高并发服务器学习笔记之二：单一迭代模型

这是最简单的一种服务器模型，简单到实际开发中基本就不怎么能见到，其工作模式就是在一个死循环里不停的accept，如果有客户端接入，就进入一个子循环处理客户端的请求，直到客户端断开连接为止，然后再阻塞在accept，等待下一个客户端的接入，下面直接上代码

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>

#include <unistd.h>
#include <sys/types.h>          /* See NOTES */
#include <sys/socket.h>
#include <netinet/in.h>
#include <netinet/ip.h> /* superset of previous */
#include <arpa/inet.h>

#define LISTEN_BACKLOG 50
#define handle_error(msg) \
    do { perror(msg); exit(EXIT_FAILURE); } while (0)

int main(int argc, char ** argv)
{
    int i = 0;
    int sockfd = 0;
    int acceptfd = 0;
    ssize_t readret = 0;
    socklen_t client_addr_len = 0;
    struct sockaddr_in server_addr, client_addr;

    char client_ip[16] = { 0 };
    char read_buff[256] = { 0 };
    char write_buff[256] = { 0 };

    memset(&server_addr, 0, sizeof(server_addr));
    memset(&client_addr, 0, sizeof(client_addr));

    if((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
        handle_error("socket");

    server_addr.sin_family = AF_INET;
    server_addr.sin_port = htons(9527);
    server_addr.sin_addr.s_addr = htonl(INADDR_ANY);
    if(bind(sockfd, (struct sockaddr *)&server_addr, sizeof(server_addr)) < 0)
    {
        close(sockfd);
        handle_error("bind");
    }

    if(listen(sockfd, LISTEN_BACKLOG) < 0)
    {
        close(sockfd);
        handle_error("listen");
    }


    while(1)
    {
        client_addr_len = sizeof(client_addr);
        if((acceptfd = accept(sockfd, (struct sockaddr *)&client_addr, &client_addr_len)) < 0)
        {
            close(sockfd);
            handle_error("accept");
        }
       
        memset(client_ip, 0, sizeof(client_ip));
        inet_ntop(AF_INET,&client_addr.sin_addr,client_ip,sizeof(client_ip)); 
        printf("client:%s:%d\n",client_ip,ntohs(client_addr.sin_port));

		i = 0;
		while (1)
		{
			memset(read_buff, 0, sizeof(read_buff));
			readret = read(acceptfd, read_buff, sizeof(read_buff));
			if (readret == 0)
				break;

			printf("%s\n", read_buff);

			memset(write_buff, 0, sizeof(write_buff));
			sprintf(write_buff, "This is server send message:%d", i++);
			write(acceptfd, write_buff, sizeof(write_buff));
		}
      
        printf("\n");
        close(acceptfd);
        sleep(1);
    }

    close(sockfd);

    return 0;
}

这种模式只能同时处理一个客户端的请求，其他客户端需要排队等待，很显然效率是非常低的。虽然这种模式简单，但却是后面其他所有模式服务端的基础。