\u5728Linux\u7f51\u7edc\u7f16\u7a0b\u4e2d，\u5982\u4f55\u9ad8\u6548\u5730\u7ba1\u7406\u591a\u4e2a\u5ba2\u6237\u7aef\u8fde\u63a5\u662f\u4e00\u4e2a\u6838\u5fc3\u95ee\u9898\u3002\u65e9\u671f\u4f7f\u7528select，\u4f46\u5b83\u6709\u8bf8\u591a\u9650\u5236，\u4e8e\u662fpoll\u5e94\u8fd0\u800c\u751f\u3002\u672c\u6587\u5c06\u5e26\u4f60\u5168\u9762\u4e86\u89e3poll\u7684\u5de5\u4f5c\u539f\u7406\u3001\u4f7f\u7528\u65b9\u6cd5，\u5e76\u4e0eselect\u8fdb\u884c\u5bf9\u6bd4，\u5e2e\u52a9\u4f60\u5728\u5b9e\u9645\u5f00\u53d1\u4e2d\u505a\u51fa\u6b63\u786e\u9009\u62e9\u3002<\/p>\n
\u5f53\u6211\u4eec\u7f16\u5199\u4e00\u4e2aTCP\u670d\u52a1\u5668\u65f6，\u901a\u5e38\u9700\u8981\u540c\u65f6\u5904\u7406\u591a\u4e2a\u5ba2\u6237\u7aef\u5957\u63a5\u5b57\u3002\u6700\u7b80\u5355\u7684\u505a\u6cd5\u662f\u4f7f\u7528\u591a\u7ebf\u7a0b\u6216\u591a\u8fdb\u7a0b，\u4f46\u6bcf\u4e2a\u8fde\u63a5\u90fd\u521b\u5efa\u4e00\u4e2a\u7ebf\u7a0b\u6216\u8fdb\u7a0b\u4f1a\u6d88\u8017\u5927\u91cf\u7cfb\u7edf\u8d44\u6e90，\u5c24\u5176\u5728\u9ad8\u5e76\u53d1\u573a\u666f\u4e0b\u4e0d\u582a\u91cd\u8d1f\u3002<\/p>\n
I\/O\u591a\u8def\u590d\u7528\u6280\u672f\u5141\u8bb8\u4e00\u4e2a\u8fdb\u7a0b\u540c\u65f6\u76d1\u89c6\u591a\u4e2a\u6587\u4ef6\u63cf\u8ff0\u7b26，\u5f53\u5176\u4e2d\u4efb\u4f55\u4e00\u4e2a\u51c6\u5907\u597d\u8fdb\u884cI\/O\u64cd\u4f5c\u65f6，\u8fdb\u7a0b\u5c31\u4f1a\u5f97\u5230\u901a\u77e5\u3002select\u662f\u65e9\u671f\u7684\u89e3\u51b3\u65b9\u6848，\u4f46\u5b83\u5b58\u5728\u4e24\u4e2a\u81f4\u547d\u7f3a\u9677：<\/p>\n
\u6700\u5927\u6587\u4ef6\u63cf\u8ff0\u7b26\u6570\u91cf\u9650\u5236：\u901a\u5e38\u4e3a1024（\u7531FD_SETSIZE\u51b3\u5b9a），\u65e0\u6cd5\u5e94\u5bf9\u5927\u89c4\u6a21\u5e76\u53d1\u3002<\/p>\n<\/li>\n
\u6548\u7387\u4f4e\u4e0b：\u6bcf\u6b21\u8c03\u7528\u90fd\u9700\u8981\u5c06\u6574\u4e2afd_set\u4ece\u7528\u6237\u6001\u62f7\u8d1d\u5230\u5185\u6838\u6001，\u4e14\u5185\u6838\u91c7\u7528\u8f6e\u8be2\u65b9\u5f0f\u626b\u63cf\u6240\u6709\u63cf\u8ff0\u7b26，\u968f\u7740\u6570\u91cf\u589e\u52a0\u6027\u80fd\u6025\u5267\u4e0b\u964d\u3002<\/p>\n<\/li>\n<\/ul>\n
poll\u6b63\u662f\u4e3a\u4e86\u6539\u8fdbselect\u800c\u751f，\u5b83\u6d88\u9664\u4e86\u6587\u4ef6\u63cf\u8ff0\u7b26\u4e0a\u9650，\u5e76\u91c7\u7528\u66f4\u7075\u6d3b\u7684\u6570\u636e\u7ed3\u6784，\u4e3a\u540e\u7eed\u7684epoll\u94fa\u5e73\u4e86\u9053\u8def\u3002<\/p>\n
#include <poll.h><\/p>\n
int poll(struct pollfd *fds, nfds_t nfds, int timeout);<\/p>\n
fds：\u6307\u5411struct pollfd\u6570\u7ec4\u7684\u6307\u9488，\u8be5\u6570\u7ec4\u63cf\u8ff0\u4e86\u8981\u76d1\u89c6\u7684\u6240\u6709\u6587\u4ef6\u63cf\u8ff0\u7b26\u53ca\u5176\u4e8b\u4ef6\u3002<\/p>\n<\/li>\n
