refactor: Simplify D-Bus handling by using address-based connections

Replaced direct `SystemBus` and `SessionBus` instances with
address-based D-Bus connections. BusProviders will open their own bus
connections and close it at the end.

Signed-off-by: Sven Sager <s.sager@kunbus.com>

src/revpi_middleware/daemon.py

@@ -4,16 +4,16 @@
 """Main daemon of revpi-middleware."""
 
 from logging import getLogger
+from os import getuid, environ
 from threading import Event
 from time import perf_counter
-from typing import Union, List
+from typing import List
 
-from dbus import SystemBus, SessionBus
+from gi.repository import Gio
 
 from . import proginit as pi
 from .dbus_ios1 import BusProviderIos1
 from .dbus_middleware1 import BusProviderMiddleware1
-from .helper import get_new_session_dbus_connection, get_new_system_dbus_connection
 
 log = getLogger(__name__)
 
@@ -43,19 +43,23 @@ class MiddlewareDaemon:
 
         log.debug("leave MiddlewareDaemon._configure")
 
-    def _get_bus(self) -> Union[SystemBus, SessionBus]:
+    @staticmethod
-        return (
+    def _get_bus_address() -> str:
-            get_new_session_dbus_connection()
+        if pi.pargs.use_session_bus:
-            if pi.pargs.use_session_bus
+            environ_name = "DBUS_SESSION_BUS_ADDRESS"
-            else get_new_system_dbus_connection()
+            bus_address = Gio.dbus_address_get_for_bus_sync(Gio.BusType.SESSION)
-        )
+        else:
+            environ_name = "DBUS_SYSTEM_BUS_ADDRESS"
+            bus_address = Gio.dbus_address_get_for_bus_sync(Gio.BusType.SYSTEM)
+
+        return environ.get(environ_name, bus_address)
 
     def dbus_start(self):
         log.debug("enter MiddlewareDaemon.dbus_start")
 
         dbus_middleware1_running = self.bp_middleware1 and self.bp_middleware1.is_alive()
         if not dbus_middleware1_running:
-            self.bp_middleware1 = BusProviderMiddleware1(self._get_bus())
+            self.bp_middleware1 = BusProviderMiddleware1(self._get_bus_address())
             self.bp_middleware1.start()
 
         dbus_ios1_running = self.bp_ios1 and self.bp_ios1.is_alive()
@@ -79,14 +83,12 @@ class MiddlewareDaemon:
             self.bp_middleware1.join(timeout=10.0)
             if self.bp_middleware1.is_alive():
                 log.warning("dbus middleware1 provider thread is still alive")
-            self.bp_middleware1.bus.con.close()
 
         if self.bp_ios1 and self.bp_ios1 in bus_filter:
             self.bp_ios1.stop()
             self.bp_ios1.join(timeout=10.0)
             if self.bp_ios1.is_alive():
                 log.warning("dbus ios1 provider thread is still alive")
-            self.bp_ios1.bus.con.close()
 
         log.debug("leave MiddlewareDaemon.dbus_stop")
 

src/revpi_middleware/dbus_ios1/bus_provider_ios1.py

@@ -5,11 +5,10 @@
 
 from logging import getLogger
 from threading import Thread, Event
-from typing import Union
 
 import revpimodio2
 from gi.repository import GLib
-from pydbus import SessionBus, SystemBus
+from pydbus import connect
 
 from . import REVPI_DBUS_NAME
 from .interface_devices import (
@@ -29,14 +28,14 @@ class BusProviderIos1(Thread):
 
     def __init__(
         self,
-        dbus: Union[SystemBus, SessionBus],
+        dbus_address: str,
         picontrol_device="/dev/piControl0",
         config_rsc="/etc/revpi/config.rsc",
     ):
         log.debug("enter BusProviderIos1.__init__")
         super().__init__()
 
-        self._bus = dbus
+        self._bus_address = dbus_address
         self._loop = GLib.MainLoop()
         self._lst_device_interfaces = []
         self._lst_io_interfaces = []
@@ -52,22 +51,23 @@ class BusProviderIos1(Thread):
 
     def run(self):
         log.debug("enter BusProviderIos1.run")
+        bus = connect(self._bus_address)
 
         self._lst_device_interfaces.clear()
         self._lst_io_interfaces.clear()
 
         for device in self._modio.device:
             self._lst_device_interfaces.append(
-                InterfaceDevice(self._bus, device),
+                InterfaceDevice(bus, device),
             )
 
         for io in self._modio.io:
             interface = None
             try:
                 if io.type == revpimodio2.INP:
-                    interface = InterfaceInput(self._bus, io)
+                    interface = InterfaceInput(bus, io)
                 elif io.type == revpimodio2.OUT:
-                    interface = InterfaceOutput(self._bus, io)
+                    interface = InterfaceOutput(bus, io)
                 elif io.type == revpimodio2.MEM:
                     # todo: Implement memory
                     pass
@@ -85,7 +85,7 @@ class BusProviderIos1(Thread):
             (interface.object_path, interface) for interface in self._lst_io_interfaces
         ]
         try:
-            self._bus.publish(
+            bus.publish(
                 REVPI_DBUS_NAME,
                 InterfaceDeviceManager(self._lst_device_interfaces),
                 InterfaceIoManager(self._lst_io_interfaces, self._modio),
@@ -100,6 +100,7 @@ class BusProviderIos1(Thread):
         except Exception as e:
             log.error(f"can not run dbus mainloop: {e}")
 
