fix(ekka): run cleanups on node down events

When using the RLOG DB Backend with Mria, replicant nodes do not
generate `mnesia down` events.  Therefore, cleanup procedures that
some modules do when a node goes down do not work for replicants.

However, replicant do generate `node down` events, so that may be a
safer way to handle cleanup to take into account that type of node.

apps/emqx/src/emqx_cm_registry.erl

@@ -122,10 +122,11 @@ handle_cast(Msg, State) ->
     {noreply, State}.
 
 handle_info({membership, {mnesia, down, Node}}, State) ->
-    global:trans({?LOCK, self()},
-                 fun() ->
-                     mria:transaction(?CM_SHARD, fun cleanup_channels/1, [Node])
-                 end),
+    cleanup_channels(Node),
+    {noreply, State};
+
+handle_info({membership, {node, down, Node}}, State) ->
+    cleanup_channels(Node),
     {noreply, State};
 
 handle_info({membership, _Event}, State) ->
@@ -146,6 +147,12 @@ code_change(_OldVsn, State, _Extra) ->
 %%--------------------------------------------------------------------
 
 cleanup_channels(Node) ->
+    global:trans({?LOCK, self()},
+                 fun() ->
+                     mria:transaction(?CM_SHARD, fun do_cleanup_channels/1, [Node])
+                 end).
+
+do_cleanup_channels(Node) ->
     Pat = [{#channel{pid = '$1', _ = '_'}, [{'==', {node, '$1'}, Node}], ['$_']}],
     lists:foreach(fun delete_channel/1, mnesia:select(?TAB, Pat, write)).
 

apps/emqx/src/emqx_router_helper.erl

@@ -21,6 +21,7 @@
 -include("emqx.hrl").
 -include("logger.hrl").
 -include("types.hrl").
+-include_lib("snabbkaffe/include/snabbkaffe.hrl").
 
 
 %% Mnesia bootstrap
@@ -91,6 +92,7 @@ monitor(Node) when is_atom(Node) ->
 %%--------------------------------------------------------------------
 
 init([]) ->
+    process_flag(trap_exit, true),
     ok = ekka:monitor(membership),
     _ = mria:wait_for_tables([?ROUTING_NODE]),
     {ok, _} = mnesia:subscribe({table, ?ROUTING_NODE, simple}),
@@ -136,11 +138,15 @@ handle_info({nodedown, Node}, State = #{nodes := Nodes}) ->
                      mria:transaction(?ROUTE_SHARD, fun cleanup_routes/1, [Node])
                  end),
     ok = mria:dirty_delete(?ROUTING_NODE, Node),
+    ?tp(emqx_router_helper_cleanup_done, #{node => Node}),
     {noreply, State#{nodes := lists:delete(Node, Nodes)}, hibernate};
 
 handle_info({membership, {mnesia, down, Node}}, State) ->
     handle_info({nodedown, Node}, State);
 
+handle_info({membership, {node, down, Node}}, State) ->
+    handle_info({nodedown, Node}, State);
+
 handle_info({membership, _Event}, State) ->
     {noreply, State};
 

apps/emqx/test/emqx_cm_registry_SUITE.erl

@@ -65,7 +65,7 @@ t_register_unregister_channel(_) ->
     emqx_cm_registry:unregister_channel(ClientId),
     ?assertEqual([], emqx_cm_registry:lookup_channels(ClientId)).
 
-t_cleanup_channels(_) ->
+t_cleanup_channels_mnesia_down(_) ->
     ClientId = <<"clientid">>,
     ClientId2 = <<"clientid2">>,
     emqx_cm_registry:register_channel(ClientId),
@@ -76,3 +76,13 @@ t_cleanup_channels(_) ->
     ?assertEqual([], emqx_cm_registry:lookup_channels(ClientId)),
     ?assertEqual([], emqx_cm_registry:lookup_channels(ClientId2)).
 
+t_cleanup_channels_node_down(_) ->
+    ClientId = <<"clientid">>,
+    ClientId2 = <<"clientid2">>,
+    emqx_cm_registry:register_channel(ClientId),
+    emqx_cm_registry:register_channel(ClientId2),
+    ?assertEqual([self()], emqx_cm_registry:lookup_channels(ClientId)),
+    emqx_cm_registry ! {membership, {node, down, node()}},
+    ct:sleep(100),
+    ?assertEqual([], emqx_cm_registry:lookup_channels(ClientId)),
+    ?assertEqual([], emqx_cm_registry:lookup_channels(ClientId2)).

apps/emqx/test/emqx_router_helper_SUITE.erl

@@ -19,18 +19,61 @@
 -compile(export_all).
 -compile(nowarn_export_all).
 
