From 297d4985abcc7b571b8c090ee90622357fc60e16 Mon Sep 17 00:00:00 2001 From: Thomas Haller Date: Mon, 26 Feb 2018 13:51:52 +0100 Subject: 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 --- src/nm-active-connection.h | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) (limited to 'src/nm-active-connection.h') diff --git a/src/nm-active-connection.h b/src/nm-active-connection.h index 3015b5c584..4d893e2c76 100644 --- a/src/nm-active-connection.h +++ b/src/nm-active-connection.h @@ -21,10 +21,9 @@ #ifndef __NETWORKMANAGER_ACTIVE_CONNECTION_H__ #define __NETWORKMANAGER_ACTIVE_CONNECTION_H__ -#include "nm-exported-object.h" -#include "nm-connection.h" - #include "nm-utils/c-list.h" +#include "nm-connection.h" +#include "nm-dbus-object.h" #define NM_TYPE_ACTIVE_CONNECTION (nm_active_connection_get_type ()) #define NM_ACTIVE_CONNECTION(obj) (G_TYPE_CHECK_INSTANCE_CAST ((obj), NM_TYPE_ACTIVE_CONNECTION, NMActiveConnection)) @@ -71,7 +70,7 @@ struct _NMActiveConnectionPrivate; struct _NMActiveConnection { - NMExportedObject parent; + NMDBusObject parent; struct _NMActiveConnectionPrivate *_priv; /* active connection can be tracked in a list by NMManager. This is @@ -80,7 +79,7 @@ struct _NMActiveConnection { }; typedef struct { - NMExportedObjectClass parent; + NMDBusObjectClass parent; /* re-emits device state changes as a convenience for subclasses for * device states >= DISCONNECTED. -- cgit v1.2.1