{"id":148503,"date":"2022-01-11T13:58:43","date_gmt":"2022-01-11T05:58:43","guid":{"rendered":"http:\/\/www.idc.net\/help\/148503\/"},"modified":"2022-01-11T13:58:43","modified_gmt":"2022-01-11T05:58:43","slug":"%e6%b7%b1%e5%85%a5%e4%ba%86%e8%a7%a3fd_set%e7%bb%93%e6%9e%84%e4%bd%93%e5%9c%a8linux%e4%b8%ad%e7%9a%84%e4%bd%bf%e7%94%a8%e6%96%b9%e6%b3%95-fd_set%e7%bb%93%e6%9e%84%e4%bd%93linux","status":"publish","type":"post","link":"https:\/\/idc.net\/help\/148503\/","title":{"rendered":"\u6df1\u5165\u4e86\u89e3fd_set\u7ed3\u6784\u4f53\u5728Linux\u4e2d\u7684\u4f7f\u7528\u65b9\u6cd5 (fd_set\u7ed3\u6784\u4f53linux)"},"content":{"rendered":"<p>\u5728Linux\u4e2d\uff0c\u7f51\u7edc\u7f16\u7a0b\u7ecf\u5e38\u4f1a\u6d89\u53ca\u5230fd_set\u7ed3\u6784\u4f53\u7684\u4f7f\u7528\u3002\u8be5\u7ed3\u6784\u4f53\u662f\u64cd\u4f5c\u7cfb\u7edf\u63d0\u4f9b\u7684\u4e00\u79cd\u6570\u636e\u7c7b\u578b\uff0c\u4e3b\u8981\u7528\u4e8e\u63cf\u8ff0\u4e00\u7ec4\u6587\u4ef6\u63cf\u8ff0\u7b26\uff0c\u53ef\u4ee5\u5728\u540c\u4e00\u4e2a\u6570\u7ec4\u4e2d\u540c\u65f6\u5b58\u653e\u591a\u4e2a\u6587\u4ef6\u63cf\u8ff0\u7b26\u3002\u5728\u672c\u6587\u4e2d\uff0c\u6211\u4eec\u5c06\u3002<\/p>\n<p>\u4e00\u3001fd_set\u7ed3\u6784\u4f53\u7684\u5b9a\u4e49<\/p>\n<p>fd_set\u7ed3\u6784\u4f53\u662fLinux\u7cfb\u7edf\u4e2d\u7684\u4e00\u4e2a\u6570\u636e\u7c7b\u578b\uff0c\u5b9a\u4e49\u5728\u5934\u6587\u4ef6\u4e2d\uff1a<\/p>\n<\/p>\n<p> typedef struct fd_set {<\/p>\n<p> __fd_mask fds_bits[__FD_SETSIZE \/ __NFDBITS];<\/p>\n<p> } fd_set;<\/p>\n<p>\u5176\u4e2d\uff0c__fd_mask\u548c__FD_SETSIZE\u662f\u7cfb\u7edf\u5b9a\u4e49\u7684\u5b8f\uff0c__NFDBITS\u662f\u4e00\u4e2a\u6570\u503c\u5e38\u91cf\u3002fds_bits\u6570\u7ec4\u662f\u4e00\u4e2a\u4f4d\u5411\u91cf\uff0c\u5b58\u653e\u7684\u662f\u6587\u4ef6\u63cf\u8ff0\u7b26\u7684\u72b6\u6001\u3002<\/p>\n<p>\u4e8c\u3001\u51fd\u6570\u5206\u6790<\/p>\n<p>1\u3001FD_ZERO\uff08fd_set *set\uff09\u51fd\u6570<\/p>\n<p>FD_ZERO\u51fd\u6570\u7528\u4e8e\u6e05\u7a7afd_set\u7ed3\u6784\u4f53\u7684\u6240\u6709\u5143\u7d20\uff0c\u5373\u5c06\u6bcf\u4e2a\u5143\u7d20\u90fd\u8bbe\u7f6e\u4e3a0\u3002\u51fd\u6570\u539f\u578b\u5982\u4e0b\uff1a<\/p>\n<p> int FD_ZERO(fd_set* set);<\/p>\n<p>\u53c2\u6570set\u662f\u4e00\u4e2a\u6307\u5411fd_set\u7ed3\u6784\u4f53\u7684\u6307\u9488\uff0c\u8fd4\u56de\u503c\u4e3a0\u8868\u793a\u6e05\u7a7a\u6210\u529f\uff0c-1\u8868\u793a\u5931\u8d25\u3002<\/p>\n<p>2\u3001FD_SET\uff08int fd, fd_set *set\uff09\u51fd\u6570<\/p>\n<p>FD_SET\u51fd\u6570\u7528\u4e8e\u5c06\u6587\u4ef6\u63cf\u8ff0\u7b26fd\u6dfb\u52a0\u5230fd_set\u7ed3\u6784\u4f53set\u4e2d\u3002\u51fd\u6570\u539f\u578b\u5982\u4e0b\uff1a<\/p>\n<p> void FD_SET(int fd, fd_set* set);<\/p>\n<p>\u53c2\u6570fd\u662f\u5f85\u6dfb\u52a0\u7684\u6587\u4ef6\u63cf\u8ff0\u7b26\uff0cset\u662f\u6307\u5411\u4fdd\u5b58\u6587\u4ef6\u63cf\u8ff0\u7b26\u7684fd_set\u7ed3\u6784\u4f53\u7684\u6307\u9488\u3002FD_SET\u51fd\u6570\u5c06fd\u6587\u4ef6\u63cf\u8ff0\u7b26\u6dfb\u52a0\u5230set\u4e2d\uff0c\u4ee5\u4fbf\u8fdb\u4e00\u6b65\u4f7f\u7528\u3002\u5982\u679cfd\u5931\u8d25\u6216\u8005\u5df2\u7ecf\u5b58\u5728\u4e8eset\u4e2d\uff0c\u5c06\u4e0d\u505a\u4efb\u4f55\u6539\u53d8\u3002<\/p>\n<p>3\u3001FD_CLR\uff08int fd, fd_set *set\uff09\u51fd\u6570<\/p>\n<p>FD_CLR\u51fd\u6570\u7528\u4e8e\u5c06\u6587\u4ef6\u63cf\u8ff0\u7b26fd\u4ecefd_set\u7ed3\u6784\u4f53set\u4e2d\u5220\u9664\u3002\u51fd\u6570\u539f\u578b\u5982\u4e0b\uff1a<\/p>\n<p> void FD_CLR(int fd, fd_set* set);<\/p>\n<p>\u53c2\u6570fd\u662f\u5f85\u5220\u9664\u7684\u6587\u4ef6\u63cf\u8ff0\u7b26\uff0cset\u662f\u6307\u5411\u4fdd\u5b58\u6587\u4ef6\u63cf\u8ff0\u7b26\u7684fd_set\u7ed3\u6784\u4f53\u7684\u6307\u9488\u3002FD_CLR\u51fd\u6570\u5c06fd\u6587\u4ef6\u63cf\u8ff0\u7b26\u4eceset\u4e2d\u5220\u9664\uff0c\u4ee5\u4fbf\u8fdb\u4e00\u6b65\u4f7f\u7528\u3002\u5982\u679cfd\u4e0d\u5728fd_set\u7ed3\u6784\u4f53\u4e2d\uff0cFD_CLR\u51fd\u6570\u5c06\u4e0d\u505a\u4efb\u4f55\u6539\u53d8\u3002<\/p>\n<p>4\u3001FD_ISSET\uff08int fd, fd_set *set\uff09\u51fd\u6570<\/p>\n<p>FD_ISSET\u51fd\u6570\u7528\u4e8e\u5224\u65ad\u6587\u4ef6\u63cf\u8ff0\u7b26fd\u662f\u5426\u5728fd_set\u7ed3\u6784\u4f53set\u4e2d\u3002\u51fd\u6570\u539f\u578b\u5982\u4e0b\uff1a<\/p>\n<p> int FD_ISSET(int