+-include("emqx.hrl").
 -include_lib("eunit/include/eunit.hrl").
+-include_lib("common_test/include/ct.hrl").
+-include_lib("snabbkaffe/include/snabbkaffe.hrl").
 
 -define(ROUTER_HELPER, emqx_router_helper).
+-define(ROUTE_TAB, emqx_route).
 
 all() -> emqx_common_test_helpers:all(?MODULE).
 
 init_per_suite(Config) ->
+    DistPid = case net_kernel:nodename() of
+                  ignored ->
+                      %% calling `net_kernel:start' without `epmd'
+                      %% running will result in a failure.
+                      start_epmd(),
+                      {ok, Pid} = net_kernel:start(['test@127.0.0.1', longnames]),
+                      Pid;
+                  _ ->
+                      undefined
+              end,
     emqx_common_test_helpers:start_apps([]),
+    [{dist_pid, DistPid} | Config].
+
+end_per_suite(Config) ->
+    DistPid = ?config(dist_pid, Config),
+    case DistPid of
+        Pid when is_pid(Pid) ->
+            net_kernel:stop();
+        _ ->
+            ok
+    end,
+    emqx_common_test_helpers:stop_apps([]).
+
+init_per_testcase(TestCase, Config)
+      when TestCase =:= t_cleanup_membership_mnesia_down;
+           TestCase =:= t_cleanup_membership_node_down;
+           TestCase =:= t_cleanup_monitor_node_down ->
+    ok = snabbkaffe:start_trace(),
+    Slave = start_slave(some_node),
+    [{slave, Slave} | Config];
+init_per_testcase(_TestCase, Config) ->
     Config.
 
-end_per_suite(_Config) ->
-    emqx_common_test_helpers:stop_apps([]).
+end_per_testcase(TestCase, Config)
+      when TestCase =:= t_cleanup_membership_mnesia_down;
+           TestCase =:= t_cleanup_membership_node_down;
+           TestCase =:= t_cleanup_monitor_node_down ->
+    Slave = ?config(slave, Config),
+    stop_slave(Slave),
+    mria:transaction(?ROUTE_SHARD, fun() -> mnesia:clear_table(?ROUTE_TAB) end),
+    snabbkaffe:stop(),
+    ok;
+end_per_testcase(_TestCase, _Config) ->
+    ok.
 
 t_monitor(_) ->
     ok = emqx_router_helper:monitor({undefined, node()}),
@@ -44,7 +87,74 @@ t_mnesia(_) ->
     ?ROUTER_HELPER ! {membership, {mnesia, down, node()}},
     ct:sleep(200).
 
+t_cleanup_membership_mnesia_down(Config) ->
+    Slave = ?config(slave, Config),
+    emqx_router:add_route(<<"a/b/c">>, Slave),
+    emqx_router:add_route(<<"d/e/f">>, node()),
+    ?assertMatch([_, _], emqx_router:topics()),
+    ?wait_async_action(
+       ?ROUTER_HELPER ! {membership, {mnesia, down, Slave}},
+       #{?snk_kind := emqx_router_helper_cleanup_done, node := Slave},
+       1_000),
+    ?assertEqual([<<"d/e/f">>], emqx_router:topics()).
+
+t_cleanup_membership_node_down(Config) ->
+    Slave = ?config(slave, Config),
+    emqx_router:add_route(<<"a/b/c">>, Slave),
+    emqx_router:add_route(<<"d/e/f">>, node()),
+    ?assertMatch([_, _], emqx_router:topics()),
+    ?wait_async_action(
+       ?ROUTER_HELPER ! {membership, {node, down, Slave}},
+       #{?snk_kind := emqx_router_helper_cleanup_done, node := Slave},
+       1_000),
+    ?assertEqual([<<"d/e/f">>], emqx_router:topics()).
+
+t_cleanup_monitor_node_down(Config) ->
+    Slave = ?config(slave, Config),
+    emqx_router:add_route(<<"a/b/c">>, Slave),
+    emqx_router:add_route(<<"d/e/f">>, node()),
+    ?assertMatch([_, _], emqx_router:topics()),
+    ?wait_async_action(
+       stop_slave(Slave),
+       #{?snk_kind := emqx_router_helper_cleanup_done, node := Slave},
+       1_000),
+    ?assertEqual([<<"d/e/f">>], emqx_router:topics()).
+
 t_message(_) ->
     ?ROUTER_HELPER ! testing,
     gen_server:cast(?ROUTER_HELPER, testing),
     gen_server:call(?ROUTER_HELPER, testing).
+
+%%------------------------------------------------------------------------------
+%% Internal functions
+%%------------------------------------------------------------------------------
+
+start_epmd() ->
+    [] = os:cmd("\"" ++ epmd_path() ++ "\" -daemon"),
+    ok.
+
+epmd_path() ->
+    case os:find_executable("epmd") of
+        false ->
+            ct:pal(critical, "Could not find epmd.~n"),
+            exit(epmd_not_found);
+        GlobalEpmd ->
+            GlobalEpmd
+    end.
+
+start_slave(Name) ->
+    CommonBeamOpts = "+S 1:1 ", % We want VMs to only occupy a single core
+    {ok, Node} = slave:start_link(host(), Name, CommonBeamOpts ++ ebin_path()),
+    Node.
+
+stop_slave(Node) ->
+    slave:stop(Node).
+
+host() ->
+    [_, Host] = string:tokens(atom_to_list(node()), "@"), Host.
+
+ebin_path() ->
+    string:join(["-pa" | lists:filter(fun is_lib/1, code:get_path())], " ").
+
+is_lib(Path) ->
+    string:prefix(Path, code:lib_dir()) =:= nomatch.

