fix(shared): retab and dropped handling

src/emqx_shared_sub.erl

@@ -40,7 +40,7 @@
 
 -export([ dispatch/3
         , dispatch_to_non_self/3
-       	]).
+        ]).
 
 -export([ maybe_ack/1
         , maybe_nack_dropped/1
@@ -268,7 +268,7 @@ pick(sticky, ClientId, SourceTopic, Group, Topic, FailedSubs) ->
         false ->
             %% randomly pick one for the first message
             FailedSubs1 = maps_put_new(FailedSubs, Sub0, inactive),
-						case do_pick(random, ClientId, SourceTopic, Group, Topic, FailedSubs1) of
+            case do_pick(random, ClientId, SourceTopic, Group, Topic, FailedSubs1) of
               false -> false;
               {Type, Sub} ->
                 %% stick to whatever pick result
@@ -288,10 +288,14 @@ do_pick(Strategy, ClientId, SourceTopic, Group, Topic, FailedSubs) ->
         [] ->
             %% All offline? pick one anyway
             %% We redispatch only to subs who dropped the message because inflight was full.
-            Dropped = maps_find_by(FailedSubs, fun({SubPid, FailReason}) ->
+            Found = maps_find_by(FailedSubs, fun({SubPid, FailReason}) ->
                 FailReason == dropped andalso is_alive_sub(SubPid)
             end),
-            {retry, pick_subscriber(Group, Topic, Strategy, ClientId, SourceTopic, Dropped)};
+            case Found of
+                error -> false;
+                {ok, Dropped} ->
+                    {retry, pick_subscriber(Group, Topic, Strategy, ClientId, SourceTopic, [Dropped])}
+            end;
         Subs ->
             %% More than one available
             {fresh, pick_subscriber(Group, Topic, Strategy, ClientId, SourceTopic, Subs)}

test/emqx_shared_sub_SUITE.erl

@@ -1,4 +1,4 @@
-%fresh, fresh, fresh, %--------------------------------------------------------------------
+%%--------------------------------------------------------------------
 %% Copyright (c) 2018-2022 EMQ Technologies Co., Ltd. All Rights Reserved.
 %%
 %% Licensed under the Apache License, Version 2.0 (the "License");
@@ -470,13 +470,13 @@ t_dispatch_when_inflights_are_full(_) ->
     sys:suspend(ConnPid1),
     sys:suspend(ConnPid2),
 
-  	%% Fill in the inflight for first client
-  	?assertMatch([{_, _, {ok, 1}}], emqx:publish(Message1)),
+    %% Fill in the inflight for first client
+    ?assertMatch([{_, _, {ok, 1}}], emqx:publish(Message1)),
 
-  	%% Fill in the inflight for second client
-  	?assertMatch([{_, _, {ok, 1}}], emqx:publish(Message2)),
+    %% Fill in the inflight for second client
+    ?assertMatch([{_, _, {ok, 1}}], emqx:publish(Message2)),
 
-  	%% Now kill any client
+    %% Now kill any client
     erlang:exit(ConnPid1, normal),
     ct:sleep(100),