Unix网络编程poll模型echo服务器

poll函数和select函数差不多。以下是一个简单的回显服务器



#include <iostream>
using namespace std;
#include <poll.h>
#include <limits.h>

#define OPEN_MAX 64

int main()
{
    int i, maxi, listenfd, connfd, sockfd;
    int nready;
    ssize_t n;
    socklen_t clilen;
    struct pollfd client[OPEN_MAX];
    struct sockaddr_in cliaddr, servaddr;

    listenfd = socket(AF_INET, SOCK_STREAM, 0);

    servaddr.sin_family = AF_INET;
    servaddr.sin_port = htons(10002);
    servaddr.sin_addr.s_addr = inet_addr("127.0.0.1");

    if(bind(listenfd, (sockaddr*)&servaddr, sizeof(servaddr)) == -1)
    {
        cout << "bind error" << endl;
        return -1;
    }

    listen(listenfd, 5);

    client[0].fd = listenfd;
    client[0].events = POLLRDNORM;
    for(int i = 1; i < OPEN_MAX; i++)
    {
        client[i].fd = -1;
    }

    maxi = 0;

    cout << "startup sucess port : " << servaddr.sin_port << endl;
    cout << "Max connect :" << OPEN_MAX << endl;

    for(;;)
    {
        nready = poll(client, maxi + 1, -1);
        if(nready == -1)
        {
            cout << "poll error" << endl;
        }

        if(client[0].revents & POLLRDNORM)//new client connection
        {
            clilen = sizeof(cliaddr);
            connfd = accept(listenfd, (sockaddr*)&cliaddr, &clilen);

            for(i = 1; i < OPEN_MAX; i++)
            {
                if(client[i].fd < 0)
                {
                    client[i].fd = connfd; //save des
                    break;
                }
            }

            if(i == OPEN_MAX)
            {
                cout << "too many clients" << endl;
                return -1;
            }

            client[i].events = POLLRDNORM;
            if(i > maxi)
            {
                maxi = i;
            }

            if(--nready <= 0)
            {
                continue;
            }
        }

        for(i = 1; i <= maxi; i++)
        {
            if((sockfd = client[i].fd) < 0)
            {
                continue;
            }

            if(client[i].revents & (POLLRDNORM | POLLERR))
            {
                char buffer[1024] = {0};
                if((n = recv(sockfd, buffer, 1024, 0)) < 0)
                {
                    if(errno == ECONNRESET)
                    {
                        //connection reset by client
                        close(sockfd);
                        client[i].fd = -1;
                    }
                    else
                    {
                        cout << "read error" << endl;
                    }
                }
                else if(n == 0)
                {
                    //connect close by client
                    close(sockfd);
                    client[i].fd = -1;
                }
                else
                {
                    send(sockfd, buffer, 1024, 0);
                }

                if(--nready <= 0)
                {
                    break;
                }
            }
        }

    }

    return 0;
}