GRPC Core  9.0.0
time_precise.h
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1 /*
2  *
3  * Copyright 2015 gRPC authors.
4  *
5  * Licensed under the Apache License, Version 2.0 (the "License");
6  * you may not use this file except in compliance with the License.
7  * You may obtain a copy of the License at
8  *
9  * http://www.apache.org/licenses/LICENSE-2.0
10  *
11  * Unless required by applicable law or agreed to in writing, software
12  * distributed under the License is distributed on an "AS IS" BASIS,
13  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14  * See the License for the specific language governing permissions and
15  * limitations under the License.
16  *
17  */
18 
19 #ifndef GRPC_CORE_LIB_GPR_TIME_PRECISE_H
20 #define GRPC_CORE_LIB_GPR_TIME_PRECISE_H
21 
23 
25 #include <grpc/support/time.h>
26 
27 // Depending on the platform gpr_get_cycle_counter() can have a resolution as
28 // low as a usec. Use other clock sources or gpr_precise_clock_now(),
29 // where you need high resolution clocks.
30 //
31 // Using gpr_get_cycle_counter() is preferred to using ExecCtx::Get()->Now()
32 // whenever possible.
33 
34 #if GPR_CYCLE_COUNTER_RDTSC_32
35 typedef int64_t gpr_cycle_counter;
36 inline gpr_cycle_counter gpr_get_cycle_counter() {
37  int64_t ret;
38  __asm__ volatile("rdtsc" : "=A"(ret));
39  return ret;
40 }
41 #elif GPR_CYCLE_COUNTER_RDTSC_64
42 typedef int64_t gpr_cycle_counter;
43 inline gpr_cycle_counter gpr_get_cycle_counter() {
44  uint64_t low, high;
45  __asm__ volatile("rdtsc" : "=a"(low), "=d"(high));
46  return (high << 32) | low;
47 }
48 #elif GPR_CYCLE_COUNTER_FALLBACK
49 // TODO(soheil): add support for mrs on Arm.
50 
51 // Real time in micros.
52 typedef double gpr_cycle_counter;
53 gpr_cycle_counter gpr_get_cycle_counter();
54 #else
55 #error Must define exactly one of \
56  GPR_CYCLE_COUNTER_RDTSC_32, \
57  GPR_CYCLE_COUNTER_RDTSC_64, or \
58  GPR_CYCLE_COUNTER_FALLBACK
59 #endif
60 
61 void gpr_precise_clock_init(void);
63 gpr_timespec gpr_cycle_counter_to_time(gpr_cycle_counter cycles);
64 gpr_timespec gpr_cycle_counter_sub(gpr_cycle_counter a, gpr_cycle_counter b);
65 
66 #endif /* GRPC_CORE_LIB_GPR_TIME_PRECISE_H */
gpr_timespec gpr_cycle_counter_to_time(gpr_cycle_counter cycles)
void gpr_precise_clock_now(gpr_timespec *clk)
Analogous to struct timespec.
Definition: gpr_types.h:47
gpr_timespec gpr_cycle_counter_sub(gpr_cycle_counter a, gpr_cycle_counter b)
void gpr_precise_clock_init(void)