搭建一个后台服务器--服务端(异步,大并发)
来源:互联网 发布:阿国网络随笔123 编辑:程序博客网 时间:2024/06/05 11:41
from:
http://blog.csdn.net/xiaofei_hah0000/article/details/8743627
上篇的阻塞模式下服务器的并发只有几K,而真正的server 像nginx, apache, yumeiz 轻轻松松处理几万个并发完全不在话下,因此大并发的场合下是不能用阻塞的。
1W的并发是一个分隔点,如果单进程模型下能达到 的话,说明至少在服务器这块你已经很厉害了。
服务器开发就像一门气功,能不能搞出大并发,容错性处理得怎么样,就是你有没有内功,内功有多深。
异步模式是专门为大并发而生,Linux下一般用 epoll 来管理事件,下面就开始我们的异步大并发服务器实战吧。
跟阻塞开发一样,先来看看设计过程:
1.创建事件模型。
2.创建监听连接并监听。
3.将监听连接加入事件模型。
4.当有事件时,判断事件类型。
5.若事件为监听连接,则产生客户连接同时加入事件模型,对客户连接接收发送。
6.若事件为客户连接,处理相应IO请求。
为了让大家一概全貌,我用一个函数实现的( 一个函数写一个2W并发的服务器,你试过么),可读性可能会差点,但是对付这道面试题是绰绰有余了。
实际开发过程如下:
先定义一个事件结构,用于对客户连接进行缓存
- struct my_event_s
- {
- int fd;
- char recv[64];
- char send[64];
-
- int rc_pos;
- int sd_pos;
- };
建立缓存对象:
- struct epoll_event wait_events[ EPOLL_MAX ];
- struct my_event_s my_event[ EPOLL_MAX ];
创建监听连接:
- sock_server = socket( AF_INET, SOCK_STREAM, 0 );
- flag = fcntl( sock_server, F_GETFL, 0 );
- fcntl( sock_server, F_SETFL, flag | O_NONBLOCK );
绑定地址并监听:
- flag = bind( sock_server, ( struct sockaddr* )&addr_server, sizeof( struct sockaddr ) );
- if( flag < 0 )
- {
- printf( "your bind is not ok\n" );
- close( sock_server );
- return 0;
- }
-
- flag = listen( sock_server, 1024 );
- if( flag < 0 )
- {
- printf( "your listen is not ok\n");
- close( sock_server );
- return 0;
- }
创建事件模型:- epfd = epoll_create( EPOLL_MAX );
- if( epfd <= 0 )
- {
- printf( "event module could not be setup\n");
- close( sock_server );
- return 0;
- }
将监听事件加入事件模型:- tobe_event.events = EPOLLIN;
- tobe_event.data.fd = sock_server;
-
- epoll_ctl( epfd, EPOLL_CTL_ADD, sock_server, &tobe_event );
事件模型处理:
- e_num = epoll_wait( epfd, wait_events, EPOLL_MAX, WAIT_TIME_OUT );
- if( e_num <= 0 )
- {
- continue;
- }
-
- for( i = 0; i < e_num; ++i )
- {
监听处理:- if( sock_server == wait_events[ i ].data.fd )
- { while(1){
连接客户端:
- sock_client = accept( sock_server, ( struct sockaddr* )&addr_client, ( socklen_t*)&size );
- if( sock_client < 0 )
- {
- if( errno == EAGAIN )
- {
- break;
- }
- if( errno == EINTR )
- {
- continue;
- }
- break;
- }
将客户端连接设置为异步:- flag = fcntl( sock_client, F_GETFL, 0 );
- fcntl( sock_client, F_SETFL, flag | O_NONBLOCK );
将客户端连接加入到 事件模型:- tobe_event.events = EPOLLIN | EPOLLET;
- tobe_event.data.u32 = my_empty_index;
-
- epoll_ctl( epfd, EPOLL_CTL_ADD, sock_client, &tobe_event );
统计每秒并发数并得到系统当前时间:- ++num;
- current = time( 0 );
- if( current > last )
- {
- printf( "last sec qps:%d\n", num );
- num = 0;
- last = current;
- }
将时间填充到连接缓存中:- memcpy( tobe_myevent->send, ¤t, sizeof(time_t) );
接收连接内容:
- flag = recv( sock_client, tobe_myevent->recv, 64, 0 );
