Linux 下服务器设计（ 一 ）
这里讲的仅仅是一个简单的server的模型！为了处理同时来到很多小的链接请求( 解释：就是请求很简单，持续时间很短，那么if server在请求到来时在fork来处理它，有可能fork的时间比应答请求的还要少，那么就是不合理的服务设计 )，所以我们采用的是“prefork”和“prethread”模型！
Unix 网络编程 上的4个模型是：prefork：主进程accept
子进程accept
prethread：
主线程accept
子线程accept ( 姑且使用主线程和子线程来描述 )
第一部分是：使用“预先生成进程”处理
CODE_1 : server是：主进程accept，那么这是4种方法中最复杂的，因为要涉及到进程间传递socket描述符的问题！( 进程间传递描述符在上一篇bolg中有过 ！)，server采用轮询的方式将socket传递给子进程！
话不多说，贴上代码：
Server：
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <sys/select.h>
#include <sys/types.h>
#include <errno.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <sys/epoll.h>
#include <fcntl.h>
#define PORT 6000
#define MAXBACK 100
#define MAXLINE 1024
#define CHILD_NUM 10
typedef struct child_process
{
pid_t s_pid; //!> 子进程的pid
int s_pipe_fd; //!> 与子进程通信的pipe口
int s_status; //!> 子进程的状态！0：闲 1：忙
}child_process;
child_process child[CHILD_NUM]; //!> 定义10个子进程( 此处以10个为例 )
static int n_child_use = 0; //!> 几个child在工作( if 全忙就不给他们 )
//!> 发送socket描述符( 这个代码在上一篇博文上有 )
//!>
int send_fd( int fd_send_to, void * data, size_t len, int sock_fd )
{
struct msghdr msghdr_send; //!> the info struct
struct iovec iov[1]; //!> io vector
size_t n; //!>
union
{
struct cmsghdr cm; //!> control msg
char ctl[CMSG_SPACE(sizeof( int ))]; //!> the pointer of char
}ctl_un;
struct cmsghdr * pCmsghdr = NULL; //!> the pointer of control
msghdr_send.msg_control = ctl_un.ctl;
msghdr_send.msg_controllen = sizeof( ctl_un.ctl );
//!> design : the first info
pCmsghdr = CMSG_FIRSTHDR( &msghdr_send ); //!> the info of head
pCmsghdr->cmsg_len = CMSG_LEN(sizeof(int)); //!> the msg len
pCmsghdr->cmsg_level = SOL_SOCKET; //!> -> stream mode
pCmsghdr->cmsg_type = SCM_RIGHTS; //!> -> file descriptor
*((int *)CMSG_DATA( pCmsghdr )) = sock_fd; //!> data: the file fd
//!> these infos are nosignification
msghdr_send.msg_name = NULL; //!> the name
msghdr_send.msg_namelen = 0; //!> len of name
iov[0].iov_base = data; //!> no data here
iov[0].iov_len = len; //!> the len of data
msghdr_send.msg_iov = iov; //!> the io/vector info
msghdr_send.msg_iovlen = 1; //!> the num of iov
return ( sendmsg( fd_send_to, &msghdr_send, 0 ) ); //!> send msg now
}
//!> 接收socket描述符
//!>
int recv_sock_fd( int fd, void * data, size_t len, int * recv_fd )
{
struct msghdr msghdr_recv; //!> the info struct
struct iovec iov[1]; //!> io vector
size_t n; //!>
union
{
struct cmsghdr cm; //!> control msg
char ctl[CMSG_SPACE(sizeof( int ))]; //!> the pointer of char
}ctl_un;
struct cmsghdr * pCmsghdr = NULL; //!> the pointer of control
msghdr_recv.msg_control = ctl_un.ctl;
msghdr_recv.msg_controllen = sizeof( ctl_un.ctl );
//!> these infos are nosignification
msghdr_recv.msg_name = NULL; //!> the name
msghdr_recv.msg_namelen = 0; //!> len of name
iov[0].iov_base = data; //!> no data here
iov[0].iov_len = len; //!> the len of data
