Add manual start API

src/portal/emqx_portal.erl

@@ -36,11 +36,12 @@
 %%
 %% Batch collector state diagram
 %%
-%% [connecting] --(2)--> [connected]
-%%  |        ^                 |
-%%  |        |                 |
-%%  '--(1)---'--------(3)------'
+%% [standing_by] --(0) --> [connecting] --(2)--> [connected]
+%%                          |        ^                 |
+%%                          |        |                 |
+%%                          '--(1)---'--------(3)------'
 %%
+%% (0): auto or manual start
 %% (1): retry timeout
 %% (2): successfuly connected to remote node/cluster
 %% (3): received {disconnected, conn_ref(), Reason} OR
@@ -70,9 +71,10 @@
 -export([terminate/3, code_change/4, init/1, callback_mode/0]).
 
 %% state functions
--export([connecting/3, connected/3]).
+-export([standing_by/3, connecting/3, connected/3]).
 
 %% management APIs
+-export([ensure_started/2, ensure_stopped/1, ensure_stopped/2]).
 -export([get_forwards/1, ensure_forward_present/2, ensure_forward_absent/2]).
 -export([get_subscriptions/1, ensure_subscription_present/3, ensure_subscription_absent/2]).
 
@@ -100,6 +102,8 @@
 -define(maybe_send, {next_event, internal, maybe_send}).
 
 %% @doc Start a portal worker. Supported configs:
+%% start_type: 'manual' (default) or 'auto', when manual, portal will stay
+%%      at 'standing_by' state until a manual call to start it.
 %% connect_module: The module which implements emqx_portal_connect behaviour
 %%      and work as message batch transport layer
 %% reconnect_delay_ms: Delay in milli-seconds for the portal worker to retry
@@ -123,6 +127,38 @@ start_link(Name, Config) when is_list(Config) ->
 start_link(Name, Config) ->
     gen_statem:start_link({local, name(Name)}, ?MODULE, Config, []).
 
+%% @doc Manually start portal worker. State idempotency ensured.
+ensure_started(Name, Config) ->
+    case start_link(Name, Config) of
+        {ok, Pid} -> {ok, Pid};
+        {error, {already_started,Pid}} -> {ok, Pid}
+    end.
+
+%% @doc Manually stop portal worker. State idempotency ensured.
+ensure_stopped(Id) ->
+    ensure_stopped(Id, 1000).
+
+ensure_stopped(Id, Timeout) ->
+    Pid = case id(Id) of
+              P when is_pid(P) -> P;
+              N -> whereis(N)
+          end,
+    case Pid of
+        undefined ->
+            ok;
+        _ ->
+            MRef = monitor(process, Pid),
+            unlink(Pid),
+            _ = gen_statem:call(id(Id), ensure_stopped, Timeout),
+            receive
+                {'DOWN', MRef, _, _, _} ->
+                    ok
+            after
+                Timeout ->
+                    exit(Pid, kill)
+            end
+    end.
+
 stop(Pid) -> gen_statem:stop(Pid).
 
 %% @doc This function is to be evaluated on message/batch receiver side.
@@ -193,7 +229,6 @@ init(Config) ->
                                               true = emqx_topic:validate({filter, T}),
                                               {T, QoS}
                                       end, Get(subscriptions, []))),
-    ok = subscribe_local_topics(Topics),
     ConnectModule = maps:get(connect_module, Config),
     ConnectConfig = maps:without([connect_module,
                                   queue,
@@ -203,9 +238,10 @@ init(Config) ->
                                   forwards
                                  ], Config#{subscriptions => Subs}),
     ConnectFun = fun(SubsX) -> emqx_portal_connect:start(ConnectModule, ConnectConfig#{subscriptions := SubsX}) end,
-    {ok, connecting,
+    {ok, standing_by,
      #{connect_module => ConnectModule,
        connect_fun => ConnectFun,
+       start_type => Get(start_type, manual),
        reconnect_delay_ms => maps:get(reconnect_delay_ms, Config, ?DEFAULT_RECONNECT_DELAY_MS),
        batch_bytes_limit => GetQ(batch_bytes_limit, ?DEFAULT_BATCH_BYTES),
        batch_count_limit => GetQ(batch_count_limit, ?DEFAULT_BATCH_COUNT),
@@ -225,16 +261,36 @@ terminate(_Reason, _StateName, #{replayq := Q} = State) ->
     _ = replayq:close(Q),
     ok.
 
