gen_fsm的学习笔记

网上搜索gen_fsm的例子，90%都是code_lock，依葫芦画瓢弄了下，记录一些学习心得

init(UnLockCode) ->
    process_flag(trap_exit,true),

    io:format("init: ~p~n", [UnLockCode]),
    {ok, locked, {[], UnLockCode}}.

init返回值里面，locked为StateName，{[], UnLockCode}为StateData，在回调函数里面有用

发送event有两种方式

gen_fsm:send_event(code_lock, {button, Digit}).
gen_fsm:sync_send_event(code_lock, {button, Digit},).

一般采用第一个异步处理

异步的回调函数声明，StateName( Event, StateData)

locked({button, Digit}, {SoFar, UnlockCode}) ->
    io:format("async buttion: ~p, So far: ~p, Code: ~p~n", [Digit, SoFar, UnlockCode]),
    InputDigits = lists:append(SoFar, Digit),
    case InputDigits of
        UnlockCode ->
            do_unlock(),
            {next_state, open, {[], UnlockCode}, };
        Incomplete when length(Incomplete)<length(UnlockCode) ->
            {next_state, locked, {Digit, UnlockCode}, };
        Wrong ->

            delay:delay(),
            io:format("wrong passwd: ~p~n", [Wrong]),
            {next_state, locked, {[], UnlockCode}}
    end;

同步的回调函数声明，StateName( Event, From,StateData)

locked({button, Digit}, _From,{SoFar, UnlockCode}) ->
    io:format("sync buttion: ~p, So far: ~p, Code: ~p~n", [Digit, SoFar, UnlockCode]),
    InputDigits = lists:append(SoFar, Digit),
    case InputDigits of
        UnlockCode ->
            do_unlock(),
            {next_state, open, {[], UnlockCode}, };
        Incomplete when length(Incomplete)<length(UnlockCode) ->
            {next_state, locked, {Digit, UnlockCode}, };
        Wrong ->
            io:format("wrong passwd: ~p~n", [Wrong]),
            {next_state, locked, {[], UnlockCode}}
    end;

另，erl终端测试给gen_fsm:start_link出来的Pid发exit消息，handle_info收不到，取消link以后收到，处理大概如下

handle_info({'EXIT',Pid,Reason}, StateName, Data) ->
    io:format("exit ~n"),
    {stop, StateName, Data};

目前看起来进程池部分，用gen_server作为worker比用gen_fsm要简单点，那就gen_server吧