fix(gateway): act on voice states in the voice server (#2815)

fluxer_gateway/src/guild/guild_availability.erl

@@ -212,10 +212,8 @@ maybe_disconnect_voice(UserId, ProcessedUsers, State) ->
         true ->
             {State, ProcessedUsers};
         false ->
-            {reply, _Result, VoiceState} = guild_voice_disconnect:disconnect_voice_user(
-                #{user_id => UserId, connection_id => null}, State
-            ),
-            {VoiceState, sets:add_element(UserId, ProcessedUsers)}
+            ok = guild_voice_lifecycle:cast_disconnect_voice_user(UserId, State),
+            {State, sets:add_element(UserId, ProcessedUsers)}
     end.
 
 -spec schedule_availability_recheck(guild_state()) -> guild_state().

fluxer_gateway/src/guild/guild_state.erl

@@ -221,24 +221,38 @@ update_data_for_event_unknown_returns_data_unchanged_test() ->
     Data = #{<<"test">> => true},
     ?assertEqual(Data, update_data_for_event(unknown_event, #{}, Data, #{})).
 
-guild_member_remove_disconnects_voice_test() ->
+guild_member_remove_asks_the_voice_server_to_disconnect_test() ->
     Self = self(),
-    TestFun = fun(GId, ChId, UId, ConnId) ->
-        Self ! {force_disconnect, GId, ChId, UId, ConnId},
-        {ok, #{success => true}}
-    end,
-    State = build_voice_test_state(TestFun),
+    VoicePid = spawn(fun() ->
+        receive
+            Message -> Self ! {voice_server_got, Message}
+        end
+    end),
+    State = build_voice_test_state(VoicePid),
     EventData = #{<<"user">> => #{<<"id">> => <<"5">>}},
     UpdatedState = update_state(guild_member_remove, EventData, State),
-    ?assertEqual(#{}, maps:get(voice_states, UpdatedState)),
     ?assertEqual(#{}, maps:get(sessions, UpdatedState, #{})),
     receive
-        {force_disconnect, 42, 20, 5, <<"conn">>} -> ok
+        {voice_server_got, {'$gen_cast', {disconnect_voice_user, Request}}} ->
+            ?assertEqual(#{user_id => 5, connection_id => null}, Request)
     after 200 ->
+        exit(VoicePid, kill),
         ?assert(false)
     end.
 
-build_voice_test_state(TestFun) ->
+guild_member_remove_leaves_the_stale_guild_copy_alone_test() ->
+    VoicePid = spawn(fun() ->
+        receive
+            _ -> ok
+        end
+    end),
+    State = build_voice_test_state(VoicePid),
+    UpdatedState = update_state(
+        guild_member_remove, #{<<"user">> => #{<<"id">> => <<"5">>}}, State
+    ),
+    ?assertEqual(maps:get(voice_states, State), maps:get(voice_states, UpdatedState)).
+
+build_voice_test_state(VoicePid) ->
     #{
         id => 42,
         data => #{
@@ -256,7 +270,7 @@ build_voice_test_state(TestFun) ->
             }
         },
         sessions => #{<<"s1">> => #{user_id => 5, pid => self()}},
-        test_force_disconnect_fun => TestFun
+        voice_server_pid => VoicePid
     }.
 
 make_cache_test_state(GuildId) ->

fluxer_gateway/src/guild/guild_state_member.erl

@@ -132,12 +132,8 @@ cleanup_removed_member_sessions(_UserId, State) ->
 
 -spec maybe_disconnect_removed_member(user_id() | undefined, guild_state()) -> guild_state().
 maybe_disconnect_removed_member(UserId, State) when is_integer(UserId), UserId > 0 ->
-    {reply, _Result, NewState} =
-        guild_voice_disconnect:disconnect_voice_user(
-            #{user_id => UserId, connection_id => null},
-            State
-        ),
-    NewState;
+    ok = guild_voice_lifecycle:cast_disconnect_voice_user(UserId, State),
+    State;
 maybe_disconnect_removed_member(_, State) ->
     State.
 

fluxer_gateway/src/guild/guild_voice_lifecycle.erl

@@ -7,7 +7,9 @@
     ensure_voice_server/1,
     handle_voice_server_exit/3,
     reply_voice_server_pid/1,
-    clear_stale_cached_voice_states/2
+    clear_stale_cached_voice_states/2,
+    authoritative_voice_states/1,
+    cast_disconnect_voice_user/2
 ]).
 
