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Linux非阻塞IO(七)使用epoll重新实现客户端

使用poll与epoll的区别主要在于:

poll可以每次重新装填fd数组,但是epoll的fd是一开始就加入了,不可能每次都重新加入

于是采用这种策略:

epoll除了listenfd一开始就监听read事件,其他的客户fd加入epoll时,监听的事件都为空。

然后在每次epoll_wait之前,使用epoll_ctl重新设置fd的监听事件

所以这部分的代码如下:

 

//重新装填epoll事件        sockfd_event = 0;        stdin_event = 0;        stdout_event = 0;        //epoll无法每次都重新装填,所以给每个fd添加一个空事件                if(buffer_is_readable(&sendbuf))        {            sockfd_event |= kWriteEvent;        }        if(buffer_is_writeable(&sendbuf))        {            stdin_event |= kReadEvent;        }        if(buffer_is_readable(&recvbuf))        {            stdout_event |= kWriteEvent;        }        if(buffer_is_writeable(&recvbuf))        {            sockfd_event |= kReadEvent;        }        epoll_mod_fd(epollfd, sockfd, sockfd_event);        epoll_mod_fd(epollfd, STDIN_FILENO, stdin_event);        epoll_mod_fd(epollfd, STDOUT_FILENO, stdout_event);

理解了这部分代码,整理部分与poll基本一致:

#define _GNU_SOURCE#include "sysutil.h"#include "buffer.h"#include <sys/epoll.h>int main(int argc, char const *argv[]){    //创建client套接字    int sockfd = tcp_client(0);    //调用非阻塞connect函数    int ret = nonblocking_connect(sockfd, "localhost", 9981, 5000);    if(ret == -1)    {        perror("Connect Timeout .");        exit(EXIT_FAILURE);    }    //将三个fd设置为Non-Blocking    activate_nonblock(sockfd);    activate_nonblock(STDIN_FILENO);    activate_nonblock(STDOUT_FILENO);    buffer_t recvbuf; //sockfd -> Buffer -> stdout    buffer_t sendbuf; //stdin -> Buffer -> sockfd    //初始化缓冲区    buffer_init(&recvbuf);    buffer_init(&sendbuf);    //创建epoll    int epollfd = epoll_create1(0);    if(epollfd == -1)        ERR_EXIT("create epoll");    struct epoll_event events[1024];    uint32_t sockfd_event = 0;    uint32_t stdin_event = 0;    uint32_t stdout_event = 0;    epoll_add_fd(epollfd, sockfd, sockfd_event);    epoll_add_fd(epollfd, STDIN_FILENO, stdin_event);    epoll_add_fd(epollfd, STDOUT_FILENO, stdout_event);    while(1)    {        //重新装填epoll事件        sockfd_event = 0;        stdin_event = 0;        stdout_event = 0;        //epoll无法每次都重新装填,所以给每个fd添加一个空事件                if(buffer_is_readable(&sendbuf))        {            sockfd_event |= kWriteEvent;        }        if(buffer_is_writeable(&sendbuf))        {            stdin_event |= kReadEvent;        }        if(buffer_is_readable(&recvbuf))        {            stdout_event |= kWriteEvent;        }        if(buffer_is_writeable(&recvbuf))        {            sockfd_event |= kReadEvent;        }        epoll_mod_fd(epollfd, sockfd, sockfd_event);        epoll_mod_fd(epollfd, STDIN_FILENO, stdin_event);        epoll_mod_fd(epollfd, STDOUT_FILENO, stdout_event);        //监听fd数组        int nready = epoll_wait(epollfd, events, 1024, 5000);        if(nready == -1)            ERR_EXIT("epoll wait");        else if(nready == 0)        {            printf("epoll timeout.\n");            continue;        }        else        {            int i;            for(i = 0; i < nready; ++i)            {                int peerfd = events[i].data.fd;                int revents = events[i].events;                if(peerfd == sockfd && revents & kReadREvent)                {                    //从sockfd接收数据到recvbuf                    if(buffer_read(&recvbuf, peerfd) == 0)                    {                        fprintf(stderr, "server close.\n");                        exit(EXIT_SUCCESS);                    }                 }                                    if(peerfd == sockfd && revents & kWriteREvent)                {                    buffer_write(&sendbuf, peerfd); //将sendbuf中的数据写入sockfd                }                if(peerfd == STDIN_FILENO && revents & kReadREvent)                {                    //从stdin接收数据写入sendbuf                    if(buffer_read(&sendbuf, peerfd) == 0)                    {                        fprintf(stderr, "exit.\n");                        exit(EXIT_SUCCESS);                    }                 }                if(peerfd == STDOUT_FILENO && revents & kWriteREvent)                {                    buffer_write(&recvbuf, peerfd); //将recvbuf中的数据输出至stdout                }            }        }    }}

Linux非阻塞IO(七)使用epoll重新实现客户端