mirror of
https://gitlab.freedesktop.org/dbus/dbus.git
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95f9771d6b
* python/_dbus.py: Add WeakReferenceDictionary cache of dbus.Bus instances to stop madness of creating new instances representing the same bus connection all the time, rendering any tracking of match rules and bus names quite meaningless. Caught a bug where the private argument to SessionBus() and friends was being passed in as use_default_mainloop by mistake. Still some problems with multiple dbus_binding.Connection instances representing the same low-level connection (eg when you use both SessionBus() and StarterBus() in same process), but it's a lot better now than it was. * python/dbus_bindings.pyx: Add constants with the return values for bus_request_name(). * python/service.py: Store bus name instances in a per-dbus.Bus cache and retrieve the same instances for the same name, so deletion can be done with refcounting. Also now throws some kind of error if you don't actually get the name you requested, unlike previously... * test/python/test-client.py: Add tests for instance caching of buses and bus name objects.
300 lines
11 KiB
Python
300 lines
11 KiB
Python
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"""Module for high-level communication over the FreeDesktop.org Bus (DBus)
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DBus allows you to share and access remote objects between processes
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running on the desktop, and also to access system services (such as
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the print spool).
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To use DBus, first get a Bus object, which provides a connection to one
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of a few standard dbus-daemon instances that might be running. From the
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Bus you can get a RemoteService. A service is provided by an application or
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process connected to the Bus, and represents a set of objects. Once you
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have a RemoteService you can get a RemoteObject that implements a specific interface
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(an interface is just a standard group of member functions). Then you can call
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those member functions directly.
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You can think of a complete method call as looking something like:
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Bus:SESSION -> Service:org.gnome.Evolution -> Object:/org/gnome/Evolution/Inbox -> Interface: org.gnome.Evolution.MailFolder -> Method: Forward('message1', 'seth@gnome.org')
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This communicates over the SESSION Bus to the org.gnome.Evolution process to call the
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Forward method of the /org/gnome/Evolution/Inbox object (which provides the
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org.gnome.Evolution.MailFolder interface) with two string arguments.
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For example, the dbus-daemon itself provides a service and some objects:
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# Get a connection to the desktop-wide SESSION bus
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bus = dbus.Bus(dbus.Bus.TYPE_SESSION)
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# Get the service provided by the dbus-daemon named org.freedesktop.DBus
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dbus_service = bus.get_service('org.freedesktop.DBus')
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# Get a reference to the desktop bus' standard object, denoted
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# by the path /org/freedesktop/DBus. The object /org/freedesktop/DBus
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# implements the 'org.freedesktop.DBus' interface
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dbus_object = dbus_service.get_object('/org/freedesktop/DBus',
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'org.freedesktop.DBus')
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# One of the member functions in the org.freedesktop.DBus interface
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# is ListServices(), which provides a list of all the other services
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# registered on this bus. Call it, and print the list.
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print(dbus_object.ListServices())
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"""
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import dbus
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import dbus_bindings
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import weakref
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from proxies import *
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from exceptions import *
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from matchrules import *
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class Bus(object):
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"""A connection to a DBus daemon.
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One of three possible standard buses, the SESSION, SYSTEM,
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or STARTER bus
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"""
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TYPE_SESSION = dbus_bindings.BUS_SESSION
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TYPE_SYSTEM = dbus_bindings.BUS_SYSTEM
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TYPE_STARTER = dbus_bindings.BUS_STARTER
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"""bus_type=[Bus.TYPE_SESSION | Bus.TYPE_SYSTEM | Bus.TYPE_STARTER]
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"""
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ProxyObjectClass = ProxyObject
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START_REPLY_SUCCESS = dbus_bindings.DBUS_START_REPLY_SUCCESS
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START_REPLY_ALREADY_RUNNING = dbus_bindings.DBUS_START_REPLY_ALREADY_RUNNING
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_shared_instances = weakref.WeakValueDictionary()
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def __new__(cls, bus_type=TYPE_SESSION, use_default_mainloop=True, private=False):
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if (not private and bus_type in cls._shared_instances):
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return cls._shared_instances[bus_type]
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# this is a bit odd, but we create instances of the subtypes
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# so we can return the shared instances if someone tries to
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# construct one of them (otherwise we'd eg try and return an
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# instance of Bus from __new__ in SessionBus). why are there
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# three ways to construct this class? we just don't know.