fd, fd_set* set);<\/p>\n<p>\u53c2\u6570fd\u662f\u5f85\u5224\u65ad\u7684\u6587\u4ef6\u63cf\u8ff0\u7b26\uff0cset\u662f\u6307\u5411\u4fdd\u5b58\u4e86\u6587\u4ef6\u63cf\u8ff0\u7b26\u7684fd_set\u7ed3\u6784\u4f53\u7684\u6307\u9488\u3002FD_ISSET\u51fd\u6570\u5c06\u4f1a\u68c0\u6d4bfd\u662f\u5426\u5728set\u4e2d\uff0c\u5982\u679c\u5b58\u5728\u5219\u8fd4\u56de1\uff0c\u4e0d\u5b58\u5728\u5219\u8fd4\u56de0\u3002<\/p>\n<p>\u4e09\u3001\u4f7f\u7528\u793a\u4f8b<\/p>\n<p>\u4e3a\u4e86\u66f4\u597d\u5730\u5c55\u793afd_set\u7ed3\u6784\u4f53\u7684\u7528\u6cd5\uff0c\u6211\u4eec\u5728\u6b64\u5217\u4e3e\u4e00\u4e2a\u7b80\u5355\u7684\u7a0b\u5e8f\u793a\u4f8b\uff1a<\/p>\n<p> #include <\/p>\n<\/p>\n<p> #include <\/p>\n<\/p>\n<p> #include <\/p>\n<\/p>\n<p> #include <\/p>\n<\/p>\n<p> #include <\/p>\n<\/p>\n<p> #include <\/p>\n<\/p>\n<p> #include <\/p>\n<\/p>\n<p> #include <\/p>\n<\/p>\n<p> #define MAXLINE 1024<\/p>\n<p> #define LISTENQ 5<\/p>\n<p> int mn(int argc, char **argv) {<\/p>\n<p> int listenfd, connfd;<\/p>\n<p> struct sockaddr_in servaddr, cliaddr;<\/p>\n<p> socklen_t clilen;<\/p>\n<p> char buf[MAXLINE];<\/p>\n<p> int i, maxi, maxfd, sockfd;<\/p>\n<p> int nready, client[FD_SETSIZE];<\/p>\n<p> fd_set rset, allset;<\/p>\n<p> \/* \u521b\u5efa\u76d1\u542c\u5957\u63a5\u5b57 *\/<\/p>\n<p> listenfd = socket(AF_INET, SOCK_STREAM, 0);<\/p>\n<p> \/* \u8bbe\u7f6e\u5957\u63a5\u5b57\u5730\u5740\u91cd\u590d\u5229\u7528 *\/<\/p>\n<p> int optval = 1;<\/p>\n<p> setsockopt(listenfd, SOL_SOCKET, SO_REUSEADDR, (const void *)&amp;optval, sizeof(int));<\/p>\n<p> \/* \u7ed1\u5b9a\u5957\u63a5\u5b57\u5730\u5740 *\/<\/p>\n<p> bzero(&amp;servaddr, sizeof(servaddr));<\/p>\n<p> servaddr.sin_family = AF_INET;<\/p>\n<p> servaddr.sin_addr.s_addr = htonl(INADDR_ANY);<\/p>\n<p> servaddr.sin_port = htons(9938);<\/p>\n<p> bind(listenfd, (struct sockaddr*)&amp;servaddr, sizeof(servaddr));<\/p>\n<p> \/* \u76d1\u542c *\/<\/p>\n<p> listen(listenfd, LISTENQ);<\/p>\n<p> maxfd = listenfd;<\/p>\n<p> maxi = -1;<\/p>\n<p> for (i = 0; i <\/p>\n<p> client[i] = -1;<\/p>\n<p> }<\/p>\n<p> FD_ZERO(&amp;allset);<\/p>\n<p> FD_SET(listenfd, &amp;allset);<\/p>\n<p> while (1) {<\/p>\n<p> rset = allset;<\/p>\n<p> nready = select(maxfd + 1, &amp;rset, NULL, NULL, NULL);<\/p>\n<p> if (FD_ISSET(listenfd, &amp;rset)) {<\/p>\n<p> clilen = sizeof(cliaddr);<\/p>\n<p> connfd = accept(listenfd, (struct sockaddr *)&amp;cliaddr, &amp;clilen);<\/p>\n<p> for (i = 0; i <\/p>\n<p> if (client[i] <\/p>\n<p> client[i] = connfd;<\/p>\n<p> break;<\/p>\n<p> }<\/p>\n<p> }<\/p>\n<p> if (i == FD_SETSIZE) {<\/p>\n<p> fprintf(stderr, \u201ctoo many clients\u201d);<\/p>\n<p> exit(1);<\/p>\n<p> }<\/p>\n<p> FD_SET(connfd, &amp;allset);<\/p>\n<p> if (connfd &gt; maxfd) {<\/p>\n<p> maxfd = connfd;<\/p>\n<p> }<\/p>\n<p> if (i &gt; maxi) {<\/p>\n<p> maxi = i;<\/p>\n<p> }<\/p>\n<p> if (\u2013nready <\/p>\n<p> continue;<\/p>\n<p> }<\/p>\n<p> }<\/p>\n<p> for (i = 0; i <\/p>\n<p> if ((sockfd = client[i]) <\/p>\n<p> continue;<\/p>\n<p> }<\/p>\n<p> if (FD_ISSET(sockfd, &amp;rset)) {<\/p>\n<p> if ((n = read(sockfd, buf, MAXLINE)) == 0) {<\/p>\n<p> \/* connection closed by client *\/<\/p>\n<p> close(sockfd);<\/p>\n<p> FD_CLR(sockfd, &amp;allset);<\/p>\n<p> client[i] = -1;<\/p>\n<p> } else {<\/p>\n<p> write(sockfd, buf, n);<\/p>\n<p> }<\/p>\n<p> if (\u2013nready <\/p>\n<p> break;<\/p>\n<p> }<\/p>\n<p> }<\/p>\n<p> }<\/p>\n<p> }<\/p>\n<p> }<\/p>\n<p>\u8be5\u7a0b\u5e8f\u5b9e\u73b0\u4e86\u4e00\u4e2a\u7b80\u5355\u7684echo\u670d\u52a1\u5668\uff0c\u5176\u5177\u4f53\u5b9e\u73b0\u5982\u4e0b\uff1a<\/p>\n<p>\u2460 \u521b\u5efa\u4e00\u4e2a\u76d1\u542c\u5957\u63a5\u5b57\u3002<\/p>\n<p>\u2461 \u7ed1\u5b9a\u5957\u63a5\u5b57\u5730\u5740\u3002<\/p>\n<p>\u2462 \u76d1\u542c\u5957\u63a5\u5b57\u3002<\/p>\n<p>\u2463 \u521d\u59cb\u5316\u4e00\u4e2afd_set\u7ed3\u6784\u4f53\uff0c\u5c06\u76d1\u542c\u5957\u63a5\u5b57\u6dfb\u52a0\u5230\u5176\u4e2d\u3002<\/p>\n<p>\u2464 \u5faa\u73af\u8c03\u7528select\u51fd\u6570\uff0c\u7b49\u5f85\u8fde\u63a5\u8bf7\u6c42\u6216\u5ba2\u6237\u7aef\u6570\u636e\uff0c\u5e76\u8fdb\u884c\u76f8\u5e94\u7684\u5904\u7406\u3002<\/p>\n<p><strong>\u76f8\u5173\u95ee\u9898\u62d3\u5c55\u9605\u8bfb\uff1a<\/strong><\/p>\n<ul>\n<li>windows select\u6a21\u578b \u548clinux\u7684\u533a\u522b<\/li>\n<li>\u5173\u4e8eLinux\u4e0b\u7684select\/epoll<\/li>\n<\/ul>\n<h3>windows select\u6a21\u578b \u548clinux\u7684\u533a\u522b<\/h3>\n<p>windows