2018-2019-1 20165233 实验三 实时系统

实验三 实时系统

任务一：

• 学习使用Linux命令wc(1)

• 基于Linux Socket程序设计实现wc（1）服务器(端口号是你学号的后6位)和客户端

• 客户端传一个文本文件给服务器

• 服务器返加文本文件中的单词数

实验步骤：

• 利用命令行man 1 wc查看命令wc(1)的内容。

• 实现代码如下：

服务器端

#include<netinet/in.h>  // sockaddr_in  
#include<sys/types.h>   // socket  
#include<sys/socket.h>  // socket  
#include<stdio.h>       // printf  
#include<stdlib.h>      // exit  
#include<string.h>      // bzero  

#define SERVER_PORT 165233
#define LENGTH_OF_LISTEN_QUEUE 20  
#define BUFFER_SIZE 1024
#define FILE_NAME_MAX_SIZE 512  
#define BEGIN 1; 

int main(void)  
{  

struct sockaddr_in server_addr;  
bzero(&server_addr, sizeof(server_addr));  
server_addr.sin_family = AF_INET;  
server_addr.sin_addr.s_addr = htons(INADDR_ANY);  
server_addr.sin_port = htons(SERVER_PORT);  

int server_socket_fd = socket(PF_INET, SOCK_STREAM, 0);  
if(server_socket_fd < 0)  
{  
    perror("Create Socket Failed:");  
    exit(1);  
}  
int opt = 1;  
setsockopt(server_socket_fd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt));  

if(-1 == (bind(server_socket_fd, (struct sockaddr*)&server_addr, sizeof(server_addr))))  
{  
    perror("Server Bind Failed:");  
    exit(1);  
}  
    
if(-1 == (listen(server_socket_fd, LENGTH_OF_LISTEN_QUEUE)))  
{  
    perror("Server Listen Failed:");  
    exit(1);  
}  

while(1)  
{  
    struct sockaddr_in client_addr;  
    socklen_t client_addr_length = sizeof(client_addr);  

    int new_server_socket_fd = accept(server_socket_fd, (struct sockaddr*)&client_addr, &client_addr_length);  
    if(new_server_socket_fd < 0)  
    {  
        perror("Server Accept Failed:");  
        break;  
    }  


    char buffer[BUFFER_SIZE];  
    bzero(buffer, BUFFER_SIZE);  
    if(recv(new_server_socket_fd, buffer, BUFFER_SIZE, 0) < 0)  
    {  
        perror("Server Recieve Data Failed:");  
        break;  
    }  


    char file_name[FILE_NAME_MAX_SIZE+1];  
    bzero(file_name, FILE_NAME_MAX_SIZE+1);  
    strncpy(file_name, buffer, strlen(buffer)>FILE_NAME_MAX_SIZE?FILE_NAME_MAX_SIZE:strlen(buffer));  
    printf("%s
", file_name);  


    FILE *fp = fopen(file_name, "w");  
    if(NULL == fp)  
    {  
        printf("File:	%s Can Not Open To Write
", file_name);  
        exit(1);  
    }  


    bzero(buffer, BUFFER_SIZE);  
    int length = 0;  
    while((length = recv(new_server_socket_fd, buffer, BUFFER_SIZE, 0)) > 0)  
    {  
    if(strcmp(buffer,"OK")==0) break;
        if(fwrite(buffer, sizeof(char), length, fp) < length)  
        {  
            printf("File:	%s Write Failed
", file_name);  
            break;  
        }  
        bzero(buffer, BUFFER_SIZE);  
    }  

    printf("Receive File:	%s From Client IP Successful!
", file_name);  
    fclose(fp);

int words=0;
char s[100];
FILE *fp2;
if((fp2=fopen(file_name,"r"))==NULL){
    printf("ERROR!
");
    exit(0);
}
while(fscanf(fp2,"%s",s)!=EOF)
    words++;
fclose(fp2);
printf("%d words.
",words);

char sendbuf[50];
sprintf(sendbuf,"%d",words);

send(new_server_socket_fd,sendbuf,50,0);

    close(new_server_socket_fd);  
}  

close(server_socket_fd);  
return 0;  
}

客户端

#include<netinet/in.h>   // sockaddr_in  
#include<sys/types.h>    // socket  
#include<sys/socket.h>   // socket  
#include<stdio.h>        // printf  
#include<stdlib.h>       // exit  
#include<string.h>       // bzero  

