anchor.diff:  stop(Pid) ->
       gen_server:call(Pid, {stop}, ?LONG_TIME).
   
  +checkpoint(Pid) ->
  +    gen_server:call(Pid, {sync_checkpoint}, ?LONG_TIME).
  +
   %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
   
   init([PageSize, SequencerPid, Proj, CallbackMod, StreamNum]) ->
  
positive.code:     State2 = #state{i_state=I_State} = roll_log_forward(State),
      Reply = CallbackMod:do_pure_op(Op, I_State),
      {reply, Reply, State2};
  handle_call({stop}, _From, State) ->
      {stop, normal, ok, State};
  handle_call(_Request, _From, State) ->
  
negative.code: 
  handle_call({cb_dirty_op, Op}, From,
              #state{proj=Proj0, cb_mod=CallbackMod, stream_num=StreamNum,
                     page_size=PageSize, back_ps=BackPs, i_state=I_State}=State)->
      {AsyncType, I_State2, Proj1, LPN, NewBackPs} =
          CallbackMod:do_dirty_op(Op, From, I_State, StreamNum,
                                  Proj0, PageSize, BackPs),
  