Merging bug 23157 into default

8 files changed, 562 insertions, 492 deletions

diff --git a/src/gen_server2.erl b/src/gen_server2.erl
index 9fb9e2fe..e2bb940f 100644
--- a/src/gen_server2.erl
+++ b/src/gen_server2.erl
@@ -16,10 +16,12 @@
 %% The original code could reorder messages when communicating with a
 %% process on a remote node that was not currently connected.
 %%
-%% 4) The new functions gen_server2:pcall/3, pcall/4, and pcast/3
-%% allow callers to attach priorities to requests. Requests with
-%% higher priorities are processed before requests with lower
-%% priorities. The default priority is 0.
+%% 4) The callback module can optionally implement prioritise_call/3,
+%% prioritise_cast/2 and prioritise_info/2.  These functions take
+%% Message, From and State or just Message and State and return a
+%% single integer representing the priority attached to the message.
+%% Messages with higher priorities are processed before requests with
+%% lower priorities. The default priority is 0.
 %%
 %% 5) The callback module can optionally implement
 %% handle_pre_hibernate/1 and handle_post_hibernate/1. These will be
@@ -82,13 +84,13 @@
 %%%
 %%% The idea behind THIS server is that the user module
 %%% provides (different) functions to handle different
-%%% kind of inputs. 
+%%% kind of inputs.
 %%% If the Parent process terminates the Module:terminate/2
 %%% function is called.
 %%%
 %%% The user module should export:
 %%%
-%%%   init(Args)  
+%%%   init(Args)
 %%%     ==> {ok, State}
 %%%         {ok, State, Timeout}
 %%%         {ok, State, Timeout, Backoff}
@@ -101,21 +103,21 @@
 %%%        {reply, Reply, State, Timeout}
 %%%        {noreply, State}
 %%%        {noreply, State, Timeout}
-%%%        {stop, Reason, Reply, State}  
+%%%        {stop, Reason, Reply, State}
 %%%              Reason = normal | shutdown | Term terminate(State) is called
 %%%
 %%%   handle_cast(Msg, State)
 %%%
 %%%    ==> {noreply, State}
 %%%        {noreply, State, Timeout}
-%%%        {stop, Reason, State} 
+%%%        {stop, Reason, State}
 %%%              Reason = normal | shutdown | Term terminate(State) is called
 %%%
 %%%   handle_info(Info, State) Info is e.g. {'EXIT', P, R}, {nodedown, N}, ...
 %%%
 %%%    ==> {noreply, State}
 %%%        {noreply, State, Timeout}
-%%%        {stop, Reason, State} 
+%%%        {stop, Reason, State}
 %%%              Reason = normal | shutdown | Term, terminate(State) is called
 %%%
 %%%   terminate(Reason, State) Let the user module clean up
@@ -159,37 +161,41 @@
 
 %% API
 -export([start/3, start/4,
-	 start_link/3, start_link/4,
-	 call/2, call/3, pcall/3, pcall/4,
-	 cast/2, pcast/3, reply/2,
-	 abcast/2, abcast/3,
-	 multi_call/2, multi_call/3, multi_call/4,
-	 enter_loop/3, enter_loop/4, enter_loop/5, enter_loop/6, wake_hib/7]).
+         start_link/3, start_link/4,
+         call/2, call/3,
+         cast/2, reply/2,
+         abcast/2, abcast/3,
+         multi_call/2, multi_call/3, multi_call/4,
+         enter_loop/3, enter_loop/4, enter_loop/5, enter_loop/6, wake_hib/1]).
 
 -export([behaviour_info/1]).
 
 %% System exports
 -export([system_continue/3,
-	 system_terminate/4,
-	 system_code_change/4,
-	 format_status/2]).
+         system_terminate/4,
+         system_code_change/4,
+         format_status/2]).
 
 %% Internal exports
 -export([init_it/6, print_event/3]).
 
 -import(error_logger, [format/2]).
 
+%% State record
+-record(gs2_state, {parent, name, state, mod, time,
+                    timeout_state, queue, debug, prioritise_call,
+                    prioritise_cast, prioritise_info}).
+
 %%%=========================================================================
 %%%  Specs. These exist only to shut up dialyzer's warnings
 %%%=========================================================================
 
 -ifdef(use_specs).
 
--spec(handle_common_termination/6 ::
-      (any(), any(), any(), atom(), any(), any()) -> no_return()).
+-spec(handle_common_termination/3 ::
+      (any(), atom(), #gs2_state{}) -> no_return()).
 
--spec(hibernate/7 ::
-      (pid(), any(), any(), atom(), any(), queue(), any()) -> no_return()).
+-spec(hibernate/1 :: (#gs2_state{}) -> no_return()).
 
 -endif.
 
@@ -238,37 +244,21 @@ start_link(Name, Mod, Args, Options) ->
 %% be monitored.
 %% If the client is trapping exits and is linked server termination
 %% is handled here (? Shall we do that here (or rely on timeouts) ?).
-%% ----------------------------------------------------------------- 
+%% -----------------------------------------------------------------
 call(Name, Request) ->
     case catch gen:call(Name, '$gen_call', Request) of
-	{ok,Res} ->
-	    Res;
-	{'EXIT',Reason} ->
-	    exit({Reason, {?MODULE, call, [Name, Request]}})
+        {ok,Res} ->
+            Res;
+        {'EXIT',Reason} ->
+            exit({Reason, {?MODULE, call, [Name, Request]}})
     end.
 
 call(Name, Request, Timeout) ->
     case catch gen:call(Name, '$gen_call', Request, Timeout) of
-	{ok,Res} ->
-	    Res;
-	{'EXIT',Reason} ->
-	    exit({Reason, {?MODULE, call, [Name, Request, Timeout]}})
-    end.
-
-pcall(Name, Priority, Request) ->
-    case catch gen:call(Name, '$gen_pcall', {Priority, Request}) of
-	{ok,Res} ->
-	    Res;
-	{'EXIT',Reason} ->
-	    exit({Reason, {?MODULE, pcall, [Name, Priority, Request]}})
-    end.
-
-pcall(Name, Priority, Request, Timeout) ->
-    case catch gen:call(Name, '$gen_pcall', {Priority, Request}, Timeout) of
-	{ok,Res} ->
-	    Res;
-	{'EXIT',Reason} ->
-	    exit({Reason, {?MODULE, pcall, [Name, Priority, Request, Timeout]}})
+        {ok,Res} ->
+            Res;
+        {'EXIT',Reason} ->
+            exit({Reason, {?MODULE, call, [Name, Request, Timeout]}})
     end.
 
 %% -----------------------------------------------------------------
@@ -277,34 +267,18 @@ pcall(Name, Priority, Request, Timeout) ->
 cast({global,Name}, Request) ->
     catch global:send(Name, cast_msg(Request)),
     ok;
-cast({Name,Node}=Dest, Request) when is_atom(Name), is_atom(Node) -> 
+cast({Name,Node}=Dest, Request) when is_atom(Name), is_atom(Node) ->
     do_cast(Dest, Request);
 cast(Dest, Request) when is_atom(Dest) ->
     do_cast(Dest, Request);
 cast(Dest, Request) when is_pid(Dest) ->
     do_cast(Dest, Request).
 
-do_cast(Dest, Request) -> 
+do_cast(Dest, Request) ->
     do_send(Dest, cast_msg(Request)),
     ok.
-    
-cast_msg(Request) -> {'$gen_cast',Request}.
 
-pcast({global,Name}, Priority, Request) ->
-    catch global:send(Name, cast_msg(Priority, Request)),
-    ok;
-pcast({Name,Node}=Dest, Priority, Request) when is_atom(Name), is_atom(Node) -> 
-    do_cast(Dest, Priority, Request);
-pcast(Dest, Priority, Request) when is_atom(Dest) ->
-    do_cast(Dest, Priority, Request);
-pcast(Dest, Priority, Request) when is_pid(Dest) ->
-    do_cast(Dest, Priority, Request).
-
-do_cast(Dest, Priority, Request) -> 
-    do_send(Dest, cast_msg(Priority, Request)),
-    ok.
-    
-cast_msg(Priority, Request) -> {'$gen_pcast', {Priority, Request}}.
+cast_msg(Request) -> {'$gen_cast',Request}.
 
 %% -----------------------------------------------------------------
 %% Send a reply to the client.
@@ -312,9 +286,9 @@ cast_msg(Priority, Request) -> {'$gen_pcast', {Priority, Request}}.
 reply({To, Tag}, Reply) ->
     catch To ! {Tag, Reply}.
 
-%% ----------------------------------------------------------------- 
-%% Asyncronous broadcast, returns nothing, it's just send'n prey
-%%-----------------------------------------------------------------  
+%% -----------------------------------------------------------------
+%% Asyncronous broadcast, returns nothing, it's just send'n pray
+%% -----------------------------------------------------------------
 abcast(Name, Request) when is_atom(Name) ->
     do_abcast([node() | nodes()], Name, cast_msg(Request)).
 
@@ -330,36 +304,36 @@ do_abcast([], _,_) -> abcast.
 %%% Make a call to servers at several nodes.
 %%% Returns: {[Replies],[BadNodes]}
 %%% A Timeout can be given
-%%% 
+%%%
 %%% A middleman process is used in case late answers arrives after
 %%% the timeout. If they would be allowed to glog the callers message
-%%% queue, it would probably become confused. Late answers will 
+%%% queue, it would probably become confused. Late answers will
 %%% now arrive to the terminated middleman and so be discarded.
 %%% -----------------------------------------------------------------
 multi_call(Name, Req)
   when is_atom(Name) ->
     do_multi_call([node() | nodes()], Name, Req, infinity).
 