nfds：\u6570\u7ec4\u4e2d\u5143\u7d20\u7684\u4e2a\u6570，\u5373\u8981\u76d1\u89c6\u7684\u6587\u4ef6\u63cf\u8ff0\u7b26\u603b\u6570\u3002<\/p>\n<\/li>\n
timeout：\u8d85\u65f6\u65f6\u95f4（\u6beb\u79d2）\u3002<\/p>\n
-1：\u963b\u585e\u7b49\u5f85，\u76f4\u5230\u6709\u4e8b\u4ef6\u53d1\u751f\u3002<\/p>\n<\/li>\n
0：\u7acb\u5373\u8fd4\u56de，\u4e0d\u963b\u585e\u3002<\/p>\n<\/li>\n
>0：\u7b49\u5f85\u6307\u5b9a\u7684\u6beb\u79d2\u6570，\u8d85\u65f6\u5219\u8fd4\u56de0\u3002<\/p>\n<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
\u6210\u529f\u65f6，\u8fd4\u56de\u53d1\u751f\u4e8b\u4ef6\u7684\u6587\u4ef6\u63cf\u8ff0\u7b26\u4e2a\u6570（revents\u4e0d\u4e3a0\u7684\u6761\u76ee\u6570）\u3002<\/p>\n<\/li>\n
\u8d85\u65f6\u8fd4\u56de0\u3002<\/p>\n<\/li>\n
\u51fa\u9519\u8fd4\u56de-1，\u5e76\u8bbe\u7f6eerrno\u3002<\/p>\n<\/li>\n<\/ul>\n
poll\u4e0d\u4f7f\u7528\u6587\u4ef6\u63cf\u8ff0\u7b26\u96c6\u5408fd_set（\u4f4d\u6570\u7ec4）\u6765\u8868\u793a\u8981\u68c0\u6d4b\u7684\u6587\u4ef6\u63cf\u8ff0\u7b26（\u5957\u63a5\u5b57） \u800c\u662f\u4f7f\u7528struct pollfd\u7ed3\u6784\u4f53\u6570\u7ec4，\u6bcf\u4e2a\u7ed3\u6784\u4f53\u6210\u5458\u8868\u793a\u4e00\u4e2a\u8981\u68c0\u6d4b\u7684\u6587\u4ef6\u63cf\u8ff0\u7b26\u3002<\/p>\n
struct pollfd {
\n int fd; \/\/ \u8981\u76d1\u89c6\u7684\u6587\u4ef6\u63cf\u8ff0\u7b26
\n short events; \/\/ \u611f\u5174\u8da3\u7684\u4e8b\u4ef6（\u8f93\u5165）
\n short revents; \/\/ \u5b9e\u9645\u53d1\u751f\u7684\u4e8b\u4ef6（\u8f93\u51fa）
\n};<\/p>\n
events\u5b57\u6bb5\u662f\u7531\u7528\u6237\u8bbe\u7f6e\u7684\u4f4d\u63a9\u7801，\u5e38\u89c1\u6807\u5fd7\u6709：<\/p>\n
POLLIN：\u6709\u6570\u636e\u53ef\u8bfb<\/p>\n<\/li>\n
POLLOUT：\u53ef\u4ee5\u5199\u5165\u6570\u636e<\/p>\n<\/li>\n
POLLERR：\u53d1\u751f\u9519\u8bef（\u4ec5\u51fa\u73b0\u5728revents）<\/p>\n<\/li>\n
POLLRDHUP：\u5bf9\u7aef\u5173\u95ed\u8fde\u63a5（\u9700\u5b9a\u4e49_GNU_SOURCE）<\/p>\n<\/li>\n<\/ul>\n<\/li>\n
revents\u7531\u5185\u6838\u586b\u5145，\u8fd4\u56de\u5b9e\u9645\u89e6\u53d1\u7684\u4e8b\u4ef6，\u53ef\u80fd\u5305\u542bPOLLERR\u3001POLLHUP\u7b49\u5f02\u5e38\u4e8b\u4ef6\u3002<\/p>\n<\/li>\n<\/ul>\n
\u4e0b\u9762\u662f\u4e00\u4e2a\u5b8c\u6574\u7684poll\u670d\u52a1\u5668\u793a\u4f8b，\u5b83\u80fd\u591f\u540c\u65f6\u5904\u7406\u6700\u591aCLIENT_MAX\u4e2a\u5ba2\u6237\u7aef\u8fde\u63a5\u3002<\/p>\n
\u521b\u5efa\u76d1\u542c\u5957\u63a5\u5b57，\u7ed1\u5b9a\u5e76\u76d1\u542c\u7aef\u53e3\u3002<\/p>\n<\/li>\n
