BOOST 线程完全攻略 - 扩展 - 事务线程

什么叫事务线程

举个例子：

我们写一个IM客户端的登录子线程，则该子线程会有这么几个事务要处理

No.1 TCP Socket物理连接

No.2 逻辑登录

No.3 好友在线查询

No.4 状态更新

我们通常的代码写法是

1. void ThreadLogin()
2. {
3.   try
4.   {
5.      if(fail(物理连接))
6.         throw;
7.      if(fail(登录))
8.         throw;
9.      if(fail(查询好友))
10.         throw;
11.      if(fail(更新))
12.         throw;
13.   }
14.   catch(exception)
15.   {
16.   }
17. }

串行的逻辑用串行的代码写，不太好看，况且中途如果主线程发出取消指令，还不好处理。

这里扩展的thread类，就是来解决这个问题的，他会提供给程序员一种事件处理的模式

1. class threadLogin
2. {
3. void onEventConnect()
4. {
5.   物理连接
6. }
7. void onEventLogin()
8. {
9.  登录
10. }
11. void onEventQuery()
12. {
13. 查询
14. }
15. void onEventUpdate()
16. {
17. 更新
18. }
19. }

源码如下

1. // thread.hpp : controlled_module_ex类的扩展
2. // 增强线程事务处理能力
3. #pragma once
4. #include "controlled_module_ex.hpp"
5.   class thread: public controlled_module_ex
6.   {
7.     protected:
8.         static const int NONE = -1;
9.         static const int WAITING =-2;
10.         static const int DONE =-3;
11.         static const int FAILED =-4;
12.     protected:
13.         struct process
14.         {
15.             int level;
16.             int status;
17.             int sequence;
18.             int trycount;
19.             int tryindex;
20.             std::string lasterror;
21.             double timeout;
22.             bool bTimeout;
23.         };
24.         process m_process;
25.         controlled_timer m_timer_process;
26.         int m_process_begin,m_process_end;
27.         double m_timeout_default;
28.     public:
29.         void startprocess(int process_begin,int process_end,double timeout_default=1.0,int cycle=1000)
30.         {
31.             m_process_begin = process_begin;
32.             m_process_end = process_end;
33.             m_timeout_default = timeout_default;
34.             m_process.level = m_process_begin;
35.             m_process.tryindex = 0;
36.             this->postmessage(BM_RING_PROCESS);
37.             m_timer_process.starttimer(cycle,this);
38.         }
39.         void tryagain()
40.         {
41.             if(this->m_process.level==thread::NONE)
42.                 return;
43.             this->m_process.tryindex++;
44.             if(this->m_process.trycount>0 && this->m_process.tryindex>=this->m_process.trycount)
45.             {
46.                 this->fail();
47.             }
48.             else
49.                 this->postmessage(BM_RING_PROCESS);
50.         }
51.         void next()
52.         {
53.             if(this->m_process.level==thread::NONE)
54.                 return;
55.             if(this->m_process.level>=this->m_process_end)
56.             {
57.                 this->m_timer_process.stoptimer();
58.                 this->postmessage(BM_RING_PROCESSEND);
59.             }
60.             else
61.             {
62.                 this->m_process.tryindex = 0;
63.                 this->m_process.level++;
64.                 this->m_process.bTimeout = false;
65.                 this->postmessage(BM_RING_PROCESS);
66.             }
67.         }
68.         void fail()
69.         {
70.             m_process.level = thread::NONE;
71.             this->m_timer_process.stoptimer();
72.             this->postmessage(BM_RING_PROCESSFAIL);
73.         }
74.         virtual void on_safestart()
75.         {
76.             m_process.level = thread::NONE;
77.             m_process.status = thread::NONE;
78.             m_process_begin = m_process_end = thread::NONE;
79.             controlled_module_ex::on_safestart();
80.         }
81.         virtual void on_safestop()
82.         {
83.             m_timer_process.stoptimer();
84.             controlled_module_ex::on_safestop();
85.         }
86.         virtual void message(const _command & cmd)
87.         {
88.             controlled_module_ex::message(cmd);
89.             if(cmd.nCmd==BM_RING_PROCESS)
90.             {
91.                 this->on_process();
92.             }
93.             if(cmd.nCmd==BM_RING_PROCESSEND)
94.             {
95.                 this->m_process.level = thread::NONE;
96.                 this->on_process_end();
97.             }
98.             if(cmd.nCmd==BM_RING_PROCESSFAIL)
99.             {
100.                 this->m_process.level = thread::NONE;
101.                 this->on_process_fail();
102.             }
103.         }
104.         virtual void on_timer(const controlled_timer * p)
105.         {
106.             if(p==this->m_timer_process)
107.             {
108.                 if(this->m_process.level!=thread::NONE)
109.                 {
110.                     if(this->m_process.level>=this->m_process_begin && this->m_process.level<=this->m_process_end)
111.                     {
112.                         if(this->m_process.status==thread::NONE)
113.                         {
114.                             this->m_process.level = this->m_process_begin;
115.                             m_process.tryindex = 0;
116.                             on_process();
117.                         }
118.                         else if(this->m_process.status==thread::WAITING)
119.                         {
120.                             if(this->m_process.timeout>0)
121.                             {
122.                                 time_t cur;
123.                                 time(&cur);
124.                                 if(difftime(cur,(time_t)this->m_process.sequence)>this->m_process.timeout)
125.                                 {
126.                                     this->m_process.bTimeout = true;
127.                                     this->tryagain();
128.                                 }
129.                             }
130.                         }
131.                         else if(this->m_process.status==thread::FAILED)
132.                         {
133.                             this->tryagain();
134.                         }
135.                         else if(this->m_process.status==thread::DONE)
136.                         {
137.                             this->m_process.level++;
138.                             m_process.tryindex = 0;
139.                             this->on_process();
140.                         }
141.                     }
142.                 }
143.             }
144.         }
145.         virtual void on_process()
146.         {
147.             time((time_t*)&m_process.sequence);
148.             m_process.timeout = m_timeout_default;
149.             m_process.status = thread::WAITING;
150.             m_process.trycount = -1;
151.         }
152.         virtual void on_process_end(){}
153.         virtual void on_process_fail(){}
154.         int get_sequence(){return m_process.sequence;}
155.         void put_timeout(double v){m_process.timeout = v;}
156.         void put_trycount(int v){m_process.trycount = v;}
157.         int get_level(){return m_process.level;}
158.         void put_level(int v){m_process.level=v;}
159.         std::string get_lasterror(){return m_process.lasterror;}
160.         void put_lasterror(std::string v){m_process.lasterror=v;}
161.         __declspec(property(put=put_trycount)) int trycount;
162.         __declspec(property(put=put_timeout)) double timeout;
163.         __declspec(property(get=get_level,put=put_level)) int level;
164.         __declspec(property(get=get_sequence)) int sequence;
165.         __declspec(property(get=get_lasterror,put=put_lasterror)) std::string lasterror;
166.   };

