From 95faf56077555635edbc8108fe77d1abb01d86d2 Mon Sep 17 00:00:00 2001
From: Erik Timan <erik.timan@emqx.io>
Date: Wed, 23 Nov 2022 10:50:25 +0100
Subject: [PATCH] feat: remove $queue in favor of $shared

This commit removes support for setting shared subscriptions with the
non-standard $queue feature. Shared subscriptions is now part of the MQTT
spec (using $shared) and we will only support that from now on.
---
 apps/emqx/include/emqx.hrl                             |  5 +----
 apps/emqx/src/emqx_topic.erl                           |  4 ----
 apps/emqx/test/emqx_proper_types.erl                   |  2 +-
 apps/emqx/test/emqx_topic_SUITE.erl                    | 10 ----------
 .../src/emqx_mgmt_api_subscriptions.erl                |  2 --
 5 files changed, 2 insertions(+), 21 deletions(-)

diff --git a/apps/emqx/include/emqx.hrl b/apps/emqx/include/emqx.hrl
index b776adab4..b1b1e2a00 100644
--- a/apps/emqx/include/emqx.hrl
+++ b/apps/emqx/include/emqx.hrl
@@ -40,15 +40,12 @@
 -define(ERTS_MINIMUM_REQUIRED, "10.0").
 
 %%--------------------------------------------------------------------
-%% Topics' prefix: $SYS | $queue | $share
+%% Topics' prefix: $SYS | $share
 %%--------------------------------------------------------------------
 
 %% System topic
 -define(SYSTOP, <<"$SYS/">>).
 
-%% Queue topic
--define(QUEUE, <<"$queue/">>).
-
 %%--------------------------------------------------------------------
 %% alarms
 %%--------------------------------------------------------------------
diff --git a/apps/emqx/src/emqx_topic.erl b/apps/emqx/src/emqx_topic.erl
index 0f0a8bf1c..2941a51fe 100644
--- a/apps/emqx/src/emqx_topic.erl
+++ b/apps/emqx/src/emqx_topic.erl
@@ -210,12 +210,8 @@ parse({TopicFilter, Options}) when is_binary(TopicFilter) ->
     parse(TopicFilter, Options).
 
 -spec parse(topic(), map()) -> {topic(), map()}.
-parse(TopicFilter = <<"$queue/", _/binary>>, #{share := _Group}) ->
-    error({invalid_topic_filter, TopicFilter});
 parse(TopicFilter = <<"$share/", _/binary>>, #{share := _Group}) ->
     error({invalid_topic_filter, TopicFilter});
-parse(<<"$queue/", TopicFilter/binary>>, Options) ->
-    parse(TopicFilter, Options#{share => <<"$queue">>});
 parse(TopicFilter = <<"$share/", Rest/binary>>, Options) ->
     case binary:split(Rest, <<"/">>) of
         [_Any] ->
diff --git a/apps/emqx/test/emqx_proper_types.erl b/apps/emqx/test/emqx_proper_types.erl
index 78fab0b38..0be10f476 100644
--- a/apps/emqx/test/emqx_proper_types.erl
+++ b/apps/emqx/test/emqx_proper_types.erl
@@ -424,7 +424,7 @@ systopic_mon() ->
 sharetopic() ->
     ?LET(
         {Type, Grp, T},
-        {oneof([<<"$queue">>, <<"$share">>]), list(latin_char()), normal_topic()},
+        {oneof([<<"$share">>]), list(latin_char()), normal_topic()},
         <<Type/binary, "/", (iolist_to_binary(Grp))/binary, "/", T/binary>>
     ).
 
diff --git a/apps/emqx/test/emqx_topic_SUITE.erl b/apps/emqx/test/emqx_topic_SUITE.erl
index 13383b69e..ff0ec92a0 100644
--- a/apps/emqx/test/emqx_topic_SUITE.erl
+++ b/apps/emqx/test/emqx_topic_SUITE.erl
@@ -186,10 +186,6 @@ t_systop(_) ->
     ?assertEqual(SysTop2, systop(<<"abc">>)).
 
 t_feed_var(_) ->
-    ?assertEqual(
-        <<"$queue/client/clientId">>,
-        feed_var(<<"$c">>, <<"clientId">>, <<"$queue/client/$c">>)
-    ),
     ?assertEqual(
         <<"username/test/client/x">>,
         feed_var(
@@ -211,10 +207,6 @@ long_topic() ->
     iolist_to_binary([[integer_to_list(I), "/"] || I <- lists:seq(0, 66666)]).
 
 t_parse(_) ->
-    ?assertError(
-        {invalid_topic_filter, <<"$queue/t">>},
-        parse(<<"$queue/t">>, #{share => <<"g">>})
-    ),
     ?assertError(
         {invalid_topic_filter, <<"$share/g/t">>},
         parse(<<"$share/g/t">>, #{share => <<"g">>})
@@ -229,11 +221,9 @@ t_parse(_) ->
     ),
     ?assertEqual({<<"a/b/+/#">>, #{}}, parse(<<"a/b/+/#">>)),
     ?assertEqual({<<"a/b/+/#">>, #{qos => 1}}, parse({<<"a/b/+/#">>, #{qos => 1}})),
-    ?assertEqual({<<"topic">>, #{share => <<"$queue">>}}, parse(<<"$queue/topic">>)),
     ?assertEqual({<<"topic">>, #{share => <<"group">>}}, parse(<<"$share/group/topic">>)),
     %% The '$local' and '$fastlane' topics have been deprecated.
     ?assertEqual({<<"$local/topic">>, #{}}, parse(<<"$local/topic">>)),
-    ?assertEqual({<<"$local/$queue/topic">>, #{}}, parse(<<"$local/$queue/topic">>)),
     ?assertEqual({<<"$local/$share/group/a/b/c">>, #{}}, parse(<<"$local/$share/group/a/b/c">>)),
     ?assertEqual({<<"$fastlane/topic">>, #{}}, parse(<<"$fastlane/topic">>)).
 
diff --git a/apps/emqx_management/src/emqx_mgmt_api_subscriptions.erl b/apps/emqx_management/src/emqx_mgmt_api_subscriptions.erl
index 03b833e84..9053b5339 100644
--- a/apps/emqx_management/src/emqx_mgmt_api_subscriptions.erl
+++ b/apps/emqx_management/src/emqx_mgmt_api_subscriptions.erl
@@ -182,8 +182,6 @@ format({_Subscriber, Topic, Options}) ->
         maps:with([qos, nl, rap, rh], Options)
     ).
 
-get_topic(Topic, #{share := <<"$queue">> = Group}) ->
-    filename:join([Group, Topic]);
 get_topic(Topic, #{share := Group}) ->
     filename:join([<<"$share">>, Group, Topic]);
 get_topic(Topic, _) ->