Merge bug23358 into default

2 files changed, 12 insertions, 6 deletions

diff --git a/src/delegate.erl b/src/delegate.erl
index 11abe73b0d..8e64f3d078 100644
--- a/src/delegate.erl
+++ b/src/delegate.erl
@@ -31,6 +31,14 @@
 
 -module(delegate).
 
+%% The reason we have local delegate processes is because we want to
+%% be able to issue calls to remote nodes in parallel. This requires
+%% segmenting the destination Pids by node, and then getting local
+%% delegates to issue calls/casts to the remote delegates in
+%% parallel. In order to ensure consistent ordering, even casts to
+%% remote Pids have to go through the local delegates rather than be
+%% sent directly.
+
 -define(DELEGATE_PROCESS_COUNT_MULTIPLIER, 2).
 
 -behaviour(gen_server2).
diff --git a/src/rabbit_amqqueue.erl b/src/rabbit_amqqueue.erl
index 71fd7a17db..e3e89211b5 100644
--- a/src/rabbit_amqqueue.erl
+++ b/src/rabbit_amqqueue.erl
@@ -503,15 +503,13 @@ pseudo_queue(QueueName, Pid) ->
               pid = Pid}.
 
 safe_delegate_call_ok(F, Pids) ->
-    {_, Bad} = delegate:invoke(Pids,
-                               fun (Pid) ->
+    case delegate:invoke(Pids, fun (Pid) ->
                                        rabbit_misc:with_exit_handler(
                                          fun () -> ok end,
                                          fun () -> F(Pid) end)
-                               end),
-    case Bad of
-        [] -> ok;
-        _  -> {error, Bad}
+                               end) of
+        {_,  []} -> ok;
+        {_, Bad} -> {error, Bad}
     end.
 
 delegate_call(Pid, Msg, Timeout) ->