select\u6a21\u578b<\/p>\n<p>\u5728widows\u4e0b\u63d0\u4f9b\u4e86\u4f17\u591a\u975e\u963b\u585e\u7684I\/O\u6a21\u578b\uff0c\u5982select\u3001WSAAsyncSelect\u3001WSAEventSelect\u3001overlapped\u3001completion port\uff0c\u5176\u4e2dIO completion port\uff08IOCP\uff09\u63d0\u4f9b\u4e86\u8f83\u597d\u7684\u4f38\u7f29\u6027\uff0c\u5728windows\u5e94\u7528\u6bd4\u8f83\u5e7f\u6cdb<\/p>\n<p>\u8bf4\u660e\uff1a\u800cselect\u6a21\u578b\u4e3b\u8981\u662f\u89e3\u51b3\u5728\u5355\u4e00\u7ebf\u7a0b\u6a21\u5f0f\u4e0b\u53ea\u80fd\u5904\u7406\u4e00\u4e2a\u5957\u63a5\u5b57\u7684\u95ee\u9898\uff0c\u8fd9\u6837\u53ef\u4ee5\u907f\u514d\u7ebf\u7a0b\u81a8\u80c0\u95ee\u9898\uff0c\u4f46\u662f\u3002\u3002\u3002\u4e0b\u9762\u770b\u5b8c\u539f\u578b\u518d\u8bb2\u8d77\u4e0d\u8db3\u4e4b\u5904<\/p>\n<p>select\u6a21\u578b\uff1awinsock\u5e93\u4e3b\u8981\u6709\u4e24\u4e2a\u7248\u672c\uff0c\u8fd9\u91cc\u4e3b\u8981\u4ee5winsock2\u7248\u672c\u4e3a\u8bf4\u660e\uff0cselect\u6a21\u578b<\/p>\n<p>int select\uff08int nfds\uff0cfd_set* readfds\uff0cfd_set* writefds\uff0cfd_set* exceptfds\uff0cconst struct timeval* timeout\uff09\uff1b<\/p>\n<p>\u5176\u5b9e\u4e3b\u8981\u662f\u4e24\u8005\u91c7\u7528\u7684\u6807\u51c6\u4e00\u81f4\uff0c\u6240\u4ee5\u63a5\u53e3\u57fa\u672c\u8ddflinux\u4e00\u81f4\uff0c\u4e0d\u8fc7nfds\u5728windows\u5176\u5b9e\u662f\u6ca1\u6709\u610f\u4e49\u7684\uff0c\u4e3b\u8981\u662f\u4e3a\u4e86\u517c\u5bb9\u5176\u4ed6\u7248\u672c<\/p>\n<p>\u5904\u7406\u8fc7\u7a0b\uff1a\u5047\u8bbe\u4ee5read\u4e3a\u4f8b\uff0c\u5728\u8fd9\u91ccwindows\u4e3b\u8981\u662f\u5148\u5c06\u5957\u63a5\u5b57s\u6dfb\u52a0\u5230readfds\u4e2d\uff0c\u7136\u540e\u7b49\u5f85select\u51fd\u6570\u8fd4\u56de\uff0c\u5728select\u51fd\u6570\u91cc\u9762\u4f1a\u79fb\u9664\u6ca1\u6709\u672a\u51b3\u7684<\/p>\n<p>I\/O\u64cd\u4f5c\u7684\u5957\u63a5\u5b57\u53e5\u67c4\uff0c\u5373\u5df2\u7ecf\u5904\u7406\u8fc7\u7684IO\u5957\u63a5\u5b57\u53e5\u67c4\uff0c\u7136\u540e\u770bs\u662f\u4fe1\u9500\u524d\u5426\u8ba4\u4ecd\u7136\u8fd8\u662freadfs\u4e2d\uff0c\u5728\u5c31\u8bf4\u660es\u53ef\u8bfb\u4e86\uff0c\u4f46\u662f\u8fd9\u91cc\u9762\u53ef\u8bfb\uff0c\u4e0d\u6ed1\u6e05\u4e00\u5b9a\u6709\u6570\u636e<\/p>\n<p>\u6709\u51e0\u79cd\u60c5\u51b5\u90fd\u4f1a\u5f15\u53d1\uff1a\u6570\u636e\u53ef\u8bfb\u3001\u8fde\u63a5\u5173\u95ed\/\u91cd\u542f\/\u4e2d\u65ad\u3001\u76d1\u542c\u5957\u63a5\u5b57\u88ab\u8c03\u7528\uff0c\u6b64\u65f6\u8fd8\u6709\u8fde\u63a5\u672a\u51b3\uff0caccept\u51fd\u6570\u63a5\u53d7\u65b0\u7684\u5957\u63a5\u5b57\u6210\u529f<\/p>\n<p>\u4e0d\u8db3\uff1a\u5176\u5b9e\u6dfb\u52a0\u5230fd_set\u5957\u63a5\u5b57\u6570\u91cf\u662f\u6709\u9650\u5236\u7684\uff0cwinsock2.h\u5b9a\u4e49\u768464\uff0c\u81ea\u5b9a\u4e49\u4e5f\u4e0d\u8d85\u8fc71024\uff0c\u56e0\u4e3a\u503c\u592a\u5927\uff0c\u4f1a\u5bf9\u670d\u52a1\u5668\u7684\u6027\u80fd\u6709\u5f71\u54cd\uff0c\u66f4\u9ad8\u7684\u5c31\u662f\u53ef\u4f38\u7f29\u7684IOCP<\/p>\n<p>linux select\u6a21\u578b<\/p>\n<p>\u5176\u5b9e\u539f\u7406\u8ddfwindows\u662f\u5dee\u4e0d\u591a\u7684\uff0c\u53ea\u662f\u5904\u7406\u8fc7\u7a0b\u5728\u5e95\u5c42\u4e0a\u6709\u70b9\u533a\u522b<\/p>\n<p>\u6a21\u578b\uff1aint select\uff08int maxfd\uff0cfd_set*readfds\uff0cfd_set* writefds\uff0cfd_set*exceptfds\uff0cconst struct timeval*timeout\uff09<\/p>\n<p>\u8fd9\u91cc\u4e3b\u8981\u662fmaxfd\uff0c\u6587\u4ef6\u63cf\u8ff0\u7b26\u7684\u8303\u56f4\uff0c\u6bd4\u5f85\u68c0\u6d4b\u7684\u66f4\u5927\u6587\u4ef6\u63cf\u8ff0\u7b26\u59271<\/p>\n<p>\u5904\u7406\u8fc7\u7a0b\uff1a\u4e5f\u662f\u5148\u5c06\u76d1\u63a7\u7684\u6587\u4ef6\u6dfb\u52a0\u5230\u6587\u4ef6\u63cf\u8ff0\u7b26\u4e2d\uff0c\u8c03\u7528select\u76d1\u63a7\uff0c\u5224\u65ad\u6587\u4ef6\u662f\u5426\u53d1\u751f\u53d8\u5316\uff0c\u4f46\u662f\u5728\u5e95\u5c42\u8c03\u7528\u7684\u786e\u662fpoll\u65b9\u6cd5\uff1b\u9996\u5148\u4f7f\u7528poll_wait\u5c06\u7b49\u5f85\u961f\u5217\u6dfb\u52a0\u5230poll_table\u4e2d\uff0c\u8fd4\u56de\u63cf\u8ff0\u7b26\u7684\u63a9\u7801<\/p>\n<p>poll\u539f\u578b\uff1aunsigned int \uff08*poll\uff09\uff08struct file*filp\uff0cpoll_wait* wait\uff09<\/p>\n<p>\u770b\u5982\u4e0b\u4e00\u4e2a\u7b80\u5355\u7684\u5904\u7406\u8fc7\u7a0b<\/p>\n<p>unsigned int mem_poll(struct file *filp, poll_table *wait)<\/p>\n<p>{<\/p>\n<p> struct mem_dev *dev = filp-&gt;private_data; <\/p>\n<p> unsigned int mask = 0;<\/p>\n<p> \/*\u5c06\u7b49\u5f85\u961f\u5217\u6dfb\u52a0\u5230poll_table *\/<\/p>\n<p> poll_wait(filp, &amp;dev-&gt;inq, wait);<\/p>\n<p> if (have_data) <\/p>\n<p> mask |= POLLIN | POLLRDNORM; \/* readable *\/<\/p>\n<p> return mask;<\/p>\n<p>}<\/p>\n<p>\u5728\u8fd9\u91cc\u53ea\u662f\u6dfb\u52a0\u961f\u5217\uff0c\u8fd4\u56de\u53ef\u8bfb\u53ef\u5199\u7684\u63a9\u7801\uff0c\u771f\u6b63\u963b\u585e\u7684\u4e0d\u662f\u8fd9\u91cc\uff0c\u662f\u5728do_select\uff08\u2026\uff09\u51fd\u6570\u4e2d\uff0c\u5728linux\u5185\u6838fs\/select.c\u91cc\u9762<\/p>\n<p>int do_select(int n, fd_set_bits *fds, struct timespec *end_time)\u8fd9\u4e2a\u51fd\u6570<\/p>\n<p> if (file) {<\/p>\n<p> f_op = file-&gt;f_op;<\/p>\n<p> mask = DEFAULT_POLLMASK;<\/p>\n<p> if (f_op &amp;&amp; f_op-&gt;poll) {<\/p>\n<p> wait_key_set(wait, in, out, bit);<\/p>\n<p> mask = (*f_op-&gt;poll)(file, wait);<\/p>\n<p> }<\/p>\n<p>\u8fd9\u91cc\u9762\u662f\u5148\u5224\u65ad\u6587\u4ef6\u5b58\u5728\uff0c\u7136\u540e\u8bfb\u53d6\u4f60\u81ea\u5df1\u5b9a\u4e49\u7684\u64cd\u4f5c\u8bbe\u5907I\/O\u7684f_op\u51fd\u6570\u6597\u76ef\uff0c\u8fd9\u91cc\u6709\u4e00\u4e2a\u9ed8\u8ba4\u7684mask\uff0c\u63a5\u7740\u624d\u5224\u65ad\u7136\u540e\u8fd4\u56de\u63cf\u8ff0\u7b26mask = (*f_op-&gt;poll)(file, wait);\u7528\u4e8e\u533a\u5206\u5f53\u524d\u54ea\u4e2a\u88ab\u89e6\u53d1\u4e86\uff1b\u63a5\u7740\u5224\u65adf_op&amp;f_op-&gt;poll\u5728\u8fd9\u91cc\u6211\u4eec\u9ed8\u8ba4\u5b9a\u4e49\u4e86poll\u51fd\u6570\uff0c\u6240\u4ee5\u8fd9\u91cc\u4f1a\u8fdb\u5165\u6b64\u5224\u65ad\u8bed\u53e5\uff0cmask = (*f_op-&gt;poll)(file, wait);\u8fd9\u4e2a\u5c31\u662f\u8c03\u7528\u9ed8\u8ba4\u7684poll\u51fd\u6570\u8fdb\u884c\u5904\u7406\uff0c\u5173\u952e\u7684\u662f\u5982\u4f55\u533a\u5206\u4e0d\u540c\u7684\u8bfb\u3001\u5199\u3001\u5f02\u5e38\u8fc7\u7a0b\uff1f<\/p>\n<p>(mask &amp; POLLIN_SET) &amp;&amp; (in &amp; bit)\uff0c\u8fd9\u91cc\u9762\u5c31\u662f\u5bf9\u5f53\u524d\u7684\u53ef\u8bfb\u3001\u5199\u3001\u5f02\u5e38\u7684&amp;&amp;\u8fc7\u7a0b\uff0c\u5c31\u662f\u4e3a\u4e86\u5224\u65ad\u548c\u533a\u5206\u5f53\u524d\u7684\u5957\u63a5\u5b57\u53ea\u662f\u67d0\u4e00\u4e2a\u5177\u4f53\u7684fd_set\u4e0b\uff1b\u5f53\u7136\u67d0\u4e00\u4e2a\u5957\u63a5\u5b57\u4e5f\u53ef\u80fd\u540c\u65f6\u5728\u53ef\u8bfb\u53ef\u5199\u91cc\u9762\uff0c\u8fd9\u65f6\u5019\u4e24\u4e2a\u4f1a\u8fdb\u884c\u5224\u65ad\u3002<\/p>\n<p> if (retval || timed_out || signal_pending(current))<\/p>\n<p> break;<\/p>\n<p>\u4e0a\u9762\u7684retval\u5982\u679c\u4e3a0\uff0c\u4e14\u5176\u4ed6\u4e5f\u4e0d\u6ee1\u8db3\u5c31\u4f1a\u5bfc\u81f4\u7a7a\u5faa\u73af\u72b6\u6001\uff0c\u5c31\u5904\u4e8e\u963b\u585e\u72b6\u6001\u4e86<\/p>\n<h3>\u5173\u4e8eLinux\u4e0b\u7684select\/epoll<\/h3>\n<p>select\u8fd9\u4e2a\u7cfb\u7edf\u8c03\u7528\u7684\u539f\u578b\u5982\u4e0b<\/p>\n<p> \u4e4b\u4e00\u4e2a\u53c2\u6570nfds\u7528\u6765\u544a\u8bc9\u5185\u6838<\/p>\n<p> \u8981\u626b\u63cf\u7684socket fd\u7684\u6570\u91cf+1<\/p>\n<p> \uff0cselect\u7cfb\u7edf\u8c03\u7528\u66f4\u5927\u63a5\u6536\u7684\u6570\u91cf\u662f1024\uff0c\u4f46\u662f\u5982\u679c\u6bcf\u6b21\u90fd\u53bb\u626b\u63cf1024\uff0c\u5b9e\u9645\u4e0a\u7684\u6570\u91cf\u5e76\u4e0d\u591a\uff0c\u5219\u6548\u7387\u592a\u4f4e\uff0c\u8fd9\u91cc\u53ef\u4ee5\u6307\u5b9a\u9700\u8981\u626b\u63cf\u7684\u6570\u91cf\u3002<\/p>\n<p> \u66f4\u5927\u6570\u91cf\u4e3a1024\uff0c\u5982\u679c\u9700\u8981\u4fee\u6539\u8fd9\u4e2a\u6570\u91cf\uff0c\u5219\u9700\u8981\u91cd\u65b0\u7f16\u8bd1Linux\u5185\u6838\u6e90\u7801\u3002<\/p>\n<p> \u7b2c2\u30013\u30014\u4e2a\u53c2\u6570\u5206\u522b\u662freadfds\u3001writefds\u3001exceptfds\uff0c\u4f20\u9012\u7684\u57cb\u660e\u53c2\u6570\u5e94\u8be5\u662ffd_set \u7c7b\u578b\u7684\u5f15\u7528\uff0c\u5185\u6838\u4f1a\u68c0\u6d4b\u6bcf\u4e2asocket\u7684fd\uff0c<\/p>\n<p> \u5982\u679c\u6ca1\u6709\u8bfb\u4e8b\u4ef6\uff0c\u5c31\u5c06\u5bf9\u5e94\u7684fd\u4ece\u7b2c\u4e8c\u4e2a\u53c2\u6570\u4f20\u5165\u7684fd_set\u4e2d\u79fb\u9664\uff0c\u5982\u679c\u6ca1\u6709\u5199\u4e8b\u4ef6\uff0c\u5c31\u5c06\u5bf9\u5e94\u7684fd\u4ece\u7b2c\u4e8c\u4e2a\u53c2\u6570\u7684fd_set\u4e2d\u79fb\u9664\uff0c\u5982\u679c\u6ca1\u6709\u5f02\u5e38\u4e8b\u4ef6\uff0c\u5c31\u5c06\u5bf9\u5e94\u7684fd\u4ece\u7b2c\u4e09\u4e2a\u53c2\u6570\u7684fd_set\u4e2d\u79fb\u9664<\/p>\n<p> \u3002\u8fd9\u91cc\u6211\u4eec\u5e94\u8be5<\/p>\n<p> \u8981\u5c06\u5b9e\u9645\u7684readfds\u3001writefds\u3001exceptfds\u62f7\u8d1d\u4e00\u4efd\u526f\u672c\u4f20\u8fdb\u53bb\uff0c\u800c\u4e0d