{"id":48359,"date":"2025-07-30T11:38:06","date_gmt":"2025-07-30T03:38:06","guid":{"rendered":"https:\/\/www.wsisp.com\/helps\/48359.html"},"modified":"2025-07-30T11:38:06","modified_gmt":"2025-07-30T03:38:06","slug":"30-%e5%a4%a9%e8%87%aa%e5%88%b6-c-%e6%9c%8d%e5%8a%a1%e5%99%a8-day3","status":"publish","type":"post","link":"https:\/\/www.wsisp.com\/helps\/48359.html","title":{"rendered":"30 \u5929\u81ea\u5236 C++ \u670d\u52a1\u5668--Day3"},"content":{"rendered":"

\u9ad8\u5e76\u53d1\u8fd8\u5f97\u7528epoll<\/h4>\n

\u5728\u4e0a\u4e00\u5929，\u6211\u4eec\u5199\u4e86\u4e00\u4e2a\u7b80\u5355\u7684echo\u670d\u52a1\u5668，\u4f46\u53ea\u80fd\u540c\u65f6\u5904\u7406\u4e00\u4e2a\u5ba2\u6237\u7aef\u7684\u8fde\u63a5\u3002\u4f46\u5728\u8fd9\u4e2a\u8fde\u63a5\u7684\u751f\u547d\u5468\u671f\u4e2d，\u7edd\u5927\u90e8\u5206\u65f6\u95f4\u90fd\u662f\u7a7a\u95f2\u7684，\u6d3b\u8dc3\u65f6\u95f4（\u53d1\u9001\u6570\u636e\u548c\u63a5\u6536\u6570\u636e\u7684\u65f6\u95f4）\u5360\u6bd4\u6781\u5c11，\u8fd9\u6837\u72ec\u5360\u4e00\u4e2a\u670d\u52a1\u5668\u662f\u4e25\u91cd\u7684\u8d44\u6e90\u6d6a\u8d39\u3002\u4e8b\u5b9e\u4e0a\u6240\u6709\u7684\u670d\u52a1\u5668\u90fd\u662f\u9ad8\u5e76\u53d1\u7684，\u53ef\u4ee5\u540c\u65f6\u4e3a\u6210\u5343\u4e0a\u4e07\u4e2a\u5ba2\u6237\u7aef\u63d0\u4f9b\u670d\u52a1，\u8fd9\u4e00\u6280\u672f\u53c8\u88ab\u79f0\u4e3aIO\u590d\u7528\u3002<\/p>\n

IO\u590d\u7528\u548c\u591a\u7ebf\u7a0b\u6709\u76f8\u4f3c\u4e4b\u5904，\u4f46\u7edd\u4e0d\u662f\u4e00\u4e2a\u6982\u5ff5\u3002IO\u590d\u7528\u662f\u9488\u5bf9IO\u63a5\u53e3，\u800c\u591a\u7ebf\u7a0b\u662f\u9488\u5bf9CPU\u3002<\/p>\n

IO\u590d\u7528\u7684\u57fa\u672c\u601d\u60f3\u662f\u4e8b\u4ef6\u9a71\u52a8，\u670d\u52a1\u5668\u540c\u65f6\u4fdd\u6301\u591a\u4e2a\u5ba2\u6237\u7aefIO\u8fde\u63a5，\u5f53\u8fd9\u4e2aIO\u4e0a\u6709\u53ef\u8bfb\u6216\u53ef\u5199\u4e8b\u4ef6\u53d1\u751f\u65f6，\u8868\u793a\u8fd9\u4e2aIO\u5bf9\u5e94\u7684\u5ba2\u6237\u7aef\u5728\u8bf7\u6c42\u670d\u52a1\u5668\u7684\u67d0\u9879\u670d\u52a1，\u6b64\u65f6\u670d\u52a1\u5668\u54cd\u5e94\u8be5\u670d\u52a1\u3002\u5728Linux\u7cfb\u7edf\u4e2d，IO\u590d\u7528\u4f7f\u7528select, poll\u548cepoll\u6765\u5b9e\u73b0\u3002epoll\u6539\u8fdb\u4e86\u524d\u4e24\u8005，\u66f4\u52a0\u9ad8\u6548\u3001\u6027\u80fd\u66f4\u597d，\u662f\u76ee\u524d\u51e0\u4e4e\u6240\u6709\u9ad8\u5e76\u53d1\u670d\u52a1\u5668\u7684\u57fa\u77f3\u3002\u8bf7\u8bfb\u8005\u52a1\u5fc5\u5148\u638c\u63e1epoll\u7684\u539f\u7406\u518d\u8fdb\u884c\u7f16\u7801\u5f00\u53d1\u3002<\/p>\n

