refactor: introduce emqx_const_v1 for immutable anonymous funs

scripts/update_appup.escript

@@ -313,7 +313,7 @@ do_merge_update_actions(App, {New0, Changed0, Deleted0}, OldActions) ->
             true ->
                 [];
             false ->
-                [{load_module, M, brutal_purge, soft_purge, []} || M <- Changed, not is_secret_module(M)] ++
+                [{load_module, M, brutal_purge, soft_purge, []} || M <- Changed, not is_const_module(M)] ++
                 [{add_module, M} || M <- New]
         end,
     {OldActionsWithStop, OldActionsAfterStop} =
@@ -325,14 +325,17 @@ do_merge_update_actions(App, {New0, Changed0, Deleted0}, OldActions) ->
             true ->
                 [];
             false ->
-                [{delete_module, M} || M <- Deleted, not is_secret_module(M)]
+                [{delete_module, M} || M <- Deleted, not is_const_module(M)]
         end ++
         AppSpecific.
 
-%% Do not reload or delet _secret modules
-is_secret_module(Module) ->
+is_const_module(Module) when is_atom(Module) ->
+    is_const_module(atom_to_list(Module));
+is_const_module("emqx_const_" ++ _) ->
+    true;
+is_const_module(Module) ->
     Suffix = "_secret",
-    case string:right(atom_to_list(Module), length(Suffix)) of
+    case string:right(Module, length(Suffix)) of
         Suffix -> true;
         _ -> false
     end.

src/emqx.appup.src

@@ -4,6 +4,7 @@
   [{"4.4.10",
     [{add_module,emqx_ocsp_cache},
      {add_module,emqx_crl_cache},
+     {add_module,emqx_const_v1},
      {load_module,emqx_listeners,brutal_purge,soft_purge,[]},
      {load_module,emqx_kernel_sup,brutal_purge,soft_purge,[]},
      {load_module,emqx_access_rule,brutal_purge,soft_purge,[]},
@@ -19,6 +20,7 @@
    {"4.4.9",
     [{add_module,emqx_ocsp_cache},
      {add_module,emqx_crl_cache},
+     {add_module,emqx_const_v1},
      {add_module,emqx_secret},
      {load_module,emqx_listeners,brutal_purge,soft_purge,[]},
      {load_module,emqx_kernel_sup,brutal_purge,soft_purge,[]},
@@ -41,6 +43,7 @@
    {"4.4.8",
     [{add_module,emqx_ocsp_cache},
      {add_module,emqx_crl_cache},
+     {add_module,emqx_const_v1},
      {add_module,emqx_secret},
      {load_module,emqx_listeners,brutal_purge,soft_purge,[]},
      {load_module,emqx_kernel_sup,brutal_purge,soft_purge,[]},
@@ -64,6 +67,7 @@
    {"4.4.7",
     [{add_module,emqx_ocsp_cache},
      {add_module,emqx_crl_cache},
+     {add_module,emqx_const_v1},
      {add_module,emqx_secret},
      {load_module,emqx_listeners,brutal_purge,soft_purge,[]},
      {load_module,emqx_kernel_sup,brutal_purge,soft_purge,[]},
@@ -87,6 +91,7 @@
    {"4.4.6",
     [{add_module,emqx_ocsp_cache},
      {add_module,emqx_crl_cache},
+     {add_module,emqx_const_v1},
      {add_module,emqx_secret},
      {load_module,emqx_listeners,brutal_purge,soft_purge,[]},
      {load_module,emqx_kernel_sup,brutal_purge,soft_purge,[]},
@@ -110,6 +115,7 @@
    {"4.4.5",
     [{add_module,emqx_ocsp_cache},
      {add_module,emqx_crl_cache},
+     {add_module,emqx_const_v1},
      {add_module,emqx_secret},
      {load_module,emqx_listeners,brutal_purge,soft_purge,[]},
      {load_module,emqx_kernel_sup,brutal_purge,soft_purge,[]},
@@ -135,6 +141,7 @@
    {"4.4.4",
     [{add_module,emqx_ocsp_cache},
      {add_module,emqx_crl_cache},
+     {add_module,emqx_const_v1},
      {add_module,emqx_secret},
      {load_module,emqx_listeners,brutal_purge,soft_purge,[]},
      {load_module,emqx_kernel_sup,brutal_purge,soft_purge,[]},
@@ -167,6 +174,7 @@
    {"4.4.3",
     [{add_module,emqx_ocsp_cache},
      {add_module,emqx_crl_cache},
+     {add_module,emqx_const_v1},
      {add_module,emqx_secret},
      {load_module,emqx_listeners,brutal_purge,soft_purge,[]},
      {load_module,emqx_kernel_sup,brutal_purge,soft_purge,[]},
@@ -206,6 +214,7 @@
    {"4.4.2",
     [{add_module,emqx_ocsp_cache},
      {add_module,emqx_crl_cache},
+     {add_module,emqx_const_v1},
      {add_module,emqx_secret},
      {load_module,emqx_listeners,brutal_purge,soft_purge,[]},
      {load_module,emqx_kernel_sup,brutal_purge,soft_purge,[]},
@@ -246,6 +255,7 @@
    {"4.4.1",
     [{add_module,emqx_ocsp_cache},
      {add_module,emqx_crl_cache},
+     {add_module,emqx_const_v1},
      {add_module,emqx_secret},
      {load_module,emqx_kernel_sup,brutal_purge,soft_purge,[]},
      {load_module,emqx_router_helper,brutal_purge,soft_purge,[]},
@@ -291,6 +301,7 @@
    {"4.4.0",
     [{add_module,emqx_ocsp_cache},
      {add_module,emqx_crl_cache},
+     {add_module,emqx_const_v1},
      {add_module,emqx_secret},
      {load_module,emqx_kernel_sup,brutal_purge,soft_purge,[]},
      {load_module,emqx_router_helper,brutal_purge,soft_purge,[]},