- if( flag < 64 )
- {
- if( flag > 0 )
- tobe_myevent->rc_pos += flag;
- continue;
- }
- if( tobe_myevent->recv[31] || tobe_myevent->recv[63] )
- {
- printf( "your recv does follow the protocal\n");
- tobe_myevent->fd = 0;
- close( sock_client );
- continue;
- }
-
-
- flag = send( sock_client, tobe_myevent->send, sizeof( time_t ), 0 );
- if( flag < sizeof( time_t ) )
- {
- <span style="white-space:pre"> </span>tobe_event.events = EPOLLET | EPOLLOUT;
- <span style="white-space:pre"> </span>epoll_ctl( epfd, EPOLL_CTL_MOD, sock_client, &tobe_event );
- if( flag > 0 )
- tobe_myevent->sd_pos += flag;
- continue;
- }
- tobe_myevent->fd = 0;
- close( sock_client );
后面进行普通连接事件处理,错误处理:
- if( event_flag & EPOLLHUP )
- {
- tobe_myevent->fd = 0;
- close( sock_client );
- continue;
- }
- else if( event_flag & EPOLLERR )
- {
- tobe_myevent->fd = 0;
- close( sock_client );
- continue;
- }
写事件:- else if( event_flag & EPOLLOUT )
- {
- if( tobe_myevent->rc_pos != 64 )
- {
- continue;
- }
-
- if( tobe_myevent->sd_pos >= sizeof( time_t ) )
- {
- tobe_myevent->fd = 0;
- close( sock_client );
- continue;
- }
-
- flag = send( sock_client, tobe_myevent->send + tobe_myevent->sd_pos, sizeof( time_t ) - tobe_myevent->sd_pos, 0 );
- if( flag < 0 )
- {
- if( errno == EAGAIN )
- {
- continue;
- }
- else if( errno == EINTR )
- {
- continue;
- }
- tobe_myevent->fd = 0;
- close( sock_client );
- continue;
- }
-
- if( flag >0 )
- {
- tobe_myevent->sd_pos += flag;
- if( tobe_myevent->sd_pos >= sizeof( time_t ) )
- {
- tobe_myevent->fd = 0;
- close( sock_client );
- continue;
- }
- }
- }
读事件:- if( event_flag & EPOLLIN )
- {
- if( tobe_myevent->rc_pos < 64 )
- {
- flag = recv( sock_client, tobe_myevent->recv + tobe_myevent->rc_pos, 64 - tobe_myevent->rc_pos, 0 );
- if( flag <= 0 )
- {
- continue;
- }
-
- tobe_myevent->rc_pos += flag;
-
- if( tobe_myevent->rc_pos < 64 )
- {
- continue;
- }
-
- if( tobe_myevent->recv[31] || tobe_myevent->recv[63] )
- {
- printf( "your recv does follow the protocal\n");
- tobe_myevent->fd = 0;
- close( sock_client );
- continue;
- }
-
- flag = send( sock_client, tobe_myevent->send, sizeof( time_t ), 0 );
- if( flag < sizeof( time_t ) )
- {
- if( flag > 0 )
- tobe_myevent->sd_pos += flag;
- <span style="white-space:pre"> </span>tobe_event.events = EPOLLET | EPOLLOUT;
- tobe_event.data.u32 = wait_events[i].data.u32;
- epoll_ctl( epfd, EPOLL_CTL_MOD, sock_client, &tobe_event );
- continue;
- }
- tobe_myevent->fd = 0;
- close( sock_client );
- }
-
- }
-
到此,一个异步服务器搭建完毕,轻松实现2W的并发量,既完成了任务,又是实实在在的锻练了一回。 0 0