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# -*- coding: utf-8 -*-
# abstractbootstrapper.py
# Copyright (C) 2013 LEAP
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
"""
Abstract bootstrapper implementation
"""
import logging
import requests
from functools import partial
from PySide import QtCore
from twisted.internet import threads
from leap.common.check import leap_assert, leap_assert_type
logger = logging.getLogger(__name__)
class AbstractBootstrapper(QtCore.QObject):
"""
Abstract Bootstrapper that implements the needed deferred callbacks
"""
PASSED_KEY = "passed"
ERROR_KEY = "error"
def __init__(self, bypass_checks=False):
"""
Constructor for the abstract bootstrapper
:param bypass_checks: Set to true if the app should bypass
first round of checks for CA
certificates at bootstrap
:type bypass_checks: bool
"""
QtCore.QObject.__init__(self)
leap_assert(self._gui_errback.im_func ==
AbstractBootstrapper._gui_errback.im_func,
"Cannot redefine _gui_errback")
leap_assert(self._errback.im_func ==
AbstractBootstrapper._errback.im_func,
"Cannot redefine _errback")
leap_assert(self._gui_notify.im_func ==
AbstractBootstrapper._gui_notify.im_func,
"Cannot redefine _gui_notify")
# **************************************************** #
# Dependency injection helpers, override this for more
# granular testing
self._fetcher = requests
# **************************************************** #
self._session = self._fetcher.session()
self._bypass_checks = bypass_checks
self._signal_to_emit = None
self._err_msg = None
def _gui_errback(self, failure):
"""
Errback used to notify the GUI of a problem, it should be used
as the last errback of the whole chain.
Traps all exceptions if a signal is defined, otherwise it just
lets it continue.
NOTE: This method is final, it should not be redefined.
:param failure: failure object that Twisted generates
:type failure: twisted.python.failure.Failure
"""
if self._signal_to_emit:
err_msg = self._err_msg \
if self._err_msg is not None \
else str(failure.value)
self._signal_to_emit.emit({
self.PASSED_KEY: False,
self.ERROR_KEY: err_msg
})
failure.trap(Exception)
def _errback(self, failure, signal=None):
"""
Regular errback used for the middle of the chain. If it's
executed, the first one will set the signal to emit as
failure.
NOTE: This method is final, it should not be redefined.
:param failure: failure object that Twisted generates
:type failure: twisted.python.failure.Failure
:param signal: Signal to emit if it fails here first
:type signal: QtCore.SignalInstance
:returns: failure object that Twisted generates
:rtype: twisted.python.failure.Failure
"""
if self._signal_to_emit is None:
self._signal_to_emit = signal
return failure
def _gui_notify(self, _, signal=None):
"""
Callback used to notify the GUI of a success. Will emit signal
if specified
NOTE: This method is final, it should not be redefined.
:param _: IGNORED. Returned from the previous callback
:type _: IGNORED
:param signal: Signal to emit if it fails here first
:type signal: QtCore.SignalInstance
"""
if signal:
logger.debug("Emitting %s" % (signal,))
signal.emit({self.PASSED_KEY: True, self.ERROR_KEY: ""})
def _callback_threader(self, cb, res, *args, **kwargs):
return threads.deferToThread(cb, res, *args, **kwargs)
def addCallbackChain(self, callbacks):
"""
Creates a callback/errback chain on another thread using
deferToThread and adds the _gui_errback to the end to notify
the GUI on an error.
:param callbacks: List of tuples of callbacks and the signal
associated to that callback
:type callbacks: list(tuple(func, func))
:returns: the defer with the callback chain
:rtype: deferred
"""
leap_assert_type(callbacks, list)
self._signal_to_emit = None
self._err_msg = None
d = None
for cb, sig in callbacks:
if d is None:
d = threads.deferToThread(cb)
else:
d.addCallback(partial(self._callback_threader, cb))
d.addErrback(self._errback, signal=sig)
d.addCallback(self._gui_notify, signal=sig)
d.addErrback(self._gui_errback)
return d
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