epoll\u539f\u7406<\/h4>\n

\"\u5728\u8fd9\u91cc\u63d2\u5165\u56fe\u7247\u63cf\u8ff0\"
\n\"\u5728\u8fd9\u91cc\u63d2\u5165\u56fe\u7247\u63cf\u8ff0\"
\n\"\u5728\u8fd9\u91cc\u63d2\u5165\u56fe\u7247\u63cf\u8ff0\"
\n\"\u5728\u8fd9\u91cc\u63d2\u5165\u56fe\u7247\u63cf\u8ff0\"
\n\"\u5728\u8fd9\u91cc\u63d2\u5165\u56fe\u7247\u63cf\u8ff0\"
\n\"\u5728\u8fd9\u91cc\u63d2\u5165\u56fe\u7247\u63cf\u8ff0\"
\n\"\u5728\u8fd9\u91cc\u63d2\u5165\u56fe\u7247\u63cf\u8ff0\"
\n\u603b\u7ed3：<\/p>\n

epoll \u7684\u6838\u5fc3\u539f\u7406\u5728\u4e8e\u6539\u53d8\u4e8b\u4ef6\u901a\u77e5\u6a21\u578b：\u5b83\u901a\u8fc7\u5728\u5185\u6838\u4f7f\u7528\u7ea2\u9ed1\u6811\u9ad8\u6548\u7ba1\u7406\u6ce8\u518c\u7684\u6587\u4ef6\u63cf\u8ff0\u7b26，\u5229\u7528\u56de\u8c03\u51fd\u6570\u5728\u4e8b\u4ef6\u53d1\u751f\u65f6\u76f4\u63a5\u5c06\u5c31\u7eea\u9879\u653e\u5165\u94fe\u8868，\u5e76\u901a\u8fc7 epoll_wait \u4ec5\u8fd4\u56de\u5b9e\u9645\u5c31\u7eea\u7684\u4e8b\u4ef6\u5217\u8868，\u8f85\u4ee5 mmap \u51cf\u5c11\u6570\u636e\u62f7\u8d1d\u3002\u8fd9\u79cd\u8bbe\u8ba1\u5f7b\u5e95\u89e3\u51b3\u4e86 select\/poll \u5728\u5904\u7406\u5927\u91cf\u6587\u4ef6\u63cf\u8ff0\u7b26\u65f6\u5b58\u5728\u7684\u6027\u80fd\u74f6\u9888（\u6bcf\u6b21\u8c03\u7528\u4f20\u9012\u5b8c\u6574\u96c6\u5408\u3001\u7ebf\u6027\u626b\u63cf\u5f00\u9500\u5927），\u4f7f\u5176\u6210\u4e3a\u6784\u5efa\u73b0\u4ee3\u9ad8\u6027\u80fd Linux \u7f51\u7edc\u670d\u52a1\u5668（\u5982 Nginx, Redis, Memcached）\u4e0d\u53ef\u6216\u7f3a\u7684\u57fa\u7840\u8bbe\u65bd\u3002\u5176\u9ad8\u6548\u7684\u6839\u6e90\u5728\u4e8e\u5c06\u65f6\u95f4\u590d\u6742\u5ea6\u4ece O(N) \u964d\u4f4e\u5230\u4e86 O(1)（\u6216 O(\u5c31\u7eea\u4e8b\u4ef6\u6570)）\u3002<\/p>\n

epoll\u4f7f\u7528<\/h4>\n

epoll\u4e3b\u8981\u7531\u4e09\u4e2a\u7cfb\u7edf\u8c03\u7528\u7ec4\u6210：<\/p>\n

\/\/int epfd = epoll_create(1024); \/\/\u53c2\u6570\u8868\u793a\u76d1\u542c\u4e8b\u4ef6\u7684\u5927\u5c0f，\u5982\u8d85\u8fc7\u5185\u6838\u4f1a\u81ea\u52a8\u8c03\u6574，\u5df2\u7ecf\u88ab\u820d\u5f03，\u65e0\u5b9e\u9645\u610f\u4e49，\u4f20\u5165\u4e00\u4e2a\u5927\u4e8e0\u7684\u6570\u5373\u53ef
\nint epfd = epoll_create1(0); \/\/\u53c2\u6570\u662f\u4e00\u4e2aflag，\u4e00\u822c\u8bbe\u4e3a0，\u8be6\u7ec6\u53c2\u8003man epoll<\/p>\n

