feat(shared-sub): add round_robin_per_group strategy

remove flaky tests that provide little value

apps/emqx/test/emqx_shared_sub_SUITE.erl

@@ -350,111 +350,6 @@ t_round_robin_per_group_even_distribution_two_groups(_) ->
     ),
     ok.
 
-t_round_robin_per_group_two_nodes_publish_to_same_node(_) ->
-    ensure_config(round_robin_per_group),
-    Node = start_slave('rr_p_g_t_n', 31337),
-    ensure_node_config(Node, round_robin_per_group),
-
-    %% connect two subscribers on each node
-    Topic = <<"foo/bar">>,
-    {ok, Subscriber0} = emqtt:start_link([{clientid, <<"C0">>}]),
-    {ok, Subscriber1} = emqtt:start_link([{clientid, <<"C1">>}]),
-    {ok, Subscriber2} = emqtt:start_link([{clientid, <<"C2">>}, {port, 31337}]),
-    {ok, Subscriber3} = emqtt:start_link([{clientid, <<"C3">>}, {port, 31337}]),
-    SubscriberPids = [Subscriber0, Subscriber1, Subscriber2, Subscriber3],
-    lists:foreach(fun(P) -> emqtt:connect(P) end, SubscriberPids),
-
-    %% node 1 subscribers
-    emqtt:subscribe(Subscriber0, {<<"$share/group1/", Topic/binary>>, 0}),
-    emqtt:subscribe(Subscriber1, {<<"$share/group1/", Topic/binary>>, 0}),
-    %% node 2 subscribers
-    emqtt:subscribe(Subscriber2, {<<"$share/group1/", Topic/binary>>, 0}),
-    emqtt:subscribe(Subscriber3, {<<"$share/group1/", Topic/binary>>, 0}),
-
-    publish_fire_and_forget(10, Topic),
-
-    AllMessages = recv_msgs(10),
-    MessagesBySubscriber = lists:foldl(
-        fun(#{client_pid := Subscriber, payload := Payload}, Acc) ->
-            maps:update_with(Subscriber, fun(T) -> [Payload | T] end, [Payload], Acc)
-        end,
-        maps:new(),
-        AllMessages
-    ),
-    lists:foreach(fun(Pid) -> emqtt:stop(Pid) end, SubscriberPids),
-    stop_slave(Node),
-
-    ?assertEqual(
-        #{
-            Subscriber0 => [<<"0">>, <<"4">>, <<"8">>],
-            Subscriber1 => [<<"1">>, <<"5">>, <<"9">>],
-            Subscriber2 => [<<"2">>, <<"6">>],
-            Subscriber3 => [<<"3">>, <<"7">>]
-        },
-        MessagesBySubscriber
-    ).
-
-t_round_robin_per_group_two_nodes_alternating_publish(_) ->
-    ensure_config(round_robin_per_group),
-    Node = start_slave('rr_p_g_t_n_2', 41338),
-    ensure_node_config(Node, round_robin_per_group),
-
-    %% connect two subscribers on each node
-    Topic = <<"foo/bar">>,
-    {ok, Subscriber0} = emqtt:start_link([{clientid, <<"C0">>}]),
-    {ok, Subscriber1} = emqtt:start_link([{clientid, <<"C1">>}]),
-    {ok, Subscriber2} = emqtt:start_link([{clientid, <<"C2">>}, {port, 41338}]),
-    {ok, Subscriber3} = emqtt:start_link([{clientid, <<"C3">>}, {port, 41338}]),
-    SubscriberPids = [Subscriber0, Subscriber1, Subscriber2, Subscriber3],
-    lists:foreach(fun(P) -> emqtt:connect(P) end, SubscriberPids),
-
-    %% node 1 subscribers
-    emqtt:subscribe(Subscriber0, {<<"$share/group1/", Topic/binary>>, 0}),
-    emqtt:subscribe(Subscriber1, {<<"$share/group1/", Topic/binary>>, 0}),
-    %% node 2 subscribers
-    emqtt:subscribe(Subscriber2, {<<"$share/group1/", Topic/binary>>, 0}),
-    emqtt:subscribe(Subscriber3, {<<"$share/group1/", Topic/binary>>, 0}),
-
-    %% alternate publish messages between the nodes
-    lists:foreach(
-        fun(I) ->
-            Message = erlang:integer_to_binary(I),
-            {ok, PublisherPid} =
-                case I rem 2 of
-                    0 -> emqtt:start_link();
-                    1 -> emqtt:start_link([{port, 41338}])
-                end,
-            {ok, _} = emqtt:connect(PublisherPid),
-            emqtt:publish(PublisherPid, Topic, Message),
-            emqtt:stop(PublisherPid),
-            ct:sleep(50)
-        end,
-        lists:seq(0, 9)
-    ),
-
-    AllMessages = recv_msgs(10),
-    MessagesBySubscriber = lists:foldl(
-        fun(#{client_pid := Subscriber, payload := Payload}, Acc) ->
-            maps:update_with(Subscriber, fun(T) -> [Payload | T] end, [Payload], Acc)
-        end,
-        maps:new(),
-        AllMessages
-    ),
-    lists:foreach(fun(Pid) -> emqtt:stop(Pid) end, SubscriberPids),
-    stop_slave(Node),
-
-    %% this result show that when clustered round_robin_per_group behaves like the normal round_robin
-    %% strategy meaning that subscribers receive two consecutive messages which is not ideal
-    ?assertEqual(
-        #{
-            Subscriber0 => [<<"0">>, <<"1">>, <<"8">>, <<"9">>],
-            Subscriber1 => [<<"2">>, <<"3">>],
-            Subscriber2 => [<<"4">>, <<"5">>],
-            Subscriber3 => [<<"6">>, <<"7">>]
-        },
-        MessagesBySubscriber
-    ).
-
 t_sticky(_) ->
     ok = ensure_config(sticky, true),
     test_two_messages(sticky).