#define SERVER_PORT 165233  
#define BUFFER_SIZE 1024  
#define FILE_NAME_MAX_SIZE 512  
#define BEGIN 1;

int main()  
{  

struct sockaddr_in client_addr;  
bzero(&client_addr, sizeof(client_addr));  
client_addr.sin_family = AF_INET;  
client_addr.sin_addr.s_addr = htons(INADDR_ANY);  
client_addr.sin_port = htons(0);  

int client_socket_fd = socket(AF_INET, SOCK_STREAM, 0);  
if(client_socket_fd < 0)  
{  
    perror("Create Socket Failed:");  
    exit(1);  
}  

if(-1 == (bind(client_socket_fd, (struct sockaddr*)&client_addr, sizeof(client_addr))))  
{  
    perror("Client Bind Failed:");  
    exit(1);  
}  

struct sockaddr_in server_addr;  
bzero(&server_addr, sizeof(server_addr));  
server_addr.sin_family = AF_INET;  
if(inet_pton(AF_INET, "127.0.0.1", &server_addr.sin_addr) == 0)  
{  
    perror("Server IP Address Error:");  
    exit(1);  
}  
server_addr.sin_port = htons(SERVER_PORT);  
socklen_t server_addr_length = sizeof(server_addr);  

if(connect(client_socket_fd, (struct sockaddr*)&server_addr, server_addr_length) < 0)  
{  
    perror("Can Not Connect To Server IP:");  
    exit(0);  
}  

char file_name[FILE_NAME_MAX_SIZE+1];  
bzero(file_name, FILE_NAME_MAX_SIZE+1);  

printf("Please Input File Name On Client:	");
scanf("%s", file_name);  

char buffer[BUFFER_SIZE];  
bzero(buffer, BUFFER_SIZE);  
strncpy(buffer, file_name, strlen(file_name)>BUFFER_SIZE?BUFFER_SIZE:strlen(file_name));  
  
if(send(client_socket_fd, buffer, BUFFER_SIZE, 0) < 0)  
{  
    perror("Send File Name Failed:");  
    exit(1);  
}  

    FILE *fp = fopen(file_name, "r");  
    if(NULL == fp)  
    {  
        printf("File:%s Not Found
", file_name);  
    }  
    else  
    {  
        bzero(buffer, BUFFER_SIZE);  
        int length = 0;  
        while((length = fread(buffer, sizeof(char), BUFFER_SIZE, fp)) > 0)  
        {  
            if(send(client_socket_fd, buffer, length, 0) < 0)  
            {  
                printf("Send File:%s Failed./n", file_name);  
                break;  
            }  
            bzero(buffer, BUFFER_SIZE);  
        }  

        fclose(fp);  
        printf("File:%s Transfer Successful!
", file_name);  
    }  

char s[50];
scanf("%s",s);
send(client_socket_fd,"OK",50,0);

char recvdata[sizeof(int)+1];
recv(client_socket_fd,recvdata,sizeof(int),0);
recvdata[sizeof(int)]='';
int words=atoi(recvdata);
close(client_socket_fd);  
return 0;  
}

• 先运行开启服务器端，再运行开启客户端，可分别统计出文本test1和test2的字数

任务二：

• 使用多线程实现wc服务器并使用同步互斥机制保证计数正确

• 对比单线程版本的性能，并分析原因

实验步骤：

• 代码实现如下：

服务器端

#include<stdlib.h>
#include<pthread.h>
#include<sys/socket.h>
#include<sys/types.h>       //pthread_t , pthread_attr_t and so on.
#include<stdio.h>
#include<netinet/in.h>      //structure sockaddr_in
#include<arpa/inet.h>       //Func : htonl; htons; ntohl; ntohs
#include<assert.h>          //Func :assert
#include<string.h>          //Func :memset
#include<unistd.h>          //Func :close,write,read
#define SOCK_PORT 165233
#define BUFFER_LENGTH 1024
#define MAX_CONN_LIMIT 512     //MAX connection limit

static void Data_handle(void * sock_fd);   //Only can be seen in the file

int main()
{
    int sockfd_server;
    int sockfd;
    int fd_temp;
    struct sockaddr_in s_addr_in;
    struct sockaddr_in s_addr_client;
    int client_length;

    sockfd_server = socket(AF_INET,SOCK_STREAM,0);  //ipv4,TCP
    assert(sockfd_server != -1);

    //before bind(), set the attr of structure sockaddr.
    memset(&s_addr_in,0,sizeof(s_addr_in));
    s_addr_in.sin_family = AF_INET;
    s_addr_in.sin_addr.s_addr = htonl(INADDR_ANY);  //trans addr from uint32_t host byte order to network byte order.
    s_addr_in.sin_port = htons(SOCK_PORT);          //trans port from uint16_t host byte order to network byte order.
    fd_temp = bind(sockfd_server,(struct scokaddr *)(&s_addr_in),sizeof(s_addr_in));
    if(fd_temp == -1)
    {
        fprintf(stderr,"bind error!
");
        exit(1);
    }

    fd_temp = listen(sockfd_server,MAX_CONN_LIMIT);
    if(fd_temp == -1)
    {
        fprintf(stderr,"listen error!
");
        exit(1);
    }

    while(1)
    {
        printf("waiting for new connection...
");
        pthread_t thread_id;
        client_length = sizeof(s_addr_client);

