{"id":24360,"date":"2025-04-19T09:56:30","date_gmt":"2025-04-19T01:56:30","guid":{"rendered":"https:\/\/www.wsisp.com\/helps\/24360.html"},"modified":"2025-04-19T09:56:30","modified_gmt":"2025-04-19T01:56:30","slug":"%e3%80%90%e7%bd%91%e7%bb%9c%e7%bc%96%e7%a8%8b%e3%80%91%e6%9c%8d%e5%8a%a1%e5%99%a8%e6%a8%a1%e5%9e%8b%ef%bc%88%e4%ba%8c%ef%bc%89%ef%bc%9a%e5%b9%b6%e5%8f%91%e6%9c%8d%e5%8a%a1%e5%99%a8%e6%a8%a1%e5%9e%8b","status":"publish","type":"post","link":"https:\/\/www.wsisp.com\/helps\/24360.html","title":{"rendered":"\u3010\u7f51\u7edc\u7f16\u7a0b\u3011\u670d\u52a1\u5668\u6a21\u578b\uff08\u4e8c\uff09\uff1a\u5e76\u53d1\u670d\u52a1\u5668\u6a21\u578b\uff08\u591a\u7ebf\u7a0b\uff09\u548c I\/O \u590d\u7528\u670d\u52a1\u5668\uff08select \/ epoll\uff09"},"content":{"rendered":"

\u4e00\u3001\u591a\u7ebf\u7a0b\u5e76\u53d1\u670d\u52a1\u5668<\/h4>\n

\u5728 \u9ad8\u5e76\u53d1\u7684 TCP \u670d\u52a1\u5668 \u4e2d，\u5355\u7ebf\u7a0b\u6216 fork() \u591a\u8fdb\u7a0b \u65b9\u5f0f\u4f1a\u5bfc\u81f4 \u8d44\u6e90\u6d6a\u8d39\u548c\u6027\u80fd\u74f6\u9888\u3002\u56e0\u6b64，\u6211\u4eec\u53ef\u4ee5\u4f7f\u7528 \u591a\u7ebf\u7a0b \u6765\u9ad8\u6548\u5904\u7406\u591a\u4e2a\u5ba2\u6237\u7aef\u7684\u8fde\u63a5\u3002<\/p>\n

\u627f\u63a5\u4e0a\u6587\u4e2d\u7684\u591a\u8fdb\u7a0b\u5e76\u53d1\u670d\u52a1\u5668，\u4ee3\u7801\u4f18\u5316\u76ee\u6807：<\/p>\n

1.\u4f7f\u7528 pthread \u5b9e\u73b0\u591a\u7ebf\u7a0b\u670d\u52a1\u5668
\n2.\u6bcf\u4e2a\u5ba2\u6237\u7aef\u8fde\u63a5\u540e，\u670d\u52a1\u5668\u521b\u5efa\u4e00\u4e2a\u72ec\u7acb\u7ebf\u7a0b\u8fdb\u884c\u5904\u7406
\n3.\u56de\u663e（Echo）\u5ba2\u6237\u7aef\u53d1\u9001\u7684\u6d88\u606f
\n4.\u652f\u6301\u591a\u4e2a\u5ba2\u6237\u7aef\u540c\u65f6\u8fde\u63a5
\n5.\u4e3b\u7ebf\u7a0b\u8d1f\u8d23\u76d1\u542c\u8fde\u63a5，\u5b50\u7ebf\u7a0b\u8d1f\u8d23\u5904\u7406\u5ba2\u6237\u7aef\u8bf7\u6c42<\/p>\n

\u5b8c\u6574\u4ee3\u7801：<\/p>\n

#<\/span>include<\/span> <stdio.h><\/span> \/\/ \u6807\u51c6\u8f93\u5165\u8f93\u51fa<\/span><\/span>
\n#<\/span>include<\/span> <stdlib.h><\/span> \/\/ exit()\u3001malloc()\u3001free()<\/span><\/span>
\n#<\/span>include<\/span> <string.h><\/span> \/\/ \u5b57\u7b26\u4e32\u64cd\u4f5c<\/span><\/span>
\n#<\/span>include<\/span> <unistd.h><\/span> \/\/ read(), write(), close()<\/span><\/span>
\n#<\/span>include<\/span> <arpa\/inet.h><\/span> \/\/ sockaddr_in, inet_addr()<\/span><\/span>
\n#<\/span>include<\/span> <sys\/socket.h><\/span> \/\/ \u5957\u63a5\u5b57 API<\/span><\/span>
\n#<\/span>include<\/span> <netinet\/in.h><\/span> \/\/ sockaddr_in \u7ed3\u6784\u4f53<\/span><\/span>
\n#<\/span>include<\/span> <pthread.h><\/span> \/\/ \u7ebf\u7a0b API<\/span><\/span><\/p>\n

#<\/span>define<\/span> PORT<\/span> 8080<\/span> <\/span>\/\/ \u670d\u52a1\u5668\u76d1\u542c\u7aef\u53e3<\/span><\/span>
\n#<\/span>define<\/span> BUFFER_SIZE<\/span> 1024<\/span> <\/span>\/\/ \u7f13\u51b2\u533a\u5927\u5c0f<\/span><\/span>
\n#<\/span>define<\/span> MAX_CLIENTS<\/span> 100<\/span> <\/span>\/\/ \u6700\u5927\u5ba2\u6237\u7aef\u8fde\u63a5\u6570<\/span><\/span><\/p>\n

\/\/ **\u7ebf\u7a0b\u5904\u7406\u5ba2\u6237\u7aef\u8bf7\u6c42**<\/span>
\nvoid<\/span> *<\/span>handle_client<\/span>(<\/span>void<\/span> *<\/span>arg)<\/span> {<\/span>
\n int<\/span> client_fd =<\/span> *<\/span>(<\/span>(<\/span>int<\/span> *<\/span>)<\/span>arg)<\/span>;<\/span>
\n free<\/span>(<\/span>arg)<\/span>;<\/span> \/\/ \u91ca\u653e\u52a8\u6001\u5206\u914d\u7684\u5185\u5b58<\/span>
\n char<\/span> buffer[<\/span>BUFFER_SIZE]<\/span>;<\/span>
\n int<\/span> bytes_read;<\/span><\/p>\n

printf<\/span>(<\/span>"\u2705 \u5ba2\u6237\u7aef\u7ebf\u7a0b\u542f\u52a8，\u5904\u7406\u5ba2\u6237\u7aef %d\\\\n"<\/span>,<\/span> client_fd)<\/span>;<\/span><\/p>\n

while<\/span> (<\/span>1<\/span>)<\/span> {<\/span>
\n memset<\/span>(<\/span>buffer,<\/span> 0<\/span>,<\/span> BUFFER_SIZE)<\/span>;<\/span> \/\/ \u6e05\u7a7a\u7f13\u51b2\u533a<\/span>
\n bytes_read =<\/span> read<\/span>(<\/span>client_fd,<\/span> buffer,<\/span> BUFFER_SIZE)<\/span>;<\/span>
\n if<\/span> (<\/span>bytes_read <=<\/span> 0<\/span>)<\/span> {<\/span>
\n printf<\/span>(<\/span>"\u274c \u5ba2\u6237\u7aef %d \u65ad\u5f00\u8fde\u63a5\\\\n"<\/span>,<\/span> client_fd)<\/span>;<\/span>
\n break<\/span>;<\/span> \/\/ \u9000\u51fa\u5faa\u73af，\u5173\u95ed\u8fde\u63a5<\/span>
\n }<\/span><\/p>\n

printf<\/span>(<\/span>"📩 \u6536\u5230\u5ba2\u6237\u7aef %d \u6d88\u606f: %s\\\\n"<\/span>,<\/span> client_fd,<\/span> buffer)<\/span>;<\/span><\/p>\n

\/\/ **\u53d1\u9001\u56de\u663e\u6d88\u606f**<\/span>
\n write<\/span>(<\/span>client_fd,<\/span> buffer,<\/span> bytes_read)<\/span>;<\/span>
\n }<\/span><\/p>\n

\/\/ **\u5173\u95ed\u5ba2\u6237\u7aef\u8fde\u63a5**<\/span>
\n close<\/span>(<\/span>client_fd)<\/span>;<\/span>
\n printf<\/span>(<\/span>"\u5173\u95ed\u5ba2\u6237\u7aef %d \u8fde\u63a5\\\\n"<\/span>,<\/span> client_fd)<\/span>;<\/span>
\n return<\/span> NULL<\/span>;<\/span>
\n}<\/span><\/p>\n

int<\/span> main<\/span>(<\/span>)<\/span> {<\/span>
\n int<\/span> server_fd,<\/span> client_fd;<\/span>
\n struct<\/span> sockaddr_in<\/span> server_addr,<\/span> client_addr;<\/span>
\n socklen_t<\/span> addr_len =<\/span> sizeof<\/span>(<\/span>client_addr)<\/span>;<\/span>
\n pthread_t<\/span> thread_id;<\/span><\/p>\n

\/\/ 1\ufe0f\u20e3 \u521b\u5efa\u670d\u52a1\u5668\u5957\u63a5\u5b57<\/span>
\n server_fd =<\/span> socket<\/span>(<\/span>AF_INET,<\/span> SOCK_STREAM,<\/span> 0<\/span>)<\/span>;<\/span>
\n if<\/span> (<\/span>server_fd ==<\/span> –<\/span>1<\/span>)<\/span> {<\/span>
\n perror<\/span>(<\/span>"\u274c Socket \u521b\u5efa\u5931\u8d25"<\/span>)<\/span>;<\/span>
\n exit<\/span>(<\/span>EXIT_FAILURE)<\/span>;<\/span>
\n }<\/span><\/p>\n

\/\/ 2\ufe0f\u20e3 \u7ed1\u5b9a\u670d\u52a1\u5668\u5730\u5740\u548c\u7aef\u53e3<\/span>
\n server_addr.<\/span>sin_family =<\/span> AF_INET;<\/span>
\n server_addr.<\/span>sin_addr.<\/span>s_addr =<\/span> INADDR_ANY;<\/span>
\n server_addr.<\/span>sin_port =<\/span> htons<\/span>(<\/span>PORT)<\/span>;<\/span><\/p>\n

if<\/span> (<\/span>bind<\/span>(<\/span>server_fd,<\/span> (<\/span>struct<\/span> sockaddr<\/span> *<\/span>)<\/span>&<\/span>server_addr,<\/span> sizeof<\/span>(<\/span>server_addr)<\/span>)<\/span> <<\/span> 0<\/span>)<\/span> {<\/span>
\n perror<\/span>(<\/span>"\u274c \u7ed1\u5b9a\u5931\u8d25"<\/span>)<\/span>;<\/span>
\n close<\/span>(<\/span>server_fd)<\/span>;<\/span>
\n exit<\/span>(<\/span>EXIT_FAILURE)<\/span>;<\/span>
\n }<\/span><\/p>\n

\/\/ 3\ufe0f\u20e3 \u76d1\u542c\u5ba2\u6237\u7aef\u8fde\u63a5<\/span>
\n if<\/span> (<\/span>listen<\/span>(<\/span>server_fd,<\/span> MAX_CLIENTS)<\/span> <<\/span> 0<\/span>)<\/span> {<\/span>
\n perror<\/span>(<\/span>"\u274c \u76d1\u542c\u5931\u8d25"<\/span>)<\/span>;<\/span>
\n close<\/span>(<\/span>server_fd)<\/span>;<\/span>
\n exit<\/span>(<\/span>EXIT_FAILURE)<\/span>;<\/span>
\n }<\/span><\/p>\n

printf<\/span>(<\/span>"\u26a1 \u591a\u7ebf\u7a0b TCP \u670d\u52a1\u5668\u5df2\u542f\u52a8，\u76d1\u542c\u7aef\u53e3 %d…\\\\n"<\/span>,<\/span> PORT)<\/span>;<\/span><\/p>\n

while<\/span> (<\/span>1<\/span>)<\/span> {<\/span>
\n printf<\/span>(<\/span>"\\\\n\u7b49\u5f85\u5ba2\u6237\u7aef\u8fde\u63a5…\\\\n"<\/span>)<\/span>;<\/span><\/p>\n