\u662f\u4f20\u5165\u539f\u5f15\u7528\uff0c\u56e0\u4e3a\u5982\u679c\u4f20\u9012\u7684\u662f\u539f\u5f15\u7528\uff0c\u67d0\u4e9bsocket\u53ef\u80fd\u5c31\u5df2\u7ecf\u4e22\u5931<\/p>\n<p> \u3002<\/p>\n<p> \u6700\u540e\u4e00\u4e2a\u53c2\u6570\u662f\u7b49\u5f85\u65f6\u95f4\uff0c<\/p>\n<p> \u4f20\u51650\u8868\u793a\u975e\u963b\u585e\uff0c\u4f20\u5165&gt;0\u8868\u793a\u7b49\u5f85\u4e00\u5b9a\u65f6\u95f4\uff0c\u4f20\u5165NULL\u8868\u793a\u963b\u585e\uff0c\u76f4\u5230\u7b49\u5230\u67d0\u4e2asocket\u5c31\u7eea<\/p>\n<p> \u3002<\/p>\n<p> FD_ZERO()\u8fd9\u4e2a\u51fd\u6570\u5c06fd_set\u4e2d\u7684\u6240\u6709bit\u6e050\uff0c\u4e00\u822c\u7528\u6765\u8fdb\u884c\u521d\u59cb\u5316\u7b49\u3002<\/p>\n<p> FD_CLR()\u8fd9\u4e2a\u51fd\u6570\u7528\u6765\u5c06bitmap(fd_set )\u4e2d\u7684\u67d0\u4e2abit\u6e050\uff0c\u5728\u5ba2\u6237\u7aef\u5f02\u5e38\u9000\u51fa\u65f6\u5c31\u4f1a\u7528\u5230\u8fd9\u4e2a\u51fd\u6570\uff0c\u5c06fd\u4ecefd_set\u4e2d\u5220\u9664\u3002<\/p>\n<p> FD_ISSET()\u7528\u6765\u5224\u65ad\u67d0\u4e2abit\u662f\u5426\u88ab\u7f6e1\u4e86\uff0c\u4e5f\u5c31\u662f\u5224\u65ad\u67d0\u4e2afd\u662f\u5426\u5728fd_set\u4e2d\u3002<\/p>\n<p> FD_SET()\u8fd9\u4e2a\u51fd\u6570\u7528\u6765\u5c06\u67d0\u4e2afd\u52a0\u5165fd_set\u4e2d\uff0c\u5f53\u5ba2\u6237\u7aef\u65b0\u52a0\u5165\u8fde\u63a5\u65f6\u5c31\u4f1a\u4f7f\u7528\u5230\u8fd9\u4e2a\u51fd\u6570\u3002<\/p>\n<p> epoll_create\u7cfb\u7edf\u8c03\u7528\u7528\u6765\u521b\u5efaepfd\uff0c\u4f1a\u5728\u5f00\u8f9f\u4e00\u5757\u5185\u5b58\u7a7a\u95f4(epoll\u7684\u7ed3\u6784\u7a7a\u95f4)\u3002size\u4e3aepoll\u4e0a\u80fd\u5173\u6ce8\u7684\u66f4\u5927\u63cf\u8ff0\u7b26\u6570\uff0c\u4e0d\u591f\u4f1a\u8fdb\u884c\u6269\u5c55\uff0csize\u53ea\u8981\uff1e0\u5c31\u884c\uff0c\u65e9\u671f\u7684\u8bbe\u8ba1size\u662f\u56fa\u5b9a\u5927\u5c0f\uff0c\u4f46\u662f\u73b0\u5728size\u53c2\u6570\u6ca1\u4ec0\u4e48\u7528\uff0c\u4f1a\u81ea\u52a8\u6269\u5c55\u3002<\/p>\n<\/p>\n<p> \u8fd4\u56de\u503c\u662fepfd\uff0c\u5982\u679c\u4e3a-1\u5219\u8bf4\u660e\u521b\u5efaepoll\u5bf9\u8c61\u5931\u8d25<\/p>\n<p> \u3002<\/p>\n<p> \u4e4b\u4e00\u4e2a\u53c2\u6570epfd\u4f20\u5165\u7684\u5c31\u662fepoll_create\u8fd4\u56de\u7684epfd\u3002<\/p>\n<p> \u7b2c\u4e8c\u4e2a\u53c2\u6570\u4f20\u5165\u5bf9\u5e94\u64cd\u4f5c\u7684\u5b8f\uff0c\u5305\u62ec<\/p>\n<p> \u589e\u5220\u6539(EPOLL_CTL_ADD\u3001EPOLL_CTL_DEL\u3001EPOLL_CTL_MOD)<\/p>\n<p> \u3002<\/p>\n<p> \u7b2c\u4e09\u4e2a\u53c2\u6570\u4f20\u5165\u7684\u662f<\/p>\n<p> \u9700\u8981\u589e\u5220\u6539\u7684socket\u7684fd<\/p>\n<p> \u3002<\/p>\n<p> \u7b2c\u56db\u4e2a\u53c2\u6570\u4f20\u5165\u7684\u662f<\/p>\n<p> \u9700\u8981\u64cd\u4f5c\u7684fd\u7684\u54ea\u4e9b\u4e8b\u4ef6<\/p>\n<p> \uff0c\u5177\u4f53\u7684\u4e8b\u4ef6\u53ef\u4ee5\u770b\u540e\u7eed\u3002<\/p>\n<\/p>\n<p> \u8fd4\u56de\u503c\u662f\u4e00\u4e2aint\u7c7b\u578b\uff0c\u5982\u679c\u4e3a-1\u5219\u8bf4\u660e\u64cd\u4f5c\u5931\u8d25<\/p>\n<p> \u3002<\/p>\n<p> \u4e4b\u4e00\u4e2a\u53c2\u6570\u662fepfd\uff0c\u4e5f\u5c31\u662fepoll_create\u7684\u8fd4\u56de\u503c\u3002<\/p>\n<p> \u7b2c\u4e8c\u4e2a\u53c2\u6570\u662f\u4e00\u4e2aepoll_event\u7c7b\u578b\u7684\u6307\u9488\uff0c\u4e5f\u5c31\u662f\u4f20\u5165\u7684\u662f\u4e00\u4e2a\u6570\u7ec4\u6307\u9488\u3002<\/p>\n<p> \u5185\u6838\u4f1a\u5c06\u5c31\u7eea\u7684socket\u7684\u4e8b\u4ef6\u62f7\u8d1d\u5230\u8fd9\u4e2a\u6570\u7ec4\u4e2d\uff0c\u7528\u6237\u53ef\u4ee5\u6839\u636e\u8fd9\u4e2a\u6570\u7ec4\u7b80\u9500\u62ff\u5230\u4e8b\u4ef6\u548c\u6d88\u606f\u7b49<\/p>\n<p> \u3002<\/p>\n<p> \u7b2c\u4e09\u4e2a\u53c2\u6570\u662fmaxevents\uff0c\u4f20\u5165\u7684\u662f<\/p>\n<p> \u7b2c\u4e8c\u4e2a\u53c2\u6570\u7684\u6570\u7ec4\u7684\u5bb9\u91cf<\/p>\n<p> \u3002<\/p>\n<p> \u7b2c\u56db\u4e2a\u53c2\u6570\u662ftimeout\uff0c<\/p>\n<p> \u5982\u679c\u8bbe\u4e3a-1\u4e00\u76f4\u963b\u585e\u76f4\u5230\u6709\u5c31\u7eea\u6570\u636e\u4e3a\u6b62\uff0c\u5982\u679c\u8bbe\u4e3a0\u7acb\u5373\u8fd4\u56de\uff0c\u5982\u679c\uff1e0\u90a3\u4e48\u963b\u585e\u4e00\u6bb5\u65f6\u95f4<\/p>\n<p> \u3002<\/p>\n<\/p>\n<p> \u8fd4\u56de\u503c\u662f\u4e00\u4e2aint\u7c7b\u578b\uff0c\u4e5f\u5c31\u662f\u5c31\u7eea\u7684socket\u7684\u4e8b\u4ef6\u7684\u6570\u91cf(\u5185\u6838\u62f7\u8d1d\u7ed9\u7528\u6237\u7684events\u7684\u5143\u7d20\u7684\u6570\u91cf)\uff0c\u901a\u8fc7\u5f2f\u5490\u544a\u8fd9\u4e2a\u6570\u91cf\u53ef\u4ee5\u8fdb\u884c\u904d\u5386\u5904\u7406\u6bcf\u4e2a\u4e8b\u4ef6<\/p>\n<p> \u3002<\/p>\n<p> \u4e00\u822c\u9700\u8981\u4f20\u5165 