专注江苏网站建设,Wordpress多语言配置,网页qq登录入口官网,网站建设海报素材1.Begins~有的人学习linux编程很久#xff0c;只知道网络编程是socket#xff0c;bind#xff0c; listen。。。#xff0c;然而这些都是网络通信软件最基本的接口。在某网络公司待了y#xff0c;也了解到公司的基础就是网络转发 #xff0c;然而网络转发实现并非我们平时…1.Begins~有的人学习linux编程很久只知道网络编程是socketbind listen。。。然而这些都是网络通信软件最基本的接口。在某网络公司待了y也了解到公司的基础就是网络转发 然而网络转发实现并非我们平时所见的简单的sendrecv。公司设备的转发都是建立在稳定并且高效的内部业务的基础上的例如一个可靠性的服务BFD(链路双向快速检测)进程内业务就是建立在内核与用户态后台处理与前台配置交互的过程上实现。在做项目的日子里渐渐的对公司BFD模块有一定了解特别是涉及到框架的地方仔细看发现一些技巧其实就是我们平日所用的技能外加一些优化。对于单进程用户态来说处理前台进程交互与内核上送消息如果没有一个高效的机制是很难处理上以千计甚至万计的消息的。在参看公司代码的初始化阶段发现一共用了至少3 个epoll回调机制一个是处理前台发送的配置及查询一个是处理与其他应用模块的交互另一个是向其他应用通报状态变化的机制。公司的epoll_event 机制不知道是不是修改了内核结构大致是这样typedef struct epoll_event { uint32_t events; // Epoll events epoll_data_t data; // User data variable ep_callback callback; /* 这跟linux内核不一样 */}EPOLL_PACK; /*在添加epoll事件的时候就多了一个回调函数注册这个十分方便了回调函数可以用一个全局变量搞定一个框架搭好随后添加就大大的简单多了*/实际内核提供给我们使用的用户态结构是这样typedef union epoll_data { void *ptr; int fd; uint32_t u32; uint64_t u64; } epoll_data_t; struct epoll_event { uint32_t events; // Epoll events epoll_data_t data; // User data variable }; 不过我们也可以将epoll_data_t这个联合体封装在一个结构只需要用指针*ptr指向封装的带fd及回调函数就可以。打算自己学习一些必要的技能暂且就记录一下吧2.Epoll APIextern int epoll_create(int size);extern int epoll_ctl(int epfd, int op, int fd, struct epoll_event *event);extern int epoll_wait(int epfd, struct epoll_event* events, int maxevents, int timeout);① int epoll_create(int size); 创建一个epoll的句柄。自从linux2.6.8之后size参数是被忽略的。需要注意的是当创建好epoll句柄后 它就是会占用一个fd值在linux下如果查看/proc/进程id/fd/是能够看到这个fd的所以在使用完epoll 后必须调用close()关闭否则可能导致fd被耗尽。 ②int epoll_ctl(int epfd, int op, int fd, struct epoll_event *event); epoll的事件注册函数它不同于select()是在监听事件时告诉内核要监听什么类型的事件而是在这里先 注册要监听的事件类型。 参数 第一个参数是epoll_create()的返回值。 第二个参数表示动作用三个宏来表示 EPOLL_CTL_ADD注册新的fd到epfd中 EPOLL_CTL_MOD修改已经注册的fd的监听事件 EPOLL_CTL_DEL从epfd中删除一个fd 第三个参数是需要监听的fd。 第四个参数是告诉内核需要监听什么事struct epoll_event结构如下enum EPOLL_EVENTS{ EPOLLIN 0x001,#define EPOLLIN EPOLLIN EPOLLPRI 0x002,#define EPOLLPRI EPOLLPRI EPOLLOUT 0x004,#define EPOLLOUT EPOLLOUT EPOLLRDNORM 0x040,#define EPOLLRDNORM EPOLLRDNORM EPOLLRDBAND 0x080,#define EPOLLRDBAND EPOLLRDBAND EPOLLWRNORM 0x100,#define EPOLLWRNORM EPOLLWRNORM EPOLLWRBAND 0x200,#define EPOLLWRBAND EPOLLWRBAND EPOLLMSG 0x400,#define EPOLLMSG EPOLLMSG EPOLLERR 0x008,#define EPOLLERR EPOLLERR EPOLLHUP 0x010,#define EPOLLHUP EPOLLHUP EPOLLRDHUP 0x2000,#define EPOLLRDHUP EPOLLRDHUP EPOLLWAKEUP 1u 29,#define EPOLLWAKEUP EPOLLWAKEUP EPOLLONESHOT 1u 30,#define EPOLLONESHOT EPOLLONESHOT EPOLLET 1u 31#define EPOLLET EPOLLET};(3)epoll_wait();参数events是分配好的epoll_event结构体数组 epoll将会把发生的事件复制到events数组中(events不可以是空指针内核只负责把数据复制到) 参数timeout 是超时时间(毫秒0表示立即返回-1表示永久阻塞) 如果函数调用成功返回对应IO上已经准备好的文件描述符数目如果返回0表示已超时如果返回值小于0表示函数失败。Linuxc/c服务器开发高阶视频学习资料后台私信【架构】获取3.epoll modeepoll的使用也很方便基本都会用到以下模型取自linux帮助手册 /*Example for suggested usageWhile the usage of epoll when employed as a level-triggered interface does have the same semantics as poll(2), the edge-triggered usage requires moreclarification to avoid stalls in the application event loop. In this example, listener is a nonblocking socket on which listen(2) has been called. Thefunction do_use_fd() uses the new ready file descriptor until EAGAIN is returned by either read(2) or write(2). An event-driven state machine applica‐tion should, after having received EAGAIN, record its current state so that at the next call to do_use_fd() it will continue to read(2) or write(2) fromwhere it stopped before.