简单进程池实现多TCP客户服务

根据预定义进程数创建进程池。

父子进程通信使用的IPC方式为：UNIX域套接字

父进程listen，aeecpt，并将连接套接字发送到子进程，交由子进程处理该连接。

子进程处理完毕，与父进程通信，实现资源回收，并在下一连接到来交由该完毕的子进程。

#include "unp.h"
#include <assert.h>
#define IDLE		0
#define BUSY		1
#define END		2


typedef struct pro {
	pid_t	id;		/*进程的进程ID*/
	int 		fd;		/*与父进程通信的描述符*/
	int		flags;	/*进程当前状态*/
	int		cnt;		/*进程服务的次数*/
}process;
process	*mypid;		/*进程池*/


ssize_t write__the_fd(int fd, void *ptr, size_t nbytes, int sendfd);
pid_t make_child( int i, int listenfd );
ssize_t read_the_fd(int fd, void *ptr, size_t nbytes, int *recvfd);
void child_func( void);
void clr(int signo);
int	main( int argc, char **argv ) {
	int 		nchild, fdmax, listenfd, connfd, i, len, nselect;
	char		c;
	struct sockaddr_in		addr, clientaddr;
	signal(SIGCHLD, clr);
	signal(SIGINT, clr);
	fd_set	rset, oset;
	if(argc != 2)
		err_quit("args");
	listenfd = socket( AF_INET, SOCK_STREAM, 0 );/*服务器监听套接字*/
	if( listenfd < 0 ) {
		err_sys("socket");
	}
	nchild = atoi(argv[1]);
	mypid = (struct pro *)malloc( nchild * sizeof( struct pro) );
	bzero( &addr, sizeof(addr));
	addr.sin_family = AF_INET;
	addr.sin_port	 = htons(SERV_PORT);
	addr.sin_addr.s_addr = htonl(INADDR_ANY);
	bind(listenfd, (SA *)&addr, sizeof(struct sockaddr));
	fdmax = listenfd; 						/*用于select */
	for( i = 0; i < nchild; i++ ) {
		make_child(i, listenfd);				/*创建子进程并等待给客户服务*/
	}									/*传入listenfd子进程关闭监听套接字*/
	int idle = nchild;						/*当前空闲的子进程*/
	len = sizeof(struct sockaddr);
	FD_ZERO(&oset);
	FD_ZERO(&rset);
	listen(listenfd,5);
	FD_SET(listenfd, &oset);
	for( ; ;) {
		if(idle == 0) 
			FD_CLR(listenfd, &oset);		/*若没有空闲子进程，则禁止accept新连接*/
		else 
			FD_SET(listenfd, &oset);	
		rset = oset;
		nselect = select(fdmax+1, &rset, NULL, NULL, NULL);
		if( FD_ISSET(listenfd, &rset) ) {		/*收到客户端连接请求*/
			connfd = accept(listenfd, (SA *)&clientaddr, &len);
			for( i = 0; i < nchild; i++) {
				if(mypid[i].flags == IDLE) {	/*查找可供服务的子进程*/
					break;
				}
			}
			/*  */
			assert(i < nchild);
			/*  */
			//connfd = accept(listenfd, (SA *)&clientaddr, &len);
			printf("the id is %d \n",i);
			mypid[i].flags = BUSY;  				/*改变子进程状态*/
			mypid[i].cnt ++;						/*子进程服务次数*/
			FD_SET(mypid[i].fd, &oset);				/*加入描述集，等待子进程*/
			fdmax = max(fdmax ,mypid[i].fd);
			idle --;								/*空闲进程减少*/
			/*通知子进程*/
			write_the_fd(mypid[i].fd, " ", 1,connfd);/*把连接套接字传送给子进程*/
			close(connfd);						/*因为有有一个confd在飞，所以这个可以关闭*/
			if(--nselect  ==0)
				continue;
		}
		else {
			for(i = 0; i < nchild; i++ ) {
				if(FD_ISSET(mypid[i].fd , &rset)) {
					read(mypid[i].fd, &c, 1);
					mypid[i].flags = IDLE;
					FD_CLR(mypid[i].fd, &oset);
					idle ++;
				}
				if(--nselect  == 0)
					break;
			}

