IO复用之poll

 #include <poll.h>
int poll(struct pollfd *fds, nfds_t nfds, int timeout);

参数：
fds：监听事件结构体数组
nfds：监听事件结构体数组长度
timeout：等于-1：一直阻塞
等于0：立即返回
大于0：等待超时时间，单位毫秒
返回值：
出错：返回-1
超时：返回0
成功：返回生效监听事件个数

struct pollfd {
    int fd;
    short events;
    short revents;
};

fd：监听文件描述符
events：监听事件集合
revents：返回事件集合结果

#define POLLIN      0x0001
#define POLLPRI     0x0002
#define POLLOUT     0x0004
#define POLLERR     0x0008
#define POLLHUP     0x0010
#define POLLNVAL    0x0020
#define POLLRDNORM  0x0040
#define POLLRDBAND  0x0080
#define POLLWRNORM  0x0100
#define POLLWRBAND  0x0200
#define POLLMSG     0x0400
#define POLLREMOVE  0x1000
#define POLLRDHUP   0x2000
#define POLLFREE    0x4000
#define POLL_BUSY_LOOP 0x8000

#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <stdlib.h>
#include <fcntl.h>
#include <poll.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#define LISTEN_BACKLOG (5)
#define BUF_SIZE (1500)
#define ACK_STR "ack ok"
#define FD_NUM (2)
void usage(void) {
    printf("*********************************\n");
    printf("./server 本端ip 本端端口\n");
    printf("*********************************\n");
}
int main(int argc, char *argv[]){
    struct sockaddr_in local;
    struct sockaddr_in peer;
    int sock_fd = 0, new_fd = 0;
    int ret = 0;
    socklen_t addrlen = 0;
    char send_buf[BUF_SIZE] = {0};
    char recv_buf[BUF_SIZE] = {0};
if (argc != 3) {
    usage();
    return -1;
}
char *ip = argv[1];
unsigned short port = atoi(argv[2]);
printf("ip:port->%s:%u\n", argv[1], port);
sock_fd = socket(AF_INET, SOCK_STREAM, 0);
if (sock_fd == -1) {
    perror("socket error");
    return -1;
}
memset(&local, 0, sizeof(struct sockaddr_in));
local.sin_family = AF_INET;
local.sin_addr.s_addr = inet_addr(ip);
local.sin_port = htons(port);
ret = bind(sock_fd, (struct sockaddr *)&local, sizeof(struct sockaddr));
if (ret == -1) {
    close(sock_fd);
    perror("bind error");
    return -1;
}
ret = listen(sock_fd, LISTEN_BACKLOG);
if (ret == -1) {
    close(sock_fd);
    perror("listen error");
    return -1;
}
struct pollfd fds[FD_NUM] = {0};
//添加监听套接字至监听事件数组    fds[0] = (struct pollfd) { .fd = sock_fd, .events = POLLIN };
nfds_t nfds = 1;
//设置超时事件    int timeout = 2000;
while (1) {
    ret = poll(fds, nfds, timeout);
    if (ret == -1) {
        perror("poll error");
        break;
    } else if (ret == 0) {
        printf("poll timeout\n");
        continue;
    } else {
        }
for (int i = 0; i < nfds; i++) {
    if (fds[i].fd == sock_fd) {
        if (fds[i].revents & POLLIN) {
            addrlen = sizeof(peer);
            new_fd = accept(sock_fd, (struct sockaddr *)&peer, &addrlen);
            if (new_fd == -1) {
                perror("accept error");
                continue;
            }
if (nfds >= FD_NUM) {
    printf("out of fd num error\n");
    close(new_fd);
} else {
    printf("accept succes new fd:%d\n", new_fd);
    for (int i = 0; i < FD_NUM; i++) {
        if (fds[i].fd == 0) {
            printf("add pos:%d, pollfd:%d\n", i, new_fd);
            //添加新套接字至监听事件数组                                fds[i] = (struct pollfd) {.fd = new_fd, .events = POLLIN};
            nfds++;
            break;
        }
    }
}
}
} else {
if (fds[i].revents & POLLIN) {
    memset(recv_buf, 0, BUF_SIZE);
    ret = recv(fds[i].fd, recv_buf, BUF_SIZE, 0);
    if (ret <= 0) {
        printf("remove pos:%d, fd:%d\n", i, fds[i].fd);
        close(fds[i].fd);
        //从监听事件数组中移除套接字                        fds[i] = (struct pollfd){0};
        nfds--;
    } else {
        printf("recv pos:%d, fd:%d, len:%d, %s\n", i, fds[i].fd, ret, recv_buf);
    }
}
}
}
}
for (int i = 0; i < nfds; i++) {
    if (fds[i].fd > 0) {
        close(fds[i].fd);
    }
}
    return 0;}

#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <stdlib.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#define LISTEN_BACKLOG (5)
#define BUF_SIZE (1500)
#define REQUEST_STR "tcp pack"
void usage(void) {
    printf("*********************************\n");
    printf("./client 对端ip 对端端口\n");
    printf("*********************************\n");
}
int main(int argc, char *argv[]){
    struct sockaddr_in client;
    struct sockaddr_in server;
    int sock_fd = 0;
    int ret = 0;
    socklen_t addrlen = 0;
    char send_buf[BUF_SIZE] = {0};
    char recv_buf[BUF_SIZE] = {0};
if (argc != 3) {
    usage();
    return -1;
}
char *ip = argv[1];
unsigned short port = atoi(argv[2]);
printf("ip:port->%s:%u\n", argv[1], port);
sock_fd = socket(AF_INET, SOCK_STREAM, 0);
if (sock_fd == -1) {
    perror("socket error");
    return -1;
}
memset(&server, 0, sizeof(struct sockaddr_in));
server.sin_family = AF_INET;
server.sin_addr.s_addr = inet_addr(ip);
server.sin_port = htons(port);
ret = connect(sock_fd, (struct sockaddr *)&server, sizeof(struct sockaddr));
if (ret == -1) {
    close(sock_fd);
    perror("connect error");
    return -1;
}
int seq = 0;
while(1) {
    memset(send_buf, 0, BUF_SIZE);
    sprintf(send_buf, "%s:%d", REQUEST_STR, seq++);
    send(sock_fd, send_buf, strlen(send_buf), 0);
    printf("send %s\n", send_buf);
    sleep(5);
}
    close(sock_fd);
    return 0;}