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# encoding: utf-8
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"""A class that manages the engines connection to the controller."""
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__docformat__ = "restructuredtext en"
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#-------------------------------------------------------------------------------
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# Copyright (C) 2008 The IPython Development Team
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#
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# Distributed under the terms of the BSD License. The full license is in
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# the file COPYING, distributed as part of this software.
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#-------------------------------------------------------------------------------
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#-------------------------------------------------------------------------------
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# Imports
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#-------------------------------------------------------------------------------
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import os
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import cPickle as pickle
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from twisted.python import log, failure
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from twisted.internet import defer
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from twisted.internet.defer import inlineCallbacks, returnValue
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from IPython.kernel.fcutil import find_furl
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from IPython.kernel.enginefc import IFCEngine
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from IPython.kernel.twistedutil import sleep_deferred
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#-------------------------------------------------------------------------------
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# The ClientConnector class
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#-------------------------------------------------------------------------------
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class EngineConnectorError(Exception):
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pass
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class EngineConnector(object):
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"""Manage an engines connection to a controller.
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This class takes a foolscap `Tub` and provides a `connect_to_controller`
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method that will use the `Tub` to connect to a controller and register
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the engine with the controller.
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"""
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def __init__(self, tub):
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self.tub = tub
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def connect_to_controller(self, engine_service, furl_or_file,
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delay=0.1, max_tries=10):
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"""
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Make a connection to a controller specified by a furl.
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This method takes an `IEngineBase` instance and a foolcap URL and uses
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the `tub` attribute to make a connection to the controller. The
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foolscap URL contains all the information needed to connect to the
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controller, including the ip and port as well as any encryption and
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authentication information needed for the connection.
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After getting a reference to the controller, this method calls the
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`register_engine` method of the controller to actually register the
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engine.
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This method will try to connect to the controller multiple times with
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a delay in between. Each time the FURL file is read anew.
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Parameters
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__________
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engine_service : IEngineBase
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An instance of an `IEngineBase` implementer
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furl_or_file : str
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A furl or a filename containing a furl
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delay : float
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The intial time to wait between connection attempts. Subsequent
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attempts have increasing delays.
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max_tries : int
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The maximum number of connection attempts.
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"""
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if not self.tub.running:
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self.tub.startService()
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self.engine_service = engine_service
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self.engine_reference = IFCEngine(self.engine_service)
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d = self._try_to_connect(furl_or_file, delay, max_tries, attempt=0)
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return d
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@inlineCallbacks
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def _try_to_connect(self, furl_or_file, delay, max_tries, attempt):
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"""Try to connect to the controller with retry logic."""
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if attempt < max_tries:
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log.msg("Attempting to connect to controller [%r]: %s" % \
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(attempt, furl_or_file))
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try:
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self.furl = find_furl(furl_or_file)
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# Uncomment this to see the FURL being tried.
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# log.msg("FURL: %s" % self.furl)
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rr = yield self.tub.getReference(self.furl)
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except:
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if attempt==max_tries-1:
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# This will propagate the exception all the way to the top
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# where it can be handled.
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raise
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else:
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yield sleep_deferred(delay)
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yield self._try_to_connect(
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furl_or_file, 1.5*delay, max_tries, attempt+1
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)
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else:
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result = yield self._register(rr)
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returnValue(result)
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else:
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raise EngineConnectorError(
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'Could not connect to controller, max_tries (%r) exceeded. '
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'This usually means that i) the controller was not started, '
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'or ii) a firewall was blocking the engine from connecting '
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'to the controller.' % max_tries
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)
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def _register(self, rr):
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self.remote_ref = rr
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# Now register myself with the controller
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desired_id = self.engine_service.id
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d = self.remote_ref.callRemote('register_engine', self.engine_reference,
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desired_id, os.getpid(), pickle.dumps(self.engine_service.properties,2))
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return d.addCallback(self._reference_sent)
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def _reference_sent(self, registration_dict):
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self.engine_service.id = registration_dict['id']
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log.msg("engine registration succeeded, got id: %r" % self.engine_service.id)
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return self.engine_service.id
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