msghdr_recv.msg_iov = iov; //!> the io/vector info
msghdr_recv.msg_iovlen = 1; //!> the num of iov
if( ( n = recvmsg( fd, &msghdr_recv, 0 ) ) < 0 ) //!> recv msg
{ //!> the msg is recv by msghdr_recv
printf("recv error : %d\n", errno);
exit(EXIT_FAILURE);
}
//!> now, we not use 'for' just because only one test_data_
if( ( pCmsghdr = CMSG_FIRSTHDR( &msghdr_recv ) ) != NULL //!> now we need only one,
&& pCmsghdr->cmsg_len == CMSG_LEN( sizeof( int ) ) //!> we should use 'for' when
) //!> there are many fds
{
if( pCmsghdr->cmsg_level != SOL_SOCKET )
{
printf("Ctl level should be SOL_SOCKET :%d \n", errno);
exit(EXIT_FAILURE);
}
if( pCmsghdr->cmsg_type != SCM_RIGHTS )
{
printf("Ctl type should be SCM_RIGHTS : %d\n", errno);
exit(EXIT_FAILURE);
}
*recv_fd =*((int*)CMSG_DATA(pCmsghdr)); //!> get the data : the file des*
}
else
{
*recv_fd = -1;
}
return n;
}
//!> 子进程具体的执行过程
//!>
void web_child( int con_fd )
{
char buf[MAXLINE];
int n_read;
int i = 0;
while( strcmp( buf, "Q" ) != 0 && strcmp( buf, "q" ) != 0 )
{
memset( buf, 0, sizeof( buf ) );
if( ( n_read = read( conn_fd, buf, MAXLINE ) ) < 0 )
{
printf( "Read errnr! :%d \n", errno );
exit( EXIT_FAILURE );
}
else if( n_read == 0 )
{
continue;
}
else
{
while( buf[i] )
{
buf[i] = toupper( buf[i] );
i++;
}
buf[i] = '\0';
printf("Child %d done! \n", ( unsigned int )pthread_self());
printf("Child %d send %s\n", ( unsigned int )pthread_self(), buf);
write( conn_fd, buf, strlen( buf ) ); //!> 写回给client
}
}
printf("Child %d : Dating end!\n", ( unsigned int )pthread_self());
}
//!> child process 的主函数
//!>
void child_main( int i )
{
char data; //!> 由于此处我们主要是传递socket，那么data一般就给一个” “做一个标志就好
int con_fd; //!> 接受con_fd
int n_read; //!> 读取长度
printf( "Child %d starting ... \n", i );
while( 1 )
{
if( ( n_read = recv_sock_fd( STDERR_FILENO, &data, 1, &con_fd ) ) == 0 )
{
continue; //!> 此处理论上应该是阻塞，但是简化为轮询
//printf( " Child process %d read errnr! : %d\n", i, errno );
//exit( EXIT_FAILURE );
}
if( con_fd < 0 )
{
printf("Child %d read connfd errnr! : %d\n", i, errno);
exit( EXIT_FAILURE );
}
web_child( con_fd ); //!> child具体的执行过程
write( STDERR_FILENO, " ", 1 ); //!> 随便写点什么让server知道我处理完成了，那么就可以将状态位置为0了
}
}
//!> 产生子进程及相关处理
//!>
void child_make( int i, int listen_fd )
{
int sock_fd[2]; //!> 为了和主进程通信创建socket pair
pid_t pid;
//!> 创建 socketpair
if( socketpair( AF_LOCAL, SOCK_STREAM, 0, sock_fd ) == -1 )
{
printf( "create socketpair error : %d\n", errno );
exit( EXIT_FAILURE );
}
if( ( pid = fork() ) > 0 ) //!> 父进程
{
close( sock_fd[1] );
child[i].s_pid = pid;
child[i].s_pipe_fd = sock_fd[0];
child[i].s_status = 0;
return;
}
if( dup2( sock_fd[0], STDERR_FILENO ) == -1 ) //!> 现在可以使用STDERR_FILENO替换刚刚创建的sock描述符
{ //!> 往后的child的操作就可以STDERR_FILENO中进行！
printf("socket pair errnr! : %d\n", errno);
exit( EXIT_FAILURE );
}
close( sock_fd[0] ); //!> 这些描述符都bu需要了!
