C/C++ select 与epoll 服务器客户端多线程传送udp数据

// Server side implementation of UDP client-server model
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/select.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <sys/epoll.h>
#define MAXLINE 1024
#include <thread>
// Driver code

#define n_ports  3
int ports []= {8080,8081,8082};

void select_server() {
    char buffer[MAXLINE];
    struct sockaddr_in cliaddr;
    memset(&cliaddr, 0, sizeof(cliaddr));


    int sockfds[n_ports];
    socklen_t len= sizeof(cliaddr);
    int n;
    fd_set readset;
    int max_fd=0;
    for(int i =0 ;i<n_ports;++i){

        int sockfd;
        struct sockaddr_in servaddr;
        memset(&servaddr, 0, sizeof(servaddr));

        // Filling server information
        servaddr.sin_family    = AF_INET; // IPv4
        servaddr.sin_addr.s_addr = INADDR_ANY;
        servaddr.sin_port = htons(ports[i]);
        // Creating socket file descriptor
        if ( (sockfd = socket(AF_INET, SOCK_DGRAM, 0)) < 0 ) {
            perror("socket creation failed");
            exit(EXIT_FAILURE);
        }

        // Bind the socket with the server address
        if ( bind(sockfd, (const struct sockaddr *)&servaddr,sizeof(servaddr)) < 0 )
        {
            perror("bind failed");
            exit(EXIT_FAILURE);
        }
        sockfds[i] = sockfd;
        max_fd = (sockfd>max_fd)?sockfd:max_fd;
    }


    printf("server begin\n");
    while(true){

        FD_ZERO(&readset);
        for(int i=0;i<n_ports;++i)
            FD_SET(sockfds[i],&readset);
        int ret = select(max_fd+1,&readset,NULL,NULL,NULL);
        if (ret == -1){
            printf("error");
            continue;
        }
        else{
            for(int i=0;i<n_ports;++i)
                if (FD_ISSET(sockfds[i],&readset)){
                    n = recvfrom(sockfds[i], (char *)buffer, MAXLINE,
                        MSG_WAITALL, ( struct sockaddr *) &cliaddr,&len);
                    buffer[n] = '\0';
                    printf("Server recive  : %s\n", buffer);
                }
        }
    }
}
void epoll_server(){
    char buffer[MAXLINE];
    struct sockaddr_in cliaddr;
    socklen_t len= sizeof(cliaddr);
    memset(&cliaddr, 0, sizeof(cliaddr));


    struct epoll_event epoll_events[n_ports];
    int n;

    int epollfd = epoll_create(1024);

    for(int i =0 ;i<n_ports;++i){

        int sockfd;
        struct sockaddr_in servaddr;
        memset(&servaddr, 0, sizeof(servaddr));

        // Filling server information
        servaddr.sin_family    = AF_INET; // IPv4
        servaddr.sin_addr.s_addr = INADDR_ANY;
        servaddr.sin_port = htons(ports[i]);
        // Creating socket file descriptor
        if ( (sockfd = socket(AF_INET, SOCK_DGRAM, 0)) < 0 ) {
            perror("socket creation failed");
            exit(EXIT_FAILURE);
        }

        // Bind the socket with the server address
        if ( bind(sockfd, (const struct sockaddr *)&servaddr,sizeof(servaddr)) < 0 )
        {
            perror("bind failed");
            exit(EXIT_FAILURE);
        }
        epoll_events[i].events = EPOLLIN;
        epoll_events[i].data.fd = sockfd;
        epoll_ctl(epollfd,EPOLL_CTL_ADD,sockfd,&epoll_events[i]);
    }

    struct epoll_event events_in[n_ports];
    while (true){
        int event_count = epoll_wait(epollfd,events_in,16,-1);
        for(int i=0;i<event_count;++i){
            if(events_in[i].events &EPOLLIN){
                int new_fd = events_in[i].data.fd;
                n = recvfrom(new_fd, (char *)buffer, MAXLINE,
                MSG_WAITALL, ( struct sockaddr *) &cliaddr,&len);
                buffer[n] = '\0';
                printf("Server recive  : %s\n", buffer);
            }

        }

    }
}

void client(int port) {
    int sockfd;
    struct sockaddr_in     servaddr;
    memset(&servaddr, 0, sizeof(servaddr));
    // Filling server information
    servaddr.sin_family = AF_INET;
    servaddr.sin_port = htons(port);
    servaddr.sin_addr.s_addr = INADDR_ANY;

    // Creating socket file descriptor
    if ( (sockfd = socket(AF_INET, SOCK_DGRAM, 0)) < 0 ) {
        perror("socket creation failed");
        exit(EXIT_FAILURE);
    }


    char write_buf[1024];
    for(int i=0;i<1000;++i){
        sprintf(write_buf,"Client:%d say %d",port,i);
        printf("%s\n",write_buf);
        sendto(sockfd, write_buf, strlen(write_buf),
            MSG_CONFIRM, (const struct sockaddr *) &servaddr,
            sizeof(servaddr));
        sleep(1);
    }
    close(sockfd);
}
int main(){
    //std::thread ta(select_server);
    std::thread ta(epoll_server);
    std::thread tb(client,8080);
    std::thread tc(client,8081);
    std::thread td(client,8082);
    ta.join();
    tb.join();
    tc.join();
    td.join();
    return 0;
}