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time_precise.h
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33 
34 #ifndef GRPC_CORE_SUPPORT_TIME_PRECISE_H_
35 #define GRPC_CORE_SUPPORT_TIME_PRECISE_H_
36 
37 #include <grpc/support/sync.h>
38 #include <grpc/support/time.h>
39 #include <stdio.h>
40 
41 #ifdef GRPC_TIMERS_RDTSC
42 #if defined(__i386__)
43 static void gpr_get_cycle_counter(long long int *clk) {
44  long long int ret;
45  __asm__ volatile("rdtsc" : "=A"(ret));
46  *clk = ret;
47 }
48 
49 // ----------------------------------------------------------------
50 #elif defined(__x86_64__) || defined(__amd64__)
51 static void gpr_get_cycle_counter(long long int *clk) {
52  unsigned long long low, high;
53  __asm__ volatile("rdtsc" : "=a"(low), "=d"(high));
54  *clk = (high << 32) | low;
55 }
56 #endif
57 
58 static gpr_once precise_clock_init = GPR_ONCE_INIT;
59 static long long cycles_per_second = 0;
60 static void gpr_precise_clock_init() {
61  time_t start = time(NULL);
62  gpr_precise_clock start_cycle;
63  gpr_precise_clock end_cycle;
64  while (time(NULL) == start)
65  ;
66  gpr_get_cycle_counter(&start_cycle);
67  while (time(NULL) == start + 1)
68  ;
69  gpr_get_cycle_counter(&end_cycle);
70  cycles_per_second = end_cycle - start_cycle;
71 }
72 
73 static double grpc_precise_clock_scaling_factor() {
74  gpr_once_init(&precise_clock_init, grpc_precise_clock_init);
75  return 1e6 / cycles_per_second;
76 }
77 
78 static void gpr_precise_clock_now(gpr_timespec *clk) {
79  long long int counter;
80  gpr_get_cycle_counter(&counter);
81  clk->clock = GPR_CLOCK_REALTIME;
82  clk->tv_sec = counter / cycles_per_second;
83  clk->tv_nsec = counter % cycles_per_second;
84 }
85 
86 #else /* GRPC_TIMERS_RDTSC */
87 static void gpr_precise_clock_now(gpr_timespec *clk) {
90 }
91 #endif /* GRPC_TIMERS_RDTSC */
92 
93 #endif /* GRPC_CORE_SUPPORT_TIME_PRECISE_ */
time_t tv_sec
Definition: time.h:64
void gpr_once_init(gpr_once *once, void(*init_routine)(void))
Definition: time.h:54
gpr_clock_type clock_type
Against which clock was this time measured? (or GPR_TIMESPAN if this is a relative time meaure) ...
Definition: time.h:68
Definition: time.h:57
pthread_once_t gpr_once
Definition: sync_posix.h:43
int tv_nsec
Definition: time.h:65
#define GPR_ONCE_INIT
Definition: sync_posix.h:45
gpr_timespec gpr_now(gpr_clock_type clock)
Definition: time.h:63