close( sock_fd[1] );
close( listen_fd );
child_main( i ); //!> child 主循环
}
//!> MAIN PROCESS
//!>
int main( int argc, char ** argv )
{
int i;
int listen_fd;
int conn_fd;
int max_fd;
int n_select;
int n_read;
char buf[5];
fd_set all_set, now_set;
struct sockaddr_in servaddr;
struct sockaddr_in cliaddr;
int len = sizeof( struct sockaddr_in );
//!> server 套接口
//!>
bzero( &servaddr, sizeof( servaddr ) );
servaddr.sin_family = AF_INET;
servaddr.sin_addr.s_addr = htonl( INADDR_ANY );
servaddr.sin_port = htons( PORT );
//!> 建立套接字
if( ( listen_fd = socket( AF_INET, SOCK_STREAM, 0 ) ) == -1 )
{
printf("Socket Error...\n" , errno );
exit( EXIT_FAILURE );
}
//!> 绑定
//!>
if( bind( listen_fd, ( struct sockaddr *)&servaddr, sizeof( servaddr ) ) == -1 )
{
printf("Bind Error : %d\n", errno);
exit( EXIT_FAILURE );
}
//!> 监听
//!>
if( listen( listen_fd, MAXBACK ) == -1 )
{
printf("Listen Error : %d\n", errno);
exit( EXIT_FAILURE );
}
FD_ZERO( &all_set );
FD_SET( listen_fd, &all_set ); //!> 将listenfd加入select
max_fd = listen_fd;
for( i = 0; i < CHILD_NUM; i++ )
{
child_make( i, listen_fd );
FD_SET( child[i].s_pipe_fd, &all_set ); //!> 将子进程socket加入
max_fd = max_fd > child[i].s_pipe_fd ? max_fd : child[i].s_pipe_fd;
}
while( 1 ) //!> 主进程循环
{
now_set = all_set;
if( n_child_use >= CHILD_NUM ) //!> 没有可以使用的child 了
{ //!> 那么就将listenfd从中清空，也就是不在响应listen了，直到有child空闲
FD_CLR( listen_fd, &now_set );
}
if( (n_select = select( max_fd + 1, &now_set, NULL, NULL, NULL )) == -1)
{
printf(" Main process select errnr~ :%d\n", errno);
exit( EXIT_FAILURE );
}
if( FD_ISSET( listen_fd, &now_set ) ) //!> if来了请求
{
if( ( conn_fd = accept( listen_fd, ( struct sockaddr *)&cliaddr , &len ) ) == -1 )
{
printf("Server accept errnr! : %d\n", errno);
exit( EXIT_FAILURE );
}
for( i = 0; i < CHILD_NUM; i++ )
{
if( child[i].s_status == 0 ) //!> 此child闲置
{
break;
}
}
if( i == CHILD_NUM ) //!> 说明child已经全部处于忙态
{
printf("All childs are busy! \n");
exit( EXIT_FAILURE ); //!> 此处可以等待哦，或者丢弃数据
}
child[i].s_status = 1; //!> busy
n_child_use++; //!> busy child ++
send_fd( child[i].s_pipe_fd, " ", 1, conn_fd ); //!> 发送socket描述符
close( conn_fd ); //!> server不需要处理了
if( --n_select == 0 ) //!> 没有其他的请求了
{
continue;
}
}
for( i = 0; i < CHILD_NUM; i++ ) //!> 看看那些child发来了msg，其实server知道肯定是child完成处理的提示标志
{
if( FD_ISSET( child[i].s_pipe_fd, &now_set ) )
{
if( ( n_read = read( child[i].s_pipe_fd, buf, 5 ) ) == 0 ) //!> 这里的buf中data没有用，仅仅是child告诉server我完成了
{
printf("Child %d exit error! : %d\n", i, errno);
exit( EXIT_FAILURE );
}
child[i].s_status = 0; //!> 状态位置闲
if( --n_select == 0 ) //!> if没有其他child回送消息就不要浪费时间for了
{
break;
}
}
}
}
return 0;
}
Client：
[cpp] view plaincopyprint?