src/emqx_const_v1.erl

@@ -0,0 +1,24 @@
+%%--------------------------------------------------------------------
+%% Copyright (c) 2022 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.
+%%
+%% @doc Never update this module, create a v2 instead.
+%%--------------------------------------------------------------------
+
+-module(emqx_const_v1).
+
+-export([make_sni_fun/1]).
+
+make_sni_fun(ListenerID) ->
+    fun(SN) -> emqx_ocsp_cache:sni_fun(SN, ListenerID) end.

src/emqx_ocsp_cache.erl

@@ -103,7 +103,7 @@ inject_sni_fun(ListenerID, Options0) ->
             Options0;
         true ->
             SSLOpts0 = proplists:get_value(ssl_options, Options0, []),
-            SNIFun = fun(SN) -> emqx_ocsp_cache:sni_fun(SN, ListenerID) end,
+            SNIFun = emqx_const_v1:make_sni_fun(ListenerID),
             Options1 = proplists:delete(ssl_options, Options0),
             Options = [{ssl_options, [{sni_fun, SNIFun} | SSLOpts0]} | Options1],
             %% save to env
@@ -177,25 +177,6 @@ handle_info(_Info, State) ->
     {noreply, State}.
 
 code_change(_Vsn, State, _Extra) ->
-    %% we need to re-create the `sni_fun' lambda that the SSL
-    %% listeners are holding onto to avoid them becoming `badfun''s.
-    ListenersToPatch =
-        lists:filter(
-          fun(#{opts := Opts}) ->
-                  OCSPOpts = proplists:get_value(ocsp_options, Opts),
-                  undefined =/= proplists:get_value(ocsp_responder_url, OCSPOpts, undefined) andalso
-                      false =/= proplists:get_bool(ocsp_stapling_enabled, OCSPOpts)
-          end,
-          emqx:get_env(listeners, [])),
-    PatchedListeners = [L#{opts => ?MODULE:inject_sni_fun(
-                                      emqx_listeners:identifier(L),
-                                      Opts)}
-                        || L = #{opts := Opts} <- ListenersToPatch],
-    lists:foreach(
-      fun(L) ->
-              emqx_listeners:update_listeners_env(update, L)
-      end,
-     PatchedListeners),
     {ok, State}.
 
 %%--------------------------------------------------------------------