rabbit_stream_coordinator: Make new_stream command idempotent

Author: the-mikedavis

deps/rabbit/src/rabbit_stream_coordinator.erl

@@ -1380,6 +1380,15 @@ filter_command(_Meta, {delete_stream, _StreamId, #{}}, undefined) ->
     %% Attempting to delete a stream which does not exist. Reply 'ok' to the
     %% caller so that this action is idempotent.
     {reply, ok};
+filter_command(_Meta, {new_stream, _StreamId, #{}}, #stream{members = Members}) ->
+    MaybeLeader = [Pid || _Node := #member{state = {running, _, Pid},
+                                           role = {writer, _}} <- Members],
+    case MaybeLeader of
+        [LeaderPid] ->
+            {reply, {ok, LeaderPid}};
+        [] ->
+            {reply, '$ra_no_reply'}
+    end;
 filter_command(_, _, _) ->
     ok.
 
@@ -1389,8 +1398,8 @@ update_stream(Meta, Cmd, Stream) ->
     catch
         _:E:Stacktrace ->
             ?LOG_WARNING(
-              "~ts failed to update stream:~n~W~n~W",
-              [?MODULE, E, 10, Stacktrace, 10]),
+              "~ts failed to update stream:~n~P~n~P",
+              [?MODULE, E, 10, Stacktrace, 30]),
             Stream
     end.
 

deps/rabbit/test/rabbit_stream_coordinator_SUITE.erl

@@ -28,6 +28,7 @@ all_tests() ->
      machine_version_upgrade_to_2,
      machine_version_upgrade_to_3,
      new_stream,
+     new_stream_idempotent,
      leader_down,
      leader_down_scenario_1,
      replica_down,
@@ -361,6 +362,31 @@ new_stream(_) ->
 
     ok.
 
+new_stream_idempotent(_) ->
+    S0 = rabbit_stream_coordinator:init(#{machine_version => 5}),
+    StreamId = atom_to_list(?FUNCTION_NAME),
+
+    TypeState = #{name => StreamId,
+                  retention => [],
+                  nodes => [node()]},
+    Q = new_q(list_to_binary(StreamId), TypeState),
+    NewStream = {new_stream, StreamId, #{leader_node => node(),
+                                         retention => [],
+                                         queue => Q}},
+    From = {self(), make_ref()},
+    StartIdx = ?LINE,
+    Meta = (meta(StartIdx))#{from => From},
+    {S1, '$ra_no_reply', _} = apply_cmd(Meta, NewStream, S0),
+    {S1, '$ra_no_reply', []} = apply_cmd(Meta#{index := ?LINE}, NewStream, S1),
+    Pid = self(),
+    {S2, _, _} = apply_cmd(meta(?LINE), {member_started, StreamId,
+                                         #{epoch => 1,
+                                           index => StartIdx,
+                                           pid => Pid}}, S1),
+    {_, {ok, Pid}, []} = apply_cmd(Meta#{index := ?LINE}, NewStream, S2),
+
+    ok.
+
 leader_down(_) ->
     E = 1,
     StreamId = atom_to_list(?FUNCTION_NAME),