*/ #define MAX_EVENTS 10struct epoll_event ev, events[MAX_EVENTS];int listen_sock, conn_sock, nfds, epollfd; /* Code to set up listening socket, listen_sock, (socket(), bind(), listen()) omitted */ static Epoll_Case(){ epollfd epoll_create1(0); if (epollfd -1) { perror(epoll_create1); exit(EXIT_FAILURE); } ev.events EPOLLIN; ev.data.fd listen_sock; if (epoll_ctl(epollfd, EPOLL_CTL_ADD, listen_sock, ev) -1) { perror(epoll_ctl: listen_sock); exit(EXIT_FAILURE); } for (;;) { nfds epoll_wait(epollfd, events, MAX_EVENTS, -1); if (nfds -1) { perror(epoll_wait); exit(EXIT_FAILURE); } for (n 0; n nfds; n) { if (events[n].data.fd listen_sock) { conn_sock accept(listen_sock, (struct sockaddr *) local, addrlen); if (conn_sock -1) { perror(accept); exit(EXIT_FAILURE); } setnonblocking(conn_sock); ev.events EPOLLIN | EPOLLET; ev.data.fd conn_sock; if (epoll_ctl(epollfd, EPOLL_CTL_ADD, conn_sock, ev) -1) { perror(epoll_ctl: conn_sock); exit(EXIT_FAILURE); } } else { do_use_fd(events[n].data.fd); } } }} /* When used as an edge-triggered interface, for performance reasons, it is possible to add the file descriptor inside the epoll interface (EPOLL_CTL_ADD)once by specifying (EPOLLIN|EPOLLOUT). This allows you to avoid continuously switching between EPOLLIN and EPOLLOUT calling epoll_ctl(2) withEPOLL_CTL_MOD.*/ 下面给出一个epoll 服务器的简单例子,参考了网上不少方式自己写了一个算不上原创把BIT_TEST部分注释打开可以忽略basetype.h,可以编译通过。创建socket的地方可以自己优化省略我实现的时候觉得这种方式比较容易看清楚socket的获取方式。#include #include #include #include #include #include #include #include #include #include #include #include #include #include basetype.h static int g_Main_Epoll_Fd -1;#define MAX_EPOLL_EVENT_COUNT 64#define MAX_LISTEN_NUM 10#define MAX_BUFF_LEN 512 /*#define BIT_TEST(a, b) ((a) (b))#define BIT_RESET(a, b) ((a) ~ (b))#define BIT_SET(a, b) ((a) | (b))#define BIT_MATCH(a,b) ((a)(b) (b))#define BIT_COMPARE(a, b, c) ((a)(b) (c))*/ static void print_socket_info(struct addrinfo *ai){ char ipstr[INET6_ADDRSTRLEN]; uint16_t port; void *addr NULL; char *ipver NULL; struct sockaddr_in *ipv4 NULL; struct sockaddr_in6 *ipv6 NULL; assert(NULL ! ai); if (ai-ai_family AF_INET) { // IPv4 ipv4 (struct sockaddr_in *)ai-ai_addr; addr (ipv4-sin_addr); ipver IPv4; port ntohs(((struct sockaddr_in*)ai-ai_addr)-sin_port); } else { // IPv6 ipv6 (struct sockaddr_in6 *)ai-ai_addr; addr (ipv6-sin6_addr); ipver IPv6; port ntohs(((struct sockaddr_in6*)ai-ai_addr)-sin6_port); } // convert the IP to a string and print it: (void)inet_ntop(ai-ai_family, addr, ipstr, sizeof ipstr); printf( server initing... AF: %s IP: %s,PORT: %u, ipver, ipstr,port); return ;} static int SetSocketNoblocking(const int sockfd){ int flags 0; int iret 0; flags fcntl (sockfd, F_GETFL, 0); if (flags -1) { perror (fcntl); return -1; } flags | O_NONBLOCK; iret fcntl (sockfd, F_SETFL, flags); if (iret -1) { perror (fcntl); return -1; } return 0;} static int Epoll_Control(const int sockfd, const int oper, const int events){ struct epoll_event ep_event; int iret 0; memset(ep_event, 0, sizeof(ep_event)); ep_event.events events; ep_event.data.fd sockfd; iret epoll_ctl(g_Main_Epoll_Fd, oper, sockfd, ep_event); if (0 iret) { perror(epoll_ctl error.); printf(epoll_ctl error opt:%d, oper); return -1; } return 0;} static int CreateServerScoket(const char *host, const char *port){ struct addrinfo hints; struct addrinfo*ailist NULL; struct addrinfo *ai NULL; int iret; int sockfd 0; int sockoptval 1; memset(hints, 0, sizeof(hints)); hints.ai_family AF_UNSPEC; // AF_INET 或 AF_INET6 hints.ai_socktype SOCK_STREAM; hints.ai_flags AI_PASSIVE; /* All