core3: event framework adjusted for global Qubes object

From now, global events are emitted by qubes.Qubes object and handlers are registered there.

qubes/__init__.py

@@ -29,6 +29,9 @@ import __builtin__
 import lxml.etree
 import xml.parsers.expat
 
+import qubes.ext
+
+
 if os.name == 'posix':
     import fcntl
 elif os.name == 'nt':
@@ -661,6 +664,8 @@ class Qubes(PropertyHolder):
 
 
     def __init__(self, store='/var/lib/qubes/qubes.xml'):
+        self._extensions = set(ext(self) for ext in qubes.ext.Extension.register.values())
+
         #: collection of all VMs managed by this Qubes instance
         self.domains = VMCollection()
 

qubes/_pluginloader.py

@@ -1,6 +1,3 @@
 from qubes.vm import *
 from qubes.ext import *
 
-import qubes.ext
-
-qubes.ext.init()

qubes/events.py

@@ -9,37 +9,28 @@ etc.
 
 import collections
 
-import qubes.vm
 
-#: collection of system-wide hooks
-system_hooks = collections.defaultdict(list)
-
-def hook(event, vm=None, system=False):
-    '''Decorator factory.
+def handler(event):
+    '''Event handler decorator factory.
 
     To hook an event, decorate a method in your plugin class with this
     decorator.
 
+    .. note::
+        For hooking events from extensions, see :py:func:`qubes.ext.handler`.
+
     :param str event: event type
-    :param type vm: VM to hook (leave as None to hook all VMs)
-    :param bool system: when :py:obj:`True`, hook is system-wide (not attached to any VM)
     '''
 
     def decorator(f):
-        f.ho_event = event
-
-        if system:
-            f.ho_vm = None
-        elif vm is None:
-            f.ho_vm = qubes.vm.BaseVM
-        else:
-            f.ho_vm = vm
-
+        f.ha_event = event
+        f.ha_bound = True
         return f
 
     return decorator
 
-def ishook(o):
+
+def ishandler(o):
     '''Test if a method is hooked to an event.
 
     :param object o: suspected hook
@@ -48,24 +39,67 @@ def ishook(o):
     '''
 
     return callable(o) \
-        and hasattr(o, 'ho_event') \
-        and hasattr(o, 'ho_vm')
+        and hasattr(o, 'ha_event')
 
-def add_system_hook(event, f):
-    '''Add system-wide hook.
 
-    :param callable f: function to call
+class EmitterMeta(type):
+    '''Metaclass for :py:class:`Emitter`'''
+    def __init__(cls, name, bases, dict_):
+        super(type, cls).__init__(name, bases, dict_)
+        cls.__handlers__ = collections.defaultdict(set)
+
+
+class Emitter(object):
+    '''Subject that can emit events
     '''
 
-    global_hooks[event].append(f)
+    __metaclass__ = EmitterMeta
 
-def fire_system_hooks(event, *args, **kwargs):
-    '''Fire system-wide hooks.
+    def __init__(self, *args, **kwargs):
+        super(Emitter, self).__init__(*args, **kwargs)
+        try:
+            propnames = set(prop.__name__ for prop in self.get_props_list())
+        except AttributeError:
+            propnames = set()
 
-    :param str event: event type
+        for attr in dir(self):
+            if attr in propnames:
+                # we have to be careful, not to getattr() on properties which
+                # may be unset
+                continue
 
-    *args* and *kwargs* are passed to all hooks.
-    '''
+            attr = getattr(self, attr)
+            if not ishandler(attr):
+                continue
 
-    for hook in system_hooks[event]:
-        hook(self, *args, **kwargs)
+            self.add_handler(attr.ha_event, attr)
+
+
+    @classmethod
+    def add_handler(cls, event, handler):
+        '''Add event handler to subject's class
+
+        :param str event: event identificator
+        :param collections.Callable handler: handler callable
+        '''
+
+        cls.__handlers__[event].add(handler)
+
+
+    def fire_event(self, event, *args, **kwargs):
+        '''Call all handlers for an event
+
+        :param str event: event identificator
+
+        All *args* and *kwargs* are passed verbatim. They are different for
+        different events.
+        '''
+
+        for handler in self.__handlers__[event]:
+            if hasattr(handler, 'ha_bound'):
+                # this is our (bound) method, self is implicit
+                handler(event, *args, **kwargs)
+            else:
+                # this is from extension or hand-added, so we see method as
+                # unbound, therefore we need to pass self
+                handler(self, event, *args, **kwargs)

qubes/ext/__init__.py

@@ -33,22 +33,56 @@ class ExtensionPlugin(qubes.plugins.Plugin):
         return cls._instance
 
 class Extension(object):
-    '''Base class for all extensions'''
+    '''Base class for all extensions
+
+    :param qubes.Qubes app: application object
+    '''
+
     __metaclass__ = ExtensionPlugin
-    def __init__(self):
+
+    def __init__(self, app):
+        self.app = app
+
         for name in dir(self):
             attr = getattr(self, name)
-            if not ishook(attr):
+            if not qubes.events.ishandler(attr):
                 continue
 