\u521d\u59cb\u5316pollfd\u6570\u7ec4：\u7b2c\u4e00\u4e2a\u5143\u7d20\u653e\u5165\u76d1\u542c\u5957\u63a5\u5b57，\u5176\u4f59\u521d\u59cb\u5316\u4e3afd = -1\u8868\u793a\u7a7a\u95f2\u3002<\/p>\n<\/li>\n
\u5faa\u73af\u8c03\u7528poll()，\u8fd4\u56de\u540e\u904d\u5386\u6570\u7ec4，\u5904\u7406\u5c31\u7eea\u4e8b\u4ef6\u3002<\/p>\n<\/li>\n
\u4e8b\u4ef6\u5904\u7406：<\/p>\n
\u82e5\u4e3a\u76d1\u542c\u5957\u63a5\u5b57，\u5219accept()\u65b0\u8fde\u63a5，\u5e76\u5c06\u5176\u6dfb\u52a0\u5230\u6570\u7ec4\u7684\u7a7a\u95f2\u69fd\u4f4d\u3002<\/p>\n<\/li>\n
\u82e5\u4e3a\u666e\u901a\u5ba2\u6237\u7aef\u5957\u63a5\u5b57，\u5219\u6839\u636erevents\u8fdb\u884c\u8bfb\u53d6\u3001\u5199\u5165\u6216\u5173\u95ed\u64cd\u4f5c\u3002<\/p>\n<\/li>\n<\/ul>\n<\/li>\n
#define _GNU_SOURCE 1 \/\/ \u5fc5\u987b\u5b9a\u4e49，\u4ee5\u4fbf\u4f7f\u7528 POLLRDHUP<\/p>\n
#include <sys\/types.h>
\n#include <sys\/socket.h>
\n#include <netinet\/in.h>
\n#include <arpa\/inet.h>
\n#include <assert.h>
\n#include <stdio.h>
\n#include <unistd.h>
\n#include <errno.h>
\n#include <string.h>
\n#include <fcntl.h>
\n#include <stdlib.h>
\n#include <poll.h>
\n#include <fcntl.h>
\n#include <sys\/poll.h><\/p>\n
#define CLIENT_MAX 5 \/\/ \u6700\u5927\u652f\u6301\u5ba2\u6237\u7aef\u6570\u91cf<\/p>\n
int main(void) {
\n char buff[BUFSIZ];
\n int server_fd = socket(PF_INET, SOCK_STREAM, 0);<\/p>\n
struct sockaddr_in address;
\n address.sin_family = AF_INET;
\n address.sin_addr.s_addr = htonl(INADDR_ANY);
\n address.sin_port = htons(8000);<\/p>\n
int ret = bind(server_fd, (struct sockaddr*)&address, sizeof(address));
\n if (ret < 0) {
\n perror("bind socket error.\\\\n");
\n exit(-1);
\n }<\/p>\n
listen(server_fd, 5);<\/p>\n
\/\/ \u521d\u59cb\u5316 pollfd \u6570\u7ec4
\n struct pollfd fds[CLIENT_MAX + 1];
\n fds[0].fd = server_fd;
\n fds[0].events = POLLIN | POLLERR; \/\/ \u76d1\u542c\u8bfb\u4e8b\u4ef6\u548c\u9519\u8bef
\n fds[0].revents = 0;<\/p>\n
int user_counter = 0; \/\/ \u5f53\u524d\u5df2\u8fde\u63a5\u7684\u5ba2\u6237\u7aef\u6570\u91cf
\n for (int i = 1; i <= CLIENT_MAX; ++i) {
\n fds[i].fd = -1;
\n fds[i].events = 0;
\n }<\/p>\n
while (1) {
\n int cur_count = user_counter + 1; \/\/ \u6570\u7ec4\u6709\u6548\u5143\u7d20\u4e2a\u6570（\u670d\u52a1\u5668 + \u5ba2\u6237\u7aef）
\n printf("poll: ");
\n for (int i = 0; i < cur_count; i++) {
\n printf("%d ", fds[i].fd);
\n }
\n printf("\\\\n");<\/p>\n
ret = poll(fds, cur_count, -1); \/\/ \u6c38\u4e45\u7b49\u5f85
\n if (ret < 0) {
\n printf("poll failure\\\\n");
\n break;
\n }<\/p>\n
\/\/ \u904d\u5386\u6240\u6709\u88ab\u76d1\u89c6\u7684\u6587\u4ef6\u63cf\u8ff0\u7b26
\n for (int i = 0; i < cur_count; ++i) {