-multi_call(Nodes, Name, Req) 
+multi_call(Nodes, Name, Req)
   when is_list(Nodes), is_atom(Name) ->
     do_multi_call(Nodes, Name, Req, infinity).
 
 multi_call(Nodes, Name, Req, infinity) ->
     do_multi_call(Nodes, Name, Req, infinity);
-multi_call(Nodes, Name, Req, Timeout) 
+multi_call(Nodes, Name, Req, Timeout)
   when is_list(Nodes), is_atom(Name), is_integer(Timeout), Timeout >= 0 ->
     do_multi_call(Nodes, Name, Req, Timeout).
 
 
 %%-----------------------------------------------------------------
-%% enter_loop(Mod, Options, State, <ServerName>, <TimeOut>, <Backoff>) ->_ 
-%%   
-%% Description: Makes an existing process into a gen_server. 
-%%              The calling process will enter the gen_server receive 
+%% enter_loop(Mod, Options, State, <ServerName>, <TimeOut>, <Backoff>) ->_
+%%
+%% Description: Makes an existing process into a gen_server.
+%%              The calling process will enter the gen_server receive
 %%              loop and become a gen_server process.
-%%              The process *must* have been started using one of the 
-%%              start functions in proc_lib, see proc_lib(3). 
-%%              The user is responsible for any initialization of the 
+%%              The process *must* have been started using one of the
+%%              start functions in proc_lib, see proc_lib(3).
+%%              The user is responsible for any initialization of the
 %%              process, including registering a name for it.
 %%-----------------------------------------------------------------
 enter_loop(Mod, Options, State) ->
@@ -386,7 +360,10 @@ enter_loop(Mod, Options, State, ServerName, Timeout, Backoff) ->
     Debug = debug_options(Name, Options),
     Queue = priority_queue:new(),
     Backoff1 = extend_backoff(Backoff),
-    loop(Parent, Name, State, Mod, Timeout, Backoff1, Queue, Debug).
+    loop(find_prioritisers(
+           #gs2_state { parent = Parent, name = Name, state = State,
+                        mod = Mod, time = Timeout, timeout_state = Backoff1,
+                        queue = Queue, debug = Debug })).
 
 %%%========================================================================
 %%% Gen-callback functions
@@ -405,39 +382,51 @@ init_it(Starter, Parent, Name0, Mod, Args, Options) ->
     Name = name(Name0),
     Debug = debug_options(Name, Options),
     Queue = priority_queue:new(),
+    GS2State = find_prioritisers(
+                 #gs2_state { parent  = Parent,
+                              name    = Name,
+                              mod     = Mod,
+                              queue   = Queue,
+                              debug   = Debug }),
     case catch Mod:init(Args) of
-	{ok, State} ->
-	    proc_lib:init_ack(Starter, {ok, self()}), 	    
-	    loop(Parent, Name, State, Mod, infinity, undefined, Queue, Debug);
-	{ok, State, Timeout} ->
-	    proc_lib:init_ack(Starter, {ok, self()}),
-	    loop(Parent, Name, State, Mod, Timeout, undefined, Queue, Debug);
-	{ok, State, Timeout, Backoff = {backoff, _, _, _}} ->
+        {ok, State} ->
+            proc_lib:init_ack(Starter, {ok, self()}),
+            loop(GS2State #gs2_state { state         = State,
+                                       time          = infinity,
+                                       timeout_state = undefined });
+        {ok, State, Timeout} ->
+            proc_lib:init_ack(Starter, {ok, self()}),
+            loop(GS2State #gs2_state { state         = State,
+                                       time          = Timeout,
+                                       timeout_state = undefined });
+        {ok, State, Timeout, Backoff = {backoff, _, _, _}} ->
             Backoff1 = extend_backoff(Backoff),
-	    proc_lib:init_ack(Starter, {ok, self()}),
-	    loop(Parent, Name, State, Mod, Timeout, Backoff1, Queue, Debug);
-	{stop, Reason} ->
-	    %% For consistency, we must make sure that the
-	    %% registered name (if any) is unregistered before
-	    %% the parent process is notified about the failure.
-	    %% (Otherwise, the parent process could get
-	    %% an 'already_started' error if it immediately
-	    %% tried starting the process again.)
-	    unregister_name(Name0),
-	    proc_lib:init_ack(Starter, {error, Reason}),
-	    exit(Reason);
-	ignore ->
-	    unregister_name(Name0),
-	    proc_lib:init_ack(Starter, ignore),
-	    exit(normal);
-	{'EXIT', Reason} ->
-	    unregister_name(Name0),
-	    proc_lib:init_ack(Starter, {error, Reason}),
-	    exit(Reason);
-	Else ->
-	    Error = {bad_return_value, Else},
-	    proc_lib:init_ack(Starter, {error, Error}),
-	    exit(Error)
+            proc_lib:init_ack(Starter, {ok, self()}),
+            loop(GS2State #gs2_state { state         = State,
+                                       time          = Timeout,
+                                       timeout_state = Backoff1 });
+        {stop, Reason} ->
+            %% For consistency, we must make sure that the
+            %% registered name (if any) is unregistered before
+            %% the parent process is notified about the failure.
+            %% (Otherwise, the parent process could get
+            %% an 'already_started' error if it immediately
+            %% tried starting the process again.)
+            unregister_name(Name0),
+            proc_lib:init_ack(Starter, {error, Reason}),
+            exit(Reason);
+        ignore ->
+            unregister_name(Name0),
+            proc_lib:init_ack(Starter, ignore),
+            exit(normal);
+        {'EXIT', Reason} ->
+            unregister_name(Name0),
+            proc_lib:init_ack(Starter, {error, Reason}),
+            exit(Reason);
+        Else ->
+            Error = {bad_return_value, Else},
+            proc_lib:init_ack(Starter, {error, Error}),
+            exit(Error)
     end.
 
 name({local,Name}) -> Name;
@@ -467,23 +456,24 @@ extend_backoff({backoff, InitialTimeout, MinimumTimeout, DesiredHibPeriod}) ->
 %%% ---------------------------------------------------
 %%% The MAIN loop.
 %%% ---------------------------------------------------
-loop(Parent, Name, State, Mod, hibernate, undefined, Queue, Debug) ->
-    pre_hibernate(Parent, Name, State, Mod, undefined, Queue, Debug);
-loop(Parent, Name, State, Mod, Time, TimeoutState, Queue, Debug) ->
-    process_next_msg(Parent, Name, State, Mod, Time, TimeoutState,
-                     drain(Queue), Debug).
+loop(GS2State = #gs2_state { time          = hibernate,
+                             timeout_state = undefined }) ->
+    pre_hibernate(GS2State);
+loop(GS2State) ->
+    process_next_msg(drain(GS2State)).
 
-drain(Queue) ->
+drain(GS2State) ->
     receive
-        Input -> drain(in(Input, Queue))
-    after 0 -> Queue
+        Input -> drain(in(Input, GS2State))
+    after 0 -> GS2State
     end.
 
-process_next_msg(Parent, Name, State, Mod, Time, TimeoutState, Queue, Debug) ->
+process_next_msg(GS2State = #gs2_state { time          = Time,
+                                         timeout_state = TimeoutState,
+                                         queue         = Queue }) ->
     case priority_queue:out(Queue) of
         {{value, Msg}, Queue1} ->
-            process_msg(Parent, Name, State, Mod,
-                        Time, TimeoutState, Queue1, Debug, Msg);
+            process_msg(Msg, GS2State #gs2_state { queue = Queue1 });
         {empty, Queue1} ->
             {Time1, HibOnTimeout}
                 = case {Time, TimeoutState} of
@@ -504,68 +494,64 @@ process_next_msg(Parent, Name, State, Mod, Time, TimeoutState, Queue, Debug) ->
                 Input ->
                     %% Time could be 'hibernate' here, so *don't* call loop
                     process_next_msg(
-                      Parent, Name, State, Mod, Time, TimeoutState,
-                      drain(in(Input, Queue1)), Debug)
+                      drain(in(Input, GS2State #gs2_state { queue = Queue1 })))
             after Time1 ->
                     case HibOnTimeout of
                         true ->
                             pre_hibernate(
-                              Parent, Name, State, Mod, TimeoutState, Queue1,
-                              Debug);
+                              GS2State #gs2_state { queue = Queue1 });
                         false ->
-                            process_msg(
-                              Parent, Name, State, Mod, Time, TimeoutState,
-                              Queue1, Debug, timeout)
+                            process_msg(timeout,
+                                        GS2State #gs2_state { queue = Queue1 })
                     end
             end
     end.
 
-wake_hib(Parent, Name, State, Mod, TS, Queue, Debug) ->
+wake_hib(GS2State = #gs2_state { timeout_state = TS }) ->
     TimeoutState1 = case TS of
                         undefined ->
                             undefined;
                         {SleptAt, TimeoutState} ->
                             adjust_timeout_state(SleptAt, now(), TimeoutState)
                     end,
-    post_hibernate(Parent, Name, State, Mod, TimeoutState1,
-                   drain(Queue), Debug).
+    post_hibernate(
+      drain(GS2State #gs2_state { timeout_state = TimeoutState1 })).
 