ev.data.fd \u548c ev.events \uff0c\u4e5f\u5c31\u662ffd\u548c\u9700\u8981\u76d1\u63a7\u7684fd\u7684\u4e8b\u4ef6\u3002\u4e8b\u4ef6\u5982\u679c\u9700\u8981\u4f20\u5165\u591a\u4e2a\uff0c\u53ef\u4ee5\u901a\u8fc7\u6309\u4f4d\u4e0e\u6765\u8fde\u63a5\uff0c\u6bd4\u5982\u9700\u8981\u76d1\u63a7\u8bfb\u5199\u4e8b\u4ef6\uff0c\u53ea\u9700\u8981\u50cf\u5982\u4e0b\u8fd9\u6837\u64cd\u4f5c\u5373\u53ef\uff1a ev.events=EPOLLIN | EPOLLOUT \u3002<\/p>\n<p> LT(\u6c34\u5e73\u89e6\u53d1)\uff0c<\/p>\n<p> \u9ed8\u8ba4<\/p>\n<p> \u7684\u5de5\u4f5c\u6a21\u5f0f\uff0c<\/p>\n<p> \u4e8b\u4ef6\u5c31\u7eea\u540e\u7528\u6237\u53ef\u4ee5\u9009\u62e9\u5904\u7406\u548c\u4e0d\u5904\u7406\uff0c\u5982\u679c\u7528\u6237\u4e0d\u5904\u7406\uff0c\u5185\u6838\u4f1a\u5bf9\u8fd9\u90e8\u5206\u6570\u636e\u8fdb\u884c\u7ef4\u62a4\uff0c\u90a3\u4e48\u4e0b\u6b21\u8c03\u7528epoll_wait()\u65f6\u4ecd\u65e7\u4f1a\u6253\u5305\u51fa\u6765<\/p>\n<p> \u3002<\/p>\n<p> ET(\u8fb9\u7f18\u89e6\u53d1)\uff0c\u4e8b\u4ef6\u5c31\u7eea\u4e4b\u540e\uff0c<\/p>\n<p> \u7528\u6237\u5fc5\u987b\u8fdb\u884c\u5904\u7406<\/p>\n<p> \uff0c\u56e0\u4e3a\u5185\u6838\u628a\u4e8b\u4ef6\u6253\u5305\u51fa\u6765\u4e4b\u540e\u5c31\u628a\u5bf9\u5e94\u7684\u5c31\u7eea\u4e8b\u4ef6\u7ed9\u6e05\u6389\u4e86\uff0c<\/p>\n<p> \u5982\u679c\u4e0d\u5904\u7406\u90a3\u4e48\u5c31\u7eea\u4e8b\u4ef6\u5c31\u6ca1\u4e86<\/p>\n<p> \u3002ET\u53ef\u4ee5\u51cf\u5c11epoll\u4e8b\u4ef6\u88ab\u91cd\u590d\u89e6\u53d1\u7684\u6b21\u6570\uff0c\u6548\u7387\u6bd4LT\u9ad8\u3002<\/p>\n<\/p>\n<p> \u5982\u679c\u9700\u8981\u8bbe\u7f6e\u4e3a\u8fb9\u7f18\u89e6\u53d1\u53ea\u9700\u8981\u8bbe\u7f6e\u4e8b\u4ef6\u4e3a\u7c7b\u4f3c ev.events=EPOLLIN | EPOLLET \u5373\u53ef<\/p>\n<p> \u3002<\/p>\n<p> select\/poll\/epoll\u662fnio\u591a\u8def\u590d\u7528\u6280\u672f\uff0c<\/p>\n<p> \u4f20\u7edf\u7684bio\u65e0\u6cd5\u5b9e\u73b0C10K\/C100K<\/p>\n<p> \uff0c\u4e5f\u5c31\u662f\u65e0\u6cd5\u6ee1\u8db31w\/10w\u7684\u5e76\u53d1\u91cf\uff0c\u5728\u8fd9\u4e48\u9ad8\u7684\u5e76\u53d1\u91cf\u4e0b\uff0c\u5728\u8fdb\u884c\u4e0a\u4e0b\u6587\u5207\u6362\u5c31\u5f88\u5bb9\u6613\u5c06\u670d\u52a1\u5668\u7684\u8d1f\u8f7d\u62c9\u98de\u3002<\/p>\n<p> 1.\u5c06fd_set\u4ece\u7528\u6237\u6001\u62f7\u8d1d\u5230\u5185\u6838\u6001<\/p>\n<p> 2.\u6839\u636efd_set\u626b\u63cf\u5185\u5b58\u4e2d\u7684socket\u7684fd\u7684\u72b6\u6001\uff0c\u65f6\u95f4\u590d\u6742\u5ea6\u4e3aO(n)<\/p>\n<p> 3.\u68c0\u67e5fd_set\uff0c\u5982\u679c\u6709\u5df2\u7ecf\u5c31\u7eea\u7684socket\uff0c\u5c31\u7ed9\u5bf9\u5e94\u7684socket\u7684fd\u6253\u6807\u8bb0\uff0c\u90a3\u4e48\u5c31return \u5c31\u7eeasocket\u7684\u6570\u91cf\u5e76\u5524\u9192\u5f53\u524d\u7ebf\u7a0b\uff0c\u5982\u679c\u6ca1\u6709\u5c31\u7eea\u7684socket\u5c31\u7ee7\u7eed\u963b\u585e\u5f53\u524d\u7ebf\u7a0b\u76f4\u5230\u6709socket\u5c31\u7eea\u624d\u5c06\u5f53\u524d\u7ebf\u7a0b\u5524\u9192\u3002<\/p>\n<p> 4.\u5982\u679c\u60f3\u8981\u83b7\u53d6\u5f53\u524d\u5df2\u7ecf\u5c31\u7eea\u7684socket\u5217\u8868\uff0c\u5219\u8fd8\u9700\u8981\u8fdb\u884c\u4e00\u6b21\u7cfb\u7edf\u8c03\u7528\uff0c\u4f7f\u7528O(n)\u7684\u65f6\u95f4\u53bb\u626b\u63cfsocket\u7684fd\u5217\u8868\uff0c\u5c06\u5df2\u7ecf\u6253\u4e0a\u6807\u8bb0\u7684socket\u7684fd\u8fd4\u56de\u3002<\/p>\n<p> CPU\u5728\u540c\u4e00\u4e2a\u65f6\u523b\u53ea\u80fd\u6267\u884c\u4e00\u4e2a\u7a0b\u5e8f\uff0c\u901a\u8fc7RR\u65f6\u95f4\u7247\u8f6e\u8f6c\u53bb\u5207\u6362\u6267\u884c\u5404\u4e2a\u7a0b\u5e8f\u3002\u6ca1\u6709\u88ab\u6302\u8d77\u7684\u8fdb\u7a0b(\u7ebf\u7a0b)\u5219\u5728\u5de5\u4f5c\u961f\u5217\u4e2d\u6392\u961f\u7b49\u5f85CPU\u7684\u6267\u884c\uff0c\u5c06\u8fdb\u7a0b(\u7ebf\u7a0b)\u4ece\u5de5\u4f5c\u961f\u5217\u4e2d\u79fb\u9664\u5c31\u662f\u6302\u8d77\uff0c\u53cd\u6620\u5230Java\u5c42\u9762\u7684\u5c31\u662f\u7ebf\u7a0b\u7684\u963b\u585e\u3002<\/p>\n<p> \u4ec0\u4e48\u662f\u4e2d\u65ad\uff1f\u5f53\u6211\u4eec\u4f7f\u7528\u952e\u76d8\u3001\u9f20\u6807\u7b49IO\u8bbe\u5907\u7684\u65f6\u5019\uff0c\u4f1a\u7ed9\u4e3b\u677f\u4e00\u4e2a\u7535\u6d41\u4fe1\u53f7\uff0c\u8fd9\u4e2a\u7535\u6d41\u4fe1\u53f7\u5c31\u7ed9CPU\u4e00\u4e2a\u4e2d\u65ad\u4fe1\u53f7\uff0cCPU\u6267\u884c\u5b8c\u5f53\u524d\u7684\u6307\u4ee4\u4fbf\u4f1a\u4fdd\u5b58\u73b0\u573a\uff0c\u7136\u540e\u6267\u884c\u952e\u76d8\/\u9f20\u6807\u7b49\u8bbe\u5907\u7684\u4e