Erlang入门：构建application练习5（监督树）

1、前言

2、编写监督树回调模块bank_sup.erl

%% @author Rolong<rolong@vip.qq.com>
-module(bank_sup).
-behaviour(supervisor).
-export([start_link/0]).
-export([init/1]).

%% 定义一个启动本监督树的API
start_link() ->
    supervisor:start_link({local, ?MODULE}, ?MODULE, []).

init([]) ->
    %% 启动2个子进程
    BankCenterSpec = {
      center %% 指定本进程(在子进程中唯一)的名称
      ,{bank_center, start_link, []} %% 进程启动函数：{M,F,A}
      ,transient %% 重启策略：permanent | transient | temporary
      ,5000 %% 关闭方式：brutal_kill | int()>0 | infinity
      ,worker %% 进程类型：worker 或 supervisor
      ,[bank_center] %% 回调模块名称：[Module] | dynamic
     },
    BankCenterSpec2 = {
      center2
      ,{bank_center2, start_link, []}
      ,transient
      ,5000
      ,worker
      ,[bank_center2]
     },
    %% {ok, {{RestartStrategy, MaxR, MaxT}, [ChildSpec]}}
    {ok, {{one_for_one, 5, 30}, [BankCenterSpec, BankCenterSpec2]}}.

3、监督树实验

handle_info(error, Money) ->
%% Error Return ...
{ok, Money};

handle_info(force_stop, Money) ->
{stop, "Force STOP", Money};

handle_info(normal_stop, Money) ->
{stop, normal, Money};

handle_info(shutdown, Money) ->
{stop, shutdown, Money};

handle_info({shutdown,Term}, Money) ->
{stop, {shutdown,Term}, Money};

3.1、测试{RestartStrategy, MaxR, MaxT}={one_for_one, 5, 30}

Eshell V5.10.4 (abort with ^G)
1> appmon:start().
{ok,<0.40.0>}
2> bank_center ! normal_stop.
##[<0.38.0>bank_center:59] terminate: normal
normal_stop
##[<0.51.0>bank_center:23] Start bank_center ...
3> bank_center ! normal_stop.
##[<0.51.0>bank_center:59] terminate: normal
normal_stop
##[<0.53.0>bank_center:23] Start bank_center ...
4> bank_center ! normal_stop.
##[<0.53.0>bank_center:59] terminate: normal
normal_stop
##[<0.55.0>bank_center:23] Start bank_center ...
5> bank_center2 ! normal_stop.
##[<0.39.0>bank_center2:59] terminate: normal
normal_stop
##[<0.57.0>bank_center2:23] Start bank_center2 ...
6> bank_center2 ! normal_stop.
##[<0.57.0>bank_center2:59] terminate: normal
normal_stop
##[<0.59.0>bank_center2:23] Start bank_center2 ...
7> bank_center2 ! normal_stop.
##[<0.59.0>bank_center2:59] terminate: normal
##[<0.55.0>bank_center:59] terminate: shutdown
normal_stop
8> ##[<0.34.0>bank_app:16] Stop bank_app!

=INFO REPORT==== 17-Jan-2015::16:19:15 ===
application: bank
exited: shutdown
type: temporary

3.2、测试transient重启策略

Eshell V5.10.4 (abort with ^G)
1> bank_center ! error.
##[<0.38.0>bank_center:59] terminate: {bad_return_value,{ok,0}}
error
##[<0.40.0>bank_center:23] Start bank_center ...
2> 
=ERROR REPORT==== 17-Jan-2015::17:09:15 ===
** Generic server bank_center terminating 
** Last message in was error
** When Server state == 0
** Reason for termination == 
** {bad_return_value,{ok,0}}

2> bank_center ! force_stop.
##[<0.40.0>bank_center:59] terminate: "Force STOP"

=ERROR REPORT==== 17-Jan-2015::17:09:28 ===
** Generic server bank_center terminating 
** Last message in was force_stop
** When Server state == 0
** Reason for termination == 
** "Force STOP"
force_stop
##[<0.42.0>bank_center:23] Start bank_center ...
3> 
3> bank_center ! normal_stop.
##[<0.42.0>bank_center:59] terminate: normal
normal_stop
4> 
4> whereis(bank_center). 
undefined
5> supervisor:restart_child(bank_sup, center).
##[<0.46.0>bank_center:23] Start bank_center ...
{ok,<0.46.0>}
6> whereis(bank_center). 
<0.46.0>
7> bank_center ! shutdown. 
##[<0.46.0>bank_center:59] terminate: shutdown
shutdown
8> whereis(bank_center). 
undefined
9> supervisor:restart_child(bank_sup, center).
##[<0.51.0>bank_center:23] Start bank_center ...
{ok,<0.51.0>}
10> whereis(bank_center). 
<0.51.0>
11> bank_center ! {shutdown, test}. 
##[<0.51.0>bank_center:59] terminate: {shutdown,test}
{shutdown,test}
12> whereis(bank_center). 
undefined

由上可见，进程退出的Reason为normal或shutdown或{shutdown, Term}时，bank_center不会被重启，其他Reason时会被重启。

4、完整演示代码下载

地址：http://download.csdn.net/detail/u011471961/8371361

Erlang入门：构建application练习5（监督树）

原文：http://blog.csdn.net/zhongruixian/article/details/42806659