-hibernate(Parent, Name, State, Mod, TimeoutState, Queue, Debug) ->
+hibernate(GS2State = #gs2_state { timeout_state = TimeoutState }) ->
     TS = case TimeoutState of
              undefined             -> undefined;
              {backoff, _, _, _, _} -> {now(), TimeoutState}
          end,
-    proc_lib:hibernate(?MODULE, wake_hib, [Parent, Name, State, Mod,
-                                           TS, Queue, Debug]).
+    proc_lib:hibernate(?MODULE, wake_hib,
+                       [GS2State #gs2_state { timeout_state = TS }]).
 
-pre_hibernate(Parent, Name, State, Mod, TimeoutState, Queue, Debug) ->
+pre_hibernate(GS2State = #gs2_state { state   = State,
+                                      mod     = Mod }) ->
     case erlang:function_exported(Mod, handle_pre_hibernate, 1) of
         true ->
             case catch Mod:handle_pre_hibernate(State) of
                 {hibernate, NState} ->
-                    hibernate(Parent, Name, NState, Mod, TimeoutState, Queue,
-                              Debug);
+                    hibernate(GS2State #gs2_state { state = NState } );
                 Reply ->
-                    handle_common_termination(Reply, Name, pre_hibernate,
-                                              Mod, State, Debug)
+                    handle_common_termination(Reply, pre_hibernate, GS2State)
             end;
         false ->
-            hibernate(Parent, Name, State, Mod, TimeoutState, Queue, Debug)
+            hibernate(GS2State)
     end.
 
-post_hibernate(Parent, Name, State, Mod, TimeoutState, Queue, Debug) ->
+post_hibernate(GS2State = #gs2_state { state = State,
+                                       mod   = Mod }) ->
     case erlang:function_exported(Mod, handle_post_hibernate, 1) of
         true ->
             case catch Mod:handle_post_hibernate(State) of
                 {noreply, NState} ->
-                    process_next_msg(Parent, Name, NState, Mod, infinity,
-                                     TimeoutState, Queue, Debug);
+                    process_next_msg(GS2State #gs2_state { state = NState,
+                                                           time  = infinity });
                 {noreply, NState, Time} ->
-                    process_next_msg(Parent, Name, NState, Mod, Time,
-                                     TimeoutState, Queue, Debug);
+                    process_next_msg(GS2State #gs2_state { state = NState,
+                                                           time  = Time });
                 Reply ->
-                    handle_common_termination(Reply, Name, post_hibernate,
-                                              Mod, State, Debug)
+                    handle_common_termination(Reply, post_hibernate, GS2State)
             end;
         false ->
             %% use hibernate here, not infinity. This matches
@@ -574,8 +560,7 @@ post_hibernate(Parent, Name, State, Mod, TimeoutState, Queue, Debug) ->
             %% still set to hibernate, iff that msg is the very msg
             %% that woke us up (or the first msg we receive after
             %% waking up).
-            process_next_msg(Parent, Name, State, Mod, hibernate,
-                             TimeoutState, Queue, Debug)
+            process_next_msg(GS2State #gs2_state { time = hibernate })
     end.
 
 adjust_timeout_state(SleptAt, AwokeAt, {backoff, CurrentTO, MinimumTO,
@@ -596,32 +581,40 @@ adjust_timeout_state(SleptAt, AwokeAt, {backoff, CurrentTO, MinimumTO,
     CurrentTO1 = Base + Extra,
     {backoff, CurrentTO1, MinimumTO, DesiredHibPeriod, RandomState1}.
 
-in({'$gen_pcast', {Priority, Msg}}, Queue) ->
-    priority_queue:in({'$gen_cast', Msg}, Priority, Queue);
-in({'$gen_pcall', From, {Priority, Msg}}, Queue) ->
-    priority_queue:in({'$gen_call', From, Msg}, Priority, Queue);
-in(Input, Queue) ->
-    priority_queue:in(Input, Queue).
-
-process_msg(Parent, Name, State, Mod, Time, TimeoutState, Queue,
-            Debug, Msg) ->
+in({'$gen_cast', Msg}, GS2State = #gs2_state { prioritise_cast = PC,
+                                               queue           = Queue }) ->
+    GS2State #gs2_state { queue = priority_queue:in(
+                                    {'$gen_cast', Msg},
+                                    PC(Msg, GS2State), Queue) };
+in({'$gen_call', From, Msg}, GS2State = #gs2_state { prioritise_call = PC,
+                                                     queue           = Queue }) ->
+    GS2State #gs2_state { queue = priority_queue:in(
+                                    {'$gen_call', From, Msg},
+                                    PC(Msg, From, GS2State), Queue) };
+in(Input, GS2State = #gs2_state { prioritise_info = PI, queue = Queue }) ->
+    GS2State #gs2_state { queue = priority_queue:in(
+                                    Input, PI(Input, GS2State), Queue) }.
+
+process_msg(Msg,
+            GS2State = #gs2_state { parent = Parent,
+                                    name   = Name,
+                                    debug  = Debug }) ->
     case Msg of
-	{system, From, Req} ->
-	    sys:handle_system_msg(
+        {system, From, Req} ->
+            sys:handle_system_msg(
               Req, From, Parent, ?MODULE, Debug,
-              [Name, State, Mod, Time, TimeoutState, Queue]);
+              GS2State);
         %% gen_server puts Hib on the end as the 7th arg, but that
         %% version of the function seems not to be documented so
         %% leaving out for now.
-	{'EXIT', Parent, Reason} ->
-	    terminate(Reason, Name, Msg, Mod, State, Debug);
-	_Msg when Debug =:= [] ->
-	    handle_msg(Msg, Parent, Name, State, Mod, TimeoutState, Queue);
-	_Msg ->
-	    Debug1 = sys:handle_debug(Debug, {?MODULE, print_event}, 
-				      Name, {in, Msg}),
-	    handle_msg(Msg, Parent, Name, State, Mod, TimeoutState, Queue,
-                       Debug1)
+        {'EXIT', Parent, Reason} ->
+            terminate(Reason, Msg, GS2State);
+        _Msg when Debug =:= [] ->
+            handle_msg(Msg, GS2State);
+        _Msg ->
+            Debug1 = sys:handle_debug(Debug, {?MODULE, print_event},
+                                      Name, {in, Msg}),
+            handle_msg(Msg, GS2State #gs2_state { debug = Debug1 })
     end.
 
 %%% ---------------------------------------------------
@@ -638,35 +631,35 @@ do_multi_call(Nodes, Name, Req, Timeout) ->
     Tag = make_ref(),
     Caller = self(),
     Receiver =
-	spawn(
-	  fun () ->
-		  %% Middleman process. Should be unsensitive to regular
-		  %% exit signals. The sychronization is needed in case
-		  %% the receiver would exit before the caller started
-		  %% the monitor.
-		  process_flag(trap_exit, true),
-		  Mref = erlang:monitor(process, Caller),
-		  receive
-		      {Caller,Tag} ->
-			  Monitors = send_nodes(Nodes, Name, Tag, Req),
-			  TimerId = erlang:start_timer(Timeout, self(), ok),
-			  Result = rec_nodes(Tag, Monitors, Name, TimerId),
-			  exit({self(),Tag,Result});
-		      {'DOWN',Mref,_,_,_} ->
-			  %% Caller died before sending us the go-ahead.
-			  %% Give up silently.
-			  exit(normal)
-		  end
-	  end),
+        spawn(
+          fun () ->
+                  %% Middleman process. Should be unsensitive to regular
+                  %% exit signals. The sychronization is needed in case
+                  %% the receiver would exit before the caller started
+                  %% the monitor.
+                  process_flag(trap_exit, true),
+                  Mref = erlang:monitor(process, Caller),
+                  receive
+                      {Caller,Tag} ->
+                          Monitors = send_nodes(Nodes, Name, Tag, Req),
+                          TimerId = erlang:start_timer(Timeout, self(), ok),
+                          Result = rec_nodes(Tag, Monitors, Name, TimerId),
+                          exit({self(),Tag,Result});
+                      {'DOWN',Mref,_,_,_} ->
+                          %% Caller died before sending us the go-ahead.
+                          %% Give up silently.
+                          exit(normal)
+                  end
+          end),
     Mref = erlang:monitor(process, Receiver),
     Receiver ! {self(),Tag},
     receive
-	{'DOWN',Mref,_,_,{Receiver,Tag,Result}} ->
-	    Result;
-	{'DOWN',Mref,_,_,Reason} ->
-	    %% The middleman code failed. Or someone did 
-	    %% exit(_, kill) on the middleman process => Reason==killed
-	    exit(Reason)
+        {'DOWN',Mref,_,_,{Receiver,Tag,Result}} ->
+            Result;
+        {'DOWN',Mref,_,_,Reason} ->
+            %% The middleman code failed. Or someone did
+            %% exit(_, kill) on the middleman process => Reason==killed
+            exit(Reason)
     end.
 
 send_nodes(Nodes, Name, Tag, Req) ->
@@ -681,7 +674,7 @@ send_nodes([Node|Tail], Name, Tag, Req, Monitors)
 send_nodes([_Node|Tail], Name, Tag, Req, Monitors) ->
     %% Skip non-atom Node
     send_nodes(Tail, Name, Tag, Req, Monitors);
-send_nodes([], _Name, _Tag, _Req, Monitors) -> 
+send_nodes([], _Name, _Tag, _Req, Monitors) ->
     Monitors.
 
