Use cache for authentication backends

The commit introduces the following API incompatibilities:

In ejabberd_auth.erl:
* dirty_get_registered_users/0 is renamed to get_users/0
* get_vh_registered_users/1 is renamed to get_users/1
* get_vh_registered_users/2 is renamed to get_users/2
* get_vh_registered_users_number/1 is renamed to count_users/1
* get_vh_registered_users_number/2 is renamed to count_users/2

In ejabberd_auth callbacks
* plain_password_required/0 is replaced by plain_password_required/1
  where the argument is a virtual host
* store_type/0 is replaced by store_type/1 where the argument is
  a virtual host
* set_password/3 is now an optional callback
* remove_user/3 callback is no longer needed
* remove_user/2 now should return `ok | {error, atom()}`
* is_user_exists/2 now must only be implemented for backends
  with `external` store type
* check_password/6 is no longer needed
* check_password/4 now must only be implemented for backends
  with `external` store type
* try_register/3 is now an optional callback and should return
  `ok | {error, atom()}`
* dirty_get_registered_users/0 is no longer needed
* get_vh_registered_users/1 is no longer needed
* get_vh_registered_users/2 is renamed to get_users/2
* get_vh_registered_users_number/1 is no longer needed
* get_vh_registered_users_number/2 is renamed to count_users/2
* get_password_s/2 is no longer needed
* get_password/2 now must only be implemented for backends with
  `plain` or `scram` store type

Additionally, the commit introduces two new callbacks:
* use_cache/1 where the argument is a virtual host
* cache_nodes/1 where the argument is a virtual host

New options are also introduced: `auth_use_cache`, `auth_cache_missed`,
`auth_cache_life_time` and `auth_cache_size`.

1 files changed, 3 insertions, 3 deletions

diff --git a/src/ejabberd_piefxis.erl b/src/ejabberd_piefxis.erl
index aea28059..ecb4908a 100644
--- a/src/ejabberd_piefxis.erl
+++ b/src/ejabberd_piefxis.erl
@@ -135,7 +135,7 @@ export_host(Dir, FnH, Host) ->
         {ok, Fd} ->
             print(Fd, make_piefxis_xml_head()),
             print(Fd, make_piefxis_host_head(Host)),
-            Users = ejabberd_auth:get_vh_registered_users(Host),
+            Users = ejabberd_auth:get_users(Host),
             case export_users(Users, Host, Fd) of
                 ok ->
                     print(Fd, make_piefxis_host_tail()),
@@ -402,9 +402,9 @@ process_user(#xmlel{name = <<"user">>, attrs = Attrs, children = Els},
             stop("Invalid 'user': ~s", [Name]);
         LUser ->
             case ejabberd_auth:try_register(LUser, LServer, Pass) of
-                {atomic, _} ->
+                ok ->
                     process_user_els(Els, State#state{user = LUser});
-                Err ->
+                {error, Err} ->
                     stop("Failed to create user '~s': ~p", [Name, Err])
             end
     end.