\n \/\/ —– 1. \u5904\u7406\u670d\u52a1\u5668\u5957\u63a5\u5b57：\u6709\u65b0\u7684\u5ba2\u6237\u7aef\u8fde\u63a5 —–
\n if ((fds[i].fd == server_fd) && (fds[i].revents & POLLIN)) {
\n struct sockaddr_in client_address;
\n int client_addrlength = sizeof(client_address);
\n int connfd = accept(server_fd, (struct sockaddr*)&client_address,
\n &client_addrlength);
\n if (connfd < 0) {
\n perror("accept failed.");
\n continue;
\n }
\n if (user_counter >= CLIENT_MAX) {
\n printf("\u5ba2\u6237\u7aef\u8fde\u63a5\u6570\u5df2\u8fbe\u4e0a\u9650：%d\\\\n", CLIENT_MAX);
\n close(connfd);
\n continue;
\n }
\n user_counter++;
\n fds[user_counter].fd = connfd;
\n fds[user_counter].events = POLLIN | POLLRDHUP | POLLERR;
\n fds[user_counter].revents = 0;
\n printf("\u6dfb\u52a0\u65b0\u7684\u5ba2\u6237\u7aef，\u73b0\u5728\u4e00\u5171\u76d1\u542c%d\u4e2a\u5ba2\u6237\u7aef\\\\n", user_counter);
\n }
\n \/\/ —– 2. \u5904\u7406\u9519\u8bef\u4e8b\u4ef6 —–
\n else if (fds[i].revents & POLLERR) {
\n printf("get an error from %d\\\\n", fds[i].fd);
\n char errors[256];
\n memset(errors, 0, sizeof(errors));
\n socklen_t length = sizeof(errors);
\n if (getsockopt(fds[i].fd, SOL_SOCKET, SO_ERROR, &errors, &length) < 0) {
\n printf("get socket option failed\\\\n");
\n } else {
\n printf("error: %s\\\\n", errors);
\n }
\n continue;
\n }
\n \/\/ —– 3. \u5904\u7406\u5ba2\u6237\u7aef\u5173\u95ed（\u5bf9\u7aef\u6302\u65ad）—–
\n else if (fds[i].revents & POLLRDHUP) {
\n close(fds[i].fd);
\n printf("\u5ba2\u6237\u7aef(%d)\u5173\u95ed\\\\n", fds[i].fd);
\n if (i < user_counter) {
\n \/\/ \u7528\u6570\u7ec4\u5c3e\u90e8\u5143\u7d20\u8986\u76d6\u5f53\u524d\u4f4d\u7f6e，\u7136\u540e\u51cf\u5c11\u8ba1\u6570
\n fds[i] = fds[user_counter];
\n i–; \/\/ \u7ee7\u7eed\u68c0\u67e5\u5f53\u524d\u4f4d\u7f6e（\u56e0\u4e3a\u6362\u5165\u4e86\u65b0fd）
\n }
\n user_counter–;
\n }
\n \/\/ —– 4. \u5904\u7406\u666e\u901a\u53ef\u8bfb\u4e8b\u4ef6 —–
\n else if (fds[i].revents & POLLIN) {
\n int connfd = fds[i].fd;
\n ret = read(connfd, buff, sizeof(buff));
\n if (ret <= 0) {
\n if (ret < 0) perror("read failed.");
\n close(connfd);
\n if (i < user_counter) {
\n fds[i] = fds[user_counter];
\n i–;
\n }
\n user_counter–;
\n } else {
\n printf("\u4ece\u5ba2\u6237\u7aef(%d)\u8bfb\u5230%d\u4e2a\u5b57\u8282：%s\\\\n", connfd, ret, buff);
\n \/\/ \u4e1a\u52a1\u5904\u7406：\u8fd4\u56de\u5b57\u7b26\u4e32\u957f\u5ea6
\n sprintf(buff, "LEN = %zd", strlen(buff));
\n write(connfd, buff, strlen(buff) + 1);
\n }
\n }
\n }
\n }
\n close(server_fd);
\n return 0;
