anchor.diff:          _ ->
               Module  = gc_mod(T1GCState),
               Handler = gc_hand(T1GCState),
  -            try Handler(Msg, UState) of
  +            try handle_message(Msg, UState, Handler) of
                   kill ->
                       log:log(info, "[ gen_component ] ~.0p killed (~.0p:~.0p/2):",
                               [self(), Module, Handler]),
  
positive.code: -spec on_traced_msg(comm:message(), user_state(), gc_state())
                     -> ok.
  on_traced_msg(GCMsg, UState, GCState)
    when is_tuple(GCMsg)
         andalso '$gen_component' =:= element(1, GCMsg) ->
      on_gc_msg(GCMsg, UState, GCState);
  on_traced_msg({ping, Pid}, UState, GCState) ->
      %% handle failure detector messages
      comm:send(Pid, {pong, pid_groups:my_pidname()}, [{channel, prio}]),
      MsgTag = erlang:erase('$gen_component_trace_mpath_msg_tag'),
      trace_mpath:log_info(self(), {gc_on_done, MsgTag}),
      trace_mpath:stop(),
      loop(UState, GCState);
  on_traced_msg({?send_to_group_member, Processname, Msg}, UState, GCState) ->
      %% forward a message to group member by its process name
      %% initiated via comm:send/3 with group_member
      Pid = pid_groups:get_my(Processname),
      case Pid of
          failed -> ok;
          _      -> comm:send_local(Pid, Msg)
      end,
      MsgTag = erlang:erase('$gen_component_trace_mpath_msg_tag'),
      trace_mpath:log_info(self(), {gc_on_done, MsgTag}),
      trace_mpath:stop(),
      loop(UState, GCState);
  on_traced_msg(Msg, UState, GCState) ->
      T1GCState = on_bp(Msg, UState, GCState),
      Module  = gc_mod(T1GCState),
      Handler = gc_hand(T1GCState),
      try Handler(Msg, UState) of
          kill ->
              log:log(info, "[ gen_component ] ~.0p killed (~.0p:~.0p/2):",
                      [self(), Module, Handler]),
  
negative.code:                    gc_bpactive/1, gc_set_bpactive/2,
                     gc_bpqueue/1, gc_set_bpqueue/2,
                     gc_bpstepped/1, gc_set_bpstepped/2,
                     gc_bpstepper/1, gc_set_bpstepper/2,
                     handle_message/3
                    ]}).
  
  -include("scalaris.hrl").
  