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, charconst *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epollint 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");
elseif(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recvbufif(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sendbufif(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 }
}
}
}
}
原文:http://www.cnblogs.com/inevermore/p/4055057.html
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