 %% Against old nodes:
@@ -691,89 +684,89 @@ send_nodes([], _Name, _Tag, _Req, Monitors) ->
 %% Against contemporary nodes:
 %% Wait for reply, server 'DOWN', or timeout from TimerId.
 
-rec_nodes(Tag, Nodes, Name, TimerId) -> 
+rec_nodes(Tag, Nodes, Name, TimerId) ->
     rec_nodes(Tag, Nodes, Name, [], [], 2000, TimerId).
 
 rec_nodes(Tag, [{N,R}|Tail], Name, Badnodes, Replies, Time, TimerId ) ->
     receive
-	{'DOWN', R, _, _, _} ->
-	    rec_nodes(Tag, Tail, Name, [N|Badnodes], Replies, Time, TimerId);
-	{{Tag, N}, Reply} ->  %% Tag is bound !!!
-	    unmonitor(R), 
-	    rec_nodes(Tag, Tail, Name, Badnodes, 
-		      [{N,Reply}|Replies], Time, TimerId);
-	{timeout, TimerId, _} ->	
-	    unmonitor(R),
-	    %% Collect all replies that already have arrived
-	    rec_nodes_rest(Tag, Tail, Name, [N|Badnodes], Replies)
+        {'DOWN', R, _, _, _} ->
+            rec_nodes(Tag, Tail, Name, [N|Badnodes], Replies, Time, TimerId);
+        {{Tag, N}, Reply} ->  %% Tag is bound !!!
+            unmonitor(R),
+            rec_nodes(Tag, Tail, Name, Badnodes,
+                      [{N,Reply}|Replies], Time, TimerId);
+        {timeout, TimerId, _} ->
+            unmonitor(R),
+            %% Collect all replies that already have arrived
+            rec_nodes_rest(Tag, Tail, Name, [N|Badnodes], Replies)
     end;
 rec_nodes(Tag, [N|Tail], Name, Badnodes, Replies, Time, TimerId) ->
     %% R6 node
     receive
-	{nodedown, N} ->
-	    monitor_node(N, false),
-	    rec_nodes(Tag, Tail, Name, [N|Badnodes], Replies, 2000, TimerId);
-	{{Tag, N}, Reply} ->  %% Tag is bound !!!
-	    receive {nodedown, N} -> ok after 0 -> ok end,
-	    monitor_node(N, false),
-	    rec_nodes(Tag, Tail, Name, Badnodes,
-		      [{N,Reply}|Replies], 2000, TimerId);
-	{timeout, TimerId, _} ->	
-	    receive {nodedown, N} -> ok after 0 -> ok end,
-	    monitor_node(N, false),
-	    %% Collect all replies that already have arrived
-	    rec_nodes_rest(Tag, Tail, Name, [N | Badnodes], Replies)
+        {nodedown, N} ->
+            monitor_node(N, false),
+            rec_nodes(Tag, Tail, Name, [N|Badnodes], Replies, 2000, TimerId);
+        {{Tag, N}, Reply} ->  %% Tag is bound !!!
+            receive {nodedown, N} -> ok after 0 -> ok end,
+            monitor_node(N, false),
+            rec_nodes(Tag, Tail, Name, Badnodes,
+                      [{N,Reply}|Replies], 2000, TimerId);
+        {timeout, TimerId, _} ->
+            receive {nodedown, N} -> ok after 0 -> ok end,
+            monitor_node(N, false),
+            %% Collect all replies that already have arrived
+            rec_nodes_rest(Tag, Tail, Name, [N | Badnodes], Replies)
     after Time ->
-	    case rpc:call(N, erlang, whereis, [Name]) of
-		Pid when is_pid(Pid) -> % It exists try again.
-		    rec_nodes(Tag, [N|Tail], Name, Badnodes,
-			      Replies, infinity, TimerId);
-		_ -> % badnode
-		    receive {nodedown, N} -> ok after 0 -> ok end,
-		    monitor_node(N, false),
-		    rec_nodes(Tag, Tail, Name, [N|Badnodes],
-			      Replies, 2000, TimerId)
-	    end
+            case rpc:call(N, erlang, whereis, [Name]) of
+                Pid when is_pid(Pid) -> % It exists try again.
+                    rec_nodes(Tag, [N|Tail], Name, Badnodes,
+                              Replies, infinity, TimerId);
+                _ -> % badnode
+                    receive {nodedown, N} -> ok after 0 -> ok end,
+                    monitor_node(N, false),
+                    rec_nodes(Tag, Tail, Name, [N|Badnodes],
+                              Replies, 2000, TimerId)
+            end
     end;
 rec_nodes(_, [], _, Badnodes, Replies, _, TimerId) ->
     case catch erlang:cancel_timer(TimerId) of
-	false ->  % It has already sent it's message
-	    receive
-		{timeout, TimerId, _} -> ok
-	    after 0 ->
-		    ok
-	    end;
-	_ -> % Timer was cancelled, or TimerId was 'undefined'
-	    ok
+        false ->  % It has already sent it's message
+            receive
+                {timeout, TimerId, _} -> ok
+            after 0 ->
+                    ok
+            end;
+        _ -> % Timer was cancelled, or TimerId was 'undefined'
+            ok
     end,
     {Replies, Badnodes}.
 
 %% Collect all replies that already have arrived
 rec_nodes_rest(Tag, [{N,R}|Tail], Name, Badnodes, Replies) ->
     receive
-	{'DOWN', R, _, _, _} ->
-	    rec_nodes_rest(Tag, Tail, Name, [N|Badnodes], Replies);
-	{{Tag, N}, Reply} -> %% Tag is bound !!!
-	    unmonitor(R),
-	    rec_nodes_rest(Tag, Tail, Name, Badnodes, [{N,Reply}|Replies])
+        {'DOWN', R, _, _, _} ->
+            rec_nodes_rest(Tag, Tail, Name, [N|Badnodes], Replies);
+        {{Tag, N}, Reply} -> %% Tag is bound !!!
+            unmonitor(R),
+            rec_nodes_rest(Tag, Tail, Name, Badnodes, [{N,Reply}|Replies])
     after 0 ->
-	    unmonitor(R),
-	    rec_nodes_rest(Tag, Tail, Name, [N|Badnodes], Replies)
+            unmonitor(R),
+            rec_nodes_rest(Tag, Tail, Name, [N|Badnodes], Replies)
     end;
 rec_nodes_rest(Tag, [N|Tail], Name, Badnodes, Replies) ->
     %% R6 node
     receive
-	{nodedown, N} ->
-	    monitor_node(N, false),
-	    rec_nodes_rest(Tag, Tail, Name, [N|Badnodes], Replies);
-	{{Tag, N}, Reply} ->  %% Tag is bound !!!
-	    receive {nodedown, N} -> ok after 0 -> ok end,
-	    monitor_node(N, false),
-	    rec_nodes_rest(Tag, Tail, Name, Badnodes, [{N,Reply}|Replies])
+        {nodedown, N} ->
+            monitor_node(N, false),
+            rec_nodes_rest(Tag, Tail, Name, [N|Badnodes], Replies);
+        {{Tag, N}, Reply} ->  %% Tag is bound !!!
+            receive {nodedown, N} -> ok after 0 -> ok end,
+            monitor_node(N, false),
+            rec_nodes_rest(Tag, Tail, Name, Badnodes, [{N,Reply}|Replies])
     after 0 ->
-	    receive {nodedown, N} -> ok after 0 -> ok end,
-	    monitor_node(N, false),
-	    rec_nodes_rest(Tag, Tail, Name, [N|Badnodes], Replies)
+            receive {nodedown, N} -> ok after 0 -> ok end,
+            monitor_node(N, false),
+            rec_nodes_rest(Tag, Tail, Name, [N|Badnodes], Replies)
     end;
 rec_nodes_rest(_Tag, [], _Name, Badnodes, Replies) ->
     {Replies, Badnodes}.
@@ -785,28 +778,28 @@ rec_nodes_rest(_Tag, [], _Name, Badnodes, Replies) ->
 
 start_monitor(Node, Name) when is_atom(Node), is_atom(Name) ->
     if node() =:= nonode@nohost, Node =/= nonode@nohost ->
-	    Ref = make_ref(),
-	    self() ! {'DOWN', Ref, process, {Name, Node}, noconnection},
-	    {Node, Ref};
+            Ref = make_ref(),
+            self() ! {'DOWN', Ref, process, {Name, Node}, noconnection},
+            {Node, Ref};
        true ->
-	    case catch erlang:monitor(process, {Name, Node}) of
-		{'EXIT', _} ->
-		    %% Remote node is R6
-		    monitor_node(Node, true),
-		    Node;
-		Ref when is_reference(Ref) ->
-		    {Node, Ref}
-	    end
+            case catch erlang:monitor(process, {Name, Node}) of
+                {'EXIT', _} ->
+                    %% Remote node is R6
+                    monitor_node(Node, true),
+                    Node;
+                Ref when is_reference(Ref) ->
+                    {Node, Ref}
+            end
     end.
 
 %% Cancels a monitor started with Ref=erlang:monitor(_, _).
 unmonitor(Ref) when is_reference(Ref) ->
     erlang:demonitor(Ref),
     receive
-	{'DOWN', Ref, _, _, _} ->
-	    true
+        {'DOWN', Ref, _, _, _} ->
+            true
     after 0 ->
-	    true
+            true
     end.
 
 %%% ---------------------------------------------------
@@ -818,130 +811,114 @@ dispatch({'$gen_cast', Msg}, Mod, State) ->
 dispatch(Info, Mod, State) ->
     Mod:handle_info(Info, State).
 