\n}<\/p>\n
#include <sys\/types.h>
\n#include <sys\/socket.h>
\n#include <stdio.h>
\n#include <netinet\/in.h>
\n#include <arpa\/inet.h>
\n#include <unistd.h>
\n#include <stdlib.h>
\n#include <string.h><\/p>\n
#define BUFSIZE 1024<\/p>\n
int main() {
\n \/\/ \u521b\u5efa\u5ba2\u6237\u7aef\u5957\u63a5\u5b57
\n int sockfd = socket(AF_INET, SOCK_STREAM, 0);
\n if (sockfd < 0) {
\n perror("socket failed.");
\n exit(1);
\n }<\/p>\n
\/\/ \u8bbe\u7f6e\u670d\u52a1\u5668\u5730\u5740
\n struct sockaddr_in address;
\n address.sin_family = AF_INET;
\n address.sin_addr.s_addr = inet_addr("127.0.0.1");
\n address.sin_port = htons(8000);<\/p>\n
int ret = connect(sockfd, (struct sockaddr*)&address, sizeof(address));
\n if (ret == -1) {
\n perror("connect failed.");
\n exit(1);
\n }<\/p>\n
\/\/ \u63a5\u6536\u7528\u6237\u8f93\u5165
\n char buff[BUFSIZE];
\n printf("Please input: ");
\n fgets(buff, sizeof(buff), stdin);
\n buff[strlen(buff) – 1] = 0; \/\/ \u53bb\u6389\u6362\u884c\u7b26<\/p>\n
\/\/ \u5411\u670d\u52a1\u5668\u53d1\u9001\u6570\u636e
\n write(sockfd, buff, strlen(buff) + 1);<\/p>\n
\/\/ \u8bfb\u53d6\u670d\u52a1\u5668\u53d1\u56de\u7684\u6570\u636e
\n read(sockfd, buff, sizeof(buff));
\n printf("Received: %s\\\\n", buff);<\/p>\n
\/\/ \u5173\u95ed\u5957\u63a5\u5b57
\n close(sockfd);
\n return 0;
\n}<\/p>\n
#define _GNU_SOURCE 1<\/p>\n
POLLRDHUP\u00a0\u662f GNU \u6269\u5c55，\u7528\u4e8e\u68c0\u6d4b\u5bf9\u7aef\u662f\u5426\u5173\u95ed\u4e86\u8fde\u63a5（\u76f8\u5f53\u4e8e TCP \u7684 FIN）\u3002\u5fc5\u987b\u5b9a\u4e49\u6b64\u5b8f\u624d\u80fd\u4f7f\u7528\u8be5\u4e8b\u4ef6\u6807\u5fd7\u3002<\/p>\n
\u5934\u6587\u4ef6\u5305\u542b\u4e86\u7f51\u7edc\u7f16\u7a0b\u548cpoll\u6240\u9700\u7684\u5168\u90e8\u5e93\u3002<\/p>\n
#define CLIENT_MAX 5<\/p>\n
\u9650\u5236\u6700\u5927\u5e76\u53d1\u5ba2\u6237\u7aef\u6570\u4e3a 5，\u65b9\u4fbf\u6f14\u793a，\u5b9e\u9645\u53ef\u8c03\u5927\u3002<\/p>\n
int server_fd = socket(PF_INET, SOCK_STREAM, 0);
\nstruct sockaddr_in address;
\naddress.sin_family = AF_INET;
\naddress.sin_addr.s_addr = htonl(INADDR_ANY);
\naddress.sin_port = htons(8000);
\nbind(server_fd, …);
\nlisten(server_fd, 5);<\/p>\n
\u8fd9\u90e8\u5206\u662f\u6807\u51c6 TCP \u670d\u52a1\u5668\u521d\u59cb\u5316，\u76d1\u542c\u6240\u6709\u7f51\u5361（INADDR_ANY），\u7aef\u53e3 8000\u3002<\/p>\n
struct pollfd fds[CLIENT_MAX + 1];
\nfds[0].fd = server_fd;
\nfds[0].events = POLLIN | POLLERR;
\nfds[0].revents = 0;<\/p>\n
int user_counter = 0;
\nfor (int i = 1; i <= CLIENT_MAX; ++i) {
\n fds[i].fd = -1;
\n fds[i].events = 0;
