高并发服务器学习笔记之三：多进程模型

该模型是在单一迭代模型的基础上的改进，父进程只在一个死循环里进行accept，当一个客户端接入时，父进程会fork一个子进程，然后父进程关闭该连接的socket，并继续accept，等待下一个客户端接入，子进程可以关闭监听socket，然后去处理客户端请求，处理结束后关闭连接socket，结束自身进程。

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

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

#include "public_head.h"
#include "fileio.h"

#define LISTEN_BACKLOG 50

static void grim_reaper(int sig)
{
	int saved_error = errno;
	while (waitpid(-1, NULL, WNOHANG) >= 0)
		continue;

	errno = saved_error;
}

static void handle_request(int acceptfd)
{
    int i = 0;
    ssize_t readret = 0;
    char read_buff[256] = { 0 };
    char write_buff[256] = { 0 };
   
	while (1)
	{
		memset(read_buff, 0, sizeof(read_buff));
		readret = read(acceptfd, read_buff, sizeof(read_buff));
		if (readret == 0)
			break;

		printf("progress id:%d, recv message:%s\n", getpid(), 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);
    return;
}

int main(int argc, char ** argv)
{
	pid_t pid;
    int sockfd = 0;
    int acceptfd = 0;
    socklen_t client_addr_len = 0;
	struct sigaction sa;
    struct sockaddr_in server_addr, client_addr;

    char client_ip[16] = { 0 };

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

	sigemptyset(&sa.sa_mask); 
	sa.sa_flags = SA_RESTART;
	sa.sa_handler = grim_reaper;
	if(sigaction(SIGCHLD, &sa, NULL) < 0)
		handle_error("sigaction");

    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)
    {
		char buff[256] = { 0 };
        close(sockfd);
		strerror_r(errno, buff, sizeof(buff));
        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)
        {
			handle_warning("accept");
			continue;
        }
       
        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));

		pid = fork();
		if (pid > 0)	//parent
		{
			close(acceptfd);
			continue;
		} 
		else if (pid == 0)	//child
		{
			close(sockfd);
			handle_request(acceptfd);
			exit(EXIT_SUCCESS);
		} 
		else
		{
			handle_warning("fork");
			continue;
		}
    }
    
    close(sockfd);

	exit(EXIT_SUCCESS);
}