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ftruncate a big file
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| #include <stdio.h> | |
| #include <unistd.h> | |
| #include <stdlib.h> | |
| #include <sys/stat.h> | |
| #include <time.h> | |
| // Purpose: ftruncate big file | |
| // | |
| // argv[1] file | |
| // argv[2] shrinked size each loop, default is 100m | |
| long current_time() { | |
| struct timeval t; | |
| gettimeofday(&t, NULL); | |
| return t.tv_sec * 1000l + t.tv_usec/ 1000l; | |
| } | |
| int main(int argc, char* argv[]) { | |
| struct stat st; | |
| stat(argv[1], &st); | |
| printf("file size is %ld\n", st.st_size); | |
| off_t l = st.st_size; | |
| off_t shrink_size = 100*1024*1024; | |
| if (argc == 3) | |
| shrink_size = atoi(argv[2]); | |
| off_t shrinked = 0; | |
| while (l > 0) { | |
| if (l > shrink_size) { | |
| l = l - shrink_size; | |
| shrinked = shrink_size; | |
| } else { | |
| shrinked = l; | |
| l = 0; | |
| } | |
| long s1 = current_time(); | |
| truncate(argv[1], l); | |
| long s2 = current_time(); | |
| printf("--shrinked %ld, now is %ld , spend is %dms --\n", shrinked, l, s2-s1); | |
| sleep(1); | |
| } | |
| return 0; | |
| } |
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