\n}<\/p>\n
\u6570\u7ec4\u957f\u5ea6\u4e3a\u00a0CLIENT_MAX + 1，\u7d22\u5f15 0 \u56fa\u5b9a\u7ed9\u670d\u52a1\u5668\u5957\u63a5\u5b57，\u5176\u4f59\u7ed9\u5ba2\u6237\u7aef\u3002<\/p>\n<\/li>\n
\u6bcf\u4e2a\u00a0pollfd\u00a0\u7ed3\u6784\u5305\u542b\u4e86\u6587\u4ef6\u63cf\u8ff0\u7b26\u548c\u611f\u5174\u8da3\u7684\u4e8b\u4ef6\u3002\u670d\u52a1\u5668\u53ea\u9700\u76d1\u542c\u00a0POLLIN（\u6709\u8fde\u63a5\u8bf7\u6c42）\u548c\u00a0POLLERR（\u9519\u8bef）\u3002<\/p>\n<\/li>\n
\u672a\u4f7f\u7528\u7684\u69fd\u4f4d\u7f6e\u00a0fd = -1，\u8868\u793a\u65e0\u6548，poll\u00a0\u4f1a\u5ffd\u7565\u3002<\/p>\n<\/li>\n<\/ul>\n
while (1) {
\n int cur_count = user_counter + 1;
\n ret = poll(fds, cur_count, -1);
\n …
\n}<\/p>\n
cur_count\u00a0\u662f\u5f53\u524d\u6709\u6548\u76d1\u89c6\u7684\u63cf\u8ff0\u7b26\u4e2a\u6570，\u5373\u670d\u52a1\u5668（1\u4e2a）+ \u5df2\u8fde\u63a5\u7684\u5ba2\u6237\u7aef\u6570\u3002<\/p>\n<\/li>\n
poll\u00a0\u7b2c\u4e09\u4e2a\u53c2\u6570\u4e3a\u00a0-1，\u8868\u793a\u65e0\u9650\u7b49\u5f85，\u76f4\u5230\u6709\u4e8b\u4ef6\u53d1\u751f\u3002<\/p>\n<\/li>\n
-1\u00a0\u8868\u793a\u65e0\u9650\u963b\u585e，\u4e5f\u5c31\u662f\u201c\u6c38\u8fdc\u7b49\u5f85，\u76f4\u5230\u6709\u4e8b\u4ef6\u53d1\u751f\u201d\u3002<\/p>\n<\/li>\n
\u5f53\u00a0poll\u00a0\u88ab\u8c03\u7528\u65f6，\u5f53\u524d\u7ebf\u7a0b（\u4e3b\u5faa\u73af）\u4f1a\u6682\u505c\u5728\u8fd9\u91cc，\u4e0d\u4f1a\u7ee7\u7eed\u6267\u884c\u540e\u9762\u7684\u4efb\u4f55\u4ee3\u7801\u3002<\/p>\n<\/li>\n
\u5728\u7b49\u5f85\u671f\u95f4，poll\u00a0\u51fd\u6570\u4e0d\u4f1a\u8fd4\u56de，\u56e0\u6b64\u5176\u540e\u9762\u7684\u00a0for\u00a0\u5faa\u73af\u6839\u672c\u4e0d\u4f1a\u88ab\u6267\u884c\u2014\u2014\u56e0\u4e3a\u7a0b\u5e8f\u6ca1\u8d70\u5230\u90a3\u4e00\u6b65\u3002<\/p>\n<\/li>\n<\/ul>\n
if ((fds[i].fd == server_fd) && (fds[i].revents & POLLIN)) {
\n int connfd = accept(…);
\n if (connfd < 0) continue;
\n if (user_counter >= CLIENT_MAX) { close(connfd); continue; }
\n user_counter++;
\n fds[user_counter].fd = connfd;
\n fds[user_counter].events = POLLIN | POLLRDHUP | POLLERR;
\n fds[user_counter].revents = 0;
\n}<\/p>\n
\u5f53\u670d\u52a1\u5668\u5957\u63a5\u5b57\u6709\u53ef\u8bfb\u4e8b\u4ef6\u65f6，\u8bf4\u660e\u6709\u5ba2\u6237\u7aef\u5c1d\u8bd5\u5efa\u7acb\u8fde\u63a5，\u8c03\u7528\u00a0accept\u00a0\u63a5\u53d7\u3002<\/p>\n<\/li>\n
\u5982\u679c\u5ba2\u6237\u7aef\u6570\u91cf\u672a\u8fbe\u4e0a\u9650，\u5c06\u65b0\u5957\u63a5\u5b57\u653e\u5165\u6570\u7ec4\u7684\u4e0b\u4e00\u4e2a\u7a7a\u95f2\u4f4d\u7f6e，\u5e76\u8bbe\u7f6e\u76d1\u542c\u4e8b\u4ef6：<\/p>\n
