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#
# This file is part of Checkbox.
#
# Copyright 2008 Canonical Ltd.
#
# Checkbox 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.
#
# Checkbox 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 Checkbox. If not, see <http://www.gnu.org/licenses/>.
#
import logging
import threading
from checkbox.lib.log import format_object
class EventID(object):
def __init__(self, event_type, pair):
self._event_type = event_type
self._pair = pair
class StopException(Exception):
pass
class StopAllException(Exception):
pass
class Reactor(object):
def __init__(self):
self._event_handlers = {}
self._local = threading.local()
self._depth = 0
def call_on(self, event_type, handler, priority=0):
pair = (handler, priority)
logging.debug("Calling %s on %s.", format_object(handler), event_type)
handlers = self._event_handlers.setdefault(event_type, [])
handlers.append(pair)
return EventID(event_type, pair)
def fire(self, event_type, *args, **kwargs):
indent = " " * self._depth
self._depth += 1
logging.debug("%sStarted firing %s.", indent, event_type)
handlers = self._event_handlers.get(event_type, ())
if not handlers:
logging.debug("%sNo handlers found for event type: %s", indent, event_type)
results = []
handlers = sorted(handlers, key=lambda pair: pair[1])
for handler, priority in handlers:
try:
logging.debug("%sCalling %s for %s with priority %d.",
indent, format_object(handler, *args, **kwargs),
event_type, priority)
results.append(handler(*args, **kwargs))
except StopException:
break
except StopAllException:
raise
except KeyboardInterrupt:
logging.exception("Keyboard interrupt while running event "
"handler %s for event type %r",
format_object(handler, *args, **kwargs),
event_type)
self.stop_all()
except:
logging.exception("Error running event handler %s for "
"event type %r",
format_object(handler, *args, **kwargs),
event_type)
logging.debug("%sFinished firing %s.", indent, event_type)
self._depth -= 1
return results
def has_call(self, event_type):
return event_type in self._event_handlers
def cancel_call(self, id):
if type(id) is EventID:
self._event_handlers[id._event_type].remove(id._pair)
else:
raise Exception, "EventID instance expected, received %r" % id
def cancel_all_calls(self, event_type):
del self._event_handlers[event_type]
def run(self):
try:
self.fire("run")
except StopAllException:
pass
self.fire("stop")
def stop(self):
raise StopException
def stop_all(self):
raise StopAllException
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