• 简单调试

    简单调试

    sys 模块包含了简单调试用行为实现的进程的函数。我们用来自 Gen_Event行为 一章中的 code_lock 例子来进行解释：

    1. % erl
    2. Erlang (BEAM) emulator version 5.2.3.6 [hipe] [threads:0]
    3.  
    4. Eshell V5.2.3.6  (abort with ^G)
    5. 1> code_lock:start_link([1,2,3,4]).
    6. {ok,<0.32.0>}
    7. 2> sys:statistics(code_lock, true).
    8. ok
    9. 3> sys:trace(code_lock, true).
    10. ok
    11. 4> code_lock:button(4).
    12. *DBG* code_lock got event {button,4} in state closed
    13. ok
    14. *DBG* code_lock switched to state closed
    15. 5> code_lock:button(3).
    16. *DBG* code_lock got event {button,3} in state closed
    17. ok
    18. *DBG* code_lock switched to state closed
    19. 6> code_lock:button(2).
    20. *DBG* code_lock got event {button,2} in state closed
    21. ok
    22. *DBG* code_lock switched to state closed
    23. 7> code_lock:button(1).
    24. *DBG* code_lock got event {button,1} in state closed
    25. ok
    26. OPEN DOOR
    27. *DBG* code_lock switched to state open
    28. *DBG* code_lock got event timeout in state open
    29. CLOSE DOOR
    30. *DBG* code_lock switched to state closed
    31. 8> sys:statistics(code_lock, get).
    32. {ok,[{start_time,{{2003,6,12},{14,11,40}}},
    33.      {current_time,{{2003,6,12},{14,12,14}}},
    34.      {reductions,333},
    35.      {messages_in,5},
    36.      {messages_out,0}]}
    37. 9> sys:statistics(code_lock, false).
    38. ok
    39. 10> sys:trace(code_lock, false).
    40. ok
    41. 11> sys:get_status(code_lock).
    42. {status,<0.32.0>,
    43.         {module,gen_fsm},
    44.         [[{'$ancestors',[<0.30.0>]},
    45.           {'$initial_call',{gen,init_it,
    46.                                 [gen_fsm,<0.30.0>,<0.30.0>,
    47.                                  {local,code_lock},
    48.                                  code_lock,
    49.                                  [1,2,3,4],
    50.                                  []]}}],
    51.          running,<0.30.0>,[],
    52.          [code_lock,closed,{[],[1,2,3,4]},code_lock,infinity]]}