text: #
  # MIT License
  #
  # Copyright 2017 Launchpad project contributors (see COPYRIGHT.md)
  #
  # Permission is hereby granted, free of charge, to any person obtaining a
  # copy of this software and associated documentation files (the "Software"),
  # to deal in the Software without restriction, including without limitation
  # the rights to use, copy, modify, merge, publish, distribute, sublicense,
  # and/or sell copies of the Software, and to permit persons to whom the
  # Software is furnished to do so, subject to the following conditions:
  #
  # The above copyright notice and this permission notice shall be included in
  # all copies or substantial portions of the Software.
  #
  # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  # IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  # FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  # THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  # LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  # FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
  # DEALINGS IN THE SOFTWARE.
  #
  import marshal
  import importlib.util
  from contextlib import suppress
  
  import tinyrpc
  from django.db import transaction
  from django.utils import timezone
  
  from common.session import LaunchpadSession
  from dashboard.models import Client
  
  
  class LaunchpadServerSession(LaunchpadSession):
      def __init__(self, client_id):
          self.client_id = client_id
          super().__init__()
          # Register self as rpc server
          self._dispatcher.register_object('server', self)
          # Retrieve client to rpc server on the other end
          self.client = self._dispatcher.get_object('client')
  
      def on_connect(self, connection):
          try:
              with transaction.atomic():
                  client = Client.objects.get(client_id=self.client_id)
                  client.date_connected = timezone.now()
                  client.save()
          except Client.DoesNotExist as e:
              raise ConnectionError() from e
          else:
              super().on_connect(connection)
  
      def on_disconnect(self):
          super().on_disconnect()
          with suppress(Client.DoesNotExist):
              with transaction.atomic():
                  client = Client.objects.get(client_id=self.client_id)
                  client.date_disconnected = timezone.now()
                  client.save()
  
      @tinyrpc.public
      def import_module(self, module_name):
          try:
              spec = importlib.util.find_spec(module_name)
              if not spec:
                  return None
              with open(spec.origin, 'rb') as fp:
                  return marshal.dumps(compile(fp.read(), '<frozen>', 'exec'))
          except FileNotFoundError:
              return None
  