core/dbus: rework D-Bus implementation to use lower layer GDBusConnection API
Previously, we used the generated GDBusInterfaceSkeleton types and glued
them via the NMExportedObject base class to our NM types. We also used
GDBusObjectManagerServer.
Don't do that anymore. The resulting code was more complicated despite (or
because?) using generated classes. It was hard to understand, complex, had
ordering-issues, and had a runtime and memory overhead.
This patch refactors this entirely and uses the lower layer API GDBusConnection
directly. It replaces the generated code, GDBusInterfaceSkeleton, and
GDBusObjectManagerServer. All this is now done by NMDbusObject and NMDBusManager
and static descriptor instances of type GDBusInterfaceInfo.
This adds a net plus of more then 1300 lines of hand written code. I claim
that this implementation is easier to understand. Note that previously we
also required extensive and complex glue code to bind our objects to the
generated skeleton objects. Instead, now glue our objects directly to
GDBusConnection. The result is more immediate and gets rid of layers of
code in between.
Now that the D-Bus glue us more under our control, we can address issus and
bottlenecks better, instead of adding code to bend the generated skeletons
to our needs.
Note that the current implementation now only supports one D-Bus connection.
That was effectively the case already, although there were places (and still are)
where the code pretends it could also support connections from a private socket.
We dropped private socket support mainly because it was unused, untested and
buggy, but also because GDBusObjectManagerServer could not export the same
objects on multiple connections. Now, it would be rather straight forward to
fix that and re-introduce ObjectManager on each private connection. But this
commit doesn't do that yet, and the new code intentionally supports only one
D-Bus connection.
Also, the D-Bus startup was simplified. There is no retry, either nm_dbus_manager_start()
succeeds, or it detects the initrd case. In the initrd case, bus manager never tries to
connect to D-Bus. Since the initrd scenario is not yet used/tested, this is good enough
for the moment. It could be easily extended later, for example with polling whether the
system bus appears (like was done previously). Also, restart of D-Bus daemon isn't
supported either -- just like before.
Note how NMDBusManager now implements the ObjectManager D-Bus interface
directly.
Also, this fixes race issues in the server, by no longer delaying
PropertiesChanged signals. NMExportedObject would collect changed
properties and send the signal out in idle_emit_properties_changed()
on idle. This messes up the ordering of change events w.r.t. other
signals and events on the bus. Note that not only NMExportedObject
messed up the ordering. Also the generated code would hook into
notify() and process change events in and idle handle, exhibiting the
same ordering issue too.
No longer do that. PropertiesChanged signals will be sent right away
by hooking into dispatch_properties_changed(). This means, changing
a property in quick succession will no longer be combined and is
guaranteed to emit signals for each individual state. Quite possibly
we emit now more PropertiesChanged signals then before.
However, we are now able to group a set of changes by using standard
g_object_freeze_notify()/g_object_thaw_notify(). We probably should
make more use of that.
Also, now that our signals are all handled in the right order, we
might find places where we still emit them in the wrong order. But that
is then due to the order in which our GObjects emit signals, not due
to an ill behavior of the D-Bus glue. Possibly we need to identify
such ordering issues and fix them.
Numbers (for contrib/rpm --without debug on x86_64):
- the patch changes the code size of NetworkManager by
- 2809360 bytes
+ 2537528 bytes (-9.7%)
- Runtime measurements are harder because there is a large variance
during testing. In other words, the numbers are not reproducible.
Currently, the implementation performs no caching of GVariants at all,
but it would be rather simple to add it, if that turns out to be
useful.
Anyway, without strong claim, it seems that the new form tends to
perform slightly better. That would be no surprise.
$ time (for i in {1..1000}; do nmcli >/dev/null || break; echo -n .; done)
- real 1m39.355s
+ real 1m37.432s
$ time (for i in {1..2000}; do busctl call org.freedesktop.NetworkManager /org/freedesktop org.freedesktop.DBus.ObjectManager GetManagedObjects > /dev/null || break; echo -n .; done)
- real 0m26.843s
+ real 0m25.281s
- Regarding RSS size, just looking at the processes in similar
conditions, doesn't give a large difference. On my system they
consume about 19MB RSS. It seems that the new version has a
slightly smaller RSS size.