-handle_msg({'$gen_call', From, Msg},
-           Parent, Name, State, Mod, TimeoutState, Queue) ->
-    case catch Mod:handle_call(Msg, From, State) of
-	{reply, Reply, NState} ->
-	    reply(From, Reply),
-	    loop(Parent, Name, NState, Mod, infinity, TimeoutState, Queue, []);
-	{reply, Reply, NState, Time1} ->
-	    reply(From, Reply),
-	    loop(Parent, Name, NState, Mod, Time1, TimeoutState, Queue, []);
-	{noreply, NState} ->
-	    loop(Parent, Name, NState, Mod, infinity, TimeoutState, Queue, []);
-	{noreply, NState, Time1} ->
-	    loop(Parent, Name, NState, Mod, Time1, TimeoutState, Queue, []);
-	{stop, Reason, Reply, NState} ->
-	    {'EXIT', R} = 
-		(catch terminate(Reason, Name, Msg, Mod, NState, [])),
-	    reply(From, Reply),
-	    exit(R);
-	Other -> handle_common_reply(Other, Parent, Name, Msg, Mod, State,
-                                     TimeoutState, Queue)
-    end;
-handle_msg(Msg,
-           Parent, Name, State, Mod, TimeoutState, Queue) ->
-    Reply = (catch dispatch(Msg, Mod, State)),
-    handle_common_reply(Reply, Parent, Name, Msg, Mod, State,
-                        TimeoutState, Queue).
-
-handle_msg({'$gen_call', From, Msg},
-           Parent, Name, State, Mod, TimeoutState, Queue, Debug) ->
+common_reply(_Name, From, Reply, _NState, [] = _Debug) ->
+    reply(From, Reply),
+    [];
+common_reply(Name, From, Reply, NState, Debug) ->
+    reply(Name, From, Reply, NState, Debug).
+
+common_debug([] = _Debug, _Func, _Info, _Event) ->
+    [];
+common_debug(Debug, Func, Info, Event) ->
+    sys:handle_debug(Debug, Func, Info, Event).
+
+handle_msg({'$gen_call', From, Msg}, GS2State = #gs2_state { mod = Mod,
+                                                             state = State,
+                                                             name = Name,
+                                                             debug = Debug }) ->
     case catch Mod:handle_call(Msg, From, State) of
-	{reply, Reply, NState} ->
-	    Debug1 = reply(Name, From, Reply, NState, Debug),
-	    loop(Parent, Name, NState, Mod, infinity, TimeoutState, Queue,
-                 Debug1);
-	{reply, Reply, NState, Time1} ->
-	    Debug1 = reply(Name, From, Reply, NState, Debug),
-	    loop(Parent, Name, NState, Mod, Time1, TimeoutState, Queue, Debug1);
-	{noreply, NState} ->
-	    Debug1 = sys:handle_debug(Debug, {?MODULE, print_event}, Name,
-				      {noreply, NState}),
-	    loop(Parent, Name, NState, Mod, infinity, TimeoutState, Queue,
-                 Debug1);
-	{noreply, NState, Time1} ->
-	    Debug1 = sys:handle_debug(Debug, {?MODULE, print_event}, Name,
-				      {noreply, NState}),
-	    loop(Parent, Name, NState, Mod, Time1, TimeoutState, Queue, Debug1);
-	{stop, Reason, Reply, NState} ->
-	    {'EXIT', R} = 
-		(catch terminate(Reason, Name, Msg, Mod, NState, Debug)),
-	    reply(Name, From, Reply, NState, Debug),
-	    exit(R);
-	Other ->
-	    handle_common_reply(Other, Parent, Name, Msg, Mod, State,
-                                TimeoutState, Queue, Debug)
+        {reply, Reply, NState} ->
+            Debug1 = common_reply(Name, From, Reply, NState, Debug),
+            loop(GS2State #gs2_state { state = NState,
+                                       time  = infinity,
+                                       debug = Debug1 });
+        {reply, Reply, NState, Time1} ->
+            Debug1 = common_reply(Name, From, Reply, NState, Debug),
+            loop(GS2State #gs2_state { state = NState,
+                                       time  = Time1,
+                                       debug = Debug1});
+        {noreply, NState} ->
+            Debug1 = common_debug(Debug, {?MODULE, print_event}, Name,
+                                  {noreply, NState}),
+            loop(GS2State #gs2_state {state = NState,
+                                      time  = infinity,
+                                      debug = Debug1});
+        {noreply, NState, Time1} ->
+            Debug1 = common_debug(Debug, {?MODULE, print_event}, Name,
+                                  {noreply, NState}),
+            loop(GS2State #gs2_state {state = NState,
+                                      time  = Time1,
+                                      debug = Debug1});
+        {stop, Reason, Reply, NState} ->
+            {'EXIT', R} =
+                (catch terminate(Reason, Msg,
+                                 GS2State #gs2_state { state = NState })),
+            reply(Name, From, Reply, NState, Debug),
+            exit(R);
+        Other ->
+            handle_common_reply(Other, Msg, GS2State)
     end;
-handle_msg(Msg,
-           Parent, Name, State, Mod, TimeoutState, Queue, Debug) ->
+handle_msg(Msg, GS2State = #gs2_state { mod = Mod, state = State }) ->
     Reply = (catch dispatch(Msg, Mod, State)),
-    handle_common_reply(Reply, Parent, Name, Msg, Mod, State,
-                        TimeoutState, Queue, Debug).
+    handle_common_reply(Reply, Msg, GS2State).
 
-handle_common_reply(Reply, Parent, Name, Msg, Mod, State,
-                    TimeoutState, Queue) ->
+handle_common_reply(Reply, Msg, GS2State = #gs2_state { name  = Name,
+                                                        debug = Debug}) ->
     case Reply of
-	{noreply, NState} ->
-	    loop(Parent, Name, NState, Mod, infinity, TimeoutState, Queue, []);
-	{noreply, NState, Time1} ->
-	    loop(Parent, Name, NState, Mod, Time1, TimeoutState, Queue, []);
+        {noreply, NState} ->
+            Debug1 = common_debug(Debug, {?MODULE, print_event}, Name,
+                                  {noreply, NState}),
+            loop(GS2State #gs2_state { state = NState,
+                                       time  = infinity,
+                                       debug = Debug1 });
+        {noreply, NState, Time1} ->
+            Debug1 = common_debug(Debug, {?MODULE, print_event}, Name,
+                                  {noreply, NState}),
+            loop(GS2State #gs2_state { state = NState,
+                                       time  = Time1,
+                                       debug = Debug1 });
         _ ->
-            handle_common_termination(Reply, Name, Msg, Mod, State, [])
+            handle_common_termination(Reply, Msg, GS2State)
     end.
 
-handle_common_reply(Reply, Parent, Name, Msg, Mod, State, TimeoutState, Queue,
-                    Debug) ->
+handle_common_termination(Reply, Msg, GS2State) ->
     case Reply of
-	{noreply, NState} ->
-	    Debug1 = sys:handle_debug(Debug, {?MODULE, print_event}, Name,
-				      {noreply, NState}),
-	    loop(Parent, Name, NState, Mod, infinity, TimeoutState, Queue,
-                 Debug1);
-	{noreply, NState, Time1} ->
-	    Debug1 = sys:handle_debug(Debug, {?MODULE, print_event}, Name,
-				      {noreply, NState}),
-	    loop(Parent, Name, NState, Mod, Time1, TimeoutState, Queue, Debug1);
+        {stop, Reason, NState} ->
+            terminate(Reason, Msg, GS2State #gs2_state { state = NState });
+        {'EXIT', What} ->
+            terminate(What, Msg, GS2State);
         _ ->
-            handle_common_termination(Reply, Name, Msg, Mod, State, Debug)
-    end.
-
-handle_common_termination(Reply, Name, Msg, Mod, State, Debug) ->
-    case Reply of
-	{stop, Reason, NState} ->
-	    terminate(Reason, Name, Msg, Mod, NState, Debug);
-	{'EXIT', What} ->
-	    terminate(What, Name, Msg, Mod, State, Debug);
-	_ ->
-	    terminate({bad_return_value, Reply}, Name, Msg, Mod, State, Debug)
+            terminate({bad_return_value, Reply}, Msg, GS2State)
     end.
 
 reply(Name, {To, Tag}, Reply, State, Debug) ->
     reply({To, Tag}, Reply),
-    sys:handle_debug(Debug, {?MODULE, print_event}, Name, 
-		     {out, Reply, To, State} ).
+    sys:handle_debug(
+      Debug, {?MODULE, print_event}, Name, {out, Reply, To, State}).
 
 
 %%-----------------------------------------------------------------
 %% Callback functions for system messages handling.
 %%-----------------------------------------------------------------
-system_continue(Parent, Debug, [Name, State, Mod, Time, TimeoutState, Queue]) ->
-    loop(Parent, Name, State, Mod, Time, TimeoutState, Queue, Debug).
+system_continue(Parent, Debug, GS2State) ->
+    loop(GS2State #gs2_state { parent = Parent, debug = Debug }).
 
 -ifdef(use_specs).
 -spec system_terminate(_, _, _, [_]) -> no_return().
 -endif.
 
