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打扰我的长篇文章。我会发布代码,以便更容易理解我面临的问题。看起来如果一个有信号的套接字被添加到epoll实例中,那么epoll实例上的epoll_wait将不会被阻塞。下面的例子已经让我相信这一点:epoll_wait阻塞信号插座
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <time.h>
#include <sys/epoll.h>
int MAX_EVENT_COUNT = 10;
int main(int argc, char *argv[])
{
int epollfd = epoll_create(MAX_EVENT_COUNT);
if (epollfd == -1)
{
printf("\n Error : epoll_create \n");
return 1;
}
epoll_event ev;
memset(&ev,0,sizeof(ev));
ev.events = EPOLLIN | EPOLLET;
int pipefd[2];
if (pipe(pipefd) == -1)
{
perror("pipe");
exit(EXIT_FAILURE);
}
char ch = 'a';
write(pipefd[1], &ch, 1);
if (epoll_ctl(epollfd , EPOLL_CTL_ADD, pipefd[0], &ev) == -1)
{
printf("\n Error : epoll add result \n");
return 1;
}
epoll_event rawResult [MAX_EVENT_COUNT];
int32_t res = epoll_wait(epollfd, rawResult, MAX_EVENT_COUNT, -1);
if(res!=1)
{
printf("\n Epoll problem \n");
}
else
{
printf("\n OK \n");
}
}
但是下面的例子是几乎相同的,但这次我一个信号插座添加到epoll的,此时epoll_wait调用块
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <time.h>
#include <sys/epoll.h>
int MAX_EVENT_COUNT = 10;
int main(int argc, char *argv[])
{
int listenfd = 0;
{
struct sockaddr_in serv_addr;
char sendBuff[1025];
listenfd = socket(AF_INET, SOCK_STREAM, 0);
memset(&serv_addr, '0', sizeof(serv_addr));
memset(sendBuff, '0', sizeof(sendBuff));
serv_addr.sin_family = AF_INET;
serv_addr.sin_addr.s_addr = htonl(INADDR_ANY);
serv_addr.sin_port = htons(5000);
bind(listenfd, (struct sockaddr*)&serv_addr, sizeof(serv_addr));
listen(listenfd, 10);
}
int sockfd = 0, n = 0;
char recvBuff[1024];
struct sockaddr_in serv_addr;
memset(recvBuff, '0',sizeof(recvBuff));
if((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
{
printf("\n Error : Could not create socket \n");
return 1;
}
memset(&serv_addr, '0', sizeof(serv_addr));
serv_addr.sin_family = AF_INET;
serv_addr.sin_port = htons(5000);
if(inet_pton(AF_INET, "127.0.0.1", &serv_addr.sin_addr)<=0)
{
printf("\n inet_pton error occured\n");
return 1;
}
if(connect(sockfd, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) < 0)
{
printf("\n Error : Connect Failed \n");
return 1;
}
int connfd = accept(listenfd, (struct sockaddr*)NULL, NULL);
int epollfd = epoll_create(MAX_EVENT_COUNT);
if (epollfd == -1)
{
printf("\n Error : epoll_create \n");
return 1;
}
epoll_event ev;
memset(&ev,0,sizeof(ev));
ev.events = EPOLLIN | EPOLLET;
if (epoll_ctl(epollfd , EPOLL_CTL_ADD, sockfd, &ev) == -1)
{
printf("\n Error : epoll add result \n");
return 1;
}
epoll_event rawResult [MAX_EVENT_COUNT];
int32_t res = epoll_wait(epollfd, rawResult, MAX_EVENT_COUNT, -1);
}
我明白你的意思,但它对我来说似乎仍然不合逻辑,因为epoll是tcp层下的“原始”,所以它应该将三次握手作为数据报告。此外,有些人似乎正在使用它(http://stackoverflow.com/questions/2875002/non-blocking-tcp-connect-with-epoll) –
@YordanPavlov:你没有执行异步'accept()'。如果你想让tcp'SYN'触发'epoll_wait()'唤醒,你需要在监听套接字上轮询,而不是由'accept()'返回的套接字轮询。在accept()返回套接字之后,三次握手(或者三种方式中的至少两种)已经完成。 – jxh
感谢您的回复,您似乎参考了服务器端。在我的情况下,我在客户端套接字轮询,我期待的SYN-ACK触发epoll_wait()。 –