Refine emqx_mock_client

Before this change, eqmx_mock_client uses a shared ets table
to store last received message, this causes troulbe when we
want to start / stop two or more clients in one test case
the ets table gets owned by the first spanwed client and
gets closed when the owner client dies.

Now it keeps the last received message in process state
and a gen_server call is added to retrieve it for verification

Along with this change in emqx_mock_client, it made possible
to write test case to verify the actual subscriber pid
used in shared subscription strategy, so test cases were
added (and modified) to verify different strategies

test/emqx_mock_client.erl

@@ -16,15 +16,12 @@
 
 -behaviour(gen_server).
 
--export([start_link/1, open_session/3, close_session/2, stop/1, get_last_message/0,
-         try_get_last_message/0]).
+-export([start_link/1, open_session/3, close_session/2, stop/1, get_last_message/1]).
 
 -export([init/1, handle_call/3, handle_cast/2, handle_info/2,
          terminate/2, code_change/3]).
 
--record(state, {clean_start, client_id, client_pid}).
-
--define(TAB, messages).
+-record(state, {clean_start, client_id, client_pid, last_msg}).
 
 start_link(ClientId) ->
     gen_server:start_link(?MODULE, [ClientId], []).
@@ -38,25 +35,14 @@ close_session(ClientPid, SessPid) ->
 stop(CPid) ->
     gen_server:call(CPid, stop).
 
-get_last_message() ->
-    [{last_message, Msg}] = ets:lookup(?TAB, last_message),
-    Msg.
-
-try_get_last_message() ->
-    case ets:lookup(?TAB, last_message) of
-        [{last_message, Msg}] -> Msg;
-        [] -> false
-    end.
+get_last_message(Pid) ->
+    gen_server:call(Pid, get_last_message).
 
 init([ClientId]) ->
-    Result = lists:member(?TAB, ets:all()),
-    if Result == false -> 
-        ets:new(?TAB, [set, named_table, public]);
-       true -> ok
-    end,
-    {ok, 
-     #state{clean_start = true,
-            client_id = ClientId}
+    {ok, #state{clean_start = true,
+                client_id = ClientId,
+                last_msg = undefined
+               }
     }.
 
 handle_call({start_session, ClientPid, ClientId, Zone}, _From, State) ->
@@ -68,28 +54,26 @@ handle_call({start_session, ClientPid, ClientId, Zone}, _From, State) ->
                expiry_interval  => 0
              },
     {ok, SessPid} = emqx_sm:open_session(Attrs),
-    {reply, {ok, SessPid}, State#state{
-                             clean_start = true,
+    {reply, {ok, SessPid},
+     State#state{clean_start = true,
                  client_id = ClientId,
                  client_pid = ClientPid
                 }};
-
 handle_call({stop_session, SessPid}, _From, State) ->
     emqx_sm:close_session(SessPid),
     {stop, normal, ok, State};
-
+handle_call(get_last_message, _From, #state{last_msg = Msg} = State) ->
+    {reply, Msg, State};
 handle_call(stop, _From, State) ->
     {stop, normal, ok, State};
-
 handle_call(_Request, _From, State) ->
     {reply, ok, State}.
 
 handle_cast(_Msg, State) ->
     {noreply, State}.
 
-handle_info({_, Msg}, State) ->
-    ets:insert(?TAB, {last_message, Msg}),
-    {noreply, State};
+handle_info({deliver, Msg}, State) ->
+    {noreply, State#state{last_msg = Msg}};
 handle_info(_Info, State) ->
     {noreply, State}.
 

test/emqx_session_SUITE.erl

@@ -40,7 +40,7 @@ t_session_all(_) ->
     [{<<"topic">>, _}] = emqx:subscriptions({SPid, <<"ClientId">>}),
     emqx_session:publish(SPid, 1, Message1),
     timer:sleep(200),
-    {publish, 1, _} = emqx_mock_client:get_last_message(),
+    {publish, 1, _} = emqx_mock_client:get_last_message(ConnPid),
     emqx_session:puback(SPid, 2),
     emqx_session:puback(SPid, 3, reasoncode),
     emqx_session:pubrec(SPid, 4),

test/emqx_shared_sub_SUITE.erl

@@ -19,6 +19,7 @@
 -export([t_random_basic/1, t_random/1, t_round_robin/1, t_sticky/1, t_hash/1, t_not_so_sticky/1]).
 
