refactor(ds): Factor out configuration to a separate module

apps/emqx_replay/src/emqx_replay_conf.erl

@@ -0,0 +1,46 @@
+%%--------------------------------------------------------------------
+%% Copyright (c) 2023 EMQ Technologies Co., Ltd. All Rights Reserved.
+%%
+%% Licensed under the Apache License, Version 2.0 (the "License");
+%% you may not use this file except in compliance with the License.
+%% You may obtain a copy of the License at
+%%
+%%     http://www.apache.org/licenses/LICENSE-2.0
+%%
+%% Unless required by applicable law or agreed to in writing, software
+%% distributed under the License is distributed on an "AS IS" BASIS,
+%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+%% See the License for the specific language governing permissions and
+%% limitations under the License.
+%%--------------------------------------------------------------------
+-module(emqx_replay_conf).
+
+%% TODO: make a proper HOCON schema and all...
+
+%% API:
+-export([zone_config/1, db_options/0]).
+
+%%================================================================================
+%% API funcions
+%%================================================================================
+
+-define(APP, emqx_replay).
+
+-spec zone_config(emqx_types:zone()) ->
+    {module(), term()}.
+zone_config(Zone) ->
+    DefaultConf =
+        #{
+            timestamp_bits => 64,
+            topic_bits_per_level => [8, 8, 8, 32, 16],
+            max_tau => 5
+        },
+    DefaultZoneConfig = application:get_env(
+        ?APP, default_zone_config, {emqx_replay_message_storage, DefaultConf}
+    ),
+    Zones = application:get_env(?APP, zone_config, #{}),
+    maps:get(Zone, Zones, DefaultZoneConfig).
+
+-spec db_options() -> emqx_replay_local_store:db_options().
+db_options() ->
+    application:get_env(?APP, db_options, []).

apps/emqx_replay/src/emqx_replay_local_store.erl

@@ -168,7 +168,7 @@ ensure_current_generation(S = #s{zone = Zone, db = DBHandle, column_families = C
 create_new_generation_schema(
     GenId, S = #s{zone = Zone, db = DBHandle, column_families = CFs}
 ) ->
-    {Module, Options} = new_generation_config(Zone),
+    {Module, Options} = emqx_replay_conf:zone_config(Zone),
     {NewGenData, NewCFs} = Module:create_new(DBHandle, GenId, Options),
     NewGen = #generation{
         module = Module,
@@ -178,23 +178,10 @@ create_new_generation_schema(
     ok = schema_put_gen(DBHandle, GenId, NewGen),
     S#s{column_families = NewCFs ++ CFs}.
 
--spec new_generation_config(emqx_types:zone()) ->
-    {module(), term()}.
-new_generation_config(Zone) ->
-    %% TODO: make a proper HOCON schema and all...
-    Zones = application:get_env(emqx_replay, zone_config, #{}),
-    DefaultConf =
-        #{
-            timestamp_bits => 64,
-            topic_bits_per_level => [8, 8, 8, 32, 16],
-            max_tau => 5
-        },
-    maps:get(Zone, Zones, {emqx_replay_message_storage, DefaultConf}).
-
 -spec open_db(emqx_types:zone()) -> {ok, rocksdb:db_handle(), cf_refs()} | {error, _TODO}.
 open_db(Zone) ->
     Filename = atom_to_list(Zone),
-    DBOptions = application:get_env(emqx_replay, db_options, []),
+    DBOptions = emqx_replay_conf:db_options(),
     ColumnFamiles =
         case rocksdb:list_column_families(Filename, DBOptions) of
             {ok, ColumnFamiles0} ->