\/\/ 4\ufe0f\u20e3 \u63a5\u53d7\u5ba2\u6237\u7aef\u8fde\u63a5<\/span>
\n client_fd =<\/span> accept<\/span>(<\/span>server_fd,<\/span> (<\/span>struct<\/span> sockaddr<\/span> *<\/span>)<\/span>&<\/span>client_addr,<\/span> &<\/span>addr_len)<\/span>;<\/span>
\n if<\/span> (<\/span>client_fd <<\/span> 0<\/span>)<\/span> {<\/span>
\n perror<\/span>(<\/span>"\u274c \u63a5\u53d7\u5ba2\u6237\u7aef\u8fde\u63a5\u5931\u8d25"<\/span>)<\/span>;<\/span>
\n continue<\/span>;<\/span> \/\/ \u7ee7\u7eed\u7b49\u5f85\u4e0b\u4e00\u4e2a\u5ba2\u6237\u7aef<\/span>
\n }<\/span><\/p>\n

printf<\/span>(<\/span>"\u2705 \u5ba2\u6237\u7aef\u8fde\u63a5\u6210\u529f！IP: %s, \u7aef\u53e3: %d\\\\n"<\/span>,<\/span>
\n inet_ntoa<\/span>(<\/span>client_addr.<\/span>sin_addr)<\/span>,<\/span> ntohs<\/span>(<\/span>client_addr.<\/span>sin_port)<\/span>)<\/span>;<\/span><\/p>\n

\/\/ 5\ufe0f\u20e3 \u521b\u5efa\u7ebf\u7a0b\u5904\u7406\u5ba2\u6237\u7aef<\/span>
\n int<\/span> *<\/span>new_sock =<\/span> malloc<\/span>(<\/span>sizeof<\/span>(<\/span>int<\/span>)<\/span>)<\/span>;<\/span> \/\/ \u52a8\u6001\u5206\u914d\u5185\u5b58，\u907f\u514d\u7ebf\u7a0b\u51b2\u7a81<\/span>
\n *<\/span>new_sock =<\/span> client_fd;<\/span>
\n if<\/span> (<\/span>pthread_create<\/span>(<\/span>&<\/span>thread_id,<\/span> NULL<\/span>,<\/span> handle_client,<\/span> (<\/span>void<\/span> *<\/span>)<\/span>new_sock)<\/span> !=<\/span> 0<\/span>)<\/span> {<\/span>
\n perror<\/span>(<\/span>"\u274c \u7ebf\u7a0b\u521b\u5efa\u5931\u8d25"<\/span>)<\/span>;<\/span>
\n close<\/span>(<\/span>client_fd)<\/span>;<\/span>
\n free<\/span>(<\/span>new_sock)<\/span>;<\/span>
\n }<\/span> else<\/span> {<\/span>
\n pthread_detach<\/span>(<\/span>thread_id)<\/span>;<\/span> \/\/ \u8ba9\u7ebf\u7a0b\u81ea\u52a8\u56de\u6536<\/span>
\n }<\/span>
\n }<\/span><\/p>\n

\/\/ 6\ufe0f\u20e3 \u5173\u95ed\u670d\u52a1\u5668（\u901a\u5e38\u4e0d\u4f1a\u6267\u884c\u5230\u8fd9\u91cc）<\/span>
\n close<\/span>(<\/span>server_fd)<\/span>;<\/span>
\n return<\/span> 0<\/span>;<\/span>
\n}<\/span><\/p>\n

\u2705 \u4ee3\u7801\u8fd0\u884c\u6b65\u9aa4<\/h6>\n
  • \u7f16\u8bd1：（\u5047\u8bbe\u6587\u4ef6\u540d\u4e3a tcp_server_threads.c）<\/li>\n

    gcc tcp_server_threads.c -o<\/span> tcp_server_threads -pthread<\/span><\/p>\n

  • \u8fd0\u884c\u670d\u52a1\u5668<\/li>\n

    .\/tcp_server_threads<\/p>\n

    \u8f93\u51fa\u793a\u4f8b：<\/p>\n

    \u591a\u7ebf\u7a0b TCP \u670d\u52a1\u5668\u5df2\u542f\u52a8，\u76d1\u542c\u7aef\u53e3 8080<\/span>..<\/span>.
    \n\u7b49\u5f85\u5ba2\u6237\u7aef\u8fde\u63a5..<\/span>.<\/p>\n

    \u2705 \u8fde\u63a5\u6d4b\u8bd5<\/h6>\n

    \u65b9\u5f0f 1：\u4f7f\u7528 telnet<\/p>\n

    telnet 127.0<\/span>.0.1 8080<\/span>
    \n# \u8f93\u5165\u6d88\u606f\u540e\u6309 Enter，\u670d\u52a1\u5668\u4f1a\u8fd4\u56de\u76f8\u540c\u7684\u6d88\u606f\u3002<\/span><\/p>\n

    \u65b9\u5f0f 2：\u4f7f\u7528 nc（Netcat）<\/p>\n

    🔹 \u542f\u52a8\u591a\u4e2a\u5ba2\u6237\u7aef<\/p>\n

    nc<\/span> 127.0<\/span>.0.1 8080<\/span><\/p>\n

    \u8f93\u5165\u5185\u5bb9，\u670d\u52a1\u5668\u4f1a\u56de\u663e，\u5982：<\/p>\n

    Hello Server
    \nHello Server # \u670d\u52a1\u5668\u8fd4\u56de\u76f8\u540c\u5185\u5bb9<\/span><\/p>\n

    \u8be6\u7ec6\u6b65\u9aa4\u6d41\u7a0b：
    \n1. \u521b\u5efa TCP \u5957\u63a5\u5b57 — socket() — \u521b\u5efa\u670d\u52a1\u5668 socket
    \n2. \u7ed1\u5b9a IP \u548c\u7aef\u53e3 — bind() — \u76d1\u542c 8080 \u7aef\u53e3
    \n3. \u76d1\u542c\u8fde\u63a5 — listen() — \u5141\u8bb8\u6700\u591a MAX_CLIENTS \u4e2a\u5ba2\u6237\u7aef\u6392\u961f
    \n4. \u7b49\u5f85\u5ba2\u6237\u7aef\u8fde\u63a5 — accept() — \u63a5\u53d7\u4e00\u4e2a\u5ba2\u6237\u7aef\u8fde\u63a5
    \n5. \u521b\u5efa\u7ebf\u7a0b — pthread_create() — \u8ba9\u6bcf\u4e2a\u5ba2\u6237\u7aef\u7531\u4e00\u4e2a\u7ebf\u7a0b\u5904\u7406
    \n6. \u5904\u7406\u5ba2\u6237\u7aef\u8bf7\u6c42 — read() — \u8bfb\u53d6\u5ba2\u6237\u7aef\u53d1\u9001\u7684\u6570\u636e
    \n7. \u53d1\u9001\u56de\u663e\u6570\u636e — write() — \u628a\u6570\u636e\u53d1\u56de\u5ba2\u6237\u7aef
    \n8. \u5173\u95ed\u8fde\u63a5 — close() — \u91ca\u653e\u8d44\u6e90<\/p>\n

    \u8be5\u4ee3\u7801\u662f\u4e00\u4e2a\u57fa\u672c\u7684 TCP \u591a\u7ebf\u7a0b\u5e76\u53d1\u670d\u52a1\u5668，\u9002\u7528\u4e8e \u4e2d\u7b49\u5e76\u53d1\u8d1f\u8f7d， \u76f8\u6bd4 fork()，\u4f7f\u7528 pthread \u53ef\u4ee5\u51cf\u5c11\u8d44\u6e90\u6d88\u8017，\u63d0\u5347\u5e76\u53d1\u6027\u80fd\u3002<\/p>\n

    \u540e\u7eed\u4ee3\u7801\u53ef\u4f18\u5316<\/p>\n

    1.\u4f7f\u7528\u7ebf\u7a0b\u6c60
    \n\u7ebf\u7a0b\u6c60\u53ef\u4ee5\u590d\u7528\u7ebf\u7a0b，\u907f\u514d pthread_create() \u8fc7\u591a\u6d88\u8017\u8d44\u6e90\u3002
    \n\u53c2\u8003 pthread pool \u673a\u5236，\u9884\u521b\u5efa\u56fa\u5b9a\u6570\u91cf\u7ebf\u7a0b，\u907f\u514d\u9891\u7e41\u521b\u5efa\u9500\u6bc1\u3002
    \n2.\u4f7f\u7528 epoll \u7ed3\u5408\u7ebf\u7a0b\u6c60
    \n\u7ed3\u5408 epoll \u76d1\u542c accept()，\u51cf\u5c11 CPU \u8d1f\u62c5\u3002
    \n3.\u65e5\u5fd7\u7ba1\u7406
    \n\u670d\u52a1\u5668\u53ef\u4ee5\u4f7f\u7528 syslog() \u6216\u6587\u4ef6\u5199\u5165\u65b9\u5f0f\u8bb0\u5f55 \u5ba2\u6237\u7aef\u8fde\u63a5\u4fe1\u606f\u3002
    \n4.\u8d85\u65f6\u5904\u7406
    \n\u670d\u52a1\u5668\u53ef\u4ee5\u8bbe\u7f6e setsockopt() \u9650\u5236\u5ba2\u6237\u7aef\u8fde\u63a5\u65f6\u95f4：<\/p>\n

    struct<\/span> timeval<\/span> timeout =<\/span> {<\/span>5<\/span>,<\/span> 0<\/span>}<\/span>;<\/span> \/\/ 5 \u79d2\u8d85\u65f6<\/span>
    \nsetsockopt<\/span>(<\/span>client_fd,<\/span> SOL_SOCKET,<\/span> SO_RCVTIMEO,<\/span> &<\/span>timeout,<\/span> sizeof<\/span>(<\/span>timeout)<\/span>)<\/span>;<\/span><\/p>\n

    \u4e8c\u3001I\/O \u590d\u7528\u670d\u52a1\u5668（select \/ poll）<\/h4>\n

    \u5728 UNIX\/Linux \u4e0b\u4e3b\u8981\u67094\u79cd I\/O \u6a21\u578b：<\/p>\n

    \u963b\u585eI\/O： \u6700\u5e38\u7528\u3001\u6700\u7b80\u5355\u3001\u6548\u7387\u6700\u4f4e
    \n\u975e\u963b\u585eI\/O：\u53ef\u9632\u6b62\u8fdb\u7a0b\u963b\u585e\u5728I\/O\u64cd\u4f5c\u4e0a，\u9700\u8981\u8f6e\u8be2
    \nI\/O \u591a\u8def\u590d\u7528：\u5141\u8bb8\u540c\u65f6\u5bf9\u591a\u4e2aI\/O\u8fdb\u884c\u63a7\u5236
    \n\u4fe1\u53f7\u9a71\u52a8I\/O: \u4e00\u79cd\u5f02\u6b65\u901a\u4fe1\u6a21\u578b<\/p>\n