 -type guild_state() :: map().
@@ -160,32 +162,58 @@ schedule_stale_cleanup(ConnectionIds) ->
 
 -spec read_authoritative_voice_states(guild_state()) -> {ok, map()} | {error, term()}.
 read_authoritative_voice_states(State) ->
+    case voice_server_pid(State) of
+        {ok, VoiceServerPid} -> read_from_pid(VoiceServerPid);
+        error -> {error, no_voice_server}
+    end.
+
+-spec authoritative_voice_states(guild_state()) -> map().
+authoritative_voice_states(State) ->
+    case read_authoritative_voice_states(State) of
+        {ok, VoiceStates} -> VoiceStates;
+        {error, _Reason} -> voice_state_utils:voice_states(State)
+    end.
+
+-spec cast_disconnect_voice_user(integer(), guild_state()) -> ok.
+cast_disconnect_voice_user(UserId, State) when is_integer(UserId), UserId > 0 ->
+    case voice_server_pid(State) of
+        {ok, VoiceServerPid} ->
+            gen_server:cast(
+                VoiceServerPid,
+                {disconnect_voice_user, #{user_id => UserId, connection_id => null}}
+            );
+        error ->
+            ok
+    end;
+cast_disconnect_voice_user(_UserId, _State) ->
+    ok.
+
+-spec voice_server_pid(guild_state()) -> {ok, pid()} | error.
+voice_server_pid(State) ->
     case maps:get(voice_server_pid, State, undefined) of
-        VoiceServerPid when is_pid(VoiceServerPid) ->
-            read_from_pid_or_registry(VoiceServerPid, State);
-        _ ->
-            read_from_registry(State)
+        Pid when is_pid(Pid) -> live_voice_server_pid(Pid, State);
+        _ -> registered_voice_server_pid(State)
     end.
 
--spec read_from_pid_or_registry(pid(), guild_state()) -> {ok, map()} | {error, term()}.
-read_from_pid_or_registry(Pid, State) ->
-    case process_liveness:is_alive(Pid) of
-        true -> read_from_pid(Pid);
-        false -> read_from_registry(State)
+-spec live_voice_server_pid(pid(), guild_state()) -> {ok, pid()} | error.
+live_voice_server_pid(Pid, State) ->
+    case Pid =/= self() andalso process_liveness:is_alive(Pid) of
+        true -> {ok, Pid};
+        false -> registered_voice_server_pid(State)
     end.
 
--spec read_from_registry(guild_state()) -> {ok, map()} | {error, term()}.
-read_from_registry(State) ->
+-spec registered_voice_server_pid(guild_state()) -> {ok, pid()} | error.
+registered_voice_server_pid(State) ->
     case state_guild_id(State) of
-        {ok, Id} -> read_registered_pid(Id);
-        error -> {error, no_guild_id}
+        {ok, Id} -> registered_pid_for_guild(Id);
+        error -> error
     end.
 
--spec read_registered_pid(integer()) -> {ok, map()} | {error, term()}.
-read_registered_pid(Id) ->
+-spec registered_pid_for_guild(integer()) -> {ok, pid()} | error.
+registered_pid_for_guild(Id) ->
     case guild_voice_server:lookup_registered(Id) of
-        {ok, Pid} -> read_from_pid(Pid);
-        {error, Reason} -> {error, Reason}
+        {ok, Pid} when Pid =/= self() -> {ok, Pid};
+        _ -> error
     end.
 