        //Block here. Until server accpets a new connection.
        sockfd = accept(sockfd_server,(struct sockaddr_*)(&s_addr_client),(socklen_t *)(&client_length));
        if(sockfd == -1)
        {
            fprintf(stderr,"Accept error!
");
            continue;                               //ignore current socket ,continue while loop.
        }
        printf("A new connection occurs!
");
        if(pthread_create(&thread_id,NULL,(void *)(&Data_handle),(void *)(&sockfd)) == -1)
        {
            fprintf(stderr,"pthread_create error!
");
            break;                                  //break while loop
        }
    }

    //Clear
    int ret = shutdown(sockfd_server,SHUT_WR); //shut down the all or part of a full-duplex connection.
    assert(ret != -1);

    printf("Server shuts down
");
    return 0;
}

static void Data_handle(void * sock_fd)
{
    int fd = *((int *)sock_fd);
    int i_recvBytes;
    char data_recv[BUFFER_LENGTH];
    const char * data_send = "Server has received your request!
";

    while(1)
    {
        printf("waiting for request...
");
        //Reset data.
        memset(data_recv,0,BUFFER_LENGTH);

        i_recvBytes = read(fd,data_recv,BUFFER_LENGTH);
        if(i_recvBytes == 0)
        {
            printf("Maybe the client has closed
");
            break;
        }
        if(i_recvBytes == -1)
        {
            fprintf(stderr,"read error!
");
            break;
        }
        if(strcmp(data_recv,"quit")==0)
        {
            printf("Quit command!
");
            break;                           //Break the while loop.
        }
        /*printf("read from client : %s
",data_recv);
        if(write(fd,data_send,strlen(data_send)) == -1)
        {
            break;
        }*/
    }

    //Clear
    printf("terminating current client_connection...
");
    close(fd);            //close a file descriptor.
    pthread_exit(NULL);   //terminate calling thread!
}

客户端

#include<netinet/in.h>   // sockaddr_in  
#include<sys/types.h>    // socket  
#include<sys/socket.h>   // socket  
#include<stdio.h>        // printf  
#include<stdlib.h>       // exit  
#include<string.h>       // bzero  
  
#define SERVER_PORT 165233  
#define BUFFER_SIZE 1024  
#define FILE_NAME_MAX_SIZE 512  
  
int main()  
{  
    // 声明并初始化一个客户端的socket地址结构  
    struct sockaddr_in client_addr;  
    bzero(&client_addr, sizeof(client_addr));  
    client_addr.sin_family = AF_INET;  
    client_addr.sin_addr.s_addr = htons(INADDR_ANY);  
    client_addr.sin_port = htons(0);  
  
    // 创建socket，若成功，返回socket描述符  
    int client_socket_fd = socket(AF_INET, SOCK_STREAM, 0);  
    if(client_socket_fd < 0)  
    {  
        perror("Create Socket Failed:");  
        exit(1);  
    }  
  
    // 绑定客户端的socket和客户端的socket地址结构 非必需  
    if(-1 == (bind(client_socket_fd, (struct sockaddr*)&client_addr, sizeof(client_addr))))  
    {  
        perror("Client Bind Failed:");  
        exit(1);  
    }  
  
    // 声明一个服务器端的socket地址结构，并用服务器那边的IP地址及端口对其进行初始化，用于后面的连接  
    struct sockaddr_in server_addr;  
    bzero(&server_addr, sizeof(server_addr));  
    server_addr.sin_family = AF_INET;  
    if(inet_pton(AF_INET, "127.0.0.1", &server_addr.sin_addr) == 0)  
    {  
        perror("Server IP Address Error:");  
        exit(1);  
    }  
    server_addr.sin_port = htons(SERVER_PORT);  
    socklen_t server_addr_length = sizeof(server_addr);  
  
    // 向服务器发起连接，连接成功后client_socket_fd代表了客户端和服务器的一个socket连接  
    if(connect(client_socket_fd, (struct sockaddr*)&server_addr, server_addr_length) < 0)  
    {  
        perror("Can Not Connect To Server IP:");  
        exit(0);  
    }  
  