apps/emqx_gateway/src/emqx_gateway_cm_registry.erl

@@ -64,7 +64,7 @@ tabname(Name) ->
 register_channel(Name, ClientId) when is_binary(ClientId) ->
     register_channel(Name, {ClientId, self()});
 
-register_channel(Name, {ClientId, ChanPid}) 
+register_channel(Name, {ClientId, ChanPid})
   when is_binary(ClientId), is_pid(ChanPid) ->
     mria:dirty_write(tabname(Name), record(ClientId, ChanPid)).
 
@@ -113,12 +113,11 @@ handle_cast(Msg, State) ->
     {noreply, State}.
 
 handle_info({membership, {mnesia, down, Node}}, State = #{name := Name}) ->
-    Tab = tabname(Name),
-    global:trans(
-      {?LOCK, self()},
-      fun() ->
-        mria:transaction(?CM_SHARD, fun cleanup_channels/2, [Node, Tab])
-      end),
+    cleanup_channels(Node, Name),
+    {noreply, State};
+
+handle_info({membership, {node, down, Node}}, State = #{name := Name}) ->
+    cleanup_channels(Node, Name),
     {noreply, State};
 
 handle_info({membership, _Event}, State) ->
@@ -138,7 +137,15 @@ code_change(_OldVsn, State, _Extra) ->
 %% Internal functions
 %%--------------------------------------------------------------------
 
-cleanup_channels(Node, Tab) ->
+cleanup_channels(Node, Name) ->
+    Tab = tabname(Name),
+    global:trans(
+      {?LOCK, self()},
+      fun() ->
+        mria:transaction(?CM_SHARD, fun do_cleanup_channels/2, [Node, Tab])
+      end).
+
+do_cleanup_channels(Node, Tab) ->
     Pat = [{#channel{pid = '$1', _ = '_'}, [{'==', {node, '$1'}, Node}], ['$_']}],
     lists:foreach(fun(Chan) ->
         mnesia:delete_object(Tab, Chan, write)

apps/emqx_gateway/test/emqx_gateway_cm_registry_SUITE.erl

@@ -72,13 +72,13 @@ t_register_unregister_channel(_) ->
     ok = emqx_gateway_cm_registry:unregister_channel(?GWNAME, ?CLIENTID),
 
     ?assertEqual(
-       [], 
+       [],
        ets:tab2list(emqx_gateway_cm_registry:tabname(?GWNAME))),
     ?assertEqual(
        [],
        emqx_gateway_cm_registry:lookup_channels(?GWNAME, ?CLIENTID)).
 
-t_cleanup_channels(Conf) ->
+t_cleanup_channels_mnesia_down(Conf) ->
     Pid = proplists:get_value(registry, Conf),
     emqx_gateway_cm_registry:register_channel(?GWNAME, ?CLIENTID),
     ?assertEqual(
@@ -90,6 +90,18 @@ t_cleanup_channels(Conf) ->
        [],
        emqx_gateway_cm_registry:lookup_channels(?GWNAME, ?CLIENTID)).
 
+t_cleanup_channels_node_down(Conf) ->
+    Pid = proplists:get_value(registry, Conf),
+    emqx_gateway_cm_registry:register_channel(?GWNAME, ?CLIENTID),
+    ?assertEqual(
+       [self()],
+       emqx_gateway_cm_registry:lookup_channels(?GWNAME, ?CLIENTID)),
+    Pid ! {membership, {node, down, node()}},
+    ct:sleep(100),
+    ?assertEqual(
+       [],
+       emqx_gateway_cm_registry:lookup_channels(?GWNAME, ?CLIENTID)).
+
 t_handle_unexpected_msg(Conf) ->
     Pid = proplists:get_value(registry, Conf),
     _ = Pid ! unexpected_info,