-system_terminate(Reason, _Parent, Debug, [Name, State, Mod, _Time,
-                                          _TimeoutState, _Queue]) ->
-    terminate(Reason, Name, [], Mod, State, Debug).
+system_terminate(Reason, _Parent, Debug, GS2State) ->
+    terminate(Reason, [], GS2State #gs2_state { debug = Debug }).
 
-system_code_change([Name, State, Mod, Time, TimeoutState, Queue], _Module,
-                   OldVsn, Extra) ->
+system_code_change(GS2State = #gs2_state { mod   = Mod,
+                                           state = State },
+                   _Module, OldVsn, Extra) ->
     case catch Mod:code_change(OldVsn, State, Extra) of
-	{ok, NewState} ->
-            {ok, [Name, NewState, Mod, Time, TimeoutState, Queue]};
-	Else ->
+        {ok, NewState} ->
+            NewGS2State = find_prioritisers(
+                            GS2State #gs2_state { state = NewState }),
+            {ok, [NewGS2State]};
+        Else ->
             Else
     end.
 
@@ -951,18 +928,18 @@ system_code_change([Name, State, Mod, Time, TimeoutState, Queue], _Module,
 %%-----------------------------------------------------------------
 print_event(Dev, {in, Msg}, Name) ->
     case Msg of
-	{'$gen_call', {From, _Tag}, Call} ->
-	    io:format(Dev, "*DBG* ~p got call ~p from ~w~n",
-		      [Name, Call, From]);
-	{'$gen_cast', Cast} ->
-	    io:format(Dev, "*DBG* ~p got cast ~p~n",
-		      [Name, Cast]);
-	_ ->
-	    io:format(Dev, "*DBG* ~p got ~p~n", [Name, Msg])
+        {'$gen_call', {From, _Tag}, Call} ->
+            io:format(Dev, "*DBG* ~p got call ~p from ~w~n",
+                      [Name, Call, From]);
+        {'$gen_cast', Cast} ->
+            io:format(Dev, "*DBG* ~p got cast ~p~n",
+                      [Name, Cast]);
+        _ ->
+            io:format(Dev, "*DBG* ~p got ~p~n", [Name, Msg])
     end;
 print_event(Dev, {out, Msg, To, State}, Name) ->
-    io:format(Dev, "*DBG* ~p sent ~p to ~w, new state ~w~n", 
-	      [Name, Msg, To, State]);
+    io:format(Dev, "*DBG* ~p sent ~p to ~w, new state ~w~n",
+              [Name, Msg, To, State]);
 print_event(Dev, {noreply, State}, Name) ->
     io:format(Dev, "*DBG* ~p new state ~w~n", [Name, State]);
 print_event(Dev, Event, Name) ->
@@ -973,23 +950,26 @@ print_event(Dev, Event, Name) ->
 %%% Terminate the server.
 %%% ---------------------------------------------------
 
-terminate(Reason, Name, Msg, Mod, State, Debug) ->
+terminate(Reason, Msg, #gs2_state { name  = Name,
+                                    mod   = Mod,
+                                    state = State,
+                                    debug = Debug }) ->
     case catch Mod:terminate(Reason, State) of
-	{'EXIT', R} ->
-	    error_info(R, Reason, Name, Msg, State, Debug),
-	    exit(R);
-	_ ->
-	    case Reason of
-		normal ->
-		    exit(normal);
-		shutdown ->
-		    exit(shutdown);
-		{shutdown,_}=Shutdown ->
-		    exit(Shutdown);
-		_ ->
-		    error_info(Reason, undefined, Name, Msg, State, Debug),
-		    exit(Reason)
-	    end
+        {'EXIT', R} ->
+            error_info(R, Reason, Name, Msg, State, Debug),
+            exit(R);
+        _ ->
+            case Reason of
+                normal ->
+                    exit(normal);
+                shutdown ->
+                    exit(shutdown);
+                {shutdown,_}=Shutdown ->
+                    exit(Shutdown);
+                _ ->
+                    error_info(Reason, undefined, Name, Msg, State, Debug),
+                    exit(Reason)
+            end
     end.
 
 error_info(_Reason, _RootCause, application_controller, _Msg, _State, _Debug) ->
@@ -1038,74 +1018,109 @@ opt(_, []) ->
 
 debug_options(Name, Opts) ->
     case opt(debug, Opts) of
-	{ok, Options} -> dbg_options(Name, Options);
-	_ -> dbg_options(Name, [])
+        {ok, Options} -> dbg_options(Name, Options);
+        _ -> dbg_options(Name, [])
     end.
 
 dbg_options(Name, []) ->
-    Opts = 
-	case init:get_argument(generic_debug) of
-	    error ->
-		[];
-	    _ ->
-		[log, statistics]
-	end,
+    Opts =
+        case init:get_argument(generic_debug) of
+            error ->
+                [];
+            _ ->
+                [log, statistics]
+        end,
     dbg_opts(Name, Opts);
 dbg_options(Name, Opts) ->
     dbg_opts(Name, Opts).
 
 dbg_opts(Name, Opts) ->
     case catch sys:debug_options(Opts) of
-	{'EXIT',_} ->
-	    format("~p: ignoring erroneous debug options - ~p~n",
-		   [Name, Opts]),
-	    [];
-	Dbg ->
-	    Dbg
+        {'EXIT',_} ->
+            format("~p: ignoring erroneous debug options - ~p~n",
+                   [Name, Opts]),
+            [];
+        Dbg ->
+            Dbg
     end.
 
 get_proc_name(Pid) when is_pid(Pid) ->
     Pid;
 get_proc_name({local, Name}) ->
     case process_info(self(), registered_name) of
-	{registered_name, Name} ->
-	    Name;
-	{registered_name, _Name} ->
-	    exit(process_not_registered);
-	[] ->
-	    exit(process_not_registered)
-    end;    
+        {registered_name, Name} ->
+            Name;
+        {registered_name, _Name} ->
+            exit(process_not_registered);
+        [] ->
+            exit(process_not_registered)
+    end;
 get_proc_name({global, Name}) ->
     case global:safe_whereis_name(Name) of
-	undefined ->
-	    exit(process_not_registered_globally);
-	Pid when Pid =:= self() ->
-	    Name;
-	_Pid ->
-	    exit(process_not_registered_globally)
+        undefined ->
+            exit(process_not_registered_globally);
+        Pid when Pid =:= self() ->
+            Name;
+        _Pid ->
+            exit(process_not_registered_globally)
     end.
 
 get_parent() ->
     case get('$ancestors') of
-	[Parent | _] when is_pid(Parent)->
+        [Parent | _] when is_pid(Parent)->
             Parent;
         [Parent | _] when is_atom(Parent)->
             name_to_pid(Parent);
-	_ ->
-	    exit(process_was_not_started_by_proc_lib)
+        _ ->
+            exit(process_was_not_started_by_proc_lib)
     end.
 
 name_to_pid(Name) ->
     case whereis(Name) of
-	undefined ->
-	    case global:safe_whereis_name(Name) of
-		undefined ->
-		    exit(could_not_find_registerd_name);
-		Pid ->
-		    Pid
-	    end;
-	Pid ->
-	    Pid
+        undefined ->
+            case global:safe_whereis_name(Name) of
+                undefined ->
+                    exit(could_not_find_registerd_name);
+                Pid ->
+                    Pid
+            end;
+        Pid ->
+            Pid
+    end.
+
+find_prioritisers(GS2State = #gs2_state { mod = Mod }) ->
+    PrioriCall = function_exported_or_default(
+                   Mod, 'prioritise_call', 3,
+                   fun (_Msg, _From, _State) -> 0 end),
+    PrioriCast = function_exported_or_default(Mod, 'prioritise_cast', 2,
+                                              fun (_Msg, _State) -> 0 end),
+    PrioriInfo = function_exported_or_default(Mod, 'prioritise_info', 2,
+                                              fun (_Msg, _State) -> 0 end),
+    GS2State #gs2_state { prioritise_call = PrioriCall,
+                          prioritise_cast = PrioriCast,
+                          prioritise_info = PrioriInfo }.
+
+function_exported_or_default(Mod, Fun, Arity, Default) ->
+    case erlang:function_exported(Mod, Fun, Arity) of
+        true -> case Arity of
+                    2 -> fun (Msg, GS2State = #gs2_state { state = State }) ->
+                                 case catch Mod:Fun(Msg, State) of
+                                     Res when is_integer(Res) ->
+                                         Res;
+                                     Err ->
+                                         handle_common_termination(Err, Msg, GS2State)
+                                 end
+                         end;
+                    3 -> fun (Msg, From, GS2State = #gs2_state { state = State }) ->
+                                 case catch Mod:Fun(Msg, From, State) of
+                                     Res when is_integer(Res) ->
+                                         Res;
+                                     Err ->
+                                         handle_common_termination(Err, Msg, GS2State)
+                                 end
+                         end
+                end;
+        false -> Default
     end.
 
