100			:rtype: dict[int,enarksh.spawner.JobHandler.JobHandler]
101			"""
102			return self.__job_handlers
103
104			# ------------------------------------------------------------------------------------------------------------------
105			@property
106			def zmq_incoming_message_event(self):
107			"""
108			Returns the event for a ZMQ message is available.
109
110			:rtype: enarksh.event.Event.Event
111			"""
112			return self.__zmq_incoming_message_event
113
114			# ------------------------------------------------------------------------------------------------------------------
115			def add_job_handler(self, job_handler):
116			"""
117			Adds a job handler to this spawner.
118
119			:param enarksh.spawner.JobHandler.JobHandler job_handler: The job handler.
120			"""
121			self.__job_handlers[job_handler.pid] = job_handler
122
123			# ------------------------------------------------------------------------------------------------------------------
124			def remove_job_handler(self, pid):
125			"""
126			Removes a job handler to this spawner.
127
128			:param int pid: The (original) PID of the process that the jon handlers was handling.
129			"""
130			del self.__job_handlers[pid]
131
132			# ------------------------------------------------------------------------------------------------------------------
133			@staticmethod
134			def sigchld_handler(*_):
135			"""
136			Static method for SIGCHLD. Set a flag that a child has exited.
137			"""
138			Spawner.instance.sigchld_event.fire()
139
140			# ------------------------------------------------------------------------------------------------------------------
141			def __install_signal_handlers(self):
142			"""
143			Install signal handlers for SIGCHLD and SIGHUP.
144			"""
145			# Install signal handler for child has exited.
146			signal.signal(signal.SIGCHLD, self.sigchld_handler)
147
148			# ------------------------------------------------------------------------------------------------------------------
149			@staticmethod
150			def __set_unprivileged_user():
151			"""
152			Set the real and effective user and group to an unprivileged user.
153			"""
154			_, _, uid, gid, _, _, _ = pwd.getpwnam('enarksh')
155
156			os.setresgid(gid, gid, 0)
157			os.setresuid(uid, uid, 0)
158
159			# ------------------------------------------------------------------------------------------------------------------
160			def __startup(self):
161			"""
162			Performs the necessary actions for starting the spawner daemon.
163			"""
164			# Log stop of the spawner.
165			print('Start spawner')
166
167			# Set the effective user and group to an unprivileged user and group.
168			self.__set_unprivileged_user()
169
170			# Install signal handlers.
171			self.__install_signal_handlers()
172
173			# Read all user names under which the controller is allowed to start jobs.
174			JobHandler.read_allowed_users()
175
176			# ------------------------------------------------------------------------------------------------------------------
177			@staticmethod
178			def __shutdown():
179			"""
180			Performs the necessary actions for stopping the spawner.
181			"""
182			# Log stop of the spawner.
183			print('Stop spawner')
184
185			# ------------------------------------------------------------------------------------------------------------------
186			def __register_sockets(self):
187			"""
188			Registers ZMQ sockets for communication with other processes in Enarksh.
189			"""
190			# Register socket for receiving asynchronous incoming messages.
191			self.__message_controller.register_end_point('pull', zmq.PULL, enarksh.SPAWNER_PULL_END_POINT)
192
193			# Register socket for sending asynchronous messages to the controller.
194			self.__message_controller.register_end_point('controller', zmq.PUSH, enarksh.CONTROLLER_PULL_END_POINT)
195
196			# Register socket for sending asynchronous messages to the logger.
197			self.__message_controller.register_end_point('logger', zmq.PUSH, enarksh.LOGGER_PULL_END_POINT)
198
199			# ------------------------------------------------------------------------------------------------------------------
200			def __register_message_types(self):
201			"""
202			Registers all message type that the spawner handles at the message controller.
203			"""
204			self.__message_controller.register_message_type(ExitMessage.MESSAGE_TYPE)
205			self.__message_controller.register_message_type(SpawnJobMessage.MESSAGE_TYPE)
206
207			# ------------------------------------------------------------------------------------------------------------------
208			def __register_events_handlers(self):
209			"""
210			Registers all event handlers at the event controller.
211			"""
212			EventQueueEmptyEventHandler.init()
213
214			# Register message received event handlers.
215			self.__message_controller.register_listener(ExitMessage.MESSAGE_TYPE, ExitMessageEventHandler.handle)
216			self.__message_controller.register_listener(SpawnJobMessage.MESSAGE_TYPE,
217			SpawnJobMessageEventHandler.handle,
218			self)
219			# Register other event handlers.
220			self.__sigchld_event.register_listener(SIGCHLDEventHandler.handle, self)
221			self.__zmq_incoming_message_event.register_listener(self.__message_controller.receive_message)
222			self.__event_controller.event_queue_empty.register_listener(EventQueueEmptyEventHandler.handle, self)
223
224			# ------------------------------------------------------------------------------------------------------------------
225			def main(self):
226			"""
227			The main function of the job spawner.
228			"""
229			self.__startup()
230
231			self.__register_sockets()
232
233			self.__register_message_types()
234
235			self.__register_events_handlers()
236
237			self.__message_controller.no_barking(3)
238
239			self.__event_controller.loop()
240
241			self.__shutdown()
242
243			# ----------------------------------------------------------------------------------------------------------------------
244

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