 -spec state_guild_id(guild_state()) -> {ok, integer()} | error.
@@ -203,3 +231,52 @@ read_from_pid(VoiceServerPid) ->
     catch
         exit:Reason -> {error, Reason}
     end.
+
+-ifdef(TEST).
+-include_lib("eunit/include/eunit.hrl").
+
+cast_disconnect_voice_user_reaches_the_voice_server_test() ->
+    Self = self(),
+    VoicePid = spawn(fun() ->
+        receive
+            Message -> Self ! {voice_server_got, Message}
+        end
+    end),
+    ok = cast_disconnect_voice_user(7, #{id => 42, voice_server_pid => VoicePid}),
+    receive
+        {voice_server_got, {'$gen_cast', {disconnect_voice_user, Request}}} ->
+            ?assertEqual(#{user_id => 7, connection_id => null}, Request)
+    after 200 ->
+        exit(VoicePid, kill),
+        ?assert(false)
+    end.
+
+cast_disconnect_voice_user_without_a_voice_server_is_a_noop_test() ->
+    ?assertEqual(ok, cast_disconnect_voice_user(7, #{id => 987654329})),
+    ?assertEqual(ok, cast_disconnect_voice_user(undefined, #{id => 987654329})).
+
+authoritative_voice_states_falls_back_to_the_guild_copy_test() ->
+    Cached = #{<<"conn">> => #{<<"user_id">> => <<"7">>}},
+    State = #{id => 987654331, voice_states => Cached},
+    ?assertEqual(Cached, authoritative_voice_states(State)).
+
+authoritative_voice_states_prefers_the_voice_server_test() ->
+    Live = #{<<"live">> => #{<<"user_id">> => <<"8">>}},
+    VoicePid = spawn(fun() -> voice_states_reply_loop(Live) end),
+    State = #{id => 987654333, voice_states => #{}, voice_server_pid => VoicePid},
+    try
+        ?assertEqual(Live, authoritative_voice_states(State))
+    after
+        exit(VoicePid, kill)
+    end.
+
+voice_states_reply_loop(VoiceStates) ->
+    receive
+        {'$gen_call', From, {get_voice_states_map}} ->
+            gen_server:reply(From, VoiceStates),
+            voice_states_reply_loop(VoiceStates);
+        _ ->
+            voice_states_reply_loop(VoiceStates)
+    end.
+
+-endif.

fluxer_gateway/src/guild/voice/guild_voice_permission_sync.erl

@@ -29,7 +29,7 @@
 
 -spec sync_user_voice_permissions(user_id(), guild_state()) -> ok.
 sync_user_voice_permissions(UserId, State) ->
-    VoiceStates = voice_state_utils:voice_states(State),
+    VoiceStates = guild_voice_lifecycle:authoritative_voice_states(State),
     case state_guild_id(State) of
         undefined ->
             ok;
@@ -56,7 +56,7 @@ maybe_sync_user_voice_state(GuildId, UserId, VoiceState, State) ->
 
 -spec sync_all_voice_permissions_for_channel(channel_id(), guild_state()) -> ok.
 sync_all_voice_permissions_for_channel(ChannelId, State) ->
-    VoiceStates = voice_state_utils:voice_states(State),
+    VoiceStates = guild_voice_lifecycle:authoritative_voice_states(State),
     case state_guild_id(State) of
         undefined ->
             ok;
@@ -236,7 +236,7 @@ enforce_voice_permissions_in_livekit(
 