    \u963b\u585eI\/O \u6a21\u5f0f\u662f\u6700\u666e\u904d\u4f7f\u7528\u7684 I\/O \u6a21\u5f0f，\u5927\u90e8\u5206\u7a0b\u5e8f\u4f7f\u7528\u7684\u90fd\u662f\u963b\u585e\u6a21\u5f0f\u7684 I\/O ；\u7f3a\u7701\u60c5\u51b5\u4e0b，\u5957\u63a5\u5b57\u5efa\u7acb\u540e\u6240\u5904\u4e8e\u7684\u6a21\u5f0f\u5c31\u662f\u963b\u585e I\/O \u6a21\u5f0f\u3002\u5f88\u591a\u8bfb\u5199\u51fd\u6570\u5728\u8c03\u7528\u8fc7\u7a0b\u4e2d\u4f1a\u53d1\u751f\u963b\u585e，\u4f8b\u5982：\u8bfb\u64cd\u4f5c\u4e2d\u7684 read\u3001recv\u3001recvfrom，\u5199\u64cd\u4f5c\u4e2d\u7684 write\u3001send，\u5176\u4ed6\u64cd\u4f5c：accept\u3001connect\u3002<\/p>\n

    \u8bfb\u963b\u585e：\u4ee5 read \u51fd\u6570\u4e3a\u4f8b： \u8fdb\u7a0b\u8c03\u7528 read \u51fd\u6570\u4ece\u5957\u63a5\u5b57\u4e0a\u8bfb\u53d6\u6570\u636e，\u5f53\u5957\u63a5\u5b57\u7684\u63a5\u6536\u7f13\u51b2\u533a\u4e2d\u8fd8\u6ca1\u6709\u6570\u636e\u53ef\u8bfb，\u51fd\u6570 read \u5c06\u53d1\u751f\u963b\u585e\u3002\u5b83\u4f1a\u4e00\u76f4\u963b\u585e\u4e0b\u53bb，\u7b49\u5f85\u5957\u63a5\u5b57\u7684\u63a5\u6536\u7f13\u51b2\u533a\u4e2d\u6709\u6570\u636e\u53ef\u8bfb\u3002\u7ecf\u8fc7\u4e00\u6bb5\u65f6\u95f4\u540e，\u7f13\u51b2\u533a\u5185\u63a5\u6536\u5230\u6570\u636e，\u4e8e\u662f\u5185\u6838\u4fbf\u53bb\u5524\u9192\u8be5\u8fdb\u7a0b，\u901a\u8fc7 read \u8bbf\u95ee\u8fd9\u4e9b\u6570\u636e\u3002\u4f46\u5982\u679c\u5728\u8fdb\u7a0b\u963b\u585e\u8fc7\u7a0b\u4e2d，\u5bf9\u65b9\u53d1\u751f\u6545\u969c，\u90a3\u8fd9\u4e2a\u8fdb\u7a0b\u5c06\u6c38\u8fdc\u963b\u585e\u4e0b\u53bb\u3002<\/p>\n

    \u5199\u963b\u585e： \u5728\u5199\u64cd\u4f5c\u65f6\u53d1\u751f\u963b\u585e\u7684\u60c5\u51b5\u8981\u6bd4\u8bfb\u64cd\u4f5c\u5c11\u3002\u4e3b\u8981\u53d1\u751f\u5728\u8981\u5199\u5165\u7684\u7f13\u51b2\u533a\u7684\u5927\u5c0f\u5c0f\u4e8e\u8981\u5199\u5165\u7684\u6570\u636e\u91cf\u7684\u60c5\u51b5\u4e0b\u3002\u8fd9\u65f6，\u5199\u64cd\u4f5c\u4e0d\u8fdb\u884c\u4efb\u4f55\u62f7\u8d1d\u5de5\u4f5c，\u5c06\u53d1\u751f\u963b\u585e\u3002\u4e00\u65e6\u53d1\u9001\u7f13\u51b2\u533a\u5185\u6709\u8db3\u591f\u7684\u7a7a\u95f4，\u5185\u6838\u5c06\u5524\u9192\u8fdb\u7a0b，\u5c06\u6570\u636e\u4ece\u7528\u6237\u7f13\u51b2\u533a\u4e2d\u62f7\u8d1d\u5230\u76f8\u5e94\u7684\u53d1\u9001\u6570\u636e\u7f13\u51b2\u533a\u3002UDP\u4e0d\u7528\u7b49\u5f85\u786e\u8ba4，\u6ca1\u6709\u5b9e\u9645\u7684\u53d1\u9001\u7f13\u51b2\u533a，\u6240\u4ee5UDP\u534f\u8bae\u4e2d\u4e0d\u5b58\u5728\u53d1\u9001\u7f13\u51b2\u533a\u6ee1\u7684\u60c5\u51b5，\u5728UDP\u5957\u63a5\u5b57\u4e0a\u6267\u884c\u7684\u5199\u64cd\u4f5c\u6c38\u8fdc\u90fd\u4e0d\u4f1a\u963b\u585e\u3002<\/p>\n

    \u975e\u963b\u585e\u6a21\u5f0fI\/O： \u5f53\u6211\u4eec\u5c06\u4e00\u4e2a\u5957\u63a5\u5b57\u8bbe\u7f6e\u4e3a\u975e\u963b\u585e\u6a21\u5f0f，\u6211\u4eec\u76f8\u5f53\u4e8e\u544a\u8bc9\u4e86\u7cfb\u7edf\u5185\u6838：\u201c\u5f53\u6211\u8bf7\u6c42\u7684I\/O \u64cd\u4f5c\u4e0d\u80fd\u591f\u9a6c\u4e0a\u5b8c\u6210，\u4f60\u60f3\u8ba9\u6211\u7684\u8fdb\u7a0b\u8fdb\u884c\u4f11\u7720\u7b49\u5f85\u7684\u65f6\u5019，\u4e0d\u8981\u8fd9\u4e48\u505a，\u8bf7\u9a6c\u4e0a\u8fd4\u56de\u4e00\u4e2a\u9519\u8bef\u7ed9\u6211\u3002\u201d<\/p>\n

    \u5f53\u4e00\u4e2a\u5e94\u7528\u7a0b\u5e8f\u4f7f\u7528\u4e86\u975e\u963b\u585e\u6a21\u5f0f\u7684\u5957\u63a5\u5b57，\u5b83\u9700\u8981\u4f7f\u7528\u4e00\u4e2a\u5faa\u73af\u6765\u4e0d\u505c\u5730\u6d4b\u8bd5\u662f\u5426\u4e00\u4e2a\u6587\u4ef6\u63cf\u8ff0\u7b26\u6709\u6570\u636e\u53ef\u8bfb（\u79f0\u505apolling）\u3002 \u5e94\u7528\u7a0b\u5e8f\u4e0d\u505c\u7684 polling \u5185\u6838\u6765\u68c0\u67e5\u662f\u5426I\/O\u64cd\u4f5c\u5df2\u7ecf\u5c31\u7eea\u3002\u8fd9\u5c06\u662f\u4e00\u4e2a\u6781\u6d6a\u8d39CPU \u8d44\u6e90\u7684\u64cd\u4f5c\u3002\u4e5f\u6b63\u56e0\u5982\u6b64，\u8fd9\u79cd\u6a21\u5f0f\u5728\u4f7f\u7528\u4e2d\u4e0d\u666e\u904d，\u592a\u6d6a\u8d39\u8d44\u6e90\u4e86\u3002 \"\u975e\u963b\u585e\u6a21\u5f0fI\/O\"<\/p>\n

    fcntl()\u51fd\u6570
    \n\u4e00\u5f00\u59cb\u5efa\u7acb\u4e00\u4e2a\u5957\u63a5\u5b57\u63cf\u8ff0\u7b26\u7684\u65f6\u5019，\u7cfb\u7edf\u5185\u6838\u5c06\u5176\u8bbe\u7f6e\u4e3a\u963b\u585eIO\u6a21\u5f0f\u3002
    \n\u53ef\u4ee5\u4f7f\u7528\u51fd\u6570fcntl()\u8bbe\u7f6e\u4e00\u4e2a\u5957\u63a5\u5b57\u7684\u6807\u5fd7\u4e3aO_NONBLOCK \u6765\u5b9e\u73b0\u975e\u963b\u585e\u3002
    \nint fcntl(int fd, int cmd, long arg);
    \n int flag；
    \n flag = fcntl(sockfd, F_GETFL, 0);
    \n flag |= O_NONBLOCK;
    \n fcntl(sockfd, F_SETFL, flag);<\/p>\n

    \u591a\u8def\u590d\u7528I\/O \u5e94\u7528\u7a0b\u5e8f\u4e2d\u540c\u65f6\u5904\u7406\u591a\u8def\u8f93\u5165\u8f93\u51fa\u6d41，\u82e5\u91c7\u7528\u963b\u585e\u6a21\u5f0f，\u5c06\u5f97\u4e0d\u5230\u9884\u671f\u7684\u76ee\u7684\u3002\u53ef\u662f，\u82e5\u91c7\u7528\u975e\u963b\u585e\u6a21\u5f0f，\u5bf9\u591a\u4e2a\u8f93\u5165\u8fdb\u884c\u8f6e\u8be2，\u4f46\u53c8\u592a\u6d6a\u8d39CPU\u65f6\u95f4；\u82e5\u8bbe\u7f6e\u591a\u4e2a\u8fdb\u7a0b，\u5206\u522b\u5904\u7406\u4e00\u6761\u6570\u636e\u901a\u8def，\u5c06\u65b0\u4ea7\u751f\u8fdb\u7a0b\u95f4\u7684\u540c\u6b65\u4e0e\u901a\u4fe1\u95ee\u9898，\u4f7f\u7a0b\u5e8f\u53d8\u5f97\u66f4\u52a0\u590d\u6742；\u6bd4\u8f83\u597d\u7684\u65b9\u6cd5\u662f\u4f7f\u7528I\/O\u591a\u8def\u590d\u7528\u3002\u5176\u57fa\u672c\u601d\u60f3\u662f：<\/p>\n

    \u5148\u6784\u9020\u4e00\u5f20\u6709\u5173\u63cf\u8ff0\u7b26\u7684\u8868，\u7136\u540e\u8c03\u7528\u4e00\u4e2a\u51fd\u6570\u3002\u5f53\u8fd9\u4e9b\u6587\u4ef6\u63cf\u8ff0\u7b26\u4e2d\u7684\u4e00\u4e2a\u6216\u591a\u4e2a\u5df2\u51c6\u5907\u597d\u8fdb\u884c I\/O\u65f6\u51fd\u6570\u624d\u8fd4\u56de\u3002 \u51fd\u6570\u8fd4\u56de\u65f6\u544a\u8bc9\u8fdb\u7a0b\u90a3\u4e2a\u63cf\u8ff0\u7b26\u5df2\u5c31\u7eea，\u53ef\u4ee5\u8fdb\u884cI\/O\u64cd\u4f5c\u3002<\/p>\n

    \u5728 \u9ad8\u5e76\u53d1\u7684 TCP \u670d\u52a1\u5668 \u4e2d，\u4f20\u7edf\u7684 fork() \u591a\u8fdb\u7a0b \u6216 pthread \u591a\u7ebf\u7a0b \u65b9\u5f0f\u5bb9\u6613\u5bfc\u81f4 \u8d44\u6e90\u6d6a\u8d39\u548c\u6027\u80fd\u74f6\u9888\u3002\u56e0\u6b64，\u6211\u4eec\u624d\u4f7f\u7528 I\/O \u590d\u7528\u6280\u672f（select \/ poll \/ epoll），\u4f7f \u5355\u7ebf\u7a0b \u5c31\u80fd\u76d1\u542c \u591a\u4e2a\u5ba2\u6237\u7aef\u8fde\u63a5，\u4ece\u800c\u63d0\u9ad8\u5e76\u53d1\u6027\u80fd\u3002<\/p>\n

    \u591a\u8def\u590d\u7528select\/poll
    \n \/* According to POSIX.1-2001, POSIX.1-2008 *\/
    \n #include <sys\/select.h><\/p>\n