+%% @doc Standing by for manual start.
+standing_by(enter, _, #{start_type := auto}) ->
+    Action = {state_timeout, 0, do_connect},
+    {keep_state_and_data, Action};
+standing_by(enter, _, #{start_type := manual}) ->
+    keep_state_and_data;
+standing_by({call, From}, ensure_started, State) ->
+    {next_state, connecting, State, [{reply, From, ok}]};
+standing_by({call, From}, ensure_stopped, _State) ->
+    {stop_and_reply, {shutdown, manual}, [{reply, From, ok}]};
+standing_by(state_timeout, do_connect, State) ->
+    {next_state, connecting, State};
+standing_by({call, From}, _Call, _State) ->
+    {keep_state_and_data, [{reply, From, {error, standing_by}}]};
+standing_by(info, Info, State) ->
+    ?INFO("Portal ~p discarded info event at state standing_by:\n~p", [name(), Info]),
+    {keep_state_and_data, State}.
+
 %% @doc Connecting state is a state with timeout.
 %% After each timeout, it re-enters this state and start a retry until
 %% successfuly connected to remote node/cluster.
 connecting(enter, connected, #{reconnect_delay_ms := Timeout}) ->
     Action = {state_timeout, Timeout, reconnect},
     {keep_state_and_data, Action};
-connecting(enter, connecting, #{reconnect_delay_ms := Timeout,
-                                connect_fun := ConnectFun,
-                                subscriptions := Subs
-                               } = State) ->
+connecting(enter, _, #{reconnect_delay_ms := Timeout,
+                       connect_fun := ConnectFun,
+                       subscriptions := Subs,
+                       forwards := Forwards
+                      } = State) ->
+    ok = subscribe_local_topics(Forwards),
     case ConnectFun(Subs) of
         {ok, ConnRef, Conn} ->
             Action = {state_timeout, 0, connected},
@@ -300,6 +356,8 @@ connected(Type, Content, State) ->
     common(connected, Type, Content, State).
 
 %% Common handlers
+common(_StateName, {call, From}, ensure_started, _State) ->
+    {keep_state_and_data, [{reply, From, ok}]};
 common(_StateName, {call, From}, get_forwards, #{forwards := Forwards}) ->
     {keep_state_and_data, [{reply, From, Forwards}]};
 common(_StateName, {call, From}, get_subscriptions, #{subscriptions := Subs}) ->
@@ -310,6 +368,8 @@ common(_StateName, {call, From}, {ensure_present, What, Topic}, State) ->
 common(_StateName, {call, From}, {ensure_absent, What, Topic}, State) ->
     {Result, NewState} = ensure_absent(What, Topic, State),
     {keep_state, NewState, [{reply, From, Result}]};
+common(_StateName, {call, From}, ensure_stopped, _State) ->
+    {stop_and_reply, {shutdown, manual}, [{reply, From, ok}]};
 common(_StateName, info, {dispatch, _, Msg},
        #{replayq := Q} = State) ->
     NewQ = replayq:append(Q, collect([Msg])),

test/emqx_portal_SUITE.erl

@@ -50,7 +50,8 @@ t_mngr(Config) when is_list(Config) ->
             forwards => [<<"mngr">>],
             connect_module => emqx_portal_rpc,
             mountpoint => <<"forwarded">>,
-            subscriptions => Subs
+            subscriptions => Subs,
+            start_type => auto
            },
     Name = ?FUNCTION_NAME,
     {ok, Pid} = emqx_portal:start_link(Name, Cfg),
@@ -76,7 +77,8 @@ t_rpc(Config) when is_list(Config) ->
     Cfg = #{address => node(),
             forwards => [<<"t_rpc/#">>],
             connect_module => emqx_portal_rpc,
-            mountpoint => <<"forwarded">>
+            mountpoint => <<"forwarded">>,
+            start_type => auto
            },
     {ok, Pid} = emqx_portal:start_link(?FUNCTION_NAME, Cfg),
     ClientId = <<"ClientId">>,
@@ -125,10 +127,10 @@ t_mqtt(Config) when is_list(Config) ->
                       },
             reconnect_delay_ms => 1000,
             ssl => false,
-            start_type => manual,
             %% Consume back to forwarded message for verification
             %% NOTE: this is a indefenite loopback without mocking emqx_portal:import_batch/2
-            subscriptions => [{ForwardedTopic, _QoS = 1}]
+            subscriptions => [{ForwardedTopic, _QoS = 1}],
+            start_type => auto
            },
     Tester = self(),
     Ref = make_ref(),

test/emqx_portal_tests.erl

@@ -96,6 +96,20 @@ test_buffer_when_disconnected() ->
     ?WAIT({'DOWN', ReceiverMref, process, Receiver, normal}, 1000),
     ok = emqx_portal:stop(?PORTAL_REG_NAME).
 
+manual_start_stop_test() ->
+    Ref = make_ref(),
+    Config0 = make_config(Ref, self(), {ok, Ref, connection}),
+    Config = Config0#{start_type := manual},
+    {ok, Pid} = emqx_portal:ensure_started(?PORTAL_NAME, Config),
+    %% call ensure_started again should yeld the same result
+    {ok, Pid} = emqx_portal:ensure_started(?PORTAL_NAME, Config),
+    ?assertEqual(Pid, whereis(?PORTAL_REG_NAME)),
+    ?assertEqual({error, standing_by},
+                 emqx_portal:ensure_forward_present(Pid, "dummy")),
+    ok = emqx_portal:ensure_stopped(unknown),
+    ok = emqx_portal:ensure_stopped(Pid),
+    ok = emqx_portal:ensure_stopped(?PORTAL_REG_NAME).
+
 %% Feed messages to portal
 sender_loop(_Pid, [], _) -> exit(normal);
 sender_loop(Pid, [Num | Rest], Interval) ->
@@ -133,7 +147,8 @@ make_config(Ref, TestPid, Result) ->
       test_ref => Ref,
       connect_module => ?MODULE,
       reconnect_delay_ms => 50,
-      connect_result => Result
+      connect_result => Result,
+      start_type => auto
      }.
 
 make_msg(I) ->