interfaces */ iret getaddrinfo(host, port, hints, ailist); if (0 ! iret) { fprintf(stderr, getaddrinfo: %s, gai_strerror(iret)); return -1; } for(ai ailist;ai ! NULL; ai ai-ai_next) { sockfd socket(ai-ai_family, ai-ai_socktype, ai-ai_protocol); if (0 sockfd) { continue; } /* set reuse addr */ iret setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, sockoptval, sizeof(sockoptval)); if (0 iret) { perror(setsockopt error); freeaddrinfo(ailist); return -1; } iret bind(sockfd, ai-ai_addr, ai-ai_addrlen);/*sizeof(struct sockaddr)*/ if (0 iret) { print_socket_info(ai); break; } else { close(sockfd); } } if (NULL ai) { fprintf(stderr, get server socket error.); return -1; } freeaddrinfo(ailist); /* set no-block mode */ iret SetSocketNoblocking(sockfd); if (0 ! iret) { return -1; } /* listen socket */ iret listen(sockfd, MAX_LISTEN_NUM); if (0 iret) { perror(listen socket error.); return -1; } printf(server socket init success. listenning...); return sockfd;} static void HandleAccept(const int listen_scok, int Event){ struct sockaddr_in addr; socklen_t len sizeof(addr); int client_sock -1; if (BIT_TEST(EPOLLIN, Event)) { client_sock accept(listen_scok, (struct sockaddr *)addr, len); if(client_sock 0 ) { perror(accept infd error); return; } (void)Epoll_Control(client_sock, EPOLL_CTL_ADD, EPOLLIN); } return ;} static void ProcRecvMsg(int sockfd){ ssize_t recvlen 0; char recvBuf[MAX_BUFF_LEN]; //read ev ready; recvlen recv(sockfd, recvBuf, sizeof(recvBuf), 0); if(recvlen 0) { perror(recv error.); return ; } else if(recvlen 0) { printf(client quit); (void)Epoll_Control(sockfd, EPOLL_CTL_DEL, 0); close(sockfd); } else { (void)Epoll_Control(sockfd, EPOLL_CTL_MOD, EPOLLOUT); printf(recv msg fprom client:msg#:%s,recvBuf); } return ;} static void SendMsg2Client(const int sockfd){ ssize_t sendlen 0; char sendBuf[MAX_BUFF_LEN]; int event 0; sprintf(sendBuf, HTTP/1.0 200 OKHello Epoll! [client_fd:%d], sockfd); int sendsize send(sockfd, sendBuf, strlen(sendBuf)1, 0); if(sendsize 0) { perror(send error.); (void)Epoll_Control(sockfd, EPOLL_CTL_DEL, 0); close(sockfd); } else { printf(Server reply msg ok! data: %s, sendBuf); event EPOLLIN | EPOLLERR | EPOLLHUP; (void)Epoll_Control(sockfd, EPOLL_CTL_MOD, event); } return ;} int main(int argc, char *argv[]){ int listenfd 0; int epfd 0; int iret 0; int event 0; struct epoll_event ep_events[MAX_EPOLL_EVENT_COUNT]; int ev_num 0; int in_sockfd 0; int loop 0; if (3 argc) { printf(Usage: %s [ip_addr] [port],argv[0]); return -1; } listenfd CreateServerScoket(argv[1], argv[2]); if (0 listenfd) { return -1; } epfd epoll_create(1); if (-1 epfd) { perror(create epoll error.); return -1; } else { g_Main_Epoll_Fd epfd; } event EPOLLIN; iret Epoll_Control(listenfd, EPOLL_CTL_ADD, event); if (0 ! iret) { return -1; } /* proc epoll event regined */ printf(server init success, epoll wait now.); for(;;) { memset(ep_events, 0, sizeof(ep_events)); ev_num epoll_wait(g_Main_Epoll_Fd, ep_events, MAX_EPOLL_EVENT_COUNT, -1); switch (ev_num) { case 0: { printf(epoll_wait timeout.); break; } case -1: { perror(epoll_wait error.); break; } default: { for (loop 0; loop ev_num; loop) { in_sockfd ep_events[loop].data.fd; event ep_events[loop].events; if (in_sockfd listenfd) { HandleAccept(in_sockfd, event); } else { if (BIT_TEST(EPOLLIN, event)) { /* have data to read */ ProcRecvMsg(in_sockfd); } else if (BIT_TEST(EPOLLOUT, event)) { SendMsg2Client(in_sockfd); } } } break; } } } return 0;}结果如下客户端任意都可以注意运行时需要手动输入服务器主机名及端口号。