 %%-----------------------------------------------------------------
@@ -1115,25 +1130,23 @@ format_status(Opt, StatusData) ->
     [PDict, SysState, Parent, Debug,
      [Name, State, Mod, _Time, _TimeoutState, Queue]] = StatusData,
     NameTag = if is_pid(Name) ->
-		      pid_to_list(Name);
-		 is_atom(Name) ->
-		      Name
-	      end,
+                      pid_to_list(Name);
+                 is_atom(Name) ->
+                      Name
+              end,
     Header = lists:concat(["Status for generic server ", NameTag]),
     Log = sys:get_debug(log, Debug, []),
-    Specfic = 
-	case erlang:function_exported(Mod, format_status, 2) of
-	    true ->
-		case catch Mod:format_status(Opt, [PDict, State]) of
-		    {'EXIT', _} -> [{data, [{"State", State}]}];
-		    Else -> Else
-		end;
-	    _ ->
-		[{data, [{"State", State}]}]
-	end,
+    Specfic =
+        case erlang:function_exported(Mod, format_status, 2) of
+            true -> case catch Mod:format_status(Opt, [PDict, State]) of
+                        {'EXIT', _} -> [{data, [{"State", State}]}];
+                        Else        -> Else
+                    end;
+            _    -> [{data, [{"State", State}]}]
+        end,
     [{header, Header},
      {data, [{"Status", SysState},
-	     {"Parent", Parent},
-	     {"Logged events", Log},
+             {"Parent", Parent},
+             {"Logged events", Log},
              {"Queued messages", priority_queue:to_list(Queue)}]} |
      Specfic].
diff --git a/src/rabbit_amqqueue.erl b/src/rabbit_amqqueue.erl
index 7116653c..3e677c38 100644
--- a/src/rabbit_amqqueue.erl
+++ b/src/rabbit_amqqueue.erl
@@ -332,10 +332,10 @@ info_keys() -> rabbit_amqqueue_process:info_keys().
 map(VHostPath, F) -> rabbit_misc:filter_exit_map(F, list(VHostPath)).
 
 info(#amqqueue{ pid = QPid }) ->
-    delegate_pcall(QPid, 9, info, infinity).
+    delegate_call(QPid, info, infinity).
 
 info(#amqqueue{ pid = QPid }, Items) ->
-    case delegate_pcall(QPid, 9, {info, Items}, infinity) of
+    case delegate_call(QPid, {info, Items}, infinity) of
         {ok, Res}      -> Res;
         {error, Error} -> throw(Error)
     end.
@@ -345,7 +345,7 @@ info_all(VHostPath) -> map(VHostPath, fun (Q) -> info(Q) end).
 info_all(VHostPath, Items) -> map(VHostPath, fun (Q) -> info(Q, Items) end).
 
 consumers(#amqqueue{ pid = QPid }) ->
-    delegate_pcall(QPid, 9, consumers, infinity).
+    delegate_call(QPid, consumers, infinity).
 
 consumers_all(VHostPath) ->
     lists:concat(
@@ -357,7 +357,7 @@ consumers_all(VHostPath) ->
 stat(#amqqueue{pid = QPid}) -> delegate_call(QPid, stat, infinity).
 
 emit_stats(#amqqueue{pid = QPid}) ->
-    delegate_pcast(QPid, 7, emit_stats).
+    delegate_cast(QPid, emit_stats).
 
 delete(#amqqueue{ pid = QPid }, IfUnused, IfEmpty) ->
     delegate_call(QPid, {delete, IfUnused, IfEmpty}, infinity).
@@ -380,10 +380,10 @@ requeue(QPid, MsgIds, ChPid) ->
     delegate_call(QPid, {requeue, MsgIds, ChPid}, infinity).
 
 ack(QPid, Txn, MsgIds, ChPid) ->
-    delegate_pcast(QPid, 7, {ack, Txn, MsgIds, ChPid}).
+    delegate_cast(QPid, {ack, Txn, MsgIds, ChPid}).
 
 reject(QPid, MsgIds, Requeue, ChPid) ->
-    delegate_pcast(QPid, 7, {reject, MsgIds, Requeue, ChPid}).
+    delegate_cast(QPid, {reject, MsgIds, Requeue, ChPid}).
 
 commit_all(QPids, Txn, ChPid) ->
     safe_delegate_call_ok(
@@ -419,10 +419,10 @@ basic_cancel(#amqqueue{pid = QPid}, ChPid, ConsumerTag, OkMsg) ->
                        infinity).
 
 notify_sent(QPid, ChPid) ->
-    delegate_pcast(QPid, 7, {notify_sent, ChPid}).
+    delegate_cast(QPid, {notify_sent, ChPid}).
 
 unblock(QPid, ChPid) ->
-    delegate_pcast(QPid, 7, {unblock, ChPid}).
+    delegate_cast(QPid, {unblock, ChPid}).
 
 flush_all(QPids, ChPid) ->
     delegate:invoke_no_result(
@@ -452,20 +452,19 @@ internal_delete(QueueName) ->
     end.
 
 maybe_run_queue_via_backing_queue(QPid, Fun) ->
-    gen_server2:pcall(QPid, 6, {maybe_run_queue_via_backing_queue, Fun},
-                      infinity).
+    gen_server2:call(QPid, {maybe_run_queue_via_backing_queue, Fun}, infinity).
 
 update_ram_duration(QPid) ->
-    gen_server2:pcast(QPid, 8, update_ram_duration).
+    gen_server2:cast(QPid, update_ram_duration).
 
 set_ram_duration_target(QPid, Duration) ->
-    gen_server2:pcast(QPid, 8, {set_ram_duration_target, Duration}).
+    gen_server2:cast(QPid, {set_ram_duration_target, Duration}).
 
 set_maximum_since_use(QPid, Age) ->
-    gen_server2:pcast(QPid, 8, {set_maximum_since_use, Age}).
+    gen_server2:cast(QPid, {set_maximum_since_use, Age}).
 
 maybe_expire(QPid) ->
-    gen_server2:pcast(QPid, 8, maybe_expire).
+    gen_server2:cast(QPid, maybe_expire).
 
 on_node_down(Node) ->
     [Hook() ||
@@ -505,11 +504,6 @@ safe_delegate_call_ok(F, Pids) ->
 delegate_call(Pid, Msg, Timeout) ->
     delegate:invoke(Pid, fun (P) -> gen_server2:call(P, Msg, Timeout) end).
 
-delegate_pcall(Pid, Pri, Msg, Timeout) ->
-    delegate:invoke(Pid,
-                    fun (P) -> gen_server2:pcall(P, Pri, Msg, Timeout) end).
-
-delegate_pcast(Pid, Pri, Msg) ->
-    delegate:invoke_no_result(Pid,
-                              fun (P) -> gen_server2:pcast(P, Pri, Msg) end).
+delegate_cast(Pid, Msg) ->
+    delegate:invoke(Pid, fun (P) -> gen_server2:cast(P, Msg) end).
 
diff --git a/src/rabbit_amqqueue_process.erl b/src/rabbit_amqqueue_process.erl
index 9a40580e..91877efb 100644
--- a/src/rabbit_amqqueue_process.erl
+++ b/src/rabbit_amqqueue_process.erl
@@ -42,7 +42,8 @@
 -export([start_link/1, info_keys/0]).
 
 -export([init/1, terminate/2, code_change/3, handle_call/3, handle_cast/2,
-         handle_info/2, handle_pre_hibernate/1]).
+         handle_info/2, handle_pre_hibernate/1, prioritise_call/3,
+         prioritise_cast/2]).
 
 -import(queue).
 -import(erlang).
@@ -589,6 +590,29 @@ emit_stats(State) ->
 
 %---------------------------------------------------------------------------
 
+prioritise_call(Msg, _From, _State) ->
+    case Msg of
+        info                                      -> 9;
+        {info, _Items}                            -> 9;
+        consumers                                 -> 9;
+        {maybe_run_queue_via_backing_queue, _Fun} -> 6;
+        _                                         -> 0
+    end.
+
+prioritise_cast(Msg, _State) ->
+    case Msg of
+        update_ram_duration                  -> 8;
+        {set_ram_duration_target, _Duration} -> 8;
+        {set_maximum_since_use, _Age}        -> 8;
+        maybe_expire                         -> 8;
+        emit_stats                           -> 7;
+        {ack, _Txn, _MsgIds, _ChPid}         -> 7;
+        {reject, _MsgIds, _Requeue, _ChPid}  -> 7;
+        {notify_sent, _ChPid}                -> 7;
+        {unblock, _ChPid}                    -> 7;
+        _                                    -> 0
+    end.
+
 handle_call({init, Recover}, From,
             State = #q{q = #amqqueue{exclusive_owner = none}}) ->
     declare(Recover, From, State);
diff --git a/src/rabbit_channel.erl b/src/rabbit_channel.erl
index 174eab40..f19f98d2 100644
--- a/src/rabbit_channel.erl
+++ b/src/rabbit_channel.erl
@@ -41,7 +41,8 @@
 -export([emit_stats/1, flush/1]).
 
 -export([init/1, terminate/2, code_change/3, handle_call/3, handle_cast/2,
-         handle_info/2, handle_pre_hibernate/1]).
+         handle_info/2, handle_pre_hibernate/1, prioritise_call/3,
+         prioritise_cast/2]).
 
 -record(ch, {state, channel, reader_pid, writer_pid, limiter_pid,
              start_limiter_fun, transaction_id, tx_participants, next_tag,
@@ -131,10 +132,10 @@ list() ->
 info_keys() -> ?INFO_KEYS.
 
 info(Pid) ->
-    gen_server2:pcall(Pid, 9, info, infinity).
+    gen_server2:call(Pid, info, infinity).
 
 info(Pid, Items) ->
-    case gen_server2:pcall(Pid, 9, {info, Items}, infinity) of
+    case gen_server2:call(Pid, {info, Items}, infinity) of
         {ok, Res}      -> Res;
         {error, Error} -> throw(Error)
     end.
@@ -146,7 +147,7 @@ info_all(Items) ->
     rabbit_misc:filter_exit_map(fun (C) -> info(C, Items) end, list()).
 
 emit_stats(Pid) ->
-    gen_server2:pcast(Pid, 7, emit_stats).
+    gen_server2:cast(Pid, emit_stats).
 
 flush(Pid) ->
     gen_server2:call(Pid, flush).
@@ -179,6 +180,19 @@ init([Channel, ReaderPid, WriterPid, Username, VHost, CollectorPid,
     {ok, State, hibernate,
      {backoff, ?HIBERNATE_AFTER_MIN, ?HIBERNATE_AFTER_MIN, ?DESIRED_HIBERNATE}}.
 
