Pass upstream sets around less, simplifying a bunch of APIs.

deps/rabbitmq_federation/src/rabbit_federation_db.erl

@@ -23,7 +23,7 @@
 
 -import(rabbit_federation_util, [name/1]).
 
--export([get_active_suffix/3, set_active_suffix/3, prune_scratch/2]).
+-export([get_active_suffix/3, set_active_suffix/3, prune_scratch/1]).
 
 %%----------------------------------------------------------------------------
 
@@ -43,7 +43,8 @@ set_active_suffix(XName, Upstream, Suffix) ->
            XName, federation,
            fun(D) -> ?DICT:store(key(Upstream), Suffix, D) end).
 
-prune_scratch(XName, Upstreams) ->
+prune_scratch(X = #exchange{name = XName}) ->
+    Upstreams = rabbit_federation_upstream:for(X),
     ok = rabbit_exchange:update_scratch(
            XName, federation,
            fun(undefined) -> ?DICT:new();

deps/rabbitmq_federation/src/rabbit_federation_exchange.erl

@@ -86,23 +86,17 @@ federate(#exchange{internal = true}) ->
     false;
 
 federate(X) ->
-    case rabbit_federation_upstream:for(X) of
+    case rabbit_federation_upstream:set_for(X) of
         {ok, _}    -> true;
         {error, _} -> false
     end.
 
 maybe_start(X = #exchange{name = XName})->
     case federate(X) of
-        true ->
-            %% TODO the extent to which we pass Set around can
-            %% probably be simplified.
-            {ok, Set} = rabbit_federation_upstream:for(X),
-            Upstreams = rabbit_federation_upstream:from_set(Set, X),
-            ok = rabbit_federation_db:prune_scratch(XName, Upstreams),
-            {ok, _} = rabbit_federation_link_sup_sup:start_child(X, {Set, X}),
+        true  -> ok = rabbit_federation_db:prune_scratch(X),
+                 {ok, _} = rabbit_federation_link_sup_sup:start_child(X),
                  ok;
-        false ->
-            ok
+        false -> ok
     end.
 
 maybe_stop(X = #exchange{name = XName}) ->

deps/rabbitmq_federation/src/rabbit_federation_link_sup.erl

@@ -26,22 +26,16 @@
 -export([start_link/1, adjust/3]).
 -export([init/1]).
 
-start_link(Args) -> supervisor2:start_link(?MODULE, Args).
+start_link(X) -> supervisor2:start_link(?MODULE, X).
 
 adjust(Sup, X, everything) ->
     [stop(Sup, Upstream) ||
         {Upstream, _, _, _} <- supervisor2:which_children(Sup)],
-    case rabbit_federation_upstream:for(X) of
-        {ok, UpstreamSet} ->
-            [{ok, _Pid} = supervisor2:start_child(Sup, Spec) ||
-                Spec <- specs(UpstreamSet, X)];
-        {error, not_found} ->
-            ok
-    end;
+    [{ok, _Pid} = supervisor2:start_child(Sup, Spec) || Spec <- specs(X)];
 
 adjust(Sup, X, {connection, ConnName}) ->
     OldUpstreams0 = children(Sup, ConnName),
-    NewUpstreams0 = upstreams(X, ConnName),
+    NewUpstreams0 = rabbit_federation_upstream:for(X, ConnName),
     %% If any haven't changed, don't restart them. The broker will
     %% avoid telling us about connections that have not changed
     %% syntactically, but even if one has, this X may not have that
@@ -58,14 +52,13 @@ adjust(Sup, X, {connection, ConnName}) ->
     [start(Sup, NewUpstream, X) || NewUpstream <- NewUpstreams];
 
 adjust(Sup, X = #exchange{name = XName}, {clear_connection, ConnName}) ->
-    ok = rabbit_federation_db:prune_scratch(XName, upstreams(X)),
+    ok = rabbit_federation_db:prune_scratch(X),
     [stop(Sup, Upstream) || Upstream <- children(Sup, ConnName)];
 
 %% TODO handle changes of upstream sets minimally (bug 24853)
 adjust(Sup, X = #exchange{name = XName}, {upstream_set, Set}) ->
-    case rabbit_federation_upstream:for(X) of
-        {ok, Set} -> Us = rabbit_federation_upstream:from_set(Set, X),
-                     ok = rabbit_federation_db:prune_scratch(XName, Us);
+    case rabbit_federation_upstream:set_for(X) of
+        {ok, Set} -> ok = rabbit_federation_db:prune_scratch(X);
         _         -> ok
     end,
     adjust(Sup, X, everything);
@@ -90,32 +83,15 @@ children(Sup, ConnName) ->
     rabbit_federation_util:find_upstreams(
       ConnName, [U || {U, _, _, _} <- supervisor2:which_children(Sup)]).
 