\u521b\u5efa\u4e00\u4e2aepoll\u6587\u4ef6\u63cf\u8ff0\u7b26\u5e76\u8fd4\u56de，\u5931\u8d25\u5219\u8fd4\u56de-1\u3002<\/p>\n

epoll\u76d1\u542c\u4e8b\u4ef6\u7684\u63cf\u8ff0\u7b26\u4f1a\u653e\u5728\u4e00\u9897\u7ea2\u9ed1\u6811\u4e0a，\u6211\u4eec\u5c06\u8981\u76d1\u542c\u7684IO\u53e3\u653e\u5165epoll\u7ea2\u9ed1\u6811\u4e2d，\u5c31\u53ef\u4ee5\u76d1\u542c\u8be5IO\u4e0a\u7684\u4e8b\u4ef6\u3002<\/p>\n

epoll_ctl(epfd, EPOLL_CTL_ADD, sockfd, &ev); \/\/\u6dfb\u52a0\u4e8b\u4ef6\u5230epoll
\nepoll_ctl(epfd, EPOLL_CTL_MOD, sockfd, &ev); \/\/\u4fee\u6539epoll\u7ea2\u9ed1\u6811\u4e0a\u7684\u4e8b\u4ef6
\nepoll_ctl(epfd, EPOLL_CTL_DEL, sockfd, NULL); \/\/\u5220\u9664\u4e8b\u4ef6<\/p>\n

\u5176\u4e2dsockfd\u8868\u793a\u6211\u4eec\u8981\u6dfb\u52a0\u7684IO\u6587\u4ef6\u63cf\u8ff0\u7b26，ev\u662f\u4e00\u4e2aepoll_event\u7ed3\u6784\u4f53，\u5176\u4e2d\u7684events\u8868\u793a\u4e8b\u4ef6，\u5982EPOLLIN\u7b49，data\u662f\u4e00\u4e2a\u7528\u6237\u6570\u636eunion:<\/p>\n

typedef union epoll_data {
\n void *ptr;
\n int fd;
\n uint32_t u32;
\n uint64_t u64;
\n} epoll_data_t;
\nstruct epoll_event {
\n uint32_t events;\/* Epoll events *\/
\n epoll_data_t data;\/* User data variable *\/
\n} __EPOLL_PACKED;<\/p>\n

epoll\u9ed8\u8ba4\u91c7\u7528LT\u89e6\u53d1\u6a21\u5f0f，\u5373\u6c34\u5e73\u89e6\u53d1，\u53ea\u8981fd\u4e0a\u6709\u4e8b\u4ef6，\u5c31\u4f1a\u4e00\u76f4\u901a\u77e5\u5185\u6838\u3002\u8fd9\u6837\u53ef\u4ee5\u4fdd\u8bc1\u6240\u6709\u4e8b\u4ef6\u90fd\u5f97\u5230\u5904\u7406\u3001\u4e0d\u5bb9\u6613\u4e22\u5931，\u4f46\u53ef\u80fd\u53d1\u751f\u7684\u5927\u91cf\u91cd\u590d\u901a\u77e5\u4e5f\u4f1a\u5f71\u54cdepoll\u7684\u6027\u80fd\u3002\u5982\u4f7f\u7528ET\u6a21\u5f0f，\u5373\u8fb9\u7f18\u89e6\u6cd5，fd\u4ece\u65e0\u4e8b\u4ef6\u5230\u6709\u4e8b\u4ef6\u7684\u53d8\u5316\u4f1a\u901a\u77e5\u5185\u6838\u4e00\u6b21，\u4e4b\u540e\u5c31\u4e0d\u4f1a\u518d\u6b21\u901a\u77e5\u5185\u6838\u3002\u8fd9\u79cd\u65b9\u5f0f\u5341\u5206\u9ad8\u6548，\u53ef\u4ee5\u5927\u5927\u63d0\u9ad8\u652f\u6301\u7684\u5e76\u53d1\u5ea6，\u4f46\u7a0b\u5e8f\u903b\u8f91\u5fc5\u987b\u4e00\u6b21\u6027\u5f88\u597d\u5730\u5904\u7406\u8be5fd\u4e0a\u7684\u4e8b\u4ef6，\u7f16\u7a0b\u6bd4LT\u66f4\u7e41\u7410\u3002\u6ce8\u610fET\u6a21\u5f0f\u5fc5\u987b\u642d\u914d\u975e\u963b\u585e\u5f0fsocket\u4f7f\u7528\u3002<\/p>\n