    \/* According to earlier standards *\/
    \n #include <sys\/time.h>
    \n #include <sys\/types.h>
    \n #include <unistd.h><\/p>\n

    int select(int nfds, fd_set *readfds, fd_set *writefds,fd_set *exceptfds, struct timeval *timeout);
    \n \/**********************************************************************
    \n @brief: \u591a\u8def\u590d\u7528，\u5c06\u6240\u9700\u8981\u4f7f\u7528\u7684\u6216\u8005\u9700\u8981\u5173\u6ce8\u7684\u6587\u4ef6\u63cf\u8ff0\u7b26\u653e\u5728\u4e00\u4e2a\u96c6\u5408\u4e2d，\u5f53\u96c6\u5408\u4e2d\u7684\u6587\u4ef6\u63cf\u8ff0\u7b26
    \n \u88ab\u89e6\u53d1\u4e86\u4f1a\u53bb\u6267\u884c\u76f8\u5e94\u7684\u4efb\u52a1<\/p>\n

    @nfds： \u6700\u5927\u6587\u4ef6\u63cf\u8ff0\u7b26 + 1<\/p>\n

    @readfds： \u6240\u6709\u8981\u8bfb\u7684\u6587\u4ef6\u6587\u4ef6\u63cf\u8ff0\u7b26\u7684\u96c6\u5408<\/p>\n

    @writefds: \u6240\u6709\u8981\u7684\u5199\u6587\u4ef6\u6587\u4ef6\u63cf\u8ff0\u7b26\u7684\u96c6\u5408<\/p>\n

    @exceptfds：\u5176\u4ed6\u8981\u5411\u6211\u4eec\u901a\u77e5\u7684\u6587\u4ef6\u63cf\u8ff0\u7b26 <\/p>\n

    @timeout： \u8d85\u65f6\u8bbe\u7f6e.
    \n NULL：\u4e00\u76f4\u963b\u585e，\u76f4\u5230\u6709\u6587\u4ef6\u63cf\u8ff0\u7b26\u5c31\u7eea\u6216\u51fa\u9519
    \n \u65f6\u95f4\u503c\u4e3a0：\u4ec5\u4ec5\u68c0\u6d4b\u6587\u4ef6\u63cf\u8ff0\u7b26\u96c6\u7684\u72b6\u6001，\u7136\u540e\u7acb\u5373\u8fd4\u56de
    \n \u65f6\u95f4\u503c\u4e0d\u4e3a0：\u5728\u6307\u5b9a\u65f6\u95f4\u5185，\u5982\u679c\u6ca1\u6709\u4e8b\u4ef6\u53d1\u751f，\u5219\u8d85\u65f6\u8fd4\u56de\u3002<\/p>\n

    struct timeval {
    \n long tv_sec; \/* seconds *\/
    \n long tv_usec; \/* microseconds *\/
    \n };<\/p>\n

    @retval: \u6210\u529f：\u8fd4\u56de\u5c31\u7eea\u7684\u6587\u4ef6\u63cf\u8ff0\u7b26\u7684\u4e2a\u6570
    \n \u5931\u8d25：\u8fd4\u56de-1，\u5e76\u4e14\u8bbe\u7f6e\u5168\u5c40\u9519\u8bef\u7801<\/p>\n

    \u4e3a\u4e86\u8bbe\u7f6e\u6587\u4ef6\u63cf\u8ff0\u7b26\u6211\u4eec\u8981\u4f7f\u7528\u51e0\u4e2a\u5b8f：
    \n \u5b8f\u7684\u5f62\u5f0f:
    \n void FD_ZERO(fd_set *fdset) \/\/\u4ecefdset\u4e2d\u6e05\u9664\u6240\u6709\u7684\u6587\u4ef6\u63cf\u8ff0\u7b26
    \n void FD_SET(int fd,fd_set *fdset) \/\/\u5c06fd\u52a0\u5165\u5230fdset
    \n void FD_CLR(int fd,fd_set *fdset) \/\/\u5c06fd\u4ecefdset\u91cc\u9762\u6e05\u9664
    \n int FD_ISSET(int fd,fd_set *fdset) \/\/\u5224\u65adfd\u662f\u5426\u5728fdset\u96c6\u5408\u4e2d
    \n **********************************************************************\/<\/p>\n

    #include <poll.h><\/p>\n

    int poll(struct pollfd *fds, nfds_t nfds, int timeout);
    \n \/**********************************************************************
    \n @brief: \u591a\u8def\u590d\u7528，\u76d1\u7ba1\u6587\u4ef6\u63cf\u8ff0\u7b26<\/p>\n

    @fds： \u8981\u76d1\u7ba1\u7684\u6587\u4ef6\u63cf\u8ff0\u7b26\u7684\u7ed3\u6784\u4f53\u6307\u9488<\/p>\n

    struct pollfd {
    \n int fd; \/* file descriptor \u5e0c\u671b\u88ab\u89e6\u53d1\u7684\u6587\u4ef6\u63cf\u8ff0\u7b26 \u7528\u6237\u8d4b\u503c*\/
    \n short events; \/* requested events \u5e0c\u671b\u88ab\u89e6\u53d1\u7684\u4e8b\u4ef6POLLIN \u7528\u6237\u8d4b\u503c*\/
    \n short revents; \/* returned events \u5e0c\u671b\u88ab\u89e6\u53d1\u7684\u4e8b\u4ef6\u53d1\u751f\u4e0e\u5426POLLIN \u7cfb\u7edf\u8d4b\u503c*\/
    \n };<\/p>\n

    The bits that may be set\/returned in events and revents are defined in <poll.h>:
    \n \/\/\u53ef\u5728man\u624b\u518c\u4e2d\u67e5\u8be2\u522b\u7684events\u548crevents\u7684\u9009\u503c
    \n POLLIN There is data to read.<\/p>\n

    POLLPRI
    \n There is some exceptional condition on the file descriptor. Possibilities
    \n include:<\/p>\n

    * There is out-of-band data on a TCP socket (see tcp(7)).<\/p>\n

    * A pseudoterminal master in packet mode has seen a state change on the
    \n slave (see ioctl_tty(2)).<\/p>\n

    * A cgroup.events file has been modified (see cgroups(7)).<\/p>\n

    POLLOUT
    \n Writing is now possible, though a write larger that the available space in a
    \n socket or pipe will still block (unless O_NONBLOCK is set).<\/p>\n

    \/**
    \n @nfds： \u6700\u5927\u6587\u4ef6\u63cf\u8ff0\u7b26 + 1<\/p>\n

    @timeout: >0:\u963b\u585e\u5bf9\u5e94\u7684\u65f6\u95f4(\u6beb\u79d2\u7ea7)
    \n =0：\u4e0d\u963b\u585e
    \n <0:\u4e00\u76f4\u963b\u585e<\/p>\n

    @retval: >0：\u96c6\u5408\u4e2d\u5df2\u5c31\u7eea\u7684\u6587\u4ef6\u63cf\u8ff0\u7b26\u4e2a\u6570
    \n =0：\u96c6\u5408\u4e2d\u6ca1\u6709\u5df2\u5c31\u7eea\u7684\u6587\u4ef6\u63cf\u8ff0\u7b26
    \n -1：poll\u8c03\u7528\u5931\u8d25，\u5e76\u4e14\u8bbe\u7f6e\u5168\u5c40\u9519\u8bef\u7801
    \n **********************************************************************\/<\/p>\n

    📌 I\/O \u590d\u7528\u7684\u4e09\u79cd\u65b9\u5f0f<\/h4>\n\n\u65b9\u6cd5\u7279\u70b9\u9002\u7528\u573a\u666f<\/tr>\n\n\n\n\n
    select()<\/td>\n\u9700\u8981\u904d\u5386\u6574\u4e2a\u6587\u4ef6\u63cf\u8ff0\u7b26\u96c6\u5408，\u6700\u5927\u652f\u6301 1024 \u4e2a\u8fde\u63a5<\/td>\n\u9002\u7528\u4e8e \u5c11\u91cf\u8fde\u63a5 \u7684\u60c5\u51b5<\/td>\n<\/tr>\n
    poll()<\/td>\n\u4f7f\u7528\u94fe\u8868\u5b58\u50a8，\u652f\u6301\u66f4\u591a\u8fde\u63a5，\u4f46\u4ecd\u7136\u9700\u8981\u904d\u5386\u6574\u4e2a\u96c6\u5408<\/td>\n\u9002\u7528\u4e8e \u4e2d\u7b49\u5e76\u53d1<\/td>\n<\/tr>\n
    epoll()<\/td>\n\u4e8b\u4ef6\u9a71\u52a8，\u53ea\u5904\u7406\u6d3b\u8dc3\u7684\u8fde\u63a5，\u6027\u80fd\u8fdc\u9ad8\u4e8e select\/poll<\/td>\n\u9002\u7528\u4e8e \u9ad8\u5e76\u53d1\u670d\u52a1\u5668<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

    \"\u8bf7\u6dfb\u52a0\u56fe\u7247\u63cf\u8ff0\"<\/p>\n

    select() \u591a\u8def\u590d\u7528\u670d\u52a1\u5668<\/h5>\n

    \u4ee3\u7801\u5b9e\u73b0：<\/p>\n

    #<\/span>include<\/span> <stdio.h><\/span><\/span>
    \n#<\/span>include<\/span> <stdlib.h><\/span><\/span>
    \n#<\/span>include<\/span> <string.h><\/span><\/span>
    \n#<\/span>include<\/span> <unistd.h><\/span><\/span>
    \n#<\/span>include<\/span> <arpa\/inet.h><\/span><\/span>
    \n#<\/span>include<\/span> <sys\/socket.h><\/span><\/span>
    \n#<\/span>include<\/span> <sys\/select.h><\/span><\/span><\/p>\n

    #<\/span>define<\/span> PORT<\/span> 8080<\/span><\/span><\/span>
    \n#<\/span>define<\/span> MAX_CLIENTS<\/span> 100<\/span><\/span><\/span>
    \n#<\/span>define<\/span> BUFFER_SIZE<\/span> 1024<\/span><\/span><\/span><\/p>\n

    int<\/span> main<\/span>(<\/span>)<\/span> {<\/span>
    \n int<\/span> server_fd,<\/span> client_fd,<\/span> max_fd,<\/span> activity,<\/span> i;<\/span>
    \n struct<\/span> sockaddr_in<\/span> server_addr,<\/span> client_addr;<\/span>
    \n socklen_t<\/span> addr_len =<\/span> sizeof<\/span>(<\/span>client_addr)<\/span>;<\/span>
    \n char<\/span> buffer[<\/span>BUFFER_SIZE]<\/span>;<\/span>
    \n fd_set read_fds,<\/span> master_fds;<\/span><\/p>\n

    \/\/ 1\ufe0f\u20e3 \u521b\u5efa TCP \u5957\u63a5\u5b57<\/span>
    \n server_fd =<\/span> socket<\/span>(<\/span>AF_INET,<\/span> SOCK_STREAM,<\/span> 0<\/span>)<\/span>;<\/span>
    \n if<\/span> (<\/span>server_fd ==<\/span> –<\/span>1<\/span>)<\/span> {<\/span>
    \n perror<\/span>(<\/span>"\u274c Socket \u521b\u5efa\u5931\u8d25"<\/span>)<\/span>;<\/span>
    \n exit<\/span>(<\/span>EXIT_FAILURE)<\/span>;<\/span>
    \n }<\/span><\/p>\n

    \/\/ 2\ufe0f\u20e3 \u7ed1\u5b9a\u670d\u52a1\u5668\u5730\u5740\u548c\u7aef\u53e3<\/span>
    \n server_addr.<\/span>sin_family =<\/span> AF_INET;<\/span>
    \n server_addr.<\/span>sin_addr.<\/span>s_addr =<\/span> INADDR_ANY;<\/span>
    \n server_addr.<\/span>sin_port =<\/span> htons<\/span>(<\/span>PORT)<\/span>;<\/span>
    \n if<\/span> (<\/span>bind<\/span>(<\/span>server_fd,<\/span> (<\/span>struct<\/span> sockaddr<\/span> *<\/span>)<\/span>&<\/span>server_addr,<\/span> sizeof<\/span>(<\/span>server_addr)<\/span>)<\/span> <<\/span> 0<\/span>)<\/span> {<\/span>
    \n perror<\/span>(<\/span>"\u274c \u7ed1\u5b9a\u5931\u8d25"<\/span>)<\/span>;<\/span>
    \n close<\/span>(<\/span>server_fd)<\/span>;<\/span>
    \n exit<\/span>(<\/span>EXIT_FAILURE)<\/span>;<\/span>
    \n }<\/span><\/p>\n

