4.29和4.30、epoll的API介绍和代码编写
- 1.epoll的IO多路复用使用流程图
- 2.epoll的相关函数的使用介绍
- 3.epoll代码编写
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1.epoll的IO多路复用使用流程图
2.epoll的相关函数的使用介绍
#include <sys/epoll.h>
int epoll_create(int size);- 参数:size : 目前没有意义了。随便写一个数,必须大于0- 返回值:-1 : 失败> 0 : 文件描述符,操作epoll实例的typedef union epoll_data {void *ptr;int fd;uint32_t u32;uint64_t u64;
} epoll_data_t;struct epoll_event {uint32_t events; epoll_data_t data;
};
常见的Epoll检测事件:- EPOLLIN- EPOLLOUT- EPOLLERR
int epoll_ctl(int epfd, int op, int fd, struct epoll_event *event);- 参数:- epfd : epoll实例对应的文件描述符- op : 要进行什么操作EPOLL_CTL_ADD: 添加EPOLL_CTL_MOD: 修改EPOLL_CTL_DEL: 删除- fd : 要检测的文件描述符- event : 检测文件描述符什么事情
int epoll_wait(int epfd, struct epoll_event *events, int maxevents, int timeout);- 参数:- epfd : epoll实例对应的文件描述符- events : 传出参数,保存了发送了变化的文件描述符的信息- maxevents : 第二个参数结构体数组的大小- timeout : 阻塞时间- 0 : 不阻塞- -1 : 阻塞,直到检测到fd数据发生变化,解除阻塞- > 0 : 阻塞的时长(毫秒)- 返回值:- 成功,返回发送变化的文件描述符的个数 > 0- 失败 -1
3.epoll代码编写
①epoll服务端
#include <iostream>
#include <unistd.h>
#include <cstring>
#include <sys/epoll.h>
#include <arpa/inet.h>using namespace std;int main() {int server_listen_fd = socket(PF_INET, SOCK_STREAM, 0);sockaddr_in server_addr;server_addr.sin_addr.s_addr = INADDR_ANY;server_addr.sin_family = AF_INET;server_addr.sin_port = htons(9999);bind(server_listen_fd, (sockaddr *)&server_addr, sizeof(server_addr));listen(server_listen_fd, 8);int epoll_fd = epoll_create(2);epoll_event event;event.events = EPOLLIN;event.data.fd = server_listen_fd;epoll_ctl(epoll_fd, EPOLL_CTL_ADD, server_listen_fd, &event);epoll_event events[1024];int events_len = 1;while (1) {int change_len = epoll_wait(epoll_fd, events, events_len, -1);if (change_len == -1) {perror("epoll_wait");exit(-1);} else if (change_len == 0) {continue;} else if (change_len > 0) {cout << "epoll wait ret: " << change_len << endl;for (int i = 0; i < change_len; i ++ ) {if (events[i].data.fd == server_listen_fd) {sockaddr_in client_addr;socklen_t client_addr_len = sizeof(client_addr);int client_fd = accept(server_listen_fd, (sockaddr *)&client_addr, &client_addr_len);event.events = EPOLLIN;event.data.fd = client_fd;epoll_ctl(epoll_fd, EPOLL_CTL_ADD, client_fd, &event);events_len ++ ;} else if ((events[i].events & EPOLLIN) == EPOLLIN) {char buf[1024];int recv_ret = recv(events[i].data.fd, buf, sizeof(buf), 0);if (recv_ret == -1) {perror("recv");exit(-1);} else if (recv_ret == 0) {cout << "clinet closed..." << endl;epoll_ctl(epoll_fd, EPOLL_CTL_DEL, events[i].data.fd, NULL);close(events[i].data.fd);events_len -- ;} else if (recv_ret > 0) {printf("I am server, data: %s\\n", buf);send(events[i].data.fd, buf, strlen(buf) + 1, 0);}}}}}close(epoll_fd);close(server_listen_fd);return 0;
}
②客户端(没变,和之前一样)
#include <iostream>
#include <unistd.h>
#include <arpa/inet.h>
#include <cstring>using namespace std;int main()
{int client_fd = socket(AF_INET, SOCK_STREAM, 0);if (client_fd == -1) {perror("socket");exit(-1);}sockaddr_in server_addr;server_addr.sin_family = AF_INET; int pton_ret = inet_pton(AF_INET, "xxx.xxx.xxx.xxx", &server_addr.sin_addr.s_addr);server_addr.sin_port = htons(9999);int cone_ret = connect(client_fd, (sockaddr *)&server_addr, sizeof(server_addr));if (cone_ret == -1) {perror("connect");exit(-1);}int num = 0;char recvBuf[1024] = {0};while (1) {sprintf(recvBuf, "hello, I am client: %d\\n", num ++ );write(client_fd, recvBuf, strlen(recvBuf) + 1);int read_ret = read(client_fd, recvBuf, sizeof(recvBuf));if (read_ret == -1) {perror("read");exit(-1);} else if (read_ret > 0) {printf("recv client data is %s\\n", recvBuf);} else if (read_ret == 0){cout << "server closed..." << endl;break;}sleep(1);}close(client_fd);return 0;
}