1 #include <stdlib.h> 2 #include <stdio.h> 3 #include <unistd.h> 4 #include <sys/limits.h> 5 #include <sys/time.h> 6 #include <time.h> 7 #include <errno.h> 8 9 #include <string.h> 10 11 12 nanotime(void)13 long long nanotime(void) 14 { 15 struct timespec t; 16 17 if(clock_gettime(CLOCK_MONOTONIC, &t)) { 18 fprintf(stderr,"clock failure\n"); 19 exit(1); 20 } 21 22 return (((long long) t.tv_sec) * 1000000000LL) + 23 ((long long) t.tv_nsec); 24 } 25 ts_sub(struct timespec a,struct timespec b)26 static struct timespec ts_sub(struct timespec a, struct timespec b) 27 { 28 struct timespec r; 29 r.tv_sec = a.tv_sec - b.tv_sec; 30 r.tv_nsec = a.tv_nsec - b.tv_nsec; 31 if(r.tv_nsec < 0) { 32 r.tv_sec--; 33 r.tv_nsec += 1000 * 1000 * 1000; 34 } 35 if(r.tv_sec < 0 && r.tv_nsec > 0) { 36 r.tv_sec++; 37 r.tv_nsec -= 1000 * 1000 * 1000; 38 } 39 return r; 40 } 41 ts_min(struct timespec a,struct timespec b)42 static struct timespec ts_min(struct timespec a, struct timespec b) 43 { 44 if(a.tv_sec < b.tv_sec || (a.tv_sec == b.tv_sec && a.tv_nsec < b.tv_nsec)) 45 return a; 46 else 47 return b; 48 } 49 ts_max(struct timespec a,struct timespec b)50 static struct timespec ts_max(struct timespec a, struct timespec b) 51 { 52 if(a.tv_sec < b.tv_sec || (a.tv_sec == b.tv_sec && a.tv_nsec < b.tv_nsec)) 53 return b; 54 else 55 return a; 56 } 57 main(int argc,char ** argv)58 int main(int argc, char **argv) 59 { 60 long long tnow, tlast; 61 struct timespec t1, dtmin, dtminp, dtmax; 62 int print_interval = 50000; 63 int print_countdown = 1; 64 int clock_id = CLOCK_MONOTONIC; 65 dtmin.tv_sec = INT_MAX; 66 dtmin.tv_nsec = 0; 67 dtminp.tv_sec = INT_MAX; 68 dtminp.tv_nsec = 0; 69 dtmax.tv_sec = 0; 70 dtmax.tv_nsec = 0; 71 tlast = 0; 72 73 if(argc == 2) { 74 clock_id = atoi(argv[1]); 75 printf("using clock %d\n", clock_id); 76 } 77 clock_gettime(clock_id, &t1); 78 79 for(;;) { 80 struct timespec t, dt; 81 clock_gettime(clock_id, &t); 82 dt = ts_sub(t, t1); 83 t1 = t; 84 dtmin = ts_min(dtmin, dt); 85 if(dt.tv_sec > 0 || dt.tv_nsec > 0) 86 dtminp = ts_min(dtminp, dt); 87 if(print_countdown != print_interval) 88 dtmax = ts_max(dtmax, dt); 89 if(--print_countdown == 0) { 90 fprintf(stderr,"%09ld.%09ld, dt %ld.%09ld, min %ld.%09ld, minp %ld.%09ld, max %ld.%09ld\n", 91 t.tv_sec, t.tv_nsec, dt.tv_sec, dt.tv_nsec, 92 dtmin.tv_sec, dtmin.tv_nsec, dtminp.tv_sec, dtminp.tv_nsec, 93 dtmax.tv_sec, dtmax.tv_nsec); 94 print_countdown = print_interval; 95 } 96 } 97 for(;;) { 98 tnow = nanotime(); 99 if(tnow < tlast) { 100 #if 0 101 fprintf(stderr,"time went backwards: %lld -> %lld\n", 102 tlast, tnow); 103 exit(1); 104 #endif 105 fprintf(stderr,"%lld ROLLBACK\n", tnow); 106 } else { 107 fprintf(stderr,"%lld\n", tnow); 108 } 109 tlast = tnow; 110 } 111 112 return 0; 113 } 114