feat(ocsp_cache): give ocsp cache table an heir

apps/emqx/src/emqx_ocsp_cache.erl

@@ -149,9 +149,10 @@ inject_sni_fun(ListenerID, Conf0) ->
 
 init(_Args) ->
     logger:set_process_metadata(#{domain => [emqx, ocsp, cache]}),
-    _ = ets:new(?CACHE_TAB, [
+    emqx_tables:new(?CACHE_TAB, [
         named_table,
-        protected,
+        public,
+        {heir, whereis(emqx_kernel_sup), none},
         {read_concurrency, true}
     ]),
     ?tp(ocsp_cache_init, #{}),

apps/emqx/test/emqx_ocsp_cache_SUITE.erl

@@ -147,6 +147,7 @@ init_per_testcase(t_ocsp_responder_error_responses, Config) ->
     hocon_tconf:check_plain(emqx_schema, ConfBin, #{required => false, atom_keys => false}),
     emqx_config:put_listener_conf(Type, Name, [], ListenerOpts),
     snabbkaffe:start_trace(),
+    _Heir = spawn_dummy_heir(),
     {ok, CachePid} = emqx_ocsp_cache:start_link(),
     [
         {cache_pid, CachePid}
@@ -164,6 +165,7 @@ init_per_testcase(_TestCase, Config) ->
             {ok, {{"HTTP/1.0", 200, 'OK'}, [], <<"ocsp response">>}}
         end
     ),
+    _Heir = spawn_dummy_heir(),
     {ok, CachePid} = emqx_ocsp_cache:start_link(),
     DataDir = ?config(data_dir, Config),
     Type = ssl,
@@ -225,6 +227,17 @@ end_per_testcase(_TestCase, Config) ->
 %% Helper functions
 %%--------------------------------------------------------------------
 
+%% The real cache makes `emqx_kernel_sup' the heir to its ETS table.
+%% In some tests, we don't start the full supervision tree, so we need
+%% this dummy process.
+spawn_dummy_heir() ->
+    spawn_link(fun() ->
+        true = register(emqx_kernel_sup, self()),
+        receive
+            stop -> ok
+        end
+    end).
+
 does_module_exist(Mod) ->
     case erlang:module_loaded(Mod) of
         true ->
@@ -508,11 +521,13 @@ t_request_ocsp_response_restart_cache(Config) ->
             ok
         end,
         fun(Trace) ->
+            %% Only one fetch because the cache table was preserved by
+            %% its heir ("emqx_kernel_sup").
             ?assertMatch(
-                [_, _],
+                [_],
                 ?of_kind(ocsp_http_fetch_and_cache, Trace)
             ),
-            assert_http_get(2),
+            assert_http_get(1),
             ok
         end
     ).