		}
		
		
	}
}
void clr(int signo) {
	pid_t pid;
	while( (pid = waitpid(-1, NULL, WNOHANG)) > 0 ) {
		printf("The child %d is done\n", pid);
	}
	sleep(2);
	kill(getpid(), SIGTERM);
	return;
}
pid_t make_child( int i, int listenfd ) {
	pid_t 	child;
	int		fd[2];
	socketpair( AF_LOCAL, SOCK_STREAM,0, fd);
	if( (child = fork( ) ) < 0 ) {
		err_quit("fork ");
	}
	if( child > 0 ) {  /*父进程*/
		//printf("the  i is  %d\n", i);
		close( fd[1] );
		mypid[i].id = child;
		mypid[i].fd= fd[0];
		mypid[i].flags = IDLE;
		mypid[i].cnt = 0;
		return child;
	}
	/*子进程*/
	close( fd[0] );
	close(listenfd);
	dup2( fd[1], STDERR_FILENO);
	close( fd[1]);
	child_func();
}

void child_func( void) {
	int 		connfd, n;
	char		c;
	char		buf[MAXLINE];
	for( ; ; ) {
		n = read_fd(STDERR_FILENO, &c, 1, &connfd);
		if(n <0 ) 
			err_sys("read_fd");
		again:
		while( (n = read(connfd, buf, sizeof(buf))) > 0 ){
			writen(connfd, buf ,n);
		}
		if((n < 0)&&( errno == EINTR))
			goto again;
		else if(n < 0)
			err_sys("error");
		else if(n ==0) {
			close(connfd);
			write(STDERR_FILENO, " ", 1);
		}
	}
}
ssize_t write_the_fd(int fd, void *ptr, size_t nbytes, int sendfd) {
	struct msghdr	msg;
	struct iovec	iov[1];
	union {
	  struct cmsghdr	cm;
	  char				control[CMSG_SPACE(sizeof(int))];
	} control_un;
	struct cmsghdr	*cmptr;
	msg.msg_control = control_un.control;
	msg.msg_controllen = sizeof(control_un.control);
	cmptr = CMSG_FIRSTHDR(&msg);
	cmptr->cmsg_len = CMSG_LEN(sizeof(int));
	cmptr->cmsg_level = SOL_SOCKET;
	cmptr->cmsg_type = SCM_RIGHTS;
	*((int *) CMSG_DATA(cmptr)) = sendfd;
	msg.msg_name = NULL;
	msg.msg_namelen = 0;
	iov[0].iov_base = ptr;
	iov[0].iov_len = nbytes;
	msg.msg_iov = iov;
	msg.msg_iovlen = 1;
	return(sendmsg(fd, &msg, 0));
}
ssize_t read_the_fd(int fd, void *ptr, size_t nbytes, int *recvfd) {
	struct msghdr	msg;
	struct iovec	iov[1];
	ssize_t			n;
	int				newfd;
	union {
	  struct cmsghdr	cm;
	  char				control[CMSG_SPACE(sizeof(int))];
	} control_un;
	struct cmsghdr	*cmptr;

	msg.msg_control = control_un.control;
	msg.msg_controllen = sizeof(control_un.control);
	msg.msg_name = NULL;
	msg.msg_namelen = 0;

	iov[0].iov_base = ptr;
	iov[0].iov_len = nbytes;
	msg.msg_iov = iov;
	msg.msg_iovlen = 1;

	if ( (n = recvmsg(fd, &msg, 0)) <= 0)
		return(n);
	if ( (cmptr = CMSG_FIRSTHDR(&msg)) != NULL &&
	    cmptr->cmsg_len == CMSG_LEN(sizeof(int))) {
		if (cmptr->cmsg_level != SOL_SOCKET)
			err_quit("control level != SOL_SOCKET");
		if (cmptr->cmsg_type != SCM_RIGHTS)
			err_quit("control type != SCM_RIGHTS");
		*recvfd = *((int *) CMSG_DATA(cmptr));
	} else
		*recvfd = -1;		
	return(n);
}