- 19356 RSS
+ 18660 RSS
This commit is contained in:
Thomas Haller
177
src/nm-dbus-utils.h
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177
src/nm-dbus-utils.h
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/* -*- Mode: C; tab-width: 4; indent-tabs-mode: t; c-basic-offset: 4 -*- */
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/* NetworkManager -- Network link manager
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Copyright 2018 Red Hat, Inc.
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*/
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#ifndef __NM_DBUS_UTILS_H__
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#define __NM_DBUS_UTILS_H__
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/*****************************************************************************/
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#define NM_EXPORT_PATH_NUMBERED(basepath) ""basepath"/%llu"
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/*****************************************************************************/
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struct _NMDBusInterfaceInfoExtended;
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struct _NMDBusMethodInfoExtended;
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struct _NMDBusPropertyInfoExtendedBase {
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GDBusPropertyInfo _parent;
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const char *property_name;
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/* Whether the properties needs to be notified on the legacy
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* PropertyChanged signal. This is only to preserve API, new
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* properties should not use this. */
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bool include_in_legacy_property_changed;
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};
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struct _NMDBusPropertyInfoExtendedReadWritable {
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struct _NMDBusPropertyInfoExtendedBase _base;
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/* this is the polkit permission type for authenticating setting
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* the property. */
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const char *permission;
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/* this is the audit operation type for writing the property. */
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const char *audit_op;
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};
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typedef struct {
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union {
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GDBusPropertyInfo _parent;
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struct _NMDBusPropertyInfoExtendedBase _base;
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struct _NMDBusPropertyInfoExtendedReadWritable writable;
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/* duplicate the base structure in the union, so that the common fields
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* are accessible directly in the parent struct. */
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struct {
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GDBusPropertyInfo parent;
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const char *property_name;
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/* Whether the properties needs to be notified on the legacy
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* PropertyChanged signal. This is only to preserve API, new
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* properties should not use this. */
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bool include_in_legacy_property_changed;
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};
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};
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} NMDBusPropertyInfoExtended;
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G_STATIC_ASSERT (G_STRUCT_OFFSET (NMDBusPropertyInfoExtended, property_name) == G_STRUCT_OFFSET (struct _NMDBusPropertyInfoExtendedBase, property_name));
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G_STATIC_ASSERT (G_STRUCT_OFFSET (NMDBusPropertyInfoExtended, include_in_legacy_property_changed) == G_STRUCT_OFFSET (struct _NMDBusPropertyInfoExtendedBase, include_in_legacy_property_changed));
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#define NM_DEFINE_DBUS_PROPERTY_INFO_EXTENDED_READABLE_FULL(m_name, m_signature, m_property_name, m_include_in_legacy_property_changed) \
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((GDBusPropertyInfo *) &((const struct _NMDBusPropertyInfoExtendedBase) { \
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._parent = { \
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.ref_count = -1, \
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.name = m_name, \
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.signature = m_signature, \
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.flags = G_DBUS_PROPERTY_INFO_FLAGS_READABLE, \
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}, \
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.property_name = m_property_name, \
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.include_in_legacy_property_changed = m_include_in_legacy_property_changed, \
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}))
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#define NM_DEFINE_DBUS_PROPERTY_INFO_EXTENDED_READABLE(m_name, m_signature, m_property_name) \
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NM_DEFINE_DBUS_PROPERTY_INFO_EXTENDED_READABLE_FULL (m_name, m_signature, m_property_name, FALSE)
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/* define a legacy property. Do not use for new code. */
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#define NM_DEFINE_DBUS_PROPERTY_INFO_EXTENDED_READABLE_L(m_name, m_signature, m_property_name) \
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NM_DEFINE_DBUS_PROPERTY_INFO_EXTENDED_READABLE_FULL (m_name, m_signature, m_property_name, TRUE)
