linux下实现多线程拷贝命令

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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 <stdio.h>#include <stdlib.h>#include <sys/types.h>#include <sys/stat.h>#include <fcntl.h>#include <pthread.h>#include <sys/mman.h>#include <string.h>#include <unistd.h>#define N 5int 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;elsenthread = 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;}

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