/*

 * copied from http://devarea.com/linux-io-multiplexing-select-vs-poll-vs-epoll/#.W1GZ0vkzZaQ

 */

#include <arpa/inet.h>

#include <errno.h>

#include <netinet/in.h>

#include <signal.h>

#include <stdio.h>

#include <stdlib.h>

#include <sys/select.h>

#include <sys/time.h>

#include <sys/types.h>

#include <unistd.h>

#include <wait.h>

#include <string.h>

// include poll header file

#include <sys/poll.h>

// include epoll header file

#include <sys/epoll.h>

#define MAXBUF 256

void child_process(void)

{

    sleep(2);

    char msg[MAXBUF];

    struct sockaddr_in addr = {0};

    int n, sockfd,num=1;

    srandom(getpid());

    /* Create socket and connect to server */

    sockfd = socket(AF_INET, SOCK_STREAM, 0);

    addr.sin_family = AF_INET;

    addr.sin_port = htons(2000);

    addr.sin_addr.s_addr = inet_addr("127.0.0.1");

    connect(sockfd, (struct sockaddr*)&addr, sizeof(addr));

    printf("child {%d} connected \n", getpid());

    while(1){

        int sl = (random() % 10 ) +  1;

        num++;

        sleep(sl);

        sprintf (msg, "Test message %d from client %d", num, getpid());

        n = write(sockfd, msg, strlen(msg));    /* Send message */

    }

}

int main()

{

    char buffer[MAXBUF];

    int fds[5];

    struct pollfd pollfds[5];

    struct epoll_event events[5];

    int epfd = epoll_create(10);

    struct sockaddr_in addr;

    struct sockaddr_in client;

    int addrlen, n,i,max=0;;

    int sockfd, commfd;

    int nfds;

    fd_set rset;

    for(i=0;i<5;i++)

    {

        if(fork() == 0)

        {

            child_process();

            exit(0);

        }

    }

    sockfd = socket(AF_INET, SOCK_STREAM, 0);

    memset(&addr, 0, sizeof (addr));

    addr.sin_family = AF_INET;

    addr.sin_port = htons(2000);

    addr.sin_addr.s_addr = INADDR_ANY;

    bind(sockfd,(struct sockaddr*)&addr ,sizeof(addr));

    listen (sockfd, 5); 

    // epoll

    for (i=0;i<5;i++)

    {

        static struct epoll_event ev;

        memset(&client, 0, sizeof (client));

        addrlen = sizeof(client);

        ev.data.fd = accept(sockfd,(struct sockaddr*)&client, (socklen_t *)&addrlen);

        ev.events = EPOLLIN;

        epoll_ctl(epfd, EPOLL_CTL_ADD, ev.data.fd, &ev);

    }

    while(1){

        puts("round again");

        nfds = epoll_wait(epfd, events, 5, 10000);

        for(i=0;i<nfds;i++) {

            memset(buffer,0,MAXBUF);

            read(events[i].data.fd, buffer, MAXBUF);

            puts(buffer);

        }

    }

    /* poll

    for (i=0;i<5;i++)

    {

        memset(&client, 0, sizeof (client));

        addrlen = sizeof(client);

        pollfds[i].fd = accept(sockfd,(struct sockaddr*)&client, (socklen_t *)&addrlen);

        pollfds[i].events = POLLIN;

    }

    sleep(1);

    while(1){

        puts("round again");

        poll(pollfds, 5, 50000);

        for(i=0;i<5;i++) {

            if (pollfds[i].revents & POLLIN){

                pollfds[i].revents = 0;

                memset(buffer,0,MAXBUF);

                read(pollfds[i].fd, buffer, MAXBUF);

                puts(buffer);

            }

        }

    }

    */

    /* select

    for (i=0;i<5;i++)

    {

        memset(&client, 0, sizeof (client));

        addrlen = sizeof(client);

        fds[i] = accept(sockfd,(struct sockaddr*)&client, (socklen_t *)&addrlen);

        if(fds[i] > max)

            max = fds[i];

    }

    while(1){

        FD_ZERO(&rset);

        for (i = 0; i< 5; i++ ) {

            FD_SET(fds[i],&rset);

        }

        puts("round again");

        select(max+1, &rset, NULL, NULL, NULL);

        for(i=0;i<5;i++) {

            if (FD_ISSET(fds[i], &rset)){

                memset(buffer,0,MAXBUF);

                read(fds[i], buffer, MAXBUF);

                puts(buffer);

            }

        }

    }

    */

    return 0;

}