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <netinet/in.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <sys/select.h>
#define MAXLINE 1024
#define SERV_PORT 6000
//!> 注意输入是由stdin，接受是由server发送过来
//!> 所以在client端也是需要select进行处理的
void send_and_recv( int connfd )
{
FILE * fp = stdin;
int lens;
char send[MAXLINE];
char recv[MAXLINE];
fd_set rset;
FD_ZERO( &rset );
int maxfd = ( fileno( fp ) > connfd ? fileno( fp ) : connfd + 1 );
//!> 输入和输出的最大值
int n;
while( 1 )
{
FD_SET( fileno( fp ), &rset );
FD_SET( connfd, &rset ); //!> 注意不要把rset看作是简单的一个变量
//!> 注意它其实是可以包含一组套接字的哦，
//!> 相当于是封装的数组！每次都要是新的哦！
if( select( maxfd, &rset, NULL, NULL, NULL ) == -1 )
{
printf("Client Select Error..\n");
exit(EXIT_FAILURE );
}
//!> if 连接口有信息
if( FD_ISSET( connfd, &rset ) ) //!> if 连接端口有信息
{
printf( "client get from server ...\n" );
memset( recv, 0, sizeof( recv ) );
n = read( connfd, recv, MAXLINE );
if( n == 0 )
{
printf("Recv ok...\n");
break;
}
else if( n == -1 )
{
printf("Recv error...\n");
break;
}
else
{
lens = strlen( recv );
recv[lens] = '\0';
//!> 写到stdout
write( STDOUT_FILENO, recv, MAXLINE );
printf("\n");
}
}
//!> if 有stdin输入
if( FD_ISSET( fileno( fp ), &rset ) ) //!> if 有输入
{
//!> printf("client stdin ...\n");
memset( send, 0, sizeof( send ) );
if( fgets( send, MAXLINE, fp ) == NULL )
{
printf("End...\n");
exit( EXIT_FAILURE );
}
else
{
//!>if( str )
lens = strlen( send );
send[lens-1] = '\0'; //!> 减一的原因是不要回车字符
//!> 经验值：这一步非常重要的哦！！！！！！！！
if( strcmp( send, "q" ) == 0 )
{
printf( "Bye..\n" );
return;
}
printf("Client send : %s\n", send);
write( connfd, send, strlen( send ) );
}
}
}
}
int main( int argc, char ** argv )
{
//!> char * SERV_IP = "10.30.97.188";
char buf[MAXLINE];
int connfd;
struct sockaddr_in servaddr;
if( argc != 2 )
{
printf("Input server ip !\n");
exit( EXIT_FAILURE );
}
//!> 建立套接字
if( ( connfd = socket( AF_INET, SOCK_STREAM, 0 ) ) == -1 )
{
printf("Socket Error...\n" , errno );
exit( EXIT_FAILURE );
}
//!> 套接字信息
bzero(&servaddr, sizeof(servaddr));
servaddr.sin_family = AF_INET;
servaddr.sin_port = htons(SERV_PORT);
inet_pton(AF_INET, argv[1], &servaddr.sin_addr);
//!> 链接server
if( connect( connfd, ( struct sockaddr * )&servaddr, sizeof( servaddr ) ) < 0 )
{
printf("Connect error..\n");
exit(EXIT_FAILURE);
}
/*else
{
printf("Connet ok..\n");
}*/
//!>
//!> send and recv
send_and_recv( connfd );
//!>
close( connfd );
printf("Exit\n");
return 0;
}
CODE_2 : server 是“子进程accept”，那么就是要比第一个简单一点，但是有一个新的问题就是，子进程要“抢”accept，那么必然存在一个“互斥”accept的问题，当然我么可以使用文件锁，但是效率比较低，而且在此处只是一个实验，所以姑且就使用“线程互斥量”，看起来有点不和谐，呵呵呵！～
Server：
[cpp] view plaincopyprint?
