Hello everyone! I wrote Twisted-based TCP server which is capable of running in several relatively different modes. When mode switch is needed, I would like the server to restart itself by some means, for it to read new mode from configuration file and create corresponding implementation. Also I wanted the restart to occur without re-running twistd process, because it seems to me more appropriate for Linux daemon.

So I organized code in the .tac file in the following way:

 

# imports...

 

CONFIG_FILE_NAME = "master.conf"

 

def main():

   print("Entered main")

   config = ConfigParser.RawConfigParser()

   config.read(CONFIG_FILE_NAME)

   context = MasterPlayerImplementationContext()

   context.config_file_name = CONFIG_FILE_NAME

   context.reactor = reactor

   print("Creating internet.TCPServer...")

   master_player_service = internet.TCPServer(config.getint(shared_types.CONFIG_SECTION_GENERAL,

                                    shared_types.CONFIG_PARAMETER_SERVER_PORT),

                      pb.PBServerFactory(MasterPlayer(context)),

                      50, config.get(shared_types.CONFIG_SECTION_GENERAL,

                                     shared_types.CONFIG_PARAMETER_SERVER_IP))

   def stop_service_succeeded(arg):

       print("Service stop succeeded! arg is {}. Restarting...".format(arg))

       main()

   def stop_service_failed(failure):

       print("Service stop failed! failure is {}. Trying to restart nevertheless...".format(failure))

       main()

   def restart_callback():

       print("Entered restart_callback")

       deferred = defer.maybeDeferred(master_player_service.disownServiceParent)

       deferred.addCallback(stop_service_succeeded).addErrback(stop_service_failed)

       print("Leaving restart_callback")

   context.restart_callback = restart_callback

   master_player_service.setServiceParent(service_collection)

   print("Exiting main")

 

application = service.Application("master_player")

service_collection = service.IServiceCollection(application)

main()

print("After main")

 

When the server is in need of restarting itself, it just calls the context.restart_callback function and restart occurs immediately.

My experience in Linux, Python and Twisted is rather modest, so I would like to consult here to determine whether solution chosen is the right one.

P.S. The second aim, in case the solution is not very bad or in case there will be better solution pointed out, is to leave answer to the “How to restart Twisted service” question in this mailing list, because it took me relatively large amount of time for searching through old mailing list entries and StackOverflow questions.

 

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Kind regards, Roman Mescheryakov