实现多线程拷贝命令,如：./multithread_copy  srcfile destfile N(拷贝线程个数)

难点：

内存映射mmap。

给每一个线程合理的分配任务。

多线程的实现。

具体的实现代码如下：

/*************************************************************************

> File Name: multithread_copy.c

> Author: lucifer

> Mail: lucifer@163.com

> Created Time: 2014年11月14日 星期五 17时43分36秒

************************************************************************/

#include

#include

#include

#include

#include

#include

#include

#include

#include

#define N 5

int nthread = 0;

struct allocate_task

{

char *start;

char *end;

int size;

int num;

};

void sys_err(const char *str)

{

perror(str);

exit(-1);

}

void *thread_copy(void *arg)

{

int i;

struct allocate_task *s = (struct allocate_task *)arg;

for(i = 0;i < nthread;i++)

{

memcpy(s[i].end,s[i].start,s[i].size);

}

}

int main(int argc, char *argv[])

{

int fdsrc, fddest, i, err, total_size,task_size;

struct stat sbuf;

char *psrc,*pdest;

if(argc < 3)

{

fprintf(stdout,"%s srcname destname\n",argv[0]);

exit(-1);

}

if(argc = 3)

nthread = N;

else

nthread = atoi(argv[3]);

if(stat(argv[1],&sbuf) < 0)

sys_err("stat");

total_size = sbuf.st_size;

fddest = open(argv[2],O_CREAT |O_RDWR | O_TRUNC,0664);

if(fddest < 0)

sys_err("open");

if(lseek(fddest,total_size - 1,SEEK_SET) < 0)

sys_err("lseek");

write(fddest,"\0",1);

fdsrc = open(argv[1],O_RDONLY);

if(fdsrc < 0)

sys_err("open");

psrc = mmap(NULL,total_size,PROT_READ,MAP_PRIVATE,fdsrc,0);

if(psrc == MAP_FAILED)

sys_err("mmap");

pdest = mmap(NULL,total_size,PROT_WRITE,MAP_SHARED,fddest,0);

if(pdest == MAP_FAILED)

sys_err("mmap");

close(fdsrc);

close(fddest);

struct allocate_task *work = malloc(nthread * sizeof(struct allocate_task));

task_size = total_size / nthread;

for(i = 0;i < nthread - 1;i++)

{

work[i].start = psrc + i * task_size;

work[i].end = pdest + i * task_size;

work[i].size = task_size;

}

work[i].start = psrc + i * task_size;

work[i].end = pdest + i * task_size;

work[i].size = total_size - task_size * (nthread - 1);

work[i].num = i;

pthread_t tid[nthread];

for(i = 0;i < nthread;i++)

{

err = pthread_create(&tid[i],NULL,thread_copy,(void *)work);

if(err != 0)

{

printf("%s\n",strerror(err));

break;

}

}

for(i = 0;i < nthread; i++)

{

pthread_join(tid[i],NULL);

}

free(work);

return 0;

}