x集成测试状态迁移

最新推荐文章于 2025-03-23 02:06:05 发布

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最新推荐文章于 2025-03-23 02:06:05 发布

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本文深入探讨了Libevent库在网络事件处理中的应用，并详细解析了TCP连接的各种状态及其迁移过程。通过具体实例展示了如何利用Libevent进行高效的事件管理。

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昨天改完后集成测试一下，不经意直接程序出现异常，apt一下

tcp 0 0 *:7777 *:* LISTEN 32686/PC_***
tcp 0 0 linux:7777 linux:38318 ESTABLISHED 32686/PC_***
tcp 0 0 linux:34833 linux:7777 CLOSE_WAIT 28132/java
tcp 0 0 linux:58603 linux:7777 CLOSE_WAIT 28132/java
tcp 0 0 linux:38318 linux:7777 ESTABLISHED 28132/java
tcp 0 0 linux:49424 linux:7777 CLOSE_WAIT 28132/java

晕怎么这么多CLOSE_WAIT ，再复习一下tcp的状态迁移

有了这个信息再看代码很快定位到异常。

顺便再把网络事件类总结一下，以免以后做别的项目了这块出问题得看半天，在X项目中把libevent的网络事件进行了二次封装;

a.两条队列一个记录设控读写事件一个记录active事件；一个树，记录设控时间
b.状态ev_flags ，与4个标志

以time为例

1.添加

event_queue_insert(base, ev, EVLIST_TIMEOUT);
{
        ......
    	ev->ev_flags |= queue;
    	......
    	case EVLIST_TIMEOUT:
        {
            wt_rbtree_insert(&base->timetree, &ev->ev_timeout_node);
            break;
        }
        .......
}

2.loop

    ......
    if (!base->event_count_active && !(flags & EVLOOP_NONBLOCK))
          timeout_next(base, &tv);
    else
          timerclear(&tv);

     /* If we have no events, we just exit */
     if (!event_haveevents(base))
          return (1);

     res = epoll_dispatch(base, evbase, &tv);

     if (res == -1)
            return (-1);

     timeout_process(base);
     ......
     
     
     void
     timeout_process(struct event_base *base) 
     {
        ......     
        
        遍历红黑树
     	event_queue_remove(base, ev, EVLIST_TIMEOUT);
     	/*
    	{
    	    case EVLIST_TIMEOUT:
            wt_rbtree_delete(&base->timetree, &ev->ev_timeout_node);
            break;
    	
    	}
    	*/
    	event_active(ev, EV_TIMEOUT, 1);
    	
        ......  
     }
     
     
     在又见到了我们熟悉的
     event_queue_insert(ev->ev_base, ev, EVLIST_ACTIVE);

3.proc

 static void
    event_process_active(struct event_base *base)
    {
          遍历
          if (ev->ev_events & EV_PERSIST)
                  event_queue_remove(base, ev, EVLIST_ACTIVE);
	  else
		  event_del(ev);
	  回调 ncalls		
			
    }

Faq

1.libevent重要结构与函数赏析

不管 什么场景只要处理 read write事件就行了(带外数据可以不考虑)

重要结构
a.事件

struct event 
{
          ....
  	    
	int ev_flags;   
};


事件状态 

#define EVLIST_INIT	0x80
#define EVLIST_INSERTED	0x02
#define EVLIST_ACTIVE	0x08
#define EVLIST_TIMEOUT	0x01



b.epoll框架

struct event_base {
    ngx_queue_t    activequeue;
    ngx_queue_t    eventqueue; 
    ngx_rbtree_t   timetree;
};

c. epoll 中
struct evepoll 
{
	struct event *evread;
	struct event *evwrite;
};

struct epollop 
{
	struct evepoll *fds;  //why has
	int nfds;
	struct epoll_event *events;
	int nevents;
	int epfd;
	sigset_t evsigmask;
} epollop;


函数

a. event_init

    ngx_queue_init(¤t_base->eventqueue);
    ngx_queue_init(¤t_base->activequeue);

    ngx_rbtree_init(¤t_base->timetree, ¤t_base->sentinel, ngx_rbtree_insert_value);

    重要初始化三个结构
    
b. event_set
   

   ev->ev_flags = EVLIST_INIT;
   
 
c. event_add  
    //对于读写事件

    if ((ev->ev_events & (EV_READ | EV_WRITE)) &&
            !(ev->ev_flags & (EVLIST_INSERTED | EVLIST_ACTIVE))) 
    { 
        event_queue_insert(base, ev, EVLIST_INSERTED);
        return (epoll_add(evbase, ev));
    }

    epoll_add
    
     
    if (evep->evread != NULL) 
    {
        events |= EPOLLIN;
        op = EPOLL_CTL_MOD;
    }
    if (evep->evwrite != NULL)
    {
        events |= EPOLLOUT;
        op = EPOLL_CTL_MOD;
    }
    
    if (ev->ev_events & EV_READ)   
        events |= EPOLLIN;
    if (ev->ev_events & EV_WRITE)
        events |= EPOLLOUT;
    
    
    if (ev->ev_events & EV_READ)
        evep->evread = ev;
    if (ev->ev_events & EV_WRITE)
        evep->evwrite = ev;
        
        
d.   event_base_loop     

     res = epoll_dispatch(base, evbase, &tv);

     if (res == -1)
          return (-1);

     timeout_process(base);

     if (base->event_count_active) 
     {
          event_process_active(base); //处理激活队列中的
          if (!base->event_count_active && (flags & EVLOOP_ONCE))
                done = 1;
     }


      
     epoll_dispatch
     
     if (evread != NULL && !(evread->ev_events & EV_PERSIST))
          event_del(evread);
     if (evwrite != NULL && evwrite != evread &&
                !(evwrite->ev_events & EV_PERSIST))
          event_del(evwrite);

     if (evread != NULL)
          event_active(evread, EV_READ, 1);
     if (evwrite != NULL)
          event_active(evwrite, EV_WRITE, 1);
            
         //处理完就删除，这个与一般的epoll不同所以要加  EV_PERSIST
         
           
    event_queue_remove       
    队列相关
    ev->ev_flags &= ~queue;
    
    event_queue_insert
    ev->ev_flags |= queue;

2. nginx 平滑重启 nginx -s reload

3. 以一种非优雅的方式断开连接的时候，我们可以设置SO_KEEPALIVE属性使得我们在2小时以后发现对方的TCP连接是否依然存在。
keepAlive = 1;
Setsockopt(listenfd, SOL_SOCKET, SO_KEEPALIVE, (void*)&keepAlive, sizeof(keepAlive))

4. 代码复杂度与sourcemonitor

参考:

1. epoll 事件类型 http://blog.youkuaiyun.com/huangjm_13/article/details/17676591
2.state与api http://blog.163.com/xychenbaihu@yeah/blog/static/13222965520118139252103/
3.closewait http://blog.chinaunix.net/uid-20357359-id-1963662.html