platform: use NMDedupMultiIndex for routes in NMPCacheth/dedup-multi

Rework platform object cache to use NMDedupMultiIndex.

Already previously, NMPCache used NMMultiIndex and had thus
O(1) for most operations. What is new is:

- NMDedupMultiIndex preserves the order of the cached items.
  This is important to handle routes properly as kernel will
  replace the first matching route based on network/plen/metric
  properties. See related bug rh#1337855.
  Without tracking the order of routes as they are exposed
  by kernel, we cannot properly maintain the route cache.

- All NMPObject instances are now treated immutable, refcounted
  and get de-duplicated via NMDedupMultiIndex. This allows
  to have a global NMDedupMultiIndex that can be shared with
  NMIP4Config and NMRouteManager. It also allows to share the
  objects themselves.
  Immutable objects are so much nicer. We can get rid of the
  update pre-hook callback, which was required previously because
  we would mutate the object inplace. Now, we can just update
  the cache, and compare obj_old and obj_new after the fact.

- NMMultiIndex was treated as an internal of NMPCache. On the other
  hand, NMDedupMultiIndex exposes NMDedupMultiHeadEntry, which is
  basically an object that allows to iterate over all related
  objects. That means, we can now lookup objects in the cache
  and give the NMDedupMultiHeadEntry instance to the caller,
  which then can iterate the list on it's own -- without need
  for copying anything.
  Currently, at various places we still create copies of lookup
  results. That can be improved later.

The ability to share NMPObject instances should enable us to
significantly improve performance and scale with large number
of routes.

1 files changed, 1 insertions, 1 deletions

diff --git a/src/nm-route-manager.c b/src/nm-route-manager.c
index b58cdeb069..6c1f78ac96 100644
--- a/src/nm-route-manager.c
+++ b/src/nm-route-manager.c
@@ -1173,7 +1173,7 @@ nm_route_manager_ip4_route_register_device_route_purge_list (NMRouteManager *sel
 		                                      ? "update" : "new",
 		                                  nmp_object_to_string (entry->obj, NMP_OBJECT_TO_STRING_PUBLIC, NULL, 0));
 		g_hash_table_replace (priv->ip4_device_routes.entries,
-		                      nmp_object_ref (entry->obj),
+		                      (NMPObject *) nmp_object_ref (entry->obj),
 		                      entry);
 	}
 	if (priv->ip4_device_routes.gc_id == 0) {