feat(mqttconn): subscribe each worker if shared subcription

Also rename `subscriptions` -> `ingress` and `forwards` -> `egress` for
consistency with the config schema.

apps/emqx_bridge/test/emqx_bridge_mqtt_SUITE.erl

@@ -221,6 +221,12 @@ t_mqtt_conn_bridge_ingress(_) ->
         request(put, uri(["bridges", BridgeIDIngress]), ServerConf)
     ),
 
+    %% non-shared subscription, verify that only one client is subscribed
+    ?assertEqual(
+        1,
+        length(emqx:subscribers(<<?INGRESS_REMOTE_TOPIC, "/#">>))
+    ),
+
     %% we now test if the bridge works as expected
     RemoteTopic = <<?INGRESS_REMOTE_TOPIC, "/1">>,
     LocalTopic = <<?INGRESS_LOCAL_TOPIC, "/", RemoteTopic/binary>>,
@@ -245,6 +251,48 @@ t_mqtt_conn_bridge_ingress(_) ->
 
     ok.
 
+t_mqtt_conn_bridge_ingress_shared_subscription(_) ->
+    PoolSize = 4,
+    Ns = lists:seq(1, 10),
+    BridgeName = atom_to_binary(?FUNCTION_NAME),
+    BridgeID = create_bridge(
+        ?SERVER_CONF(<<>>)#{
+            <<"type">> => ?TYPE_MQTT,
+            <<"name">> => BridgeName,
+            <<"pool_size">> => PoolSize,
+            <<"ingress">> => #{
+                <<"remote">> => #{
+                    <<"topic">> => <<"$share/ingress/", ?INGRESS_REMOTE_TOPIC, "/#">>,
+                    <<"qos">> => 1
+                },
+                <<"local">> => #{
+                    <<"topic">> => <<?INGRESS_LOCAL_TOPIC, "/${topic}">>,
+                    <<"qos">> => <<"${qos}">>,
+                    <<"payload">> => <<"${clientid}">>,
+                    <<"retain">> => <<"${retain}">>
+                }
+            }
+        }
+    ),
+
+    RemoteTopic = <<?INGRESS_REMOTE_TOPIC, "/1">>,
+    LocalTopic = <<?INGRESS_LOCAL_TOPIC, "/", RemoteTopic/binary>>,
+    ok = emqx:subscribe(LocalTopic),
+
+    _ = emqx_utils:pmap(
+        fun emqx:publish/1,
+        [emqx_message:make(RemoteTopic, <<>>) || _ <- Ns]
+    ),
+    _ = [assert_mqtt_msg_received(LocalTopic) || _ <- Ns],
+
+    ?assertEqual(
+        PoolSize,
+        length(emqx_shared_sub:subscribers(<<"ingress">>, <<?INGRESS_REMOTE_TOPIC, "/#">>))
+    ),
+
+    {ok, 204, <<>>} = request(delete, uri(["bridges", BridgeID]), []),
+    ok.
+
 t_mqtt_egress_bridge_ignores_clean_start(_) ->
     BridgeName = atom_to_binary(?FUNCTION_NAME),
     BridgeID = create_bridge(

apps/emqx_connector/src/emqx_connector_mqtt.erl

@@ -54,8 +54,8 @@ on_start(ResourceId, Conf) ->
     }),
     BasicOpts = mk_worker_opts(ResourceId, Conf),
     BridgeOpts = BasicOpts#{
-        subscriptions => make_sub_confs(maps:get(ingress, Conf, #{}), Conf, ResourceId),
+        ingress => mk_ingress_config(maps:get(ingress, Conf, #{}), Conf, ResourceId),
-        forwards => maps:get(egress, Conf, #{})
+        egress => maps:get(egress, Conf, #{})
     },
     {ok, ClientOpts, WorkerConf} = emqx_connector_mqtt_worker:init(ResourceId, BridgeOpts),
     case emqx_resource_pool:start(ResourceId, emqx_connector_mqtt_worker, ClientOpts) of
@@ -165,12 +165,12 @@ combine_status(Statuses) ->
             disconnected
     end.
 
