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在UNIX網絡編程卷1:圖6-22,有一段代碼如下:如何在此代碼中使用epoll而不是select?
/* include fig01 */
#include "unp.h"
int main(int argc, char **argv)
{
int i, maxi, maxfd, listenfd, connfd, sockfd;
int nready, client[FD_SETSIZE];
ssize_t n;
fd_set rset, allset;
char buf[MAXLINE];
socklen_t clilen;
struct sockaddr_in cliaddr, servaddr;
listenfd = Socket(AF_INET, SOCK_STREAM, 0);
bzero(&servaddr, sizeof(servaddr));
servaddr.sin_family = AF_INET;
servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
servaddr.sin_port = htons(SERV_PORT);
Bind(listenfd, (SA *) &servaddr, sizeof(servaddr));
Listen(listenfd, LISTENQ);
maxfd = listenfd; /* initialize */
maxi = -1; /* index into client[] array */
for (i = 0; i < FD_SETSIZE; i++)
client[i] = -1; /* -1 indicates available entry */
FD_ZERO(&allset);
FD_SET(listenfd, &allset);
/* end fig01 */
/* include fig02 */
for (; ;) {
rset = allset; /* structure assignment */
nready = Select(maxfd+1, &rset, NULL, NULL, NULL);
if (FD_ISSET(listenfd, &rset)) { /* new client connection */
clilen = sizeof(cliaddr);
connfd = Accept(listenfd, (SA *) &cliaddr, &clilen);
#ifdef NOTDEF
printf("new client: %s, port %d\n",
Inet_ntop(AF_INET, &cliaddr.sin_addr, 4, NULL),
ntohs(cliaddr.sin_port));
#endif
for (i = 0; i < FD_SETSIZE; i++)
if (client[i] < 0) {
client[i] = connfd; /* save descriptor */
break;
}
if (i == FD_SETSIZE)
err_quit("too many clients");
FD_SET(connfd, &allset); /* add new descriptor to set */
if (connfd > maxfd)
maxfd = connfd; /* for select */
if (i > maxi)
maxi = i; /* max index in client[] array */
if (--nready <= 0)
continue; /* no more readable descriptors */
}
for (i = 0; i <= maxi; i++) { /* check all clients for data */
if ((sockfd = client[i]) < 0)
continue;
if (FD_ISSET(sockfd, &rset)) {
if ((n = Read(sockfd, buf, MAXLINE)) == 0) {
/*4connection closed by client */
Close(sockfd);
FD_CLR(sockfd, &allset);
client[i] = -1;
} else
Writen(sockfd, buf, n);
if (--nready <= 0)
break; /* no more readable descriptors */
}
}
}
}
/* end fig02 */
我想知道如何在這裏使用「epoll的」,而不是「選擇」,但我有關於epoll的小知識,所以任何人都可以給我一些觀點?謝謝。
還有一點需要指出:你想在邊緣觸發模式下使用epoll還是epoll?除非啓用邊沿觸發模式,否則使用epoll覆蓋選擇幾乎沒有什麼優勢。 – 2013-03-09 19:06:28