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。