2d\u65ad\u7a0b\u5e8f\uff0c\u8ba9\u4e2d\u65ad\u7a0b\u5e8f\u83b7\u53d6CPU\u7684\u4f7f\u7528\u6743\uff0c\u5728\u4e2d\u65ad\u7a0b\u5e8f\u540e\u53c8\u5c06\u73b0\u573a\u6062\u590d\uff0c\u7ee7\u7eed\u6267\u884c\u4e4b\u524d\u7684\u8fdb\u7a0b\u3002<\/p>\n<p> \u5982\u679c\u4e4b\u4e00\u6b21\u6ca1\u68c0\u6d4b\u5230\u5c31\u7eea\u7684socket\uff0c\u5c31\u8981\u5c06\u5176\u8fdb\u7a0b(\u7ebf\u7a0b)\u4ece\u5de5\u4f5c\u961f\u5217\u4e2d\u79fb\u9664\uff0c\u5e76\u52a0\u5165\u5230socket\u7684\u7b49\u5f85\u961f\u5217\u4e2d\u3002<\/p>\n<p> socket\u5305\u542b\u8bfb\u7f13\u51b2\u533a+\u5199\u7f13\u51b2\u533a+\u7b49\u5f85\u961f\u5217(\u653e\u7ebf\u7a0b\u6216eventpoll\u5bf9\u8c61)<\/p>\n<p> 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\u4e4b\u540e\u8fd9\u4e2a\u8fdb\u7a0b(\u7ebf\u7a0b)\u5c31\u6267\u884cselect\u51fd\u6570\u518d\u6b21\u53bb\u68c0\u67e5fd_set\u5c31\u80fd\u53d1\u73b0\u6709socket\u7f13\u51b2\u533a\u4e2d\u6709\u6570\u636e\u4e86\uff0c\u5c31\u5c06\u8be5socket\u7684fd\u6253\u6807\u8bb0\uff0c\u8fd9\u4e2a\u65f6\u5019select\u51fd\u6570\u5c31\u6267\u884c\u5b8c\u4e86\uff0c\u8fd9\u65f6\u5019\u5c31\u4f1a\u7ed9\u4e0a\u5c42\u8fd4\u56de\u4e00\u4e2aint\u7c7b\u578b\u7684\u6570\u503c\uff0c\u8868\u793a\u5df2\u7ecf\u5c31\u7eea\u7684socket\u7684\u6570\u91cf\u6216\u8005\u662f\u53d1\u751f\u4e86\u9519\u8bef\u3002\u8fd9\u4e2a\u65f6\u5019\u5c31\u518d\u8fdb\u884c\u5185\u6838\u6001\u5230\u7528\u6237\u6001\u7684\u5207\u6362\uff0c\u5bf9\u5df2\u7ecf\u6253\u6807\u8bb0\u7684socket\u7684fd\u8fdb\u884c\u5904\u7406\u3002<\/p>\n<p> \u5c06\u539f\u672c1024bit\u957f\u5ea6\u7684bitmap(fd_set)\u6362\u6210\u4e86\u6570\u7ec4\u7684\u65b9\u5f0f\u4f20\u5165<\/p>\n<p> \uff0c\u53ef\u4ee5<\/p>\n<p> \u89e3\u51b3\u539f\u672c1024\u4e2a\u4e0d\u591f\u7528\u7684\u60c5\u51b5<\/p>\n<p> \uff0c\u56e0\u4e3a\u4f20\u5165\u7684\u662f\u6570\u7ec4\uff0c\u957f\u5ea6\u53ef\u4ee5\u4e0d\u6b62\u662f1024\u4e86\uff0c\u56e0\u6b64socket\u6570\u91cf\u53ef\u4ee5\u66f4\u591a\uff0c\u5728Kernel\u5e95\u5c42\u4f1a\u5c06\u6570\u7ec4\u8f6c\u6362\u6210\u94fe\u8868\u3002<\/p>\n<p> \u5728\u5341\u591a\u5e74\u524d\uff0clinux2.6\u4e4b\u524d\uff0c\u4e0d\u652f\u6301epoll\uff0c\u5f53\u65f6\u53ef\u80fd\u4f1a\u9009\u62e9\u7528Windows\/Unix\u7528\u4f5c\u670d\u52a1\u5668\uff0c\u800c\u4e0d\u4f1a\u53bb\u9009\u62e9Linux\uff0c\u56e0\u4e3aselect\/poll\u4f1a\u968f\u7740\u5e76\u53d1\u91cf\u7684\u4e0a\u5347\uff0c\u6027\u80fd\u53d8\u5f97\u8d8a\u6765\u8d8a\u4f4e\uff0c\u6bcf\u6b21\u90fd\u5f97\u68c0\u67e5\u6240\u6709\u7684Socket\u5217\u8868\u3002<\/p>\n<p> 1.select\/poll\u6bcf\u6b21\u8c03\u7528\u90fd\u5fc5\u987b\u6839\u636e\u63d0\u4f9b\u6240\u6709\u7684socket\uff0c\u7136\u540e\u5c31<\/p>\n<p> \u4f1a\u6d89\u53ca\u5230\u5c06\u8fd9\u4e2a\u4ece\u7528\u6237\u7a7a\u95f4\u62f7\u8d1d\u5230\u5185\u6838\u7a7a\u95f4\uff0c\u5728\u8fd9\u4e2a\u8fc7\u7a0b\u4e2d\u5f88\u8017\u8d39\u6027\u80fd<\/p>\n<p> \u3002\u4f46\u662f<\/p>\n<p> \u5176\u5b9e\u6bcf\u6b21\u7684socket\u7684\u53d8\u5316\u4e5f\u8bb8\u5e76\u4e0d\u5927\uff0c\u4e5f\u8bb8\u5c311-2\u4e2asocket<\/p>\n<p> \uff0c\u4f46\u662f\u5b83\u4f1a\u5168\u90e8\u8fdb\u884c\u62f7\u8d1d\uff0c\u5168\u90e8\u8fdb\u884c\u904d\u5386\u4e00\u4e00\u5224\u65ad\u662f\u5426\u5c31\u7eea\u3002<\/p>\n<p> 2.select\/poll\u7684\u8fd4\u56de\u7c7b\u578b\u662fint\uff0c\u53ea\u80fd\u4ee3\u8868\u5f53\u524d\u7684\u5c31\u7eea\u7684socket\u7684\u6570\u91cf\/\u53d1\u751f\u4e86\u9519\u8bef\uff0c<\/p>\n<p> \u5982\u679c\u8fd8\u9700\u8981\u77e5\u9053\u662f\u54ea\u4e9bsocket\u5c31\u7eea\u4e86\uff0c\u5219\u8fd8\u9700\u8981\u518d\u6b21\u4f7f\u7528\u7cfb\u7edf\u8c03\u7528\u53bb\u68c0\u67e5\u54ea\u4e9bsocket\u662f\u5c31\u7eea\u7684\uff0c\u53c8\u662f\u4e00\u6b21O(n)\u7684\u64cd\u4f5c\uff0c\u5f88\u8017\u8d39\u6027\u80fd<\/p>\n<p> \u3002<\/p>\n<p> 1.epoll\u5728Kernel\u5185\u6838\u4e2d\u5b58\u50a8\u4e86\u5bf9\u5e94\u7684\u6570\u636e\u7ed3\u6784(eventpoll)\u3002\u6211\u4eec\u53ef\u4ee5<\/p>\n<p> \u4f7f\u7528epoll_create()\u8fd9\u4e2a\u7cfb\u7edf\u8c03\u7528\u53bb\u521b\u5efa\u4e00\u4e2aeventpoll\u5bf9\u8c61<\/p>\n<p> \uff0c\u5e76\u8fd4\u56deeventpoll\u7684\u5bf9\u8c61id(epfd)\uff0ceventpoll\u5bf9\u8c61\u4e3b\u8981\u5305\u62ec\u4e09\u4e2a\u90e8\u5206\uff1a\u9700\u8981\u5904\u7406\u7684\u6b63\u5728\u76d1\u542c\u7684socket_fd\u5217\u8868(\u7ea2\u9ed1\u6811\u7ed3\u6784)\u3001socket\u5c31\u7eea\u5217\u8868\u4ee5\u53ca\u7b49\u5f85\u961f\u5217(\u7ebf\u7a0b)\u3002<\/p>\n<p> 2.