    \/\/ 3\ufe0f\u20e3 \u76d1\u542c\u5ba2\u6237\u7aef\u8fde\u63a5<\/span>
    \n if<\/span> (<\/span>listen<\/span>(<\/span>server_fd,<\/span> MAX_CLIENTS)<\/span> <<\/span> 0<\/span>)<\/span> {<\/span>
    \n perror<\/span>(<\/span>"\u274c \u76d1\u542c\u5931\u8d25"<\/span>)<\/span>;<\/span>
    \n close<\/span>(<\/span>server_fd)<\/span>;<\/span>
    \n exit<\/span>(<\/span>EXIT_FAILURE)<\/span>;<\/span>
    \n }<\/span><\/p>\n

    printf<\/span>(<\/span>"`select()` \u591a\u8def\u590d\u7528\u670d\u52a1\u5668\u5df2\u542f\u52a8，\u76d1\u542c\u7aef\u53e3 %d…\\\\n"<\/span>,<\/span> PORT)<\/span>;<\/span><\/p>\n

    \/\/ 4\ufe0f\u20e3 \u521d\u59cb\u5316 `select` \u7684\u6587\u4ef6\u63cf\u8ff0\u7b26\u96c6\u5408<\/span>
    \n FD_ZERO<\/span>(<\/span>&<\/span>master_fds)<\/span>;<\/span>
    \n FD_SET<\/span>(<\/span>server_fd,<\/span> &<\/span>master_fds)<\/span>;<\/span>
    \n max_fd =<\/span> server_fd;<\/span><\/p>\n

    while<\/span> (<\/span>1<\/span>)<\/span> {<\/span>
    \n read_fds =<\/span> master_fds;<\/span> \/\/ \u6bcf\u6b21\u5faa\u73af\u90fd\u590d\u5236 `master_fds`<\/span><\/p>\n

    \/\/ 5\ufe0f\u20e3 \u76d1\u542c\u591a\u4e2a\u6587\u4ef6\u63cf\u8ff0\u7b26 `select`<\/span>
    \n activity =<\/span> select<\/span>(<\/span>max_fd +<\/span> 1<\/span>,<\/span> &<\/span>read_fds,<\/span> NULL<\/span>,<\/span> NULL<\/span>,<\/span> NULL<\/span>)<\/span>;<\/span>
    \n if<\/span> (<\/span>activity <<\/span> 0<\/span>)<\/span> {<\/span>
    \n perror<\/span>(<\/span>"\u274c `select` \u8c03\u7528\u5931\u8d25"<\/span>)<\/span>;<\/span>
    \n continue<\/span>;<\/span>
    \n }<\/span><\/p>\n

    \/\/ 6\ufe0f\u20e3 \u5904\u7406\u65b0\u5ba2\u6237\u7aef\u8fde\u63a5<\/span>
    \n if<\/span> (<\/span>FD_ISSET<\/span>(<\/span>server_fd,<\/span> &<\/span>read_fds)<\/span>)<\/span> {<\/span>
    \n client_fd =<\/span> accept<\/span>(<\/span>server_fd,<\/span> (<\/span>struct<\/span> sockaddr<\/span> *<\/span>)<\/span>&<\/span>client_addr,<\/span> &<\/span>addr_len)<\/span>;<\/span>
    \n if<\/span> (<\/span>client_fd <<\/span> 0<\/span>)<\/span> {<\/span>
    \n perror<\/span>(<\/span>"\u274c \u5ba2\u6237\u7aef\u8fde\u63a5\u5931\u8d25"<\/span>)<\/span>;<\/span>
    \n continue<\/span>;<\/span>
    \n }<\/span><\/p>\n

    printf<\/span>(<\/span>"\u65b0\u5ba2\u6237\u7aef\u8fde\u63a5：%s:%d\\\\n"<\/span>,<\/span> inet_ntoa<\/span>(<\/span>client_addr.<\/span>sin_addr)<\/span>,<\/span> ntohs<\/span>(<\/span>client_addr.<\/span>sin_port)<\/span>)<\/span>;<\/span><\/p>\n

    FD_SET<\/span>(<\/span>client_fd,<\/span> &<\/span>master_fds)<\/span>;<\/span>
    \n if<\/span> (<\/span>client_fd ><\/span> max_fd)<\/span> {<\/span>
    \n max_fd =<\/span> client_fd;<\/span>
    \n }<\/span>
    \n }<\/span><\/p>\n

    \/\/ 7\ufe0f\u20e3 \u5904\u7406\u5df2\u8fde\u63a5\u7684\u5ba2\u6237\u7aef\u6570\u636e<\/span>
    \n for<\/span> (<\/span>i =<\/span> server_fd +<\/span> 1<\/span>;<\/span> i <=<\/span> max_fd;<\/span> i++<\/span>)<\/span> {<\/span>
    \n if<\/span> (<\/span>FD_ISSET<\/span>(<\/span>i,<\/span> &<\/span>read_fds)<\/span>)<\/span> {<\/span>
    \n memset<\/span>(<\/span>buffer,<\/span> 0<\/span>,<\/span> BUFFER_SIZE)<\/span>;<\/span>
    \n int<\/span> bytes_read =<\/span> read<\/span>(<\/span>i,<\/span> buffer,<\/span> BUFFER_SIZE)<\/span>;<\/span>
    \n if<\/span> (<\/span>bytes_read <=<\/span> 0<\/span>)<\/span> {<\/span>
    \n printf<\/span>(<\/span>"\u274c \u5ba2\u6237\u7aef\u65ad\u5f00\u8fde\u63a5\\\\n"<\/span>)<\/span>;<\/span>
    \n close<\/span>(<\/span>i)<\/span>;<\/span>
    \n FD_CLR<\/span>(<\/span>i,<\/span> &<\/span>master_fds)<\/span>;<\/span>
    \n }<\/span> else<\/span> {<\/span>
    \n printf<\/span>(<\/span>"📩 \u5ba2\u6237\u7aef\u6d88\u606f: %s\\\\n"<\/span>,<\/span> buffer)<\/span>;<\/span>
    \n write<\/span>(<\/span>i,<\/span> buffer,<\/span> bytes_read)<\/span>;<\/span> \/\/ \u56de\u663e<\/span>
    \n }<\/span>
    \n }<\/span>
    \n }<\/span>
    \n }<\/span><\/p>\n

    close<\/span>(<\/span>server_fd)<\/span>;<\/span>
    \n return<\/span> 0<\/span>;<\/span>
    \n}<\/span><\/p>\n

    poll() \u591a\u8def\u590d\u7528\u670d\u52a1\u5668<\/h5>\n

    #<\/span>include<\/span> <poll.h><\/span><\/span>
    \n#<\/span>include<\/span> <stdio.h><\/span><\/span>
    \n#<\/span>include<\/span> <stdlib.h><\/span><\/span>
    \n#<\/span>include<\/span> <string.h><\/span><\/span>
    \n#<\/span>include<\/span> <unistd.h><\/span><\/span>
    \n#<\/span>include<\/span> <arpa\/inet.h><\/span><\/span><\/p>\n

    #<\/span>define<\/span> PORT<\/span> 8080<\/span><\/span><\/span>
    \n#<\/span>define<\/span> MAX_CLIENTS<\/span> 100<\/span><\/span><\/span>
    \n#<\/span>define<\/span> BUFFER_SIZE<\/span> 1024<\/span><\/span><\/span><\/p>\n

    int<\/span> main<\/span>(<\/span>)<\/span> {<\/span>
    \n int<\/span> server_fd,<\/span> client_fd,<\/span> i;<\/span>
    \n struct<\/span> sockaddr_in<\/span> server_addr,<\/span> client_addr;<\/span>
    \n socklen_t<\/span> addr_len =<\/span> sizeof<\/span>(<\/span>client_addr)<\/span>;<\/span>
    \n char<\/span> buffer[<\/span>BUFFER_SIZE]<\/span>;<\/span><\/p>\n

    struct<\/span> pollfd<\/span> fds[<\/span>MAX_CLIENTS]<\/span>;<\/span>
    \n int<\/span> nfds =<\/span> 1<\/span>;<\/span><\/p>\n

    \/\/ 1\ufe0f\u20e3 \u521b\u5efa TCP \u5957\u63a5\u5b57<\/span>
    \n server_fd =<\/span> socket<\/span>(<\/span>AF_INET,<\/span> SOCK_STREAM,<\/span> 0<\/span>)<\/span>;<\/span>
    \n if<\/span> (<\/span>server_fd ==<\/span> –<\/span>1<\/span>)<\/span> {<\/span>
    \n perror<\/span>(<\/span>"\u274c Socket \u521b\u5efa\u5931\u8d25"<\/span>)<\/span>;<\/span>
    \n exit<\/span>(<\/span>EXIT_FAILURE)<\/span>;<\/span>
    \n }<\/span><\/p>\n

    \/\/ 2\ufe0f\u20e3 \u7ed1\u5b9a\u670d\u52a1\u5668\u5730\u5740\u548c\u7aef\u53e3<\/span>
    \n server_addr.<\/span>sin_family =<\/span> AF_INET;<\/span>
    \n server_addr.<\/span>sin_addr.<\/span>s_addr =<\/span> INADDR_ANY;<\/span>
    \n server_addr.<\/span>sin_port =<\/span> htons<\/span>(<\/span>PORT)<\/span>;<\/span>
    \n if<\/span> (<\/span>bind<\/span>(<\/span>server_fd,<\/span> (<\/span>struct<\/span> sockaddr<\/span> *<\/span>)<\/span>&<\/span>server_addr,<\/span> sizeof<\/span>(<\/span>server_addr)<\/span>)<\/span> <<\/span> 0<\/span>)<\/span> {<\/span>
    \n perror<\/span>(<\/span>"\u274c \u7ed1\u5b9a\u5931\u8d25"<\/span>)<\/span>;<\/span>
    \n close<\/span>(<\/span>server_fd)<\/span>;<\/span>
    \n exit<\/span>(<\/span>EXIT_FAILURE)<\/span>;<\/span>
    \n }<\/span><\/p>\n

    \/\/ 3\ufe0f\u20e3 \u76d1\u542c\u5ba2\u6237\u7aef\u8fde\u63a5<\/span>
    \n if<\/span> (<\/span>listen<\/span>(<\/span>server_fd,<\/span> MAX_CLIENTS)<\/span> <<\/span> 0<\/span>)<\/span> {<\/span>
    \n perror<\/span>(<\/span>"\u274c \u76d1\u542c\u5931\u8d25"<\/span>)<\/span>;<\/span>
    \n close<\/span>(<\/span>server_fd)<\/span>;<\/span>
    \n exit<\/span>(<\/span>EXIT_FAILURE)<\/span>;<\/span>
    \n }<\/span><\/p>\n

    printf<\/span>(<\/span>"`poll()` \u591a\u8def\u590d\u7528\u670d\u52a1\u5668\u5df2\u542f\u52a8，\u76d1\u542c\u7aef\u53e3 %d…\\\\n"<\/span>,<\/span> PORT)<\/span>;<\/span><\/p>\n

    fds[<\/span>0<\/span>]<\/span>.<\/span>fd =<\/span> server_fd;<\/span>
    \n fds[<\/span>0<\/span>]<\/span>.<\/span>events =<\/span> POLLIN;<\/span><\/p>\n

    while<\/span> (<\/span>1<\/span>)<\/span> {<\/span>
    \n \/\/ 4\ufe0f\u20e3 \u76d1\u542c\u591a\u4e2a\u6587\u4ef6\u63cf\u8ff0\u7b26 `poll`<\/span>
    \n int<\/span> activity =<\/span> poll<\/span>(<\/span>fds,<\/span> nfds,<\/span> –<\/span>1<\/span>)<\/span>;<\/span>
    \n if<\/span> (<\/span>activity <<\/span> 0<\/span>)<\/span> {<\/span>
    \n perror<\/span>(<\/span>"\u274c `poll` \u8c03\u7528\u5931\u8d25"<\/span>)<\/span>;<\/span>
    \n continue<\/span>;<\/span>
    \n }<\/span><\/p>\n