/*
基本思路：
server预先创建几个子进程，由子进程进行互斥accept，
由于此处使用文件锁的效率会低一点，那么就使用互斥量
代替！
当然这是不协调的，这里只是简单处理！
*/
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <pthread.h>
#include <sys/select.h>
#include <sys/types.h>
#include <errno.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <sys/epoll.h>
#include <fcntl.h>
#define PORT 6000
#define MAXBACK 100
#define MAXLINE 1024
#define CHILD_NUM 10
pthread_mutex_t g_mutex; //!> 互斥量
pthread_mutexattr_t g_mattr ; //!> 属性
//!> 产生子进程及相关处理
//!>
void child_make( int i_num, int listen_fd )
{
int i = 0;
pid_t pid;
int conn_fd;
int n_read;
char buf[MAXLINE];
struct sockaddr_in cliaddr;
int len = sizeof( struct sockaddr_in );
if( ( pid = fork() ) > 0 )
{
return;
}
while( 1 )
{
pthread_mutex_lock( &g_mutex ); //!> 加锁
if( ( conn_fd = accept( listen_fd, ( struct sockaddr *)&cliaddr , &len ) ) == -1 )
{
printf("Accept errnr! :%d\n", errno);
exit( EXIT_FAILURE );
}
pthread_mutex_unlock( &g_mutex ); //!> 解锁
if( ( n_read = read( conn_fd, buf, MAXLINE ) ) < 0 )
{
printf( "Read errnr! :%d \n", errno );
exit( EXIT_FAILURE );
}
else if( n_read == 0 )
{
continue;
}
else
{
while( buf[i] )
{
buf[i] = toupper( buf[i] );
i++;
}
printf("Child %d done! \n", i_num);
printf("Child %d send %s\n", i_num, buf);
write( conn_fd, buf, strlen( buf ) ); //!> 写回给client
}
}
}
//!> MAIN PROCESS
//!>
int main( int argc, char ** argv )
{
int i;
int listen_fd;
int conn_fd;
int n_read;
char buf[5];
struct sockaddr_in servaddr;
//!>下面需要设置进程间共享此锁
//!>
pthread_mutexattr_init( &g_mattr );
pthread_mutexattr_setpshared( &g_mattr, PTHREAD_PROCESS_SHARED );
pthread_mutex_init( &g_mutex, &g_mattr ); //!> 初始化
//!> server 套接口
//!>
bzero( &servaddr, sizeof( servaddr ) );
servaddr.sin_family = AF_INET;
servaddr.sin_addr.s_addr = htonl( INADDR_ANY );
servaddr.sin_port = htons( PORT );
//!> 建立套接字
if( ( listen_fd = socket( AF_INET, SOCK_STREAM, 0 ) ) == -1 )
{
printf("Socket Error...\n" , errno );
exit( EXIT_FAILURE );
}
//!> 绑定
//!>
if( bind( listen_fd, ( struct sockaddr *)&servaddr, sizeof( servaddr ) ) == -1 )
{
printf("Bind Error : %d\n", errno);
exit( EXIT_FAILURE );
}
//!> 监听
//!>
if( listen( listen_fd, MAXBACK ) == -1 )
{
printf("Listen Error : %d\n", errno);
exit( EXIT_FAILURE );
}
for( i = 0; i < CHILD_NUM; i++ )
{
child_make( i, listen_fd );
}
waitpid( 0 ); //!> 等待所有子进程而已
pthread_mutex_destroy( &g_mutex ); //!> 删除互斥灯
return 0;
}
Client：和上面的一样！！！