-            if attr.ho_vm is not None:
-                attr.ho_vm.add_hook(event, attr)
+            if attr.ha_vm is not None:
+                attr.ha_vm.add_hook(attr.ha_event, attr)
             else:
                 # global hook
-                qubes.events.add_system_hook(event, attr)
+                self.app.add_hook(attr.ha_event, attr)
+
+
+def handler(event, vm=None, system=False):
+    '''Event handler decorator factory.
+
+    To hook an event, decorate a method in your plugin class with this
+    decorator. You may hook both per-vm-class and global events.
+
+    .. note::
+        This decorator is intended only for extensions! For regular use in the
+        core, see py:func:`qubes.events.handler`.
+
+    :param str event: event type
+    :param type vm: VM to hook (leave as None to hook all VMs)
+    :param bool system: when :py:obj:`True`, hook is system-wide (not attached to any VM)
+    '''
+
+    def decorator(f):
+        f.ho_event = event
+
+        if system:
+            f.ha_vm = None
+        elif vm is None:
+            f.ha_vm = qubes.vm.BaseVM
+        else:
+            f.ha_vm = vm
+
+        return f
+
+    return decorator
 
-def init():
-    for ext in Extension.register.values():
-        instance = ext()
 
 __all__ = qubes.plugins.load(__file__)

qubes/vm/__init__.py

@@ -12,7 +12,7 @@ Main public classes
 Helper classes and functions
 ----------------------------
 
-.. autoclass:: VMPlugin
+.. autoclass:: BaseVMMeta
    :members:
    :show-inheritance:
 
@@ -57,19 +57,22 @@ import dateutil.parser
 import lxml.etree
 
 import qubes
+import qubes.events
 import qubes.plugins
 
 
-class VMPlugin(qubes.plugins.Plugin):
+class BaseVMMeta(qubes.plugins.Plugin, qubes.events.EmitterMeta):
     '''Metaclass for :py:class:`.BaseVM`'''
     def __init__(cls, name, bases, dict_):
-        super(VMPlugin, cls).__init__(name, bases, dict_)
+        super(BaseVMMeta, cls).__init__(name, bases, dict_)
         cls.__hooks__ = collections.defaultdict(list)
 
 
-class BaseVM(qubes.PropertyHolder):
+class BaseVM(qubes.PropertyHolder, qubes.events.Emitter):
     '''Base class for all VMs
 
+    :param app: Qubes application context
+    :type app: :py:class:`qubes.Qubes`
     :param xml: xml node from which to deserialise
     :type xml: :py:class:`lxml.etree._Element` or :py:obj:`None`
 
@@ -78,23 +81,25 @@ class BaseVM(qubes.PropertyHolder):
     :py:class:`qubes.vm.qubesvm.QubesVM`.
     '''
 
-    __metaclass__ = VMPlugin
+    __metaclass__ = BaseVMMeta
 
-    def __init__(self, app, xml=None, load_stage=2, services={}, devices=None, tags={}, **kwargs):
+    def __init__(self, app, xml, load_stage=2, services={}, devices=None,
+            tags={}, *args, **kwargs):
         self.app = app
-        self.xml = xml
         self.services = services
         self.devices = collections.defaultdict(list) if devices is None else devices
         self.tags = tags
 
         all_names = set(prop.__name__ for prop in self.get_props_list(load_stage=2))
-        for key in kwargs:
+        for key in list(kwargs.keys()):
             if not key in all_names:
                 raise AttributeError(
                     'No property {!r} found in {!r}'.format(
                         key, self.__class__))
             setattr(self, key, kwargs[key])
+            del kwargs[key]
 
+        super(BaseVM, self).__init__(xml, *args, **kwargs)
 
     def add_new_vm(self, vm):
         '''Add new Virtual Machine to colletion

tests/events.py

@@ -0,0 +1,37 @@
+#!/usr/bin/python2 -O
+
+import sys
+import unittest
+
+sys.path.insert(0, '..')
+import qubes.events
+
+class TC_Emitter(unittest.TestCase):
+    def test_000_add_handler(self):
+        # need something mutable
+        testevent_fired = [False]
+
+        def on_testevent(subject, event):
+            if event == 'testevent':
+                testevent_fired[0] = True
+
+        emitter = qubes.events.Emitter()
+        emitter.add_handler('testevent', on_testevent)
+        emitter.fire_event('testevent')
+        self.assertTrue(testevent_fired[0])
+
+
+    def test_001_decorator(self):
+        class TestEmitter(qubes.events.Emitter):
+            def __init__(self):
+                super(TestEmitter, self).__init__()
+                self.testevent_fired = False
+
+            @qubes.events.handler('testevent')
+            def on_testevent(self, event):
+                if event == 'testevent':
+                    self.testevent_fired = True
+
+        emitter = TestEmitter()
+        emitter.fire_event('testevent')
+        self.assertTrue(emitter.testevent_fired)

tests/init.py

@@ -104,8 +104,8 @@ class TC_11_VMCollection(unittest.TestCase):
         # XXX passing None may be wrong in the future
         self.vms = qubes.VMCollection(None)
 
-        self.testvm1 = TestVM(None, qid=1, name='testvm1')
-        self.testvm2 = TestVM(None, qid=2, name='testvm2')
+        self.testvm1 = TestVM(None, None, qid=1, name='testvm1')
+        self.testvm2 = TestVM(None, None, qid=2, name='testvm2')
 
     def test_000_contains(self):
         self.vms._dict = {1: self.testvm1}
@@ -132,8 +132,8 @@ class TC_11_VMCollection(unittest.TestCase):
         with self.assertRaises(TypeError):
             self.vms.add(object())
 
-        testvm_qid_collision = TestVM(None, name='testvm2', qid=1)
-        testvm_name_collision = TestVM(None, name='testvm1', qid=2)
+        testvm_qid_collision = TestVM(None, None, name='testvm2', qid=1)
+        testvm_name_collision = TestVM(None, None, name='testvm1', qid=2)
 
         with self.assertRaises(ValueError):
             self.vms.add(testvm_qid_collision)