\u975e\u963b\u585e\u5f0fsocket\u548c\u963b\u585e\u5f0f<\/h4>\n

\"\u5728\u8fd9\u91cc\u63d2\u5165\u56fe\u7247\u63cf\u8ff0\"
\n\"\u5728\u8fd9\u91cc\u63d2\u5165\u56fe\u7247\u63cf\u8ff0\"
\n\u793a\u4f8b\u4ee3\u7801：<\/p>\n

\/\/ \u963b\u585e\u5f0f\u670d\u52a1\u7aef\u4f2a\u4ee3\u7801
\nint client = accept(server_sock); \/\/ \u963b\u585e\u76f4\u5230\u65b0\u8fde\u63a5
\nrecv(client, buf); \/\/ \u963b\u585e\u76f4\u5230\u6536\u5230\u6570\u636e
\nsend(client, response); \/\/ \u963b\u585e\u76f4\u5230\u53d1\u9001\u5b8c\u6210<\/p>\n

\"\u5728\u8fd9\u91cc\u63d2\u5165\u56fe\u7247\u63cf\u8ff0\"
\n\"\u5728\u8fd9\u91cc\u63d2\u5165\u56fe\u7247\u63cf\u8ff0\"<\/p>\n

\u8bbe\u7f6e\u65b9\u6cd5：<\/p>\n

\/\/ \u8bbe\u7f6e\u975e\u963b\u585e\u6a21\u5f0f
\nint flags = fcntl(sockfd, F_GETFL, 0);
\nfcntl(sockfd, F_SETFL, flags | O_NONBLOCK);<\/p>\n

\u5178\u578b\u5de5\u4f5c\u6d41：<\/p>\n

epoll_ctl(epfd, EPOLL_CTL_ADD, sockfd, EPOLLIN); \/\/ \u6ce8\u518c\u8bfb\u4e8b\u4ef6<\/p>\n

while (1) {
\n int n = epoll_wait(epfd, events, MAX_EVENTS, -1);
\n for (\u6bcf\u4e2a\u5c31\u7eea\u4e8b\u4ef6) {
\n if (\u4e8b\u4ef6 & EPOLLIN) {
\n while ((len = recv(fd, buf)) > 0) {
\n \/\/ \u5904\u7406\u6570\u636e
\n }
\n if (len == -1 && errno == EAGAIN) break; \/\/ \u6570\u636e\u8bfb\u5b8c
\n }
\n if (\u4e8b\u4ef6 & EPOLLOUT) {
\n \/\/ \u5904\u7406\u53ef\u5199\u4e8b\u4ef6
\n }
\n }
\n}<\/p>\n

\u5173\u952e\u5dee\u5f02\u5bf9\u6bd4：
\n\"\u5728\u8fd9\u91cc\u63d2\u5165\u56fe\u7247\u63cf\u8ff0\"
\n\u8fb9\u7f18\u89e6\u53d1 (ET) \u4e0e \u6c34\u5e73\u89e6\u53d1 (LT)
\n\u5f53\u4f7f\u7528 \u975e\u963b\u585e Socket + epoll \u65f6，\u89e6\u53d1\u6a21\u5f0f\u7684\u9009\u62e9\u81f3\u5173\u91cd\u8981：
\n\"\u5728\u8fd9\u91cc\u63d2\u5165\u56fe\u7247\u63cf\u8ff0\"
\nET \u6a21\u5f0f\u6700\u4f73\u5b9e\u8df5：<\/p>\n