-make_sub_confs(Subscriptions, _Conf, _) when map_size(Subscriptions) == 0 ->
+mk_ingress_config(Ingress, _Conf, _) when map_size(Ingress) == 0 ->
-    Subscriptions;
+    Ingress;
-make_sub_confs(Subscriptions, #{hookpoint := HookPoint}, ResourceId) ->
+mk_ingress_config(Ingress, #{hookpoint := HookPoint}, ResourceId) ->
     MFA = {?MODULE, on_message_received, [HookPoint, ResourceId]},
-    Subscriptions#{on_message_received => MFA};
+    Ingress#{on_message_received => MFA};
-make_sub_confs(_SubRemoteConf, Conf, ResourceId) ->
+mk_ingress_config(_Ingress, Conf, ResourceId) ->
     error({no_hookpoint_provided, ResourceId, Conf}).
 
 mk_worker_opts(

apps/emqx_connector/src/mqtt/emqx_connector_mqtt_worker.erl

@@ -60,21 +60,18 @@
     ssl := boolean(),
     ssl_opts := proplists:proplist(),
     % bridge options
-    subscriptions := map(),
+    ingress := map(),
-    forwards := map()
+    egress := map()
 }.
 
 -type client_option() ::
     emqtt:option()
     | {name, name()}
-    | {subscriptions, subscriptions() | undefined}.
+    | {ingress, ingress() | undefined}.
 
--type config() :: #{
+-type config() :: egress() | undefined.
-    subscriptions := subscriptions() | undefined,
-    forwards := forwards() | undefined
-}.
 
--type subscriptions() :: #{
+-type ingress() :: #{
     remote := #{
         topic := emqx_topic:topic(),
         qos => emqx_types:qos()
@@ -83,7 +80,7 @@
     on_message_received := {module(), atom(), [term()]}
 }.
 
--type forwards() :: #{
+-type egress() :: #{
     local => #{
         topic => emqx_topic:topic()
     },
@@ -103,13 +100,10 @@
 -spec init(name(), options()) ->
     {ok, [client_option()], config()}.
 init(Name, BridgeOpts) ->
-    Config = init_config(Name, BridgeOpts),
+    Ingress = pre_process_ingress(maps:get(ingress, BridgeOpts), Name, BridgeOpts),
-    ClientOpts0 = mk_client_options(Config, BridgeOpts),
+    Egress = pre_process_egress(maps:get(egress, BridgeOpts)),
-    ClientOpts = ClientOpts0#{
+    ClientOpts = mk_client_options(Name, Ingress, BridgeOpts),
-        name => Name,
+    {ok, maps:to_list(ClientOpts), Egress}.
-        subscriptions => maps:get(subscriptions, Config)
-    },
-    {ok, maps:to_list(ClientOpts), Config}.
 
 %% @doc Start a bridge worker.
 -spec connect([client_option() | {ecpool_worker_id, pos_integer()}]) ->
@@ -134,7 +128,7 @@ connect(ClientOpts0) ->
     end.
 
 mk_emqtt_opts(WorkerId, ClientOpts) ->
-    {_, ClientId} = lists:keyfind(clientid, 1, ClientOpts),
+    ClientId = proplists:get_value(clientid, ClientOpts),
     lists:keystore(clientid, 1, ClientOpts, {clientid, mk_clientid(WorkerId, ClientId)}).
 
 mk_clientid(WorkerId, ClientId) ->
@@ -143,10 +137,8 @@ mk_clientid(WorkerId, ClientId) ->
 connect(Pid, Name, WorkerId, ClientOpts) ->
     case emqtt:connect(Pid) of
         {ok, _Props} ->
-            % NOTE
+            Ingress = proplists:get_value(ingress, ClientOpts),
-            % Subscribe to remote topics only when the first worker is started.
+            case subscribe_remote_topic(Pid, WorkerId, Ingress) of
-            Subscriptions = proplists:get_value(subscriptions, ClientOpts),
-            case WorkerId =:= 1 andalso subscribe_remote_topics(Pid, Subscriptions) of
                 false ->
                     {ok, Pid};
                 {ok, _, _RCs} ->
@@ -154,7 +146,7 @@ connect(Pid, Name, WorkerId, ClientOpts) ->
                 {error, Reason} = Error ->
                     ?SLOG(error, #{
                         msg => "client_subscribe_failed",
-                        subscriptions => Subscriptions,
+                        ingress => Ingress,
                         reason => Reason
                     }),
                     _ = catch emqtt:stop(Pid),
@@ -170,25 +162,25 @@ connect(Pid, Name, WorkerId, ClientOpts) ->
             Error
     end.
 