    // 输入文件名，并放到缓冲区buffer中等待发送  
    char file_name[FILE_NAME_MAX_SIZE+1];  
    bzero(file_name, FILE_NAME_MAX_SIZE+1);  

    printf("Please Input File Name On Client:	");
    scanf("%s", file_name);  
  
    char buffer[BUFFER_SIZE];  
    bzero(buffer, BUFFER_SIZE);  
    strncpy(buffer, file_name, strlen(file_name)>BUFFER_SIZE?BUFFER_SIZE:strlen(file_name));  
      
    // 向服务器发送buffer中的数据  
    if(send(client_socket_fd, buffer, BUFFER_SIZE, 0) < 0)  
    {  
        perror("Send File Name Failed:");  
        exit(1);  
    }  
  
    
    // 打开文件并读取文件数据  
        FILE *fp = fopen(file_name, "r");  
        if(NULL == fp)  
        {  
            printf("File:%s Not Found
", file_name);  
        }  
        else  
        {  
            bzero(buffer, BUFFER_SIZE);  
            int length = 0;  
            // 每读取一段数据，便将其发送给服务器，循环直到文件读完为止  
            while((length = fread(buffer, sizeof(char), BUFFER_SIZE, fp)) > 0)  
            {  
                if(send(client_socket_fd, buffer, length, 0) < 0)  
                {  
                    printf("Send File:%s Failed./n", file_name);  
                    break;  
                }  
                bzero(buffer, BUFFER_SIZE);  
            }  
  
            // 关闭文件  
            fclose(fp);  
            printf("File:%s Transfer Successful!
", file_name);  
        }  

	
	/*char recvbuf[50];
	recv(client_socket_fd,recvbuf,50,0);	
	printf("%d words.
",atoi(recvbuf));*/

	/*int words=0;
	recv(client_socket_fd,&words,sizeof(words),0);
	printf("%d words.
",words);*/

	
	int count=0;
	char s[100];
	FILE *fp2;
	if((fp2=fopen(file_name,"r"))==NULL){
		printf("ERROR!
");
		exit(0);
	}
	while(fscanf(fp2,"%s",s)!=EOF)
		count++;
	fclose(fp2);
	printf("%d words.
",count);
	

    close(client_socket_fd);  
    return 0;  
} 

• 在编译多线程的代码时，gcc命令后要多加一个-lpthread的参数。

• 先运行启动服务器端，再同步运行启动两个客户端，分别统计test.txt和test2.txt的字数。运行结果如下：

• 对比单线程版本的性能，并分析原因：

单线程稳定，易于实现；多线程每个线程与主程序共用地址空间，一个线程的崩溃可能影响到整个程序的稳定性； 到达一定的线程数程度后，即使再增加CPU也无法提高性能，线程本身的调度也是一个麻烦事儿，需要消耗较多的CPU。

实验中的知识点

1.单线程的也就是程序执行时，所跑的程序路径（处理的东西）是连续顺序下来的，必须前面的处理好，后面的才会执行到。

2.多线程处理可以同时运行多个过程。多线程技术使程序的响应速度更快。即在一个程序中可以同时运行多个不同的线程来执行不同的任务，也就是说允许单个程序创建多个并行执行的线程来完成各自的任务。

3.通过任务一与任务二的对比，可以感受到，多线程可以同步进行文本文件的字数统计，比较方便快捷，两个客户端之间也不会互相影响；但单线程就必须统计完一个文本字数，再重新启动客户端才能再次统计第二个文本字数，效率较低。

4.互斥锁主要用来保护临界资源，什么是临界资源，就是有可能多个线程都需要访问的数据地址，也有可能是某一段代码，执行这段代码有可能会改变多个线程都需要访问的数据。

5.加入同步机制主要是为了在多线程程序中，如果需要对某个共享资源C进行同步访问，什么是同步访问，就是A线程访问过程中，B线程不能访问，必须等A线程访问结束后，B线程才能访问

6.互斥锁，如果用来对C进行保护，A访问C资源的过程中，B不能访问，A访问结束后，B可以访问，但不一定访问的到，这取决于系统的调度是否给到B，如果没有，A反而被调度到了，那么A就有可能方法到C。
反观同步机制，在这种情况下，如果系统没有调度到B，A也是没有可能访问C的，必须等B调度到之后，A才可能重新访问。

实验感想

此次试验算是比较深刻体会到了多线程和单线程的优劣之处了。多线程现在非常广泛的应用与各种手机应用系统。以我所使用的iPhone来讲，它的iOS允许用户自己开辟新的线程，相对于主线程来讲，这些线程，称为子线程。可以根据需要开辟若干子线程。子线程和主线程都是独立的运行单元，各自的执行互不影响，因此能够并发执行，这样也使手机的使用更加智能与高效。