虚拟函数thread::on_process()处理各种事务事件

虚拟函数thread::on_process_end()是所有事务处理完毕事件

虚拟函数thread::on_process_fail()是事务处理出现错误，这时所有事务被取消，线程终止

这里给一个简单的范例，

总共线程要完成3件事务，其中第二个事务要求用户确认是否继续

1. #define PROCESS_1   1
2. #define PROCESS_2   2
3. #define PROCESS_3   3
4. class thdex: public thread
5. {
6. public:
7.     virtual void on_process()
8.     {
9.         thread::on_process();
10.         if(this->level==PROCESS_1)
11.         {
12.             cout << "work on process 1..." << endl;
13.             Sleep(100);
14.             cout << "process 1 done." << endl;
15.             this->next();
16.         }
17.         else if(this->level==PROCESS_2)
18.         {
19.             cout << "work on process 2..." << endl;
20.             this->timeout = -1;
21.             if(IDNO==::MessageBox(0,"are your want continue?","ask",MB_ICONQUESTION|MB_YESNO))
22.             {
23.                 this->lasterror = "canceled by user";
24.                 this->fail();
25.             }
26.             else
27.             {
28.                 Sleep(100);
29.                 cout << "process 2 done." << endl;
30.                 this->next();
31.             }
32.         }
33.         else if(this->level==PROCESS_3)
34.         {
35.             cout << "work on process 3..." << endl;
36.             Sleep(100);
37.             cout << "process 3 done." << endl;
38.             this->next();
39.         }
40.     }
41.     virtual void on_process_fail()
42.     {
43.         cout << this->lasterror << endl;
44.     }
45.     virtual void on_process_end()
46.     {
47.         cout << "all process done." << endl;
48.     }
49. };
50. int _tmain(int argc, _TCHAR* argv[])
51. {
52.     thdex t;
53.     t.safestart();
54.     t.startprocess(PROCESS_1,PROCESS_3);
55.     char buf[10];
56.     gets_s(buf,sizeof buf);
57.     t.safestop();
58.     return 0;
59. }

thread事务还支持超时设定和重试次数设定，这里就不做介绍，读者可以自己研究代码。