-subscribe_remote_topics(Pid, #{remote := #{topic := RemoteTopic, qos := QoS}}) ->
+subscribe_remote_topic(Pid, WorkerId, #{remote := #{topic := RemoteTopic, qos := QoS}}) ->
-    emqtt:subscribe(Pid, RemoteTopic, QoS);
+    case emqx_topic:parse(RemoteTopic) of
-subscribe_remote_topics(_Ref, undefined) ->
+        {_Filter, #{share := _Name}} ->
+            % NOTE: this is shared subscription, each worker may subscribe
+            emqtt:subscribe(Pid, RemoteTopic, QoS);
+        {_Filter, #{}} when WorkerId =:= 1 ->
+            % NOTE: this is regular subscription, only the first worker should subscribe
+            emqtt:subscribe(Pid, RemoteTopic, QoS);
+        {_Filter, #{}} ->
+            false
+    end;
+subscribe_remote_topic(_Ref, _, undefined) ->
     false.
 
-init_config(Name, Opts) ->
+mk_client_options(Name, Ingress, BridgeOpts) ->
-    Subscriptions = maps:get(subscriptions, Opts, undefined),
-    Forwards = maps:get(forwards, Opts, undefined),
-    #{
-        subscriptions => pre_process_subscriptions(Subscriptions, Name, Opts),
-        forwards => pre_process_forwards(Forwards)
-    }.
-
-mk_client_options(Config, BridgeOpts) ->
     Server = iolist_to_binary(maps:get(server, BridgeOpts)),
     HostPort = emqx_connector_mqtt_schema:parse_server(Server),
-    Subscriptions = maps:get(subscriptions, Config),
     CleanStart =
-        case Subscriptions of
+        case Ingress of
             #{remote := _} ->
                 maps:get(clean_start, BridgeOpts);
             undefined ->
@@ -214,16 +206,18 @@ mk_client_options(Config, BridgeOpts) ->
         BridgeOpts
     ),
     Opts#{
-        msg_handler => mk_client_event_handler(Subscriptions, #{server => Server}),
+        name => Name,
+        ingress => Ingress,
+        msg_handler => mk_client_event_handler(Ingress, #{server => Server}),
         hosts => [HostPort],
         clean_start => CleanStart,
         force_ping => true
     }.
 
-mk_client_event_handler(Subscriptions = #{}, Opts) ->
+mk_client_event_handler(Ingress = #{}, Opts) ->
-    OnMessage = maps:get(on_message_received, Subscriptions, undefined),
+    OnMessage = maps:get(on_message_received, Ingress, undefined),
     LocalPublish =
-        case Subscriptions of
+        case Ingress of
             #{local := Local = #{topic := _}} ->
                 Local;
             #{} ->
@@ -275,26 +269,26 @@ do_send_async(Pid, Msg, Callback) when Msg /= undefined ->
 do_send_async(_Pid, undefined, _Callback) ->
     ok.
 
-pre_process_subscriptions(
+pre_process_ingress(
     #{remote := RC, local := LC} = Conf,
     BridgeName,
     BridgeOpts
 ) when is_map(Conf) ->
     Conf#{
         remote => pre_process_in_remote(RC, BridgeName, BridgeOpts),
-        local => pre_process_in_out_common(LC)
+        local => pre_process_common(LC)
     };
-pre_process_subscriptions(Conf, _, _) when is_map(Conf) ->
+pre_process_ingress(Conf, _, _) when is_map(Conf) ->
     %% have no 'local' field in the config
     undefined.
 
-pre_process_forwards(#{remote := RC} = Conf) when is_map(Conf) ->
+pre_process_egress(#{remote := RC} = Conf) when is_map(Conf) ->
-    Conf#{remote => pre_process_in_out_common(RC)};
+    Conf#{remote => pre_process_common(RC)};
-pre_process_forwards(Conf) when is_map(Conf) ->
+pre_process_egress(Conf) when is_map(Conf) ->
     %% have no 'remote' field in the config
     undefined.
 
-pre_process_in_out_common(Conf0) ->
+pre_process_common(Conf0) ->
     Conf1 = pre_process_conf(topic, Conf0),
     Conf2 = pre_process_conf(qos, Conf1),
     Conf3 = pre_process_conf(payload, Conf2),
@@ -331,9 +325,9 @@ downgrade_ingress_qos(2) ->
 downgrade_ingress_qos(QoS) ->
     QoS.
 
-export_msg(Msg, #{forwards := #{remote := Remote}}) ->
+export_msg(Msg, #{remote := Remote}) ->
     to_remote_msg(Msg, Remote);
-export_msg(Msg, #{forwards := undefined}) ->
+export_msg(Msg, undefined) ->
     ?SLOG(error, #{
         msg => "forwarding_unavailable",
         message => Msg,