-upstreams(X, ConnName) ->
-    case rabbit_federation_upstream:for(X) of
-        {ok, UpstreamSet} ->
-            rabbit_federation_upstream:from_set(UpstreamSet, X, ConnName);
-        {error, not_found} ->
-            []
-    end.
-
-upstreams(X) ->
-    case rabbit_federation_upstream:for(X) of
-        {ok, UpstreamSet} ->
-            rabbit_federation_upstream:from_set(UpstreamSet, X);
-        {error, not_found} ->
-            []
-    end.
-
 %%----------------------------------------------------------------------------
 
-init({UpstreamSet, X}) ->
+init(X) ->
     %% 1, 1 so that the supervisor can give up and get into waiting
     %% for the reconnect_delay quickly.
-    {ok, {{one_for_one, 1, 1}, specs(UpstreamSet, X)}}.
+    {ok, {{one_for_one, 1, 1}, specs(X)}}.
 
-specs(UpstreamSet, X) ->
-    [spec(Upstream, X) ||
-        Upstream <- rabbit_federation_upstream:from_set(UpstreamSet, X)].
+specs(X) ->
+    [spec(Upstream, X) || Upstream <- rabbit_federation_upstream:for(X)].
 
 spec(Upstream = #upstream{reconnect_delay = Delay}, #exchange{name = XName}) ->
     {Upstream, {rabbit_federation_link, start_link, [{Upstream, XName}]},

deps/rabbitmq_federation/src/rabbit_federation_link_sup_sup.erl

@@ -21,7 +21,7 @@
 -include_lib("rabbit_common/include/rabbit.hrl").
 -define(SUPERVISOR, rabbit_federation_link_sup_sup).
 
--export([start_link/0, start_child/2, adjust/1, stop_child/1]).
+-export([start_link/0, start_child/1, adjust/1, stop_child/1]).
 
 -export([init/1]).
 
@@ -31,10 +31,10 @@ start_link() ->
     mirrored_supervisor:start_link({local, ?SUPERVISOR},
                                    ?SUPERVISOR, ?MODULE, []).
 
-start_child(X, Args) ->
+start_child(X) ->
     {ok, _Pid} = mirrored_supervisor:start_child(
                    ?SUPERVISOR,
-                   {id(X), {rabbit_federation_link_sup, start_link, [Args]},
+                   {id(X), {rabbit_federation_link_sup, start_link, [X]},
                     transient, ?MAX_WAIT, supervisor,
                     [rabbit_federation_link_sup]}).
 

deps/rabbitmq_federation/src/rabbit_federation_upstream.erl

@@ -19,14 +19,26 @@
 -include("rabbit_federation.hrl").
 -include_lib("amqp_client/include/amqp_client.hrl").
 
--export([for/1, to_table/1, to_string/1, from_set/2, from_set/3]).
+-export([set_for/1, for/1, for/2, to_table/1, to_string/1]).
 
 -import(rabbit_misc, [pget/2, pget/3]).
 -import(rabbit_federation_util, [name/1, vhost/1]).
 
 %%----------------------------------------------------------------------------
 
-for(X) -> rabbit_policy:get(<<"federation-upstream-set">>, X).
+set_for(X) -> rabbit_policy:get(<<"federation-upstream-set">>, X).
+
+for(X) ->
+    case set_for(X) of
+        {ok, UpstreamSet}  -> from_set(UpstreamSet, X);
+        {error, not_found} -> []
+    end.
+
+for(X, ConnName) ->
+    case set_for(X) of
+        {ok, UpstreamSet}  -> from_set(UpstreamSet, X, ConnName);
+        {error, not_found} -> []
+    end.
 
 to_table(#upstream{original_uri = URI,
                    params       = Params,