\/\/ \u8fb9\u7f18\u89e6\u53d1\u5fc5\u987b\u5faa\u73af\u8bfb\u53d6\u76f4\u5230 EAGAIN
\nwhile (true) {
\n ssize_t count = read(fd, buf, sizeof(buf));
\n if (count == -1) {
\n if (errno == EAGAIN) break; \/\/ \u6570\u636e\u5df2\u8bfb\u5b8c
\n \/\/ \u5904\u7406\u771f\u5b9e\u9519\u8bef
\n }
\n if (count == 0) { \/* \u8fde\u63a5\u5173\u95ed *\/ }
\n \/\/ \u5904\u7406\u6570\u636e
\n}<\/p>\n

\"\u5728\u8fd9\u91cc\u63d2\u5165\u56fe\u7247\u63cf\u8ff0\"
\n\"\u5728\u8fd9\u91cc\u63d2\u5165\u56fe\u7247\u63cf\u8ff0\"<\/p>\n","protected":false},"excerpt":{"rendered":"

\u6587\u7ae0\u6d4f\u89c8\u9605\u8bfb1.2k\u6b21\uff0c\u70b9\u8d5e16\u6b21\uff0c\u6536\u85cf5\u6b21\u3002\u7684\u6838\u5fc3\u539f\u7406\u5728\u4e8e\u6539\u53d8\u4e8b\u4ef6\u901a\u77e5\u6a21\u578b\uff1a\u5b83\u901a\u8fc7\u5728\u5185\u6838\u4f7f\u7528\u7ea2\u9ed1\u6811\u9ad8\u6548\u7ba1\u7406\u6ce8\u518c\u7684\u6587\u4ef6\u63cf\u8ff0\u7b26\uff0c\u5229\u7528\u56de\u8c03\u51fd\u6570\u5728\u4e8b\u4ef6\u53d1\u751f\u65f6\u76f4\u63a5\u5c06\u5c31\u7eea\u9879\u653e\u5165\u94fe\u8868\uff0c\u5e76\u901a\u8fc7 epoll_wait \u4ec5\u8fd4\u56de\u5b9e\u9645\u5c31\u7eea\u7684\u4e8b\u4ef6\u5217\u8868\uff0c\u8f85\u4ee5 mmap \u51cf\u5c11\u6570\u636e\u62f7\u8d1d\u3002IO\u590d\u7528\u7684\u57fa\u672c\u601d\u60f3\u662f\u4e8b\u4ef6\u9a71\u52a8\uff0c\u670d\u52a1\u5668\u540c\u65f6\u4fdd\u6301\u591a\u4e2a\u5ba2\u6237\u7aefIO\u8fde\u63a5\uff0c\u5f53\u8fd9\u4e2aIO\u4e0a\u6709\u53ef\u8bfb\u6216\u53ef\u5199\u4e8b\u4ef6\u53d1\u751f\u65f6\uff0c\u8868\u793a\u8fd9\u4e2aIO\u5bf9\u5e94\u7684\u5ba2\u6237\u7aef\u5728\u8bf7\u6c42\u670d\u52a1\u5668\u7684\u67d0\u9879\u670d\u52a1\uff0c\u6b64\u65f6\u670d\u52a1\u5668\u54cd\u5e94\u8be5\u670d\u52a1\u3002epoll\u76d1\u542c\u4e8b\u4ef6\u7684\u63cf\u8ff0\u7b26\u4f1a\u653e\u5728\u4e00\u9897\u7ea2\u9ed1\u6811\u4e0a\uff0c\u6211\u4eec\u5c06\u8981\u76d1\u542c\u7684IO\u53e3\u653e\u5165epoll\u7ea2\u9ed1\u6811\u4e2d\uff0c\u5c31\u53ef\u4ee5\u76d1\u542c\u8be5IO\u4e0a\u7684\u4e8b\u4ef6\u3002<\/p>\n","protected":false},"author":2,"featured_media":48344,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[4675,55,43],"topic":[],"class_list":["post-48359","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-server","tag-30cppserver","tag-c","tag-43"],"yoast_head":"\n30 \u5929\u81ea\u5236 C++ \u670d\u52a1\u5668-Day3 - 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