    \/\/ 5\ufe0f\u20e3 \u5904\u7406\u65b0\u5ba2\u6237\u7aef\u8fde\u63a5<\/span>
    \n if<\/span> (<\/span>fds[<\/span>0<\/span>]<\/span>.<\/span>revents &<\/span> POLLIN)<\/span> {<\/span>
    \n client_fd =<\/span> accept<\/span>(<\/span>server_fd,<\/span> (<\/span>struct<\/span> sockaddr<\/span> *<\/span>)<\/span>&<\/span>client_addr,<\/span> &<\/span>addr_len)<\/span>;<\/span>
    \n if<\/span> (<\/span>client_fd <<\/span> 0<\/span>)<\/span> {<\/span>
    \n perror<\/span>(<\/span>"\u274c \u5ba2\u6237\u7aef\u8fde\u63a5\u5931\u8d25"<\/span>)<\/span>;<\/span>
    \n continue<\/span>;<\/span>
    \n }<\/span>
    \n printf<\/span>(<\/span>"\u65b0\u5ba2\u6237\u7aef\u8fde\u63a5：%s:%d\\\\n"<\/span>,<\/span> inet_ntoa<\/span>(<\/span>client_addr.<\/span>sin_addr)<\/span>,<\/span> ntohs<\/span>(<\/span>client_addr.<\/span>sin_port)<\/span>)<\/span>;<\/span><\/p>\n

    fds[<\/span>nfds]<\/span>.<\/span>fd =<\/span> client_fd;<\/span>
    \n fds[<\/span>nfds]<\/span>.<\/span>events =<\/span> POLLIN;<\/span>
    \n nfds++<\/span>;<\/span>
    \n }<\/span><\/p>\n

    \/\/ 6\ufe0f\u20e3 \u5904\u7406\u5df2\u8fde\u63a5\u7684\u5ba2\u6237\u7aef\u6570\u636e<\/span>
    \n for<\/span> (<\/span>i =<\/span> 1<\/span>;<\/span> i <<\/span> nfds;<\/span> i++<\/span>)<\/span> {<\/span>
    \n if<\/span> (<\/span>fds[<\/span>i]<\/span>.<\/span>revents &<\/span> POLLIN)<\/span> {<\/span>
    \n memset<\/span>(<\/span>buffer,<\/span> 0<\/span>,<\/span> BUFFER_SIZE)<\/span>;<\/span>
    \n int<\/span> bytes_read =<\/span> read<\/span>(<\/span>fds[<\/span>i]<\/span>.<\/span>fd,<\/span> buffer,<\/span> BUFFER_SIZE)<\/span>;<\/span>
    \n if<\/span> (<\/span>bytes_read <=<\/span> 0<\/span>)<\/span> {<\/span>
    \n printf<\/span>(<\/span>"\u274c \u5ba2\u6237\u7aef\u65ad\u5f00\u8fde\u63a5\\\\n"<\/span>)<\/span>;<\/span>
    \n close<\/span>(<\/span>fds[<\/span>i]<\/span>.<\/span>fd)<\/span>;<\/span>
    \n fds[<\/span>i]<\/span> =<\/span> fds[<\/span>nfds –<\/span> 1<\/span>]<\/span>;<\/span> \/\/ \u79fb\u9664\u65ad\u5f00\u7684\u5ba2\u6237\u7aef<\/span>
    \n nfds—<\/span>;<\/span>
    \n }<\/span> else<\/span> {<\/span>
    \n printf<\/span>(<\/span>"📩 \u5ba2\u6237\u7aef\u6d88\u606f: %s\\\\n"<\/span>,<\/span> buffer)<\/span>;<\/span>
    \n write<\/span>(<\/span>fds[<\/span>i]<\/span>.<\/span>fd,<\/span> buffer,<\/span> bytes_read)<\/span>;<\/span> \/\/ \u56de\u663e<\/span>
    \n }<\/span>
    \n }<\/span>
    \n }<\/span>
    \n }<\/span><\/p>\n

    close<\/span>(<\/span>server_fd)<\/span>;<\/span>
    \n return<\/span> 0<\/span>;<\/span>
    \n}<\/span><\/p>\n

    \u4f7f\u7528 epoll \u7684\u9ad8\u5e76\u53d1\u670d\u52a1\u5668（C \u8bed\u8a00）<\/h4>\n

    select() \u548c poll() \u9002\u7528\u4e8e 1000 \u4ee5\u5185\u7684\u8fde\u63a5，\u4f46\u968f\u7740\u8fde\u63a5\u6570\u589e\u52a0，\u6027\u80fd\u4e0b\u964d\u3002\u5bf9\u4e8e\u9ad8\u5e76\u53d1\u670d\u52a1\u5668，\u5efa\u8bae\u4f7f\u7528 epoll()（Linux） \u6216 kqueue()（BSD\/macOS）\u3002<\/p>\n

    epoll \u662f Linux \u4e0b \u9ad8\u6548\u7684 I\/O \u590d\u7528\u65b9\u5f0f，\u76f8\u6bd4 select() \u548c poll()，\u5b83\u652f\u6301：<\/p>\n

      \n
    • O(1) \u4e8b\u4ef6\u89e6\u53d1：\u53ea\u5904\u7406\u6d3b\u8dc3\u7684\u6587\u4ef6\u63cf\u8ff0\u7b26，\u4e0d\u7528\u904d\u5386\u6574\u4e2a fd_set\u3002<\/li>\n
    • \u652f\u6301\u5927\u89c4\u6a21\u5e76\u53d1：\u9002\u7528\u4e8e \u4e0a\u4e07\u7ea7\u522b\u7684\u8fde\u63a5，\u6bd4 select() \/ poll() \u6027\u80fd\u9ad8\u5f88\u591a\u3002<\/li>\n
    • Edge Trigger (ET) & Level Trigger (LT)：\u652f\u6301 \u8fb9\u7f18\u89e6\u53d1 \u548c \u6c34\u5e73\u89e6\u53d1，\u8fdb\u4e00\u6b65\u4f18\u5316\u6027\u80fd\u3002<\/li>\n<\/ul>\n
      epoll \u5173\u952e API<\/h5>\n

      \u51fd\u6570\u529f\u80fd
      \nepoll_create1(0)\u521b\u5efa epoll \u5b9e\u4f8b，\u8fd4\u56de epoll_fd
      \nepoll_ctl(epoll_fd, EPOLL_CTL_ADD, fd, &event)\u6dfb\u52a0\u76d1\u542c\u7684 fd
      \nepoll_ctl(epoll_fd, EPOLL_CTL_MOD, fd, &event)\u4fee\u6539\u76d1\u542c\u7684 fd
      \nepoll_ctl(epoll_fd, EPOLL_CTL_DEL, fd, &event)\u5220\u9664\u76d1\u542c\u7684 fd
      \nepoll_wait(epoll_fd, events, MAX_EVENTS, timeout)\u7b49\u5f85\u4e8b\u4ef6\u89e6\u53d1<\/p>\n

      epoll \u591a\u8def\u590d\u7528\u670d\u52a1\u5668（\u4ee3\u7801\u5b9e\u73b0）（\u91cd\u70b9）<\/h5>\n

      #<\/span>include<\/span> <stdio.h><\/span><\/span>
      \n#<\/span>include<\/span> <stdlib.h><\/span><\/span>
      \n#<\/span>include<\/span> <string.h><\/span><\/span>
      \n#<\/span>include<\/span> <unistd.h><\/span><\/span>
      \n#<\/span>include<\/span> <arpa\/inet.h><\/span><\/span>
      \n#<\/span>include<\/span> <sys\/socket.h><\/span><\/span>
      \n#<\/span>include<\/span> <sys\/epoll.h><\/span><\/span>
      \n#<\/span>include<\/span> <fcntl.h><\/span><\/span><\/p>\n

      #<\/span>define<\/span> PORT<\/span> 8080<\/span> <\/span>\/\/ \u670d\u52a1\u5668\u76d1\u542c\u7aef\u53e3<\/span><\/span>
      \n#<\/span>define<\/span> MAX_EVENTS<\/span> 1000<\/span> <\/span>\/\/ epoll \u6700\u5927\u76d1\u542c\u4e8b\u4ef6\u6570<\/span><\/span>
      \n#<\/span>define<\/span> BUFFER_SIZE<\/span> 1024<\/span> <\/span>\/\/ \u7f13\u51b2\u533a\u5927\u5c0f<\/span><\/span><\/p>\n

      \/\/ **🔹 \u8bbe\u7f6e fd \u4e3a\u975e\u963b\u585e\u6a21\u5f0f**<\/span>
      \nvoid<\/span> set_nonblocking<\/span>(<\/span>int<\/span> fd)<\/span> {<\/span>
      \n int<\/span> flags =<\/span> fcntl<\/span>(<\/span>fd,<\/span> F_GETFL,<\/span> 0<\/span>)<\/span>;<\/span>
      \n fcntl<\/span>(<\/span>fd,<\/span> F_SETFL,<\/span> flags |<\/span> O_NONBLOCK)<\/span>;<\/span>
      \n}<\/span><\/p>\n

      int<\/span> main<\/span>(<\/span>)<\/span> {<\/span>
      \n int<\/span> server_fd,<\/span> client_fd,<\/span> epoll_fd,<\/span> event_count,<\/span> i;<\/span>
      \n struct<\/span> sockaddr_in<\/span> server_addr,<\/span> client_addr;<\/span>
      \n socklen_t<\/span> addr_len =<\/span> sizeof<\/span>(<\/span>client_addr)<\/span>;<\/span>
      \n struct<\/span> epoll_event<\/span> event,<\/span> events[<\/span>MAX_EVENTS]<\/span>;<\/span>
      \n char<\/span> buffer[<\/span>BUFFER_SIZE]<\/span>;<\/span><\/p>\n

      \/\/ 1\ufe0f\u20e3 \u521b\u5efa TCP \u5957\u63a5\u5b57<\/span>
      \n server_fd =<\/span> socket<\/span>(<\/span>AF_INET,<\/span> SOCK_STREAM,<\/span> 0<\/span>)<\/span>;<\/span>
      \n if<\/span> (<\/span>server_fd ==<\/span> –<\/span>1<\/span>)<\/span> {<\/span>
      \n perror<\/span>(<\/span>"\u274c Socket \u521b\u5efa\u5931\u8d25"<\/span>)<\/span>;<\/span>
      \n exit<\/span>(<\/span>EXIT_FAILURE)<\/span>;<\/span>
      \n }<\/span><\/p>\n