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if bus_type == cls.TYPE_SESSION:
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subclass = SessionBus
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elif bus_type == cls.TYPE_SYSTEM:
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subclass = SystemBus
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elif bus_type == cls.TYPE_STARTER:
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subclass = StarterBus
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else:
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raise ValueError('invalid bus_type %s' % bus_type)
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bus = object.__new__(subclass)
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bus._bus_type = bus_type
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bus._bus_names = weakref.WeakValueDictionary()
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bus._match_rule_tree = SignalMatchTree()
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# FIXME: if you get a starter and a system/session bus connection
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# in the same process, it's the same underlying connection that
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# is returned by bus_get, but we initialise it twice
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bus._connection = dbus_bindings.bus_get(bus_type, private)
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bus._connection.add_filter(bus._signal_func)
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if use_default_mainloop:
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func = getattr(dbus, "_dbus_mainloop_setup_function", None)
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if func:
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func(bus)
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if not private:
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cls._shared_instances[bus_type] = bus
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return bus
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def __init__(self, *args, **keywords):
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# do nothing here because this can get called multiple times on the
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# same object if __new__ returns a shared instance
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pass
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def close(self):
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self._connection.close()
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def get_connection(self):
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return self._connection
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def get_session(private=False):
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"""Static method that returns the session bus"""
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return SessionBus(private=private)
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get_session = staticmethod(get_session)
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def get_system(private=False):
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"""Static method that returns the system bus"""
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return SystemBus(private=private)
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get_system = staticmethod(get_system)
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def get_starter(private=False):
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"""Static method that returns the starter bus"""
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return StarterBus(private=private)
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get_starter = staticmethod(get_starter)
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def get_object(self, named_service, object_path):
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"""Get a proxy object to call over the bus"""
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return self.ProxyObjectClass(self, named_service, object_path)
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def _create_args_dict(self, keywords):
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args_dict = None
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for (key, value) in keywords.iteritems():
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if key.startswith('arg'):
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try:
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snum = key[3:]
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num = int(snum)
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if not args_dict:
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args_dict = {}
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args_dict[num] = value
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except ValueError:
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raise TypeError("Invalid arg index %s"%snum)
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else:
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raise TypeError("Unknown keyword %s"%(key))
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return args_dict
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def add_signal_receiver(self, handler_function,
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signal_name=None,
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dbus_interface=None,
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named_service=None,
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path=None,
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**keywords):
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args_dict = self._create_args_dict(keywords)
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if (named_service and named_service[0] != ':'):
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bus_object = self.get_object('org.freedesktop.DBus', '/org/freedesktop/DBus')
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named_service = bus_object.GetNameOwner(named_service, dbus_interface='org.freedesktop.DBus')
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match_rule = SignalMatchRule(signal_name, dbus_interface, named_service, path)
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if args_dict:
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match_rule.add_args_match(args_dict)
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match_rule.add_handler(handler_function)
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self._match_rule_tree.add(match_rule)
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dbus_bindings.bus_add_match(self._connection, repr(match_rule))
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def remove_signal_receiver(self, handler_function,
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signal_name=None,
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dbus_interface=None,
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named_service=None,
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path=None,
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**keywords):
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args_dict = self._create_args_dict(keywords)
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if (named_service and named_service[0] != ':'):
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bus_object = self.get_object('org.freedesktop.DBus', '/org/freedesktop/DBus')
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named_service = bus_object.GetNameOwner(named_service, dbus_interface='org.freedesktop.DBus')
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match_rule = SignalMatchRule(signal_name, dbus_interface, named_service, path)
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if (args_dict):
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match_rule.add_args_match(args_dict)
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if (handler_function):
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match_rule.add_handler(handler_function)
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self._match_rule_tree.remove(match_rule)
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#TODO we leak match rules in the lower level bindings. We need to ref count them
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def get_unix_user(self, named_service):
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"""Get the unix user for the given named_service on this Bus"""
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return dbus_bindings.bus_get_unix_user(self._connection, named_service)
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def _signal_func(self, connection, message):
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if (message.get_type() != dbus_bindings.MESSAGE_TYPE_SIGNAL):
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return dbus_bindings.HANDLER_RESULT_NOT_YET_HANDLED
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dbus_interface = message.get_interface()
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named_service = message.get_sender()
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path = message.get_path()
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signal_name = message.get_member()
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match_rule = SignalMatchRule(signal_name, dbus_interface, named_service, path)
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self._match_rule_tree.exec_matches(match_rule, message)
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def start_service_by_name(self, named_service):
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return dbus_bindings.bus_start_service_by_name(self._connection, named_service)
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def __repr__(self):
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if self._bus_type == self.TYPE_SESSION:
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name = 'SESSION'
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elif self._bus_type == self.TYPE_SYSTEM:
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name = 'SYSTEM'
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elif self._bus_type == self.TYPE_STARTER:
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name = 'STARTER'
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else:
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assert False, 'Unable to represent unknown bus type.'
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return '<dbus.Bus on %s at %#x>' % (name, id(self))
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__str__ = __repr__
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class SystemBus(Bus):
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"""The system-wide message bus
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"""
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def __new__(cls, use_default_mainloop=True, private=False):
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return Bus.__new__(cls, Bus.TYPE_SYSTEM, use_default_mainloop, private)
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class SessionBus(Bus):
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"""The session (current login) message bus
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"""
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def __new__(cls, use_default_mainloop=True, private=False):
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return Bus.__new__(cls, Bus.TYPE_SESSION, use_default_mainloop, private)
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class StarterBus(Bus):
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"""The bus that activated this process (if
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this process was launched by DBus activation)
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"""
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def __new__(cls, use_default_mainloop=True, private=False):
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return Bus.__new__(cls, Bus.TYPE_STARTER, use_default_mainloop, private)
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class Interface:
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"""An interface into a remote object
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An Interface can be used to wrap ProxyObjects
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so that calls can be routed to their correct
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dbus interface
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"""
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def __init__(self, object, dbus_interface):
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self._obj = object
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self._dbus_interface = dbus_interface
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def connect_to_signal(self, signal_name, handler_function, dbus_interface = None, **keywords):
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if not dbus_interface:
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dbus_interface = self._dbus_interface
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self._obj.connect_to_signal(signal_name, handler_function, dbus_interface, **keywords)
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def __getattr__(self, member, **keywords):
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if (keywords.has_key('dbus_interface')):
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_dbus_interface = keywords['dbus_interface']
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else:
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_dbus_interface = self._dbus_interface
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if member == '__call__':
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return object.__call__
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else:
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ret = self._obj.__getattr__(member, dbus_interface=_dbus_interface)
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return ret
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def __repr__(self):
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return '<Interface %r implementing %r at %#x>'%(
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self._obj, self._dbus_interface, id(self))
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__str__ = __repr__
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