多进程并发编程----基于高级的预先创建进程池(accept使用线程上锁)的模型

本博文介绍如何使用线程对accept进程加锁保护。

使用线程对accept加锁，不仅适用于同一进程内各线程之间的上锁，同样适用于不同进程之间的上锁。

实现要点：

1 互斥变量必须存放在所有进程共享的内存区域内

2 告知线程函数库这是不同进程之间共享的互斥锁

服务端程序的代码如下：

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <time.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <signal.h>
#include <errno.h>
#include <fcntl.h>
#include <unistd.h>
#include <pthread.h>
#include <sys/mman.h>
#define BUFFLEN 1024
#define SERVER_PORT 8888
#define BACKLOG 5
#define PIDNUMB 5000

pthread_mutex_t *mutex;/* actual mutex will be in shared memory */
void my_lock_init(void){
pthread_mutexattr_t mutexattr;
int fd=open("/dev/zero",O_RDWR,0);
if(fd==-1)
printf("open err :%s\n",strerror(errno));
mutex=mmap(NULL,sizeof(pthread_mutex_t),PROT_READ|PROT_WRITE,MAP_SHARED,fd,0);
close(fd);

pthread_mutexattr_init(&mutexattr);
pthread_mutexattr_setpshared(&mutexattr,PTHREAD_PROCESS_SHARED);
pthread_mutex_init(mutex,&mutexattr);
}
void my_lock_wait(){
pthread_mutex_lock(mutex);
}
void my_lock_release(){
pthread_mutex_unlock(mutex);
}
static void handle_connect(int s_s,int pid)
{
int s_c;	/*客户端套接字文件描述符*/
struct sockaddr_in from;	/*客户端地址*/
int len = sizeof(from);
int count=0;
/*主处理过程*/
while(1)
{
printf("count[%d],pid[%d]\n",count,getpid());
/*接收客户端连接*/
my_lock_wait();//add write lock
s_c = accept(s_s, (struct sockaddr*)&from, &len);
my_lock_release();//release write lock
if(s_c > 0)
count++;
time_t now;		/*时间*/
char buff[BUFFLEN];/*收发数据缓冲区*/
int n = 0;
memset(buff, 0, BUFFLEN);/*清零*/
n = recv(s_c, buff, BUFFLEN,0);/*接收发送方数据*/
if(n > 0 && !strncmp(buff, "TIME", 4))/*判断是否合法接收数据*/
{
memset(buff, 0, BUFFLEN);/*清零*/
now = time(NULL);/*当前时间*/
sprintf(buff, "%24s\r\n",ctime(&now));/*将时间拷贝入缓冲区*/
send(s_c, buff, strlen(buff),0);/*发送数据*/
sleep(1);
}
/*关闭客户端*/
close(s_c);
}

}

void sig_int(int num)
{
exit(1);
}
int main(int argc, char *argv[])
{
int s_s;	/*服务器套接字文件描述符*/
struct sockaddr_in local;	/*本地地址*/
signal(SIGINT,sig_int);

/*建立TCP套接字*/
s_s = socket(AF_INET, SOCK_STREAM, 0);

int optval=1;
int ret=setsockopt(s_s,SOL_SOCKET,SO_REUSEADDR,(int *)&optval,sizeof(optval));

/*初始化地址接哦股*/
memset(&local, 0, sizeof(local));/*清零*/
local.sin_family = AF_INET;/*AF_INET协议族*/
local.sin_addr.s_addr = htonl(INADDR_ANY);/*任意本地地址*/
local.sin_port = htons(SERVER_PORT);/*服务器端口*/

/*将套接字文件描述符绑定到本地地址和端口*/
int err = bind(s_s, (struct sockaddr*)&local, sizeof(local));
err = listen(s_s, BACKLOG);/*侦听*/

//init the write lock
my_lock_init();

/*处理客户端连接*/
pid_t pid[PIDNUMB];
int i =0;
for(i=0;i<PIDNUMB;i++)
{
pid[i] = fork();
if(pid[i] == 0)/*子进程*/
{
//			printf("pid[%d]\n",getpid());
handle_connect(s_s,getpid());
}
}
while(1);

close(s_s);

return 0;
}