      \/\/ 2\ufe0f\u20e3 \u7ed1\u5b9a\u670d\u52a1\u5668\u5730\u5740\u548c\u7aef\u53e3<\/span>
      \n server_addr.<\/span>sin_family =<\/span> AF_INET;<\/span>
      \n server_addr.<\/span>sin_addr.<\/span>s_addr =<\/span> INADDR_ANY;<\/span>
      \n server_addr.<\/span>sin_port =<\/span> htons<\/span>(<\/span>PORT)<\/span>;<\/span>
      \n if<\/span> (<\/span>bind<\/span>(<\/span>server_fd,<\/span> (<\/span>struct<\/span> sockaddr<\/span> *<\/span>)<\/span>&<\/span>server_addr,<\/span> sizeof<\/span>(<\/span>server_addr)<\/span>)<\/span> <<\/span> 0<\/span>)<\/span> {<\/span>
      \n perror<\/span>(<\/span>"\u274c \u7ed1\u5b9a\u5931\u8d25"<\/span>)<\/span>;<\/span>
      \n close<\/span>(<\/span>server_fd)<\/span>;<\/span>
      \n exit<\/span>(<\/span>EXIT_FAILURE)<\/span>;<\/span>
      \n }<\/span><\/p>\n

      \/\/ 3\ufe0f\u20e3 \u5f00\u59cb\u76d1\u542c<\/span>
      \n if<\/span> (<\/span>listen<\/span>(<\/span>server_fd,<\/span> MAX_EVENTS)<\/span> <<\/span> 0<\/span>)<\/span> {<\/span>
      \n perror<\/span>(<\/span>"\u274c \u76d1\u542c\u5931\u8d25"<\/span>)<\/span>;<\/span>
      \n close<\/span>(<\/span>server_fd)<\/span>;<\/span>
      \n exit<\/span>(<\/span>EXIT_FAILURE)<\/span>;<\/span>
      \n }<\/span>
      \n printf<\/span>(<\/span>"\u26a1 `epoll` \u670d\u52a1\u5668\u542f\u52a8，\u76d1\u542c\u7aef\u53e3 %d…\\\\n"<\/span>,<\/span> PORT)<\/span>;<\/span><\/p>\n

      \/\/ 4\ufe0f\u20e3 \u521b\u5efa epoll \u5b9e\u4f8b<\/span>
      \n epoll_fd =<\/span> epoll_create1<\/span>(<\/span>0<\/span>)<\/span>;<\/span>
      \n if<\/span> (<\/span>epoll_fd ==<\/span> –<\/span>1<\/span>)<\/span> {<\/span>
      \n perror<\/span>(<\/span>"\u274c epoll_create1 \u5931\u8d25"<\/span>)<\/span>;<\/span>
      \n close<\/span>(<\/span>server_fd)<\/span>;<\/span>
      \n exit<\/span>(<\/span>EXIT_FAILURE)<\/span>;<\/span>
      \n }<\/span><\/p>\n

      \/\/ 5\ufe0f\u20e3 \u8bbe\u7f6e server_fd \u4e3a\u975e\u963b\u585e\u6a21\u5f0f，\u5e76\u6dfb\u52a0\u5230 epoll \u76d1\u542c<\/span>
      \n set_nonblocking<\/span>(<\/span>server_fd)<\/span>;<\/span>
      \n event.<\/span>events =<\/span> EPOLLIN;<\/span> \/\/ \u76d1\u542c\u53ef\u8bfb\u4e8b\u4ef6（LT \u6a21\u5f0f）<\/span>
      \n event.<\/span>data.<\/span>fd =<\/span> server_fd;<\/span>
      \n epoll_ctl<\/span>(<\/span>epoll_fd,<\/span> EPOLL_CTL_ADD,<\/span> server_fd,<\/span> &<\/span>event)<\/span>;<\/span><\/p>\n

      while<\/span> (<\/span>1<\/span>)<\/span> {<\/span>
      \n \/\/ 6\ufe0f\u20e3 \u7b49\u5f85\u4e8b\u4ef6\u89e6\u53d1<\/span>
      \n event_count =<\/span> epoll_wait<\/span>(<\/span>epoll_fd,<\/span> events,<\/span> MAX_EVENTS,<\/span> –<\/span>1<\/span>)<\/span>;<\/span>
      \n for<\/span> (<\/span>i =<\/span> 0<\/span>;<\/span> i <<\/span> event_count;<\/span> i++<\/span>)<\/span> {<\/span>
      \n if<\/span> (<\/span>events[<\/span>i]<\/span>.<\/span>data.<\/span>fd ==<\/span> server_fd)<\/span> {<\/span>
      \n \/\/ 7\ufe0f\u20e3 \u5904\u7406\u65b0\u5ba2\u6237\u7aef\u8fde\u63a5<\/span>
      \n client_fd =<\/span> accept<\/span>(<\/span>server_fd,<\/span> (<\/span>struct<\/span> sockaddr<\/span> *<\/span>)<\/span>&<\/span>client_addr,<\/span> &<\/span>addr_len)<\/span>;<\/span>
      \n if<\/span> (<\/span>client_fd <<\/span> 0<\/span>)<\/span> {<\/span>
      \n perror<\/span>(<\/span>"\u274c \u63a5\u53d7\u5ba2\u6237\u7aef\u8fde\u63a5\u5931\u8d25"<\/span>)<\/span>;<\/span>
      \n continue<\/span>;<\/span>
      \n }<\/span>
      \n printf<\/span>(<\/span>"\u2705 \u65b0\u5ba2\u6237\u7aef\u8fde\u63a5：%s:%d\\\\n"<\/span>,<\/span> inet_ntoa<\/span>(<\/span>client_addr.<\/span>sin_addr)<\/span>,<\/span> ntohs<\/span>(<\/span>client_addr.<\/span>sin_port)<\/span>)<\/span>;<\/span><\/p>\n

      set_nonblocking<\/span>(<\/span>client_fd)<\/span>;<\/span> \/\/ \u8bbe\u7f6e\u975e\u963b\u585e\u6a21\u5f0f<\/span>
      \n event.<\/span>events =<\/span> EPOLLIN |<\/span> EPOLLET;<\/span> \/\/ \u76d1\u542c\u53ef\u8bfb\u4e8b\u4ef6，ET \u6a21\u5f0f<\/span>
      \n event.<\/span>data.<\/span>fd =<\/span> client_fd;<\/span>
      \n epoll_ctl<\/span>(<\/span>epoll_fd,<\/span> EPOLL_CTL_ADD,<\/span> client_fd,<\/span> &<\/span>event)<\/span>;<\/span>
      \n }<\/span> else<\/span> {<\/span>
      \n \/\/ 8\ufe0f\u20e3 \u5904\u7406\u5ba2\u6237\u7aef\u6570\u636e<\/span>
      \n int<\/span> client_fd =<\/span> events[<\/span>i]<\/span>.<\/span>data.<\/span>fd;<\/span>
      \n memset<\/span>(<\/span>buffer,<\/span> 0<\/span>,<\/span> BUFFER_SIZE)<\/span>;<\/span>
      \n int<\/span> bytes_read =<\/span> read<\/span>(<\/span>client_fd,<\/span> buffer,<\/span> BUFFER_SIZE)<\/span>;<\/span>
      \n if<\/span> (<\/span>bytes_read <=<\/span> 0<\/span>)<\/span> {<\/span>
      \n printf<\/span>(<\/span>"\u274c \u5ba2\u6237\u7aef\u65ad\u5f00\u8fde\u63a5\\\\n"<\/span>)<\/span>;<\/span>
      \n epoll_ctl<\/span>(<\/span>epoll_fd,<\/span> EPOLL_CTL_DEL,<\/span> client_fd,<\/span> NULL<\/span>)<\/span>;<\/span>
      \n close<\/span>(<\/span>client_fd)<\/span>;<\/span>
      \n }<\/span> else<\/span> {<\/span>
      \n printf<\/span>(<\/span>"📩 \u5ba2\u6237\u7aef\u6d88\u606f: %s\\\\n"<\/span>,<\/span> buffer)<\/span>;<\/span>
      \n write<\/span>(<\/span>client_fd,<\/span> buffer,<\/span> bytes_read)<\/span>;<\/span> \/\/ \u56de\u663e<\/span>
      \n }<\/span>
      \n }<\/span>
      \n }<\/span>
      \n }<\/span><\/p>\n

      close<\/span>(<\/span>server_fd)<\/span>;<\/span>
      \n close<\/span>(<\/span>epoll_fd)<\/span>;<\/span>
      \n return<\/span> 0<\/span>;<\/span>
      \n}<\/span><\/p>\n

      \u2705 \u4ee3\u7801\u8fd0\u884c\u6b65\u9aa4<\/p>\n

    • \u7f16\u8bd1（\u5047\u8bbe\u6587\u4ef6\u540d\u4e3a epoll_server.c）<\/li>\n

      gcc epoll_server.c -o<\/span> epoll_server<\/p>\n

    • \u8fd0\u884c\u670d\u52a1\u5668<\/li>\n

      .\/epoll_server<\/p>\n

      \u8f93\u51fa\u793a\u4f8b：<\/p>\n

      `<\/span>epoll`<\/span><\/span> \u670d\u52a1\u5668\u542f\u52a8，\u76d1\u542c\u7aef\u53e3 8080<\/span>..<\/span>.<\/p>\n

      \u2705 \u8fde\u63a5\u6d4b\u8bd5<\/p>\n

      📌 \u4f7f\u7528 nc（Netcat）<\/h5>\n

      nc<\/span> 127.0<\/span>.0.1 8080<\/span><\/p>\n

      \u8f93\u5165\u5185\u5bb9，\u670d\u52a1\u5668\u4f1a\u56de\u663e，\u5982：<\/p>\n

      Hello Server
      \nHello Server # \u670d\u52a1\u5668\u8fd4\u56de\u76f8\u540c\u5185\u5bb9<\/span><\/p>\n

      epoll \u5de5\u4f5c\u6a21\u5f0f<\/h6>\n

      🔹 \u6c34\u5e73\u89e6\u53d1（LT，Level Trigger）<\/p>\n

        \n
      • \u9ed8\u8ba4\u6a21\u5f0f，\u4e8b\u4ef6\u672a\u5904\u7406\u65f6\u4f1a \u6301\u7eed\u89e6\u53d1\u3002<\/li>\n
      • \u9002\u7528\u4e8e\u963b\u585e I\/O，\u786e\u4fdd\u6570\u636e\u4e0d\u4f1a\u4e22\u5931\u3002<\/li>\n<\/ul>\n

        🔹 \u8fb9\u7f18\u89e6\u53d1（ET，Edge Trigger）<\/p>\n

          \n
        • \u4ec5\u5728\u72b6\u6001\u53d8\u5316\u65f6\u89e6\u53d1，\u4e0d\u4f1a\u91cd\u590d\u89e6\u53d1\u3002<\/li>\n
        • \u5fc5\u987b\u4f7f\u7528\u975e\u963b\u585e I\/O，\u5426\u5219\u53ef\u80fd\u4e22\u5931\u6570\u636e\u3002<\/li>\n<\/ul>\n
          \u2705 epoll vs select \/ poll<\/h6>\n\n\u7279\u70b9select()poll()epoll()<\/tr>\n\n\n\n\n
          \u6700\u5927\u8fde\u63a5\u6570<\/td>\n1024（Linux \u9ed8\u8ba4）<\/td>\n\u65e0\u9650\u5236（\u4f46\u626b\u63cf\u6240\u6709）<\/td>\n\u65e0\u9650\u5236（\u4e8b\u4ef6\u9a71\u52a8）<\/td>\n<\/tr>\n
          \u6027\u80fd<\/td>\nO(n)，\u904d\u5386 fd_set<\/td>\nO(n)，\u904d\u5386 pollfd<\/td>\nO(1)，\u53ea\u5904\u7406\u6d3b\u8dc3\u8fde\u63a5<\/td>\n<\/tr>\n
          \u9002\u7528\u573a\u666f<\/td>\n\u5c11\u91cf\u8fde\u63a5（<1000）<\/td>\n\u4e2d\u7b49\u8fde\u63a5\u6570<\/td>\n\u9ad8\u5e76\u53d1（>10000）<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

