refactor(exproto): make timer names equal to messages they send

Because keeping timer names different from the messages they send
complicates understanding of the control flow, and spends few
reductions per timer operation unnecessarily.

apps/emqx_gateway_exproto/src/emqx_exproto_channel.erl

@@ -74,12 +74,6 @@
 
 -type replies() :: emqx_types:packet() | reply() | [reply()].
 
--define(TIMER_TABLE, #{
-    alive_timer => keepalive,
-    force_timer => force_close,
-    idle_timer => force_close_idle
-}).
-
 -define(INFO_KEYS, [conninfo, conn_state, clientinfo, session, will_msg]).
 
 %%--------------------------------------------------------------------
@@ -224,7 +218,7 @@ address({Host, Port}) ->
 
 %% avoid udp connection process leak
 start_idle_checking_timer(Channel = #channel{conninfo = #{socktype := udp}}) ->
-    ensure_timer(idle_timer, Channel);
+    ensure_timer(force_close_idle, Channel);
 start_idle_checking_timer(Channel) ->
     Channel.
 
@@ -293,10 +287,10 @@ handle_timeout(
     case emqx_keepalive:check(StatVal, Keepalive) of
         {ok, NKeepalive} ->
             NChannel = Channel#channel{keepalive = NKeepalive},
-            {ok, reset_timer(alive_timer, NChannel)};
+            {ok, reset_timer(keepalive, NChannel)};
         {error, timeout} ->
             Req = #{type => 'KEEPALIVE'},
-            NChannel = remove_timer_ref(alive_timer, Channel),
+            NChannel = remove_timer_ref(keepalive, Channel),
             %% close connection if keepalive timeout
             Replies = [{event, disconnected}, {close, keepalive_timeout}],
             NChannel1 = dispatch(on_timer_timeout, Req, NChannel#channel{
@@ -419,7 +413,7 @@ handle_call(
     NConnInfo = ConnInfo#{keepalive => Interval},
     NClientInfo = ClientInfo#{keepalive => Interval},
     NChannel = Channel#channel{conninfo = NConnInfo, clientinfo = NClientInfo},
-    {reply, ok, [{event, updated}], ensure_keepalive(cancel_timer(idle_timer, NChannel))};
+    {reply, ok, [{event, updated}], ensure_keepalive(cancel_timer(force_close_idle, NChannel))};
 handle_call(
     {subscribe_from_client, TopicFilter, Qos},
     _From,
@@ -529,7 +523,7 @@ handle_info(
                     _ ->
                         Channel
                 end,
-            Channel2 = ensure_timer(force_timer, Channel1),
+            Channel2 = ensure_timer(force_close, Channel1),
             {ok, ensure_disconnected(Reason, Channel2)}
     end;
 handle_info(
@@ -547,13 +541,13 @@ handle_info(
 
     ShutdownNow =
         emqx_exproto_gcli:is_empty(GClient) andalso
-            maps:get(force_timer, Timers, undefined) =/= undefined,
+            maps:get(force_close, Timers, undefined) =/= undefined,
     case Result of
         ok when not ShutdownNow ->
             GClient1 = emqx_exproto_gcli:maybe_shoot(GClient),
             {ok, Channel#channel{gcli = GClient1}};
         ok when ShutdownNow ->
-            Channel1 = cancel_timer(force_timer, Channel),
+            Channel1 = cancel_timer(force_close, Channel),
             {shutdown, Channel1#channel.closed_reason, Channel1};
         {error, Reason} ->
             {shutdown, {error, {FunName, Reason}}, Channel}
@@ -711,7 +705,7 @@ ensure_keepalive_timer(Interval, Channel) when Interval =< 0 ->
 ensure_keepalive_timer(Interval, Channel) ->
     StatVal = emqx_gateway_conn:keepalive_stats(recv),
     Keepalive = emqx_keepalive:init(StatVal, timer:seconds(Interval)),
-    ensure_timer(alive_timer, Channel#channel{keepalive = Keepalive}).
+    ensure_timer(keepalive, Channel#channel{keepalive = Keepalive}).
 
 ensure_timer(Name, Channel = #channel{timers = Timers}) ->
     TRef = maps:get(Name, Timers, undefined),
@@ -723,8 +717,7 @@ ensure_timer(Name, Channel = #channel{timers = Timers}) ->
     end.
 
 ensure_timer(Name, Time, Channel = #channel{timers = Timers}) ->
-    Msg = maps:get(Name, ?TIMER_TABLE),
-    TRef = emqx_utils:start_timer(Time, Msg),
+    TRef = emqx_utils:start_timer(Time, Name),
     Channel#channel{timers = Timers#{Name => TRef}}.
 
 reset_timer(Name, Channel) ->
@@ -737,11 +730,11 @@ cancel_timer(Name, Channel = #channel{timers = Timers}) ->
 remove_timer_ref(Name, Channel = #channel{timers = Timers}) ->
     Channel#channel{timers = maps:remove(Name, Timers)}.
 
-interval(idle_timer, #channel{conninfo = #{idle_timeout := IdleTimeout}}) ->
+interval(force_close_idle, #channel{conninfo = #{idle_timeout := IdleTimeout}}) ->
     IdleTimeout;
-interval(force_timer, _) ->
+interval(force_close, _) ->
     15000;
-interval(alive_timer, #channel{keepalive = Keepalive}) ->
+interval(keepalive, #channel{keepalive = Keepalive}) ->
     emqx_keepalive:info(interval, Keepalive).
 
 %%--------------------------------------------------------------------