/usr/share/pyshared/checkbox/dispatcher.py is in checkbox 0.13.7.
This file is owned by root:root, with mode 0o644.
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 | # Copyright 2010-2011 Canonical Ltd. This software is licensed under the
# GNU Affero General Public License version 3 (see the file LICENSE).
__metaclass__ = type
__all__ = [
"Dispatcher",
"DispatcherList",
"DispatcherQueue",
]
import logging
from itertools import product
class Event:
"""Event payload containing the positional and keywoard arguments
passed to the handler in the event listener."""
def __init__(self, type, *args, **kwargs):
self.type = type
self.args = args
self.kwargs = kwargs
class Listener:
"""Event listener notified when events are published by the dispatcher."""
def __init__(self, event_type, handler, count):
self.event_type = event_type
self.handler = handler
self.count = count
def notify(self, event):
"""Notify the handler with the payload of the event.
:param event: The event containint the payload for the handler.
"""
if self.count is None or self.count:
self.handler(*event.args, **event.kwargs)
if self.count:
self.count -= 1
class ListenerList(Listener):
"""Event listener notified for lists of events."""
def __init__(self, *args, **kwargs):
super(ListenerList, self).__init__(*args, **kwargs)
self.event_types = set(self.event_type)
self.kwargs = {}
def notify(self, event):
"""Only notify the handler when all the events for this listener
have been published by the dispatcher. When duplicate events
occur, the latest event is preserved and the previous one are
overwritten until all events have been published.
"""
if self.count is None or self.count:
self.kwargs[event.type] = event.args[0]
if self.event_types.issubset(self.kwargs):
self.handler(**self.kwargs)
if self.count:
self.count -= 1
class ListenerQueue(ListenerList):
def notify(self, event):
"""Only notify the handler when all the events for this listener
have been published by the dispatcher. Duplicate events are enqueued
and dequeued only when all events have been published.
"""
arg = event.args[0]
queue = self.kwargs.setdefault(event.type, [])
# Strip duplicates from the queue.
if arg not in queue:
queue.append(arg)
# Once the queue has handler has been called, the queue
# then behaves like a list using the latest events.
if self.event_types.issubset(self.kwargs):
self.notify = notify = super(ListenerQueue, self).notify
keys = self.kwargs.keys()
for values in product(*self.kwargs.values()):
self.kwargs = dict(zip(keys, values))
notify(event)
class Dispatcher:
"""Register handlers and publish events for them identified by strings."""
listener_factory = Listener
def __init__(self, listener_factory=None):
self._event_listeners = {}
if listener_factory is not None:
self.listener_factory = listener_factory
def registerHandler(self, event_type, handler, count=None):
"""Register an event handler and return its listener.
:param event_type: The name of the event type to handle.
:param handler: The function handling the given event type.
:param count: Optionally, the number times to call the handler.
"""
listener = self.listener_factory(event_type, handler, count)
listeners = self._event_listeners.setdefault(event_type, [])
listeners.append(listener)
return listener
def unregisterHandler(self, handler):
"""Unregister a handler.
:param handler: The handler to unregister.
"""
for event_type, listeners in self._event_listeners.items():
listeners = [
listener for listener in listeners
if listener.handler == handler]
if listeners:
self._event_listeners[event_type] = listeners
else:
del self._event_listeners[event_type]
def unregisterListener(self, listener, event_type=None):
"""Unregister a listener.
:param listener: The listener of the handler to unregister.
:param event_type: Optionally, the event_type to unregister.
"""
if event_type is None:
event_type = listener.event_type
self._event_listeners[event_type].remove(listener)
if not self._event_listeners[event_type]:
del self._event_listeners[event_type]
def publishEvent(self, event_type, *args, **kwargs):
"""Publish an event of a given type and notify all listeners.
:param event_type: The name of the event type to publish.
:param args: Positional arguments to pass to the registered handlers.
:param kwargs: Keyword arguments to pass to the registered handlers.
"""
if event_type in self._event_listeners:
event = Event(event_type, *args, **kwargs)
for listener in list(self._event_listeners[event_type]):
try:
listener.notify(event)
if listener.count is not None and not listener.count:
self.unregisterListener(listener)
except:
logging.exception(
"Error running event handler for %r with args %r %r",
event_type, args, kwargs)
class DispatcherList(Dispatcher):
"""
Register handlers and publish events for them identified by lists
of strings.
"""
listener_factory = ListenerList
def registerHandler(self, event_types, handler, count=None):
"""See Dispatcher."""
if not isinstance(event_types, (list, tuple,)):
event_types = (event_types,)
listener = self.listener_factory(event_types, handler, count)
for event_type in event_types:
listeners = self._event_listeners.setdefault(event_type, [])
listeners.append(listener)
return listener
def unregisterListener(self, listener):
"""See Dispatcher."""
for event_type in listener.event_types:
super(DispatcherList, self).unregisterListener(
listener, event_type)
def publishEvent(self, event_type, arg):
"""See Dispatcher."""
super(DispatcherList, self).publishEvent(event_type, arg)
class DispatcherQueue(DispatcherList):
"""
Register handlers and publish events for them identified by lists
of strings in queue order.
"""
listener_factory = ListenerQueue
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