          \u4ee3\u7801\u53ef\u4f18\u5316<\/p>\n

          \u4f7f\u7528\u7ebf\u7a0b\u6c60
          \nepoll_wait() \u53ea\u8d1f\u8d23\u76d1\u542c，\u7ebf\u7a0b\u6c60 \u5904\u7406\u6570\u636e，\u63d0\u9ad8\u541e\u5410\u91cf\u3002
          \n\u4f7f\u7528 EPOLLET（\u8fb9\u7f18\u89e6\u53d1）
          \n\u7ed3\u5408 \u975e\u963b\u585e read()，\u51cf\u5c11 epoll_wait() \u89e6\u53d1\u6b21\u6570，\u63d0\u9ad8\u6548\u7387\u3002
          \nTCP SO_REUSEADDR
          \n\u907f\u514d\u670d\u52a1\u5668\u91cd\u542f\u65f6 bind() \u5931\u8d25：<\/p>\n

          int<\/span> opt =<\/span> 1<\/span>;<\/span>
          \nsetsockopt<\/span>(<\/span>server_fd,<\/span> SOL_SOCKET,<\/span> SO_REUSEADDR,<\/span> &<\/span>opt,<\/span> sizeof<\/span>(<\/span>opt)<\/span>)<\/span>;<\/span><\/p>\n

          \u8be5\u4ee3\u7801\u662f\u4e00\u4e2a\u9ad8\u6548\u7684 TCP \u5e76\u53d1\u670d\u52a1\u5668，\u4f7f\u7528 epoll \u4e8b\u4ef6\u9a71\u52a8，\u9002\u7528\u4e8e\u5927\u89c4\u6a21\u8fde\u63a5\u3002 \u76f8\u6bd4 select()，epoll \u5728\u9ad8\u5e76\u53d1\u60c5\u51b5\u4e0b\u6027\u80fd\u66f4\u597d，\u662f Linux \u670d\u52a1\u5668\u7684\u9996\u9009\u65b9\u6848！ 🎯<\/p>\n

          \u4ee5\u4e0a\u3002\u4ec5\u4f9b\u5b66\u4e60\u4e0e\u5206\u4eab\u4ea4\u6d41，\u8bf7\u52ff\u7528\u4e8e\u5546\u4e1a\u7528\u9014！\u8f6c\u8f7d\u9700\u63d0\u524d\u8bf4\u660e\u3002<\/p>\n

          \u6211\u662f\u4e00\u4e2a\u5341\u5206\u70ed\u7231\u6280\u672f\u7684\u7a0b\u5e8f\u5458，\u5e0c\u671b\u8fd9\u7bc7\u6587\u7ae0\u80fd\u591f\u5bf9\u60a8\u6709\u5e2e\u52a9，\u4e5f\u5e0c\u671b\u8ba4\u8bc6\u66f4\u591a\u70ed\u7231\u7a0b\u5e8f\u5f00\u53d1\u7684\u5c0f\u4f19\u4f34\u3002 \u611f\u8c22！<\/p>\n","protected":false},"excerpt":{"rendered":"

          \u6587\u7ae0\u6d4f\u89c8\u9605\u8bfb1k\u6b21\uff0c\u70b9\u8d5e20\u6b21\uff0c\u6536\u85cf14\u6b21\u3002UDP\u4e0d\u7528\u7b49\u5f85\u786e\u8ba4\uff0c\u6ca1\u6709\u5b9e\u9645\u7684\u53d1\u9001\u7f13\u51b2\u533a\uff0c\u6240\u4ee5UDP\u534f\u8bae\u4e2d\u4e0d\u5b58\u5728\u53d1\u9001\u7f13\u51b2\u533a\u6ee1\u7684\u60c5\u51b5\uff0c\u5728UDP\u5957\u63a5\u5b57\u4e0a\u6267\u884c\u7684\u5199\u64cd\u4f5c\u6c38\u8fdc\u90fd\u4e0d\u4f1a\u963b\u585e\u3002\u8fdb\u7a0b\u8c03\u7528 read \u51fd\u6570\u4ece\u5957\u63a5\u5b57\u4e0a\u8bfb\u53d6\u6570\u636e\uff0c\u5f53\u5957\u63a5\u5b57\u7684\u63a5\u6536\u7f13\u51b2\u533a\u4e2d\u8fd8\u6ca1\u6709\u6570\u636e\u53ef\u8bfb\uff0c\u51fd\u6570 read \u5c06\u53d1\u751f\u963b\u585e\u3002\u963b\u585eI\/O \u6a21\u5f0f\u662f\u6700\u666e\u904d\u4f7f\u7528\u7684 I\/O \u6a21\u5f0f\uff0c\u5927\u90e8\u5206\u7a0b\u5e8f\u4f7f\u7528\u7684\u90fd\u662f\u963b\u585e\u6a21\u5f0f\u7684 I\/O\uff1b\u5f53\u6211\u4eec\u5c06\u4e00\u4e2a\u5957\u63a5\u5b57\u8bbe\u7f6e\u4e3a\u975e\u963b\u585e\u6a21\u5f0f\uff0c\u6211\u4eec\u76f8\u5f53\u4e8e\u544a\u8bc9\u4e86\u7cfb\u7edf\u5185\u6838\uff1a\u201c\u5f53\u6211\u8bf7\u6c42\u7684I\/O \u64cd\u4f5c\u4e0d\u80fd\u591f\u9a6c\u4e0a\u5b8c\u6210\uff0c\u4f60\u60f3\u8ba9\u6211\u7684\u8fdb\u7a0b\u8fdb\u884c\u4f11\u7720\u7b49\u5f85\u7684\u65f6\u5019\uff0c\u4e0d\u8981\u8fd9\u4e48\u505a\uff0c\u8bf7\u9a6c\u4e0a\u8fd4\u56de\u4e00\u4e2a\u9519\u8bef\u7ed9\u6211\u3002_\u91c7\u7528\u7684\u7ebf\u7a0b\u6a21\u578b\u53caio\u590d\u7528<\/p>\n","protected":false},"author":2,"featured_media":24358,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[58,822,270,43,78,396,1363],"topic":[],"class_list":["post-24360","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-server","tag-linux","tag-mcu","tag-270","tag-43","tag-78","tag-396","tag-1363"],"yoast_head":"\n\u3010\u7f51\u7edc\u7f16\u7a0b\u3011\u670d\u52a1\u5668\u6a21\u578b\uff08\u4e8c\uff09\uff1a\u5e76\u53d1\u670d\u52a1\u5668\u6a21\u578b\uff08\u591a\u7ebf\u7a0b\uff09\u548c I\/O \u590d\u7528\u670d\u52a1\u5668\uff08select \/ epoll\uff09 - \u7f51\u7855\u4e92\u8054\u5e2e\u52a9\u4e2d\u5fc3<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.wsisp.com\/helps\/24360.html\" \/>\n<meta property=\"og:locale\" content=\"zh_CN\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"\u3010\u7f51\u7edc\u7f16\u7a0b\u3011\u670d\u52a1\u5668\u6a21\u578b\uff08\u4e8c\uff09\uff1a\u5e76\u53d1\u670d\u52a1\u5668\u6a21\u578b\uff08\u591a\u7ebf\u7a0b\uff09\u548c I\/O \u590d\u7528\u670d\u52a1\u5668\uff08select \/ epoll\uff09 - \u7f51\u7855\u4e92\u8054\u5e2e\u52a9\u4e2d\u5fc3\" \/>\n<meta property=\"og:description\" content=\"\u6587\u7ae0\u6d4f\u89c8\u9605\u8bfb1k\u6b21\uff0c\u70b9\u8d5e20\u6b21\uff0c\u6536\u85cf14\u6b21\u3002UDP\u4e0d\u7528\u7b49\u5f85\u786e\u8ba4\uff0c\u6ca1\u6709\u5b9e\u9645\u7684\u53d1\u9001\u7f13\u51b2\u533a\uff0c\u6240\u4ee5UDP\u534f\u8bae\u4e2d\u4e0d\u5b58\u5728\u53d1\u9001\u7f13\u51b2\u533a\u6ee1\u7684\u60c5\u51b5\uff0c\u5728UDP\u5957\u63a5\u5b57\u4e0a\u6267\u884c\u7684\u5199\u64cd\u4f5c\u6c38\u8fdc\u90fd\u4e0d\u4f1a\u963b\u585e\u3002\u8fdb\u7a0b\u8c03\u7528 read \u51fd\u6570\u4ece\u5957\u63a5\u5b57\u4e0a\u8bfb\u53d6\u6570\u636e\uff0c\u5f53\u5957\u63a5\u5b57\u7684\u63a5\u6536\u7f13\u51b2\u533a\u4e2d\u8fd8\u6ca1\u6709\u6570\u636e\u53ef\u8bfb\uff0c\u51fd\u6570 read \u5c06\u53d1\u751f\u963b\u585e\u3002\u963b\u585eI\/O \u6a21\u5f0f\u662f\u6700\u666e\u904d\u4f7f\u7528\u7684 I\/O \u6a21\u5f0f\uff0c\u5927\u90e8\u5206\u7a0b\u5e8f\u4f7f\u7528\u7684\u90fd\u662f\u963b\u585e\u6a21\u5f0f\u7684 I\/O\uff1b\u5f53\u6211\u4eec\u5c06\u4e00\u4e2a\u5957\u63a5\u5b57\u8bbe\u7f6e\u4e3a\u975e\u963b\u585e\u6a21\u5f0f\uff0c\u6211\u4eec\u76f8\u5f53\u4e8e\u544a\u8bc9\u4e86\u7cfb\u7edf\u5185\u6838\uff1a\u201c\u5f53\u6211\u8bf7\u6c42\u7684I\/O \u64cd\u4f5c\u4e0d\u80fd\u591f\u9a6c\u4e0a\u5b8c\u6210\uff0c\u4f60\u60f3\u8ba9\u6211\u7684\u8fdb\u7a0b\u8fdb\u884c\u4f11\u7720\u7b49\u5f85\u7684\u65f6\u5019\uff0c\u4e0d\u8981\u8fd9\u4e48\u505a\uff0c\u8bf7\u9a6c\u4e0a\u8fd4\u56de\u4e00\u4e2a\u9519\u8bef\u7ed9\u6211\u3002_\u91c7\u7528\u7684\u7ebf\u7a0b\u6a21\u578b\u53caio\u590d\u7528\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.wsisp.com\/helps\/24360.html\" \/>\n<meta property=\"og:site_name\" content=\"\u7f51\u7855\u4e92\u8054\u5e2e\u52a9\u4e2d\u5fc3\" \/>\n<meta property=\"article:published_time\" content=\"2025-04-19T01:56:30+00:00\" \/>\n<meta property=\"og:image\" content=\"https:\/\/www.wsisp.com\/helps\/wp-content\/uploads\/2025\/04\/20250419015628-680302cca3205.png\" \/>\n<meta name=\"author\" content=\"admin\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:label1\" content=\"\u4f5c\u8005\" \/>\n\t<meta name=\"twitter:data1\" content=\"admin\" \/>\n\t<meta name=\"twitter:label2\" content=\"\u9884\u8ba1\u9605\u8bfb\u65f6\u95f4\" \/>\n\t<meta name=\"twitter:data2\" content=\"11 \u5206\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\/\/schema.org\",\"@graph\":[{\"@type\":\"WebPage\",\"@id\":\"https:\/\/www.wsisp.com\/helps\/24360.html\",\"url\":\"https:\/\/www.wsisp.com\/helps\/24360.html\",\"name\":\"\u3010\u7f51\u7edc\u7f16\u7a0b\u3011\u670d\u52a1\u5668\u6a21\u578b\uff08\u4e8c\uff09\uff1a\u5e76\u53d1\u670d\u52a1\u5668\u6a21\u578b\uff08\u591a\u7ebf\u7a0b\uff09\u548c I\/O \u590d\u7528\u670d\u52a1\u5668\uff08select \/ epoll\uff09 - 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