 -include("emqx.hrl").
+-include_lib("eunit/include/eunit.hrl").
 -include_lib("common_test/include/ct.hrl").
 
 -define(wait(For, Timeout), wait_for(?FUNCTION_NAME, ?LINE, fun() -> For end, Timeout)).
@@ -32,7 +33,7 @@ init_per_suite(Config) ->
 end_per_suite(_Config) ->
     emqx_ct_broker_helpers:run_teardown_steps().
 
-t_random(_) ->
+t_random_basic(_) ->
     application:set_env(?APPLICATION, shared_subscription_strategy, random),
     ClientId = <<"ClientId">>,
     {ok, ConnPid} = emqx_mock_client:start_link(ClientId),
@@ -42,7 +43,7 @@ t_random(_) ->
     %% wait for the subscription to show up
     ?wait(ets:lookup(emqx_alive_shared_subscribers, SPid) =:= [{SPid}], 1000),
     emqx_session:publish(SPid, 1, Message1),
-    ?wait(case emqx_mock_client:try_get_last_message() of
+    ?wait(case emqx_mock_client:get_last_message(ConnPid) of
               {publish, 1, _} -> true;
               Other -> Other
           end, 1000),
@@ -55,6 +56,9 @@ t_random(_) ->
     emqx_mock_client:close_session(ConnPid, SPid),
     ok.
 
+t_random(_) ->
+    test_two_messages(random).
+
 t_round_robin(_) ->
     test_two_messages(round_robin).
 
@@ -76,17 +80,19 @@ t_not_so_sticky(_) ->
     Message1 = emqx_message:make(ClientId1, 0, <<"foo/bar">>, <<"hello1">>),
     Message2 = emqx_message:make(ClientId1, 0, <<"foo/bar">>, <<"hello2">>),
     emqx_session:subscribe(SPid1, [{<<"foo/bar">>, #{qos => 0, share => <<"group1">>}}]),
-    emqx_session:subscribe(SPid2, [{<<"foo/#">>, #{qos => 0, share => <<"group1">>}}]),
     %% wait for the subscription to show up
-    ?wait(ets:lookup(emqx_alive_shared_subscribers, SPid1) =:= [{SPid1}] andalso
-          ets:lookup(emqx_alive_shared_subscribers, SPid2) =:= [{SPid2}], 1000),
+    ?wait(ets:lookup(emqx_alive_shared_subscribers, SPid1) =:= [{SPid1}], 1000),
     emqx_session:publish(SPid1, 1, Message1),
-    ?wait(case emqx_mock_client:try_get_last_message() of
+    ?wait(case emqx_mock_client:get_last_message(ConnPid1) of
               {publish, _, #message{payload = <<"hello1">>}} -> true;
               Other -> Other
           end, 1000),
-    emqx_session:publish(SPid1, 2, Message2),
-    ?wait(case emqx_mock_client:try_get_last_message() of
+    emqx_mock_client:close_session(ConnPid1, SPid1),
+    ?wait(ets:lookup(emqx_alive_shared_subscribers, SPid1) =:= [], 1000),
+    emqx_session:subscribe(SPid2, [{<<"foo/#">>, #{qos => 0, share => <<"group1">>}}]),
+    ?wait(ets:lookup(emqx_alive_shared_subscribers, SPid2) =:= [{SPid2}], 1000),
+    emqx_session:publish(SPid2, 2, Message2),
+    ?wait(case emqx_mock_client:get_last_message(ConnPid2) of
               {publish, _, #message{payload = <<"hello2">>}} -> true;
               Other -> Other
           end, 1000),
@@ -132,11 +138,17 @@ test_two_messages(Strategy) ->
         hash -> ?assert(UsedSubPid1 =:= UsedSubPid2);
         _ -> ok
     end,
->>>>>>> 38d0d409... Add 'hash' option for shared subscription
     emqx_mock_client:close_session(ConnPid1, SPid1),
     emqx_mock_client:close_session(ConnPid2, SPid2),
     ok.
 
+last_message(_ExpectedPayload, []) -> <<"not yet?">>;
+last_message(ExpectedPayload, [Pid | Pids]) ->
+    case emqx_mock_client:get_last_message(Pid) of
+        {publish, _, #message{payload = ExpectedPayload}} -> {true, Pid};
+        _Other -> last_message(ExpectedPayload, Pids)
+    end.
+
 %%------------------------------------------------------------------------------
 %% help functions
 %%------------------------------------------------------------------------------