Refactor buffering and resending of messages (#21)

* Refactor buffering of messages in the mqtt session process
* Add test

src/mqtt_sessions.erl

@@ -1,7 +1,9 @@
 %% @author Marc Worrell <[email protected]>
-%% @copyright 2018 Marc Worrell
+%% @copyright 2018-2024 Marc Worrell
+%% @doc Session management for a MQTT server.
+%% @end
 
-%% Copyright 2018 Marc Worrell
+%% Copyright 2018-2024 Marc Worrell
 %%
 %% Licensed under the Apache License, Version 2.0 (the "License");
 %% you may not use this file except in compliance with the License.
@@ -31,8 +33,6 @@
 
     find_session/1,
     find_session/2,
-    fetch_queue/1,
-    fetch_queue/2,
 
     session_count/1,
     router_info/1,
@@ -147,17 +147,6 @@ session_count(Pool) ->
 router_info(Pool) ->
     mqtt_sessions_router:info(Pool).
 
--spec fetch_queue( session_ref() ) -> {ok, list( mqtt_packet_map:mqtt_packet() | binary() )} | {error, notfound}.
-fetch_queue(ClientId) ->
-    fetch_queue(?MQTT_SESSIONS_DEFAULT, ClientId).
-
--spec fetch_queue( atom(), session_ref() ) -> {ok, list( mqtt_packet_map:mqtt_packet() | binary() )} | {error, notfound}.
-fetch_queue(Pool, ClientId) ->
-    case find_session(Pool, ClientId) of
-        {ok, Pid} -> mqtt_sessions_process:fetch_queue(Pid);
-        {error, _} = Error -> Error
-    end.
-
 -spec get_user_context( session_ref() ) -> {ok, term()} | {error, notfound | noproc}.
 get_user_context(ClientId) ->
     get_user_context(?MQTT_SESSIONS_DEFAULT, ClientId).