Capabilities override persists after change to advanced.conf [JIRA: RIAK-2816]

[paulhenrich]

While testing the new capability override {riak_kv, object_hash_version}, I noticed that once I set it in advanced.conf, the value persists even after the override has been removed.

Observed behavior on riak-ee_2.2.0rc8

Add the following to /etc/riak/advanced.conf:

{override_capability,
 [
  {object_hash_version, {use, legacy} }
]},

riak start && riak attach

([email protected])1> riak_core_capability:get({riak_kv, object_hash_version}).
legacy

After reverting change to advanced.config, removing override, and restarting node:

([email protected])1> riak_core_capability:get({riak_kv, object_hash_version}).
legacy

Expected behavior

I expected riak_core_capability:get({riak_kv, object_hash_version}). to return undefined when no override.

Suspected Cause

@bsparrow435 tells me that the capability gets persisted in an ETS table and won't update in the management tick:

ah but maybe_update_tick just looks at the cached version of the ring compared to the one on disk and only reloads if it's different
so without a ring event, i dont think it will ever re-override the capability