+        bus.con.close()
         self._modio.cleanup()
 
         log.debug("leave BusProviderIos1.run")
@@ -109,10 +110,6 @@ class BusProviderIos1(Thread):
         self._loop.quit()
         log.debug("leave BusProviderIos1.stop")
 
-    @property
-    def bus(self) -> Union[SystemBus, SessionBus]:
-        return self._bus
-
     @property
     def running(self):
         return self._loop.is_running()

src/revpi_middleware/dbus_middleware1/bus_provider_middleware1.py

@@ -5,10 +5,9 @@
 
 from logging import getLogger
 from threading import Thread, Event
-from typing import Union
 
 from gi.repository import GLib
-from pydbus import SessionBus, SystemBus
+from pydbus import connect
 
 from . import REVPI_DBUS_NAME
 from .process_image import InterfacePiControl
@@ -21,14 +20,14 @@ class BusProviderMiddleware1(Thread):
 
     def __init__(
         self,
-        dbus: Union[SystemBus, SessionBus],
+        dbus_address: str,
         picontrol_device="/dev/piControl0",
         config_rsc="/etc/revpi/config.rsc",
     ):
         log.debug("enter BusProviderMiddleware1.__init__")
         super().__init__()
 
-        self._bus = dbus
+        self._bus_address = dbus_address
         self._loop = GLib.MainLoop()
 
         self.picontrol_device = picontrol_device
@@ -37,6 +36,7 @@ class BusProviderMiddleware1(Thread):
 
     def run(self):
         log.debug("enter BusProviderMiddleware1.run")
+        bus = connect(self._bus_address)
 
         # The 2nd, 3rd, ... arguments can be objects or tuples of a path and an object
         #   Example(),
@@ -44,13 +44,13 @@ class BusProviderMiddleware1(Thread):
         #   ("Subdir2", Example()),
         #   ("Subdir2/Whatever", Example())
         lst_interfaces = [
-            InterfacePiControl(self._bus, self.picontrol_device, self.config_rsc),
+            InterfacePiControl(bus, self.picontrol_device, self.config_rsc),
-            InterfaceRevpiConfig(self._bus),
+            InterfaceRevpiConfig(bus),
-            InterfaceSoftwareServices(self._bus),
+            InterfaceSoftwareServices(bus),
         ]
 
         try:
-            self._bus.publish(
+            bus.publish(
                 REVPI_DBUS_NAME,
                 *lst_interfaces,
             )
@@ -63,6 +63,8 @@ class BusProviderMiddleware1(Thread):
         except Exception as e:
             log.error(f"can not run dbus mainloop: {e}")
 
+        bus.con.close()
+
         # Clean up all interfaces
         for interface in lst_interfaces:
             if type(interface) is tuple:
@@ -76,10 +78,6 @@ class BusProviderMiddleware1(Thread):
         self._loop.quit()
         log.debug("leave BusProviderMiddleware1.stop")
 
-    @property
-    def bus(self) -> Union[SystemBus, SessionBus]:
-        return self._bus
-
     @property
     def running(self):
         return self._loop.is_running()

src/revpi_middleware/helper.py

@@ -1,48 +0,0 @@
-# -*- coding: utf-8 -*-
-# SPDX-FileCopyrightText: 2025 KUNBUS GmbH
-# SPDX-License-Identifier: GPL-2.0-or-later
-"""Helper functions for the root project."""
-
-from os import environ, getuid
-
-from pydbus import connect
-
-
-def get_new_system_dbus_connection():
-    """
-    Establishes a new connection to the system D-Bus.
-
-    This function retrieves the system D-Bus address from the environment
-    variable `DBUS_SYSTEM_BUS_ADDRESS`, defaulting to
-    `unix:path=/run/dbus/system_bus_socket` if the variable is not set.
-    It then establishes and returns a connection to the D-Bus at that
-    address.
-
-    Raises:
-        An error may be raised if establishing the connection fails.
-
-    Returns:
-        The established system D-Bus connection.
-    """
-    address = environ.get("DBUS_SYSTEM_BUS_ADDRESS", "unix:path=/run/dbus/system_bus_socket")
-    return connect(address)
-
-
-def get_new_session_dbus_connection():
-    """
-    Establishes a new connection to the session D-Bus.
-
-    This function retrieves the session D-Bus address from the environment
-    variable `DBUS_SESSION_BUS_ADDRESS`, defaulting to
-    `unix:path=/run/user/{UID}/bus` if the variable is not set.
-    It then establishes and returns a connection to the D-Bus at that
-    address.
-
-    Raises:
-        An error may be raised if establishing the connection fails.
-
-    Returns:
-        The established session D-Bus connection.
-    """
-    address = environ.get("DBUS_SESSION_BUS_ADDRESS", f"unix:path=/run/user/{getuid()}/bus")
-    return connect(address)