+prioritise_call(Msg, _From, _State) ->
+    case Msg of
+        info           -> 9;
+        {info, _Items} -> 9;
+        _              -> 0
+    end.
+
+prioritise_cast(Msg, _State) ->
+    case Msg of
+        emit_stats -> 7;
+        _          -> 0
+    end.
+
 handle_call(info, _From, State) ->
     reply(infos(?INFO_KEYS, State), State);
 
diff --git a/src/rabbit_limiter.erl b/src/rabbit_limiter.erl
index da7078f1..c323d7ce 100644
--- a/src/rabbit_limiter.erl
+++ b/src/rabbit_limiter.erl
@@ -34,7 +34,7 @@
 -behaviour(gen_server2).
 
 -export([init/1, terminate/2, code_change/3, handle_call/3, handle_cast/2,
-         handle_info/2]).
+         handle_info/2, prioritise_call/3]).
 -export([start_link/2]).
 -export([limit/2, can_send/3, ack/2, register/2, unregister/2]).
 -export([get_limit/1, block/1, unblock/1]).
@@ -107,7 +107,7 @@ get_limit(undefined) ->
 get_limit(Pid) ->
     rabbit_misc:with_exit_handler(
       fun () -> 0 end,
-      fun () -> gen_server2:pcall(Pid, 9, get_limit, infinity) end).
+      fun () -> gen_server2:call(Pid, get_limit, infinity) end).
 
 block(undefined) ->
     ok;
@@ -126,6 +126,9 @@ unblock(LimiterPid) ->
 init([ChPid, UnackedMsgCount]) ->
     {ok, #lim{ch_pid = ChPid, volume = UnackedMsgCount}}.
 
+prioritise_call(get_limit, _From, _State) -> 9;
+prioritise_call(_Msg,      _From, _State) -> 0.
+
 handle_call({can_send, _QPid, _AckRequired}, _From,
             State = #lim{blocked = true}) ->
     {reply, false, State};
diff --git a/src/rabbit_msg_store.erl b/src/rabbit_msg_store.erl
index 18810833..bbecbfe2 100644
--- a/src/rabbit_msg_store.erl
+++ b/src/rabbit_msg_store.erl
@@ -40,7 +40,7 @@
 -export([sync/1, gc_done/4, set_maximum_since_use/2, gc/3]). %% internal
 
 -export([init/1, handle_call/3, handle_cast/2, handle_info/2,
-         terminate/2, code_change/3]).
+         terminate/2, code_change/3, prioritise_call/3, prioritise_cast/2]).
 
 %%----------------------------------------------------------------------------
 
@@ -322,8 +322,8 @@ read(Server, Guid,
             %% 2. Check the cur file cache
             case ets:lookup(CurFileCacheEts, Guid) of
                 [] ->
-                    Defer = fun() -> {gen_server2:pcall(
-                                        Server, 2, {read, Guid}, infinity),
+                    Defer = fun() -> {gen_server2:call(
+                                        Server, {read, Guid}, infinity),
                                       CState} end,
                     case index_lookup(Guid, CState) of
                         not_found   -> Defer();
@@ -345,18 +345,18 @@ remove(Server, Guids)  -> gen_server2:cast(Server, {remove, Guids}).
 release(_Server, [])   -> ok;
 release(Server, Guids) -> gen_server2:cast(Server, {release, Guids}).
 sync(Server, Guids, K) -> gen_server2:cast(Server, {sync, Guids, K}).
-sync(Server)           -> gen_server2:pcast(Server, 8, sync). %% internal
+sync(Server)           -> gen_server2:cast(Server, sync). %% internal
 
 gc_done(Server, Reclaimed, Source, Destination) ->
-    gen_server2:pcast(Server, 8, {gc_done, Reclaimed, Source, Destination}).
+    gen_server2:cast(Server, {gc_done, Reclaimed, Source, Destination}).
 
 set_maximum_since_use(Server, Age) ->
-    gen_server2:pcast(Server, 8, {set_maximum_since_use, Age}).
+    gen_server2:cast(Server, {set_maximum_since_use, Age}).
 
 client_init(Server, Ref) ->
     {IState, IModule, Dir, GCPid,
      FileHandlesEts, FileSummaryEts, DedupCacheEts, CurFileCacheEts} =
-        gen_server2:pcall(Server, 7, {new_client_state, Ref}, infinity),
+        gen_server2:call(Server, {new_client_state, Ref}, infinity),
     #client_msstate { file_handle_cache  = dict:new(),
                       index_state        = IState,
                       index_module       = IModule,
@@ -376,7 +376,7 @@ client_delete_and_terminate(CState, Server, Ref) ->
     ok = gen_server2:cast(Server, {client_delete, Ref}).
 
 successfully_recovered_state(Server) ->
-    gen_server2:pcall(Server, 7, successfully_recovered_state, infinity).
+    gen_server2:call(Server, successfully_recovered_state, infinity).
 
 %%----------------------------------------------------------------------------
 %% Client-side-only helpers
@@ -575,6 +575,22 @@ init([Server, BaseDir, ClientRefs, StartupFunState]) ->
      hibernate,
      {backoff, ?HIBERNATE_AFTER_MIN, ?HIBERNATE_AFTER_MIN, ?DESIRED_HIBERNATE}}.
 
+prioritise_call(Msg, _From, _State) ->
+    case Msg of
+        {new_client_state, _Ref}     -> 7;
+        successfully_recovered_state -> 7;
+        {read, _Guid}                -> 2;
+        _                            -> 0
+    end.
+
+prioritise_cast(Msg, _State) ->
+    case Msg of
+        sync                                         -> 8;
+        {gc_done, _Reclaimed, _Source, _Destination} -> 8;
+        {set_maximum_since_use, _Age}                -> 8;
+        _                                            -> 0
+    end.
+
 handle_call({read, Guid}, From, State) ->
     State1 = read_message(Guid, From, State),
     noreply(State1);
diff --git a/src/rabbit_msg_store_gc.erl b/src/rabbit_msg_store_gc.erl
index c7948b7e..a7855bbf 100644
--- a/src/rabbit_msg_store_gc.erl
+++ b/src/rabbit_msg_store_gc.erl
@@ -38,7 +38,7 @@
 -export([set_maximum_since_use/2]).
 
 -export([init/1, handle_call/3, handle_cast/2, handle_info/2,
-         terminate/2, code_change/3]).
+         terminate/2, code_change/3, prioritise_cast/2]).
 
 -record(gcstate,
         {dir,
@@ -81,7 +81,7 @@ stop(Server) ->
     gen_server2:call(Server, stop, infinity).
 
 set_maximum_since_use(Pid, Age) ->
-    gen_server2:pcast(Pid, 8, {set_maximum_since_use, Age}).
+    gen_server2:cast(Pid, {set_maximum_since_use, Age}).
 
 %%----------------------------------------------------------------------------
 
@@ -97,6 +97,9 @@ init([Parent, Dir, IndexState, IndexModule, FileSummaryEts]) ->
      hibernate,
      {backoff, ?HIBERNATE_AFTER_MIN, ?HIBERNATE_AFTER_MIN, ?DESIRED_HIBERNATE}}.
 
+prioritise_cast({set_maximum_since_use, _Age}, _State) -> 8;
+prioritise_cast(_Msg,                          _State) -> 0.
+
 handle_call(stop, _From, State) ->
     {stop, normal, ok, State}.
 
diff --git a/src/worker_pool_worker.erl b/src/worker_pool_worker.erl
index 42049d50..f461a539 100644
--- a/src/worker_pool_worker.erl
+++ b/src/worker_pool_worker.erl
@@ -38,7 +38,7 @@
 -export([set_maximum_since_use/2]).
 
 -export([init/1, handle_call/3, handle_cast/2, handle_info/2,
-         terminate/2, code_change/3]).
+         terminate/2, code_change/3, prioritise_cast/2]).
 
 %%----------------------------------------------------------------------------
 
@@ -71,7 +71,7 @@ submit_async(Pid, Fun) ->
     gen_server2:cast(Pid, {submit_async, Fun}).
 
 set_maximum_since_use(Pid, Age) ->
-    gen_server2:pcast(Pid, 8, {set_maximum_since_use, Age}).
+    gen_server2:cast(Pid, {set_maximum_since_use, Age}).
 
 run({M, F, A}) ->
     apply(M, F, A);
@@ -88,6 +88,9 @@ init([WId]) ->
     {ok, WId, hibernate,
      {backoff, ?HIBERNATE_AFTER_MIN, ?HIBERNATE_AFTER_MIN, ?DESIRED_HIBERNATE}}.
 
+prioritise_cast({set_maximum_since_use, _Age}, _State) -> 8;
+prioritise_cast(_Msg,                          _State) -> 0.
+
 handle_call({submit, Fun}, From, WId) ->
     gen_server2:reply(From, run(Fun)),
     ok = worker_pool:idle(WId),