 -spec sync_users_with_role(integer(), guild_state()) -> ok.
 sync_users_with_role(RoleId, State) ->
-    VoiceStates = voice_state_utils:voice_states(State),
+    VoiceStates = guild_voice_lifecycle:authoritative_voice_states(State),
     case state_guild_id(State) of
         undefined ->
             ok;

fluxer_gateway/src/guild/voice/guild_voice_server.erl

@@ -232,6 +232,8 @@ handle_cast({store_pending_connection, ConnId, Meta}, State) ->
     Pending = maps:get(pending_voice_connections, State, #{}),
     NewPending = bounded_put(ConnId, Meta, Pending, ?MAX_PENDING_CONNECTIONS),
     {noreply, State#{pending_voice_connections => NewPending}};
+handle_cast({disconnect_voice_user, Request}, State) when is_map(Request) ->
+    {noreply, delegate_voice_cast(fun guild_voice:disconnect_voice_user/2, Request, State)};
 handle_cast({cleanup_virtual_access_for_user, UserId}, State) when is_integer(UserId) ->
     GS = guild_voice_server_state:build_guild_state(State),
     NewGS = guild_voice_disconnect:cleanup_virtual_channel_access_for_user(UserId, GS),
@@ -295,6 +297,13 @@ safe_lookup(Fun) ->
 safe_lookup_match({ok, Pid}) when is_pid(Pid) -> {ok, Pid};
 safe_lookup_match(_) -> {error, not_found}.
 
+-spec delegate_voice_cast(fun((map(), map()) -> {reply, term(), map()}), map(), server_state()) ->
+    server_state().
+delegate_voice_cast(Fun, Request, State) ->
+    GS = guild_voice_server_state:build_guild_state(State),
+    {reply, _Reply, NewGS} = Fun(Request, GS),
+    guild_voice_server_state:apply_guild_state(NewGS, State).
+
 -spec delegate_voice_call(fun((map(), map()) -> {reply, term(), map()}), map(), server_state()) ->
     {reply, term(), server_state()}.
 delegate_voice_call(Fun, Request, State) ->
@@ -433,6 +442,56 @@ enforce_map_cap(Map, MaxSize) ->
 -ifdef(TEST).
 -include_lib("eunit/include/eunit.hrl").
 
+disconnect_voice_user_cast_removes_the_voice_state_test() ->
+    Self = self(),
+    TestFun = fun(GId, ChId, UId, ConnId) ->
+        Self ! {force_disconnect, GId, ChId, UId, ConnId},
+        {ok, #{success => true}}
+    end,
+    GuildPid = spawn(fun() -> guild_state_reply_loop(TestFun) end),
+    State = #{
+        guild_id => 42,
+        guild_pid => GuildPid,
+        voice_states => #{
+            <<"conn">> => #{
+                <<"user_id">> => <<"5">>,
+                <<"guild_id">> => <<"42">>,
+                <<"channel_id">> => <<"20">>,
+                <<"connection_id">> => <<"conn">>
+            }
+        },
+        pending_voice_connections => #{},
+        recently_disconnected_voice_states => #{},
+        e2ee_room_keys => #{}
+    },
+    try
+        {noreply, NewState} = handle_cast(
+            {disconnect_voice_user, #{user_id => 5, connection_id => null}}, State
+        ),
+        ?assertEqual(#{}, maps:get(voice_states, NewState)),
+        receive
+            {force_disconnect, 42, 20, 5, <<"conn">>} -> ok
+        after 200 -> ?assert(false)
+        end
+    after
+        exit(GuildPid, kill)
+    end.
+
+guild_state_reply_loop(TestFun) ->
+    GuildState = #{
+        id => 42,
+        data => #{<<"guild">> => #{<<"owner_id">> => <<"999">>}},
+        sessions => #{},
+        test_force_disconnect_fun => TestFun
+    },
+    receive
+        {'$gen_call', From, {get_voice_guild_state}} ->
+            gen_server:reply(From, GuildState),
+            guild_state_reply_loop(TestFun);
+        _ ->
+            guild_state_reply_loop(TestFun)
+    end.
+
 apply_guild_state_preserves_e2ee_test() ->
     State = #{
         guild_id => 1,