Revert "Take policy-configured max-priority into account"

This reverts commit f5aa1fb.

This feature wasn't available in the original implementation for a reason:
policies are dynamic and can change after a queue's been declared. However,
queue priorities are (at least currently) set in stone from the moment of
queue creation. This was mentioned in the docs but not explicitly enough and got overlooked.

Credit for the [re-]discovery goes to @acogoluegnes :)

References #1590.

[#157380396]

Author: michaelklishin

src/rabbit_amqqueue_process.erl

@@ -382,7 +382,6 @@ process_args_policy(State = #q{q                   = Q,
          {<<"message-ttl">>,             fun res_min/2, fun init_ttl/2},
          {<<"max-length">>,              fun res_min/2, fun init_max_length/2},
          {<<"max-length-bytes">>,        fun res_min/2, fun init_max_bytes/2},
-         {<<"max-priority">>,            fun res_arg/2, fun init_max_priority/2},
          {<<"overflow">>,                fun res_arg/2, fun init_overflow/2},
          {<<"queue-mode">>,              fun res_arg/2, fun init_queue_mode/2}],
       drop_expired_msgs(
@@ -427,9 +426,6 @@ init_max_bytes(MaxBytes, State) ->
     {_Dropped, State1} = maybe_drop_head(State#q{max_bytes = MaxBytes}),
     State1.
 
-init_max_priority(_MaxPriority, State) ->
-    State.
-
 init_overflow(undefined, State) ->
     State;
 init_overflow(Overflow, State) ->

src/rabbit_priority_queue.erl

@@ -28,8 +28,6 @@
                     {requires,    pre_boot},
                     {enables,     kernel_ready}]}).
 
--import(rabbit_misc, [pget/2]).
-
 -export([enable/0]).
 
 -export([start/2, stop/1]).
@@ -45,8 +43,6 @@
          info/2, invoke/3, is_duplicate/2, set_queue_mode/2,
          zip_msgs_and_acks/4, handle_info/2]).
 
--export([max_priority/1, priorities/1]).
-
 -record(state, {bq, bqss, max_priority}).
 -record(passthrough, {bq, bqs}).
 
@@ -129,19 +125,9 @@ collapse_recovery(QNames, DupNames, Recovery) ->
                               end, dict:new(), lists:zip(DupNames, Recovery)),
     [dict:fetch(Name, NameToTerms) || Name <- QNames].
 
-max_priority(Q = #amqqueue{arguments = Args}) ->
-    case rabbit_misc:table_lookup(Args, <<"x-max-priority">>) of
-        {Type, RequestedMax} -> {Type, RequestedMax};
-        undefined            ->
-            case rabbit_policy:effective_definition(Q) of
-                undefined -> undefined;
-                Proplist  -> {unsignedbyte, pget(<<"max-priority">>, Proplist)}
-            end
-    end.
-
-priorities(Q) ->
+priorities(#amqqueue{arguments = Args}) ->
     Ints = [long, short, signedint, byte, unsignedbyte, unsignedshort, unsignedint],
-    case max_priority(Q) of
+    case rabbit_misc:table_lookup(Args, <<"x-max-priority">>) of
         {Type, RequestedMax} ->
             case lists:member(Type, Ints) of
                 false -> none;