Only consider exchange name when looking up number of delayed messages

The #exchange record contains fields like policy or options which can
change for an exchange after delayed messages have been stored,
resulting in no match and an apparent zero number of messages.

Author: gomoripeti

src/rabbit_delayed_message.erl

@@ -98,7 +98,8 @@ disable_plugin() ->
     ok.
 
 messages_delayed(Exchange) ->
-    MatchHead = #delay_entry{delay_key = make_key('_', Exchange),
+    ExchangeName = Exchange#exchange.name,
+    MatchHead = #delay_entry{delay_key = make_key('_', #exchange{name = ExchangeName, _ = '_'}),
                              delivery  = '_', ref       = '_'},
     Delays = mnesia:dirty_select(?TABLE_NAME, [{MatchHead, [], ['$_']}]),
     length(Delays).

test/plugin_SUITE.erl

@@ -220,13 +220,26 @@ delayed_messages_count(Config) ->
     Exchanges = rabbit_ct_broker_helpers:rpc(Config, 0,
           rabbit_exchange, info_all, [<<"/">>]),
 
-    [Exchange] = lists:filter(
+    FilterEx =
         fun(X) ->
-            {resource, <<"/">>, exchange, Ex} == proplists:get_value(name, X)
+                {resource, <<"/">>, exchange, Ex} == proplists:get_value(name, X)
         end,
-        Exchanges),
+
+    [Exchange] = lists:filter(FilterEx, Exchanges),
     {messages_delayed, 6} = proplists:lookup(messages_delayed, Exchange),
 
+    %% Set a policy for the exchange
+    P = make_policy_name(Config, "1"),
+    rabbit_ct_broker_helpers:set_policy(
+      Config, 0, P, <<"^", Ex/binary>>, <<"exchanges">>, [{<<"alternate-exchange">>,<<"altex">>}]),
+
+    %% Same message count returned for modified exchange
+    Exchanges2 = rabbit_ct_broker_helpers:rpc(Config, 0,
+          rabbit_exchange, info_all, [<<"/">>]),
+
+    [Exchange2] = lists:filter(FilterEx, Exchanges2),
+    {messages_delayed, 6} = proplists:lookup(messages_delayed, Exchange2),
+
     consume(Chan, Q, Msgs),
 
     rabbit_ct_client_helpers:close_channel(Chan),
@@ -418,3 +431,7 @@ make_exchange_name(Config, Suffix) ->
 make_queue_name(Config, Suffix) ->
     B = rabbit_ct_helpers:get_config(Config, test_resource_name),
     erlang:list_to_binary("q-" ++ B ++ "-" ++ Suffix).
+
+make_policy_name(Config, Suffix) ->
+    B = rabbit_ct_helpers:get_config(Config, test_resource_name),
+    erlang:list_to_binary("p-" ++ B ++ "-" ++ Suffix).