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#define NM_DEFINE_DBUS_PROPERTY_INFO_EXTENDED_READWRITABLE_FULL(m_name, m_signature, m_property_name, m_permission, m_audit_op, m_include_in_legacy_property_changed) \
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((GDBusPropertyInfo *) &((const struct _NMDBusPropertyInfoExtendedReadWritable) { \
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._base = { \
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._parent = { \
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.ref_count = -1, \
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.name = m_name, \
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.signature = m_signature, \
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.flags = G_DBUS_PROPERTY_INFO_FLAGS_READABLE | G_DBUS_PROPERTY_INFO_FLAGS_WRITABLE, \
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}, \
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.property_name = m_property_name, \
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.include_in_legacy_property_changed = m_include_in_legacy_property_changed, \
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}, \
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.permission = m_permission, \
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.audit_op = m_audit_op, \
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}))
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#define NM_DEFINE_DBUS_PROPERTY_INFO_EXTENDED_READWRITABLE(m_name, m_signature, m_property_name, m_permission, m_audit_op) \
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NM_DEFINE_DBUS_PROPERTY_INFO_EXTENDED_READWRITABLE_FULL (m_name, m_signature, m_property_name, m_permission, m_audit_op, FALSE)
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/* define a legacy property. Do not use for new code. */
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#define NM_DEFINE_DBUS_PROPERTY_INFO_EXTENDED_READWRITABLE_L(m_name, m_signature, m_property_name, m_permission, m_audit_op) \
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NM_DEFINE_DBUS_PROPERTY_INFO_EXTENDED_READWRITABLE_FULL (m_name, m_signature, m_property_name, m_permission, m_audit_op, TRUE)
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typedef struct _NMDBusMethodInfoExtended {
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GDBusMethodInfo parent;
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void (*handle) (NMDBusObject *obj,
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const struct _NMDBusInterfaceInfoExtended *interface_info,
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const struct _NMDBusMethodInfoExtended *method_info,
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GDBusConnection *connection,
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const char *sender,
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GDBusMethodInvocation *invocation,
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GVariant *parameters);
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} NMDBusMethodInfoExtended;
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#define NM_DEFINE_DBUS_METHOD_INFO_EXTENDED(parent_, ...) \
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((GDBusMethodInfo *) (&((const NMDBusMethodInfoExtended) { \
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.parent = parent_, \
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__VA_ARGS__ \
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})))
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typedef struct _NMDBusInterfaceInfoExtended {
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GDBusInterfaceInfo parent;
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/* Whether the interface has a legacy property changed signal (@nm_signal_info_property_changed_legacy).
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* New interfaces should not use this. */
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bool legacy_property_changed:1;
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} NMDBusInterfaceInfoExtended;
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extern const GDBusSignalInfo nm_signal_info_property_changed_legacy;
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#define NM_DBUS_INTERFACE_INFOS(...) \
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({ \
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static const NMDBusInterfaceInfoExtended *const _interface_infos[] = { \
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__VA_ARGS__, \
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NULL, \
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}; \
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_interface_infos; \
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});
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/*****************************************************************************/
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GDBusPropertyInfo *nm_dbus_utils_interface_info_lookup_property (const GDBusInterfaceInfo *interface_info,
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const char *property_name);
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GDBusMethodInfo *nm_dbus_utils_interface_info_lookup_method (const GDBusInterfaceInfo *interface_info,
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const char *method_name);
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GVariant *nm_dbus_utils_get_property (GObject *obj,
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const char *signature,
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const char *property_name);
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/*****************************************************************************/
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void nm_dbus_utils_g_value_set_object_path (GValue *value, gpointer object);
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void nm_dbus_utils_g_value_set_object_path_array (GValue *value,
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GSList *objects,
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gboolean (*filter_func) (GObject *object, gpointer user_data),
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gpointer user_data);
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#endif /* __NM_DBUS_UTILS_H__ */
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