\u6211\u4eec\u53ef\u4ee5\u4f7f\u7528epoll_ctl()\u8fd9\u4e2a\u7cfb\u7edf\u8c03\u7528\u5bf9socket_fd\u5217\u8868\u8fdb\u884cCRUD\u64cd\u4f5c\uff0c\u56e0\u4e3a\u53ef\u80fd\u9891\u7e41\u5730\u8fdb\u884cCRUD\uff0c\u56e0\u6b64<\/p>\n<p> socket_fd\u4f7f\u7528\u7684\u662f\u7ea2\u9ed1\u6811\u7684\u7ed3\u6784<\/p>\n<p> \uff0c\u8ba9\u5176\u6548\u7387\u80fd\u66f4\u9ad8\u3002epoll_ctl()\u4f20\u9012\u7684\u53c2\u6570\u4e3b\u8981\u662fepfd(eventpoll\u5bf9\u8c61id)\u3002<\/p>\n<p> 3.epoll_wait()\u8fd9\u4e2a\u7cfb\u7edf\u8c03\u7528\u9ed8\u8ba4\u4f1a<\/p>\n<p> \u5c06\u5f53\u524d\u8fdb\u7a0b(\u7ebf\u7a0b)\u963b\u585e\uff0c\u52a0\u5165\u5230eventpoll\u5bf9\u8c61\u7684\u7b49\u5f85\u961f\u5217\u4e2d\uff0c\u76f4\u5230socket\u5c31\u7eea\u5217\u8868\u4e2d\u6709socket\uff0c\u624d\u4f1a\u5c06\u8be5\u8fdb\u7a0b(\u7ebf\u7a0b)\u91cd\u65b0\u52a0\u5165\u5de5\u4f5c\u961f\u5217<\/p>\n<p> \uff0c\u5e76\u8fd4\u56de\u5c31\u7eea\u961f\u5217\u4e2d\u7684socket\u7684\u6570\u91cf\u3002<\/p>\n<p> socket\u5305\u542b\u8bfb\u7f13\u51b2\u533a\u3001\u5199\u7f13\u51b2\u533a\u548c\u7b49\u5f85\u961f\u5217\u3002\u5f53\u4f7f\u7528epoll_ctl()\u7cfb\u7edf\u8c03\u7528\u5c06socket\u65b0\u52a0\u5165socket_fd\u5217\u8868\u65f6\uff0c\u5c31\u4f1a\u5c06eventpoll\u5bf9\u8c61\u5f15\u7528\u52a0\u5230socket\u7684\u7b49\u5f85\u961f\u5217\u4e2d\uff0c<\/p>\n<p> \u5f53\u7f51\u5361\u7684\u4e2d\u65ad\u7a0b\u5e8f\u53d1\u73b0socket\u7684\u7b49\u5f85\u961f\u5217\u4e2d\u4e0d\u662f\u4e00\u4e2a\u8fdb\u7a0b(\u7ebf\u7a0b)\uff0c\u800c\u662f\u4e00\u4e2aeventpoll\u5bf9\u8c61\u7684\u5f15\u7528\uff0c\u5c31\u5c06socket\u5f15\u7528\u8ffd\u52a0\u5230eventpoll\u5bf9\u8c61\u7684\u5c31\u7eea\u5217\u8868\u7684\u5c3e\u90e8<\/p>\n<p> \u3002\u800ceventpoll\u5bf9\u8c61\u4e2d\u7684\u7b49\u5f85\u961f\u5217\u5b58\u653e\u7684\u5c31\u662f\u8c03\u7528\u4e86epoll_wait()\u7684\u8fdb\u7a0b(\u7ebf\u7a0b)\uff0c\u7f51\u5361\u7684\u4e2d\u65ad\u7a0b\u5e8f\u6267\u884c\u4f1a\u5c06\u7b49\u5f85\u961f\u5217\u4e2d\u7684\u8fdb\u7a0b(\u7ebf\u7a0b)\u91cd\u65b0\u52a0\u5165\u5de5\u4f5c\u961f\u5217\uff0c\u8ba9\u5176\u62e5\u6709\u5360\u7528CPU\u6267\u884c\u7684\u8d44\u683c\u3002epoll_wait()\u7684\u8fd4\u56de\u503c\u662fint\u7c7b\u578b\uff0c\u8fd4\u56de\u7684\u662f\u5c31\u7eea\u7684socket\u7684\u6570\u91cf\/\u53d1\u751f\u9519\u8bef\uff0c-1\u8868\u793a\u53d1\u751f\u9519\u8bef\u3002<\/p>\n<p> epoll\u7684\u53c2\u6570\u6709\u4f20\u5165\u4e00\u4e2aepoll_event\u7684\u6570\u7ec4\u6307\u9488(\u4f5c\u4e3a\u8f93\u51fa\u53c2\u6570)\uff0c\u5728\u8c03\u7528epoll_wait()\u8fd4\u56de\u7684\u540c\u65f6\uff0cKernel\u5185\u6838\u8fd8\u4f1a\u5c06\u5c31\u7eea\u7684socket\u5217\u8868\u6dfb\u52a0\u5230epoll_event\u7c7b\u578b\u7684\u6570\u7ec4\u5f53\u4e2d\u3002<\/p>\n<p>\u5173\u4e8efd_set\u7ed3\u6784\u4f53linux\u7684\u4ecb\u7ecd\u5230\u6b64\u5c31\u7ed3\u675f\u4e86\uff0c\u4e0d\u77e5\u9053\u4f60\u4ece\u4e2d\u627e\u5230\u4f60\u9700\u8981\u7684\u4fe1\u606f\u4e86\u5417 \uff1f\u5982\u679c\u4f60\u8fd8\u60f3\u4e86\u89e3\u66f4\u591a\u8fd9\u65b9\u9762\u7684\u4fe1\u606f\uff0c\u8bb0\u5f97\u6536\u85cf\u5173\u6ce8\u672c\u7ad9\u3002<\/p>\n<p><a href=\"http:https:\/\/idc.net\/\">\u9999\u6e2f\u670d\u52a1\u5668<\/a>\u9996\u9009\u540e\u6d6a\u4e91\uff0c2H2G\u9996\u670810\u5143\u5f00\u901a\u3002<br 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[&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[34],"tags":[],"class_list":["post-148503","post","type-post","status-publish","format-standard","hentry","category-linux"],"_links":{"self":[{"href":"https:\/\/idc.net\/help\/wp-json\/wp\/v2\/posts\/148503","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/idc.net\/help\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/idc.net\/help\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/idc.net\/help\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/idc.net\/help\/wp-json\/wp\/v2\/comments?post=148503"}],"version-history":[{"count":0,"href":"https:\/\/idc.net\/help\/wp-json\/wp\/v2\/posts\/148503\/revisions"}],"wp:attachment":[{"href":"https:\/\/idc.net\/help\/wp-json\/wp\/v2\/media?parent=148503"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/idc.net\/help\/wp-json\/wp\/v2\/categories?post=148503"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/idc.net\/help\/wp-json\/wp\/v2\/tags?post=148503"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}