POLLIN：\u63a5\u6536\u6570\u636e<\/p>\n<\/li>\n
POLLRDHUP：\u68c0\u6d4b\u5ba2\u6237\u7aef\u4e3b\u52a8\u5173\u95ed<\/p>\n<\/li>\n
POLLERR：\u9519\u8bef\u68c0\u6d4b<\/p>\n<\/li>\n<\/ul>\n<\/li>\n
\u6ce8\u610f：\u6570\u7ec4\u7d22\u5f15\u662f\u9012\u589e\u7684，\u4e0d\u4f1a\u590d\u7528\u5df2\u5173\u95ed\u7684\u69fd\u4f4d，\u9664\u975e\u8fdb\u884c\u538b\u7f29（\u89c1\u4e0b\u6587）\u3002<\/p>\n<\/li>\n<\/ul>\n
else if (fds[i].revents & POLLERR) {
\n char errors[256];
\n socklen_t length = sizeof(errors);
\n getsockopt(fds[i].fd, SOL_SOCKET, SO_ERROR, &errors, &length);
\n printf("error: %s\\\\n", errors);
\n continue;
\n}<\/p>\n
\u5f53\u00a0revents\u00a0\u5305\u542b\u00a0POLLERR\u00a0\u65f6，\u901a\u8fc7\u00a0getsockopt\u00a0\u83b7\u53d6\u5177\u4f53\u7684\u9519\u8bef\u4fe1\u606f\u5e76\u6253\u5370，\u7136\u540e\u8df3\u8fc7\u672c\u6b21\u5faa\u73af，\u4e0d\u5173\u95ed\u5957\u63a5\u5b57（\u9519\u8bef\u53ef\u80fd\u4ecd\u53ef\u6062\u590d）\u3002<\/p>\n
else if (fds[i].revents & POLLRDHUP) {
\n close(fds[i].fd);
\n printf("\u5ba2\u6237\u7aef(%d)\u5173\u95ed\\\\n", fds[i].fd);
\n if (i < user_counter) {
\n fds[i] = fds[user_counter];
\n i–;
\n }
\n user_counter–;
\n}<\/p>\n
\u5f53\u68c0\u6d4b\u5230\u5bf9\u7aef\u53d1\u9001 FIN \u65f6，POLLRDHUP\u00a0\u88ab\u89e6\u53d1\u3002<\/p>\n<\/li>\n
\u5173\u95ed\u8be5\u5957\u63a5\u5b57，\u5e76\u4ece\u6570\u7ec4\u4e2d\u79fb\u9664\u3002\u4e3a\u4e86\u4fdd\u6301\u6570\u7ec4\u7d27\u51d1，\u5c06\u6700\u540e\u4e00\u4e2a\u6709\u6548\u5ba2\u6237\u7aef\u79fb\u52a8\u5230\u5f53\u524d\u4f4d\u7f6e，\u7136\u540e\u51cf\u5c11\u00a0user_counter\u3002<\/p>\n<\/li>\n
\u56e0\u4e3a\u79fb\u52a8\u540e\u00a0i\u00a0\u4f4d\u7f6e\u6362\u5165\u4e86\u65b0\u7684\u63cf\u8ff0\u7b26，\u9700\u8981\u00a0i–\u00a0\u4ee5\u4fbf\u4e0b\u6b21\u5faa\u73af\u91cd\u65b0\u68c0\u67e5\u8be5\u4f4d\u7f6e\u3002<\/p>\n<\/li>\n<\/ul>\n
else if (fds[i].revents & POLLIN) {
\n int connfd = fds[i].fd;
\n ret = read(connfd, buff, sizeof(buff));
\n if (ret <= 0) {
\n \/\/ \u8bfb\u53d6\u51fa\u9519\u6216\u5bf9\u7aef\u5173\u95ed，\u5173\u95ed\u5957\u63a5\u5b57\u5e76\u79fb\u9664
\n close(connfd);
\n if (i < user_counter) {
\n fds[i] = fds[user_counter];
\n i–;
\n }
\n user_counter–;
\n } else {
\n \/\/ \u6b63\u5e38\u8bfb\u53d6，\u5904\u7406\u4e1a\u52a1（\u8fd4\u56de\u5b57\u7b26\u4e32\u957f\u5ea6）
\n sprintf(buff, "LEN = %zd", strlen(buff));
\n write(connfd, buff, strlen(buff) + 1);
\n }
\n}<\/p>\n
\u53ef\u8bfb\u4e8b\u4ef6\u610f\u5473\u7740\u6570\u636e\u5230\u8fbe，\u8c03\u7528\u00a0read\u00a0\u8bfb\u53d6\u3002<\/p>\n<\/li>\n
\u5982\u679c\u00a0read\u00a0\u8fd4\u56de \u22640，\u8868\u793a\u8fde\u63a5\u5f02\u5e38\u6216\u5bf9\u65b9\u5173\u95ed，\u5219\u6267\u884c\u5173\u95ed\u548c\u79fb\u9664\u64cd\u4f5c，\u4e0e\u00a0POLLRDHUP\u00a0\u7c7b\u4f3c（\u53cc\u4fdd\u9669）\u3002<\/p>\n<\/li>\n
\u5426\u5219，\u8fdb\u884c\u4e1a\u52a1\u5904\u7406：\u8ba1\u7b97\u63a5\u6536\u5b57\u7b26\u4e32\u7684\u957f\u5ea6\u5e76\u8fd4\u56de\u7ed9\u5ba2\u6237\u7aef\u3002<\/p>\n<\/li>\n<\/ul>\n
| \u6570\u636e\u7ed3\u6784<\/td>\n | struct pollfd\u00a0\u6570\u7ec4，\u6bcf\u4e2a\u63cf\u8ff0\u7b26\u72ec\u7acb\u63cf\u8ff0\u4e8b\u4ef6<\/td>\n | fd_set\u00a0\u4f4d\u6570\u7ec4，\u901a\u8fc7\u4e09\u4e2a\u96c6\u5408\u4f20\u9012\u8bfb\/\u5199\/\u5f02\u5e38<\/td>\n<\/tr>\n |
| \u652f\u6301\u4e8b\u4ef6\u7c7b\u578b<\/td>\n | \u4e30\u5bcc（\u5305\u62ecPOLLRDHUP,\u00a0POLLPRI\u7b49）<\/td>\n | \u4ec5\u4e09\u79cd：\u53ef\u8bfb\u3001\u53ef\u5199\u3001\u5f02\u5e38<\/td>\n<\/tr>\n |
| \u6700\u5927\u76d1\u89c6\u6570<\/td>\n | \u65e0\u786c\u6027\u4e0a\u9650，\u53d7\u7cfb\u7edf\u8d44\u6e90\u9650\u5236<\/td>\n | \u901a\u5e38\u4e3a1024（\u53d7FD_SETSIZE\u9650\u5236）<\/td>\n<\/tr>\n |
| \u6027\u80fd\u7279\u5f81<\/td>\n | \u8f6e\u8be2\u6240\u6709\u63cf\u8ff0\u7b26，O(n)\u590d\u6742\u5ea6，n\u5927\u65f6\u6027\u80fd\u4e0b\u964d<\/td>\n | \u540c\u6837\u8f6e\u8be2，\u4e14\u6bcf\u6b21\u9700\u62f7\u8d1d\u6574\u4e2a\u96c6\u5408，\u5f00\u9500\u66f4\u5927<\/td>\n<\/tr>\n |
| \u5185\u6838\u5b9e\u73b0<\/td>\n | \u4e5f\u662f\u8f6e\u8be2，\u4f46\u672a\u4f7f\u7528\u4f4d\u56fe，\u90e8\u5206\u5b9e\u73b0\u53ef\u80fd\u66f4\u9ad8\u6548<\/td>\n | \u6bcf\u6b21\u8c03\u7528\u5747\u9700\u4ece\u7528\u6237\u6001\u62f7\u8d1d\u5230\u5185\u6838\u6001<\/td>\n<\/tr>\n |
| \u53ef\u79fb\u690d\u6027<\/td>\n | POSIX\u6807\u51c6，\u5e7f\u6cdb\u652f\u6301<\/td>\n | \u51e0\u4e4e\u6240\u6709Unix\/Linux\u7cfb\u7edf\u90fd\u652f\u6301<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n \u7ed3\u8bba：poll\u662fselect\u7684\u589e\u5f3a\u7248，\u89e3\u51b3\u4e86\u63cf\u8ff0\u7b26\u4e0a\u9650\u548c\u4e8b\u4ef6\u7c7b\u578b\u4e0d\u8db3\u7684\u95ee\u9898，\u4f46\u5728\u5927\u89c4\u6a21\u5e76\u53d1\u573a\u666f\u4e0b，\u8f6e\u8be2\u7684\u672c\u8d28\u4f9d\u7136\u5bfc\u81f4\u6027\u80fd\u74f6\u9888\u3002\u56e0\u6b64，poll\u9002\u5408\u8fde\u63a5\u6570\u5728\u51e0\u767e\u5230\u51e0\u5343\u7684\u573a\u5408，\u4e14\u5bf9\u5b9e\u65f6\u6027\u6709\u4e00\u5b9a\u8981\u6c42（\u56e0\u4e3a\u5b83\u652f\u6301\u5fae\u79d2\u7ea7\u8d85\u65f6，\u800cepoll\u4e3a\u6beb\u79d2）\u3002<\/p>\n \n \u4e94\u3001poll\u7684\u9002\u7528\u573a\u666f\u4e0e\u6ce8\u610f\u4e8b\u9879<\/h3>\n
|