1// Copyright 2017 The Abseil Authors.
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7// https://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14//
15// -----------------------------------------------------------------------------
16// File: clock.h
17// -----------------------------------------------------------------------------
18//
19// This header file contains utility functions for working with the system-wide
20// realtime clock. For descriptions of the main time abstractions used within
21// this header file, consult the time.h header file.
22#ifndef ABSL_TIME_CLOCK_H_
23#define ABSL_TIME_CLOCK_H_
24
25#include "absl/base/macros.h"
26#include "absl/time/time.h"
27
28namespace absl {
29
30// Now()
31//
32// Returns the current time, expressed as an `absl::Time` absolute time value.
33absl::Time Now();
34
35// GetCurrentTimeNanos()
36//
37// Returns the current time, expressed as a count of nanoseconds since the Unix
38// Epoch (https://en.wikipedia.org/wiki/Unix_time). Prefer `absl::Now()` instead
39// for all but the most performance-sensitive cases (i.e. when you are calling
40// this function hundreds of thousands of times per second).
41int64_t GetCurrentTimeNanos();
42
43// SleepFor()
44//
45// Sleeps for the specified duration, expressed as an `absl::Duration`.
46//
47// Notes:
48// * Signal interruptions will not reduce the sleep duration.
49// * Returns immediately when passed a nonpositive duration.
50void SleepFor(absl::Duration duration);
51
52} // namespace absl
53
54// -----------------------------------------------------------------------------
55// Implementation Details
56// -----------------------------------------------------------------------------
57
58// In some build configurations we pass --detect-odr-violations to the
59// gold linker. This causes it to flag weak symbol overrides as ODR
60// violations. Because ODR only applies to C++ and not C,
61// --detect-odr-violations ignores symbols not mangled with C++ names.
62// By changing our extension points to be extern "C", we dodge this
63// check.
64extern "C" {
65void AbslInternalSleepFor(absl::Duration duration);
66} // extern "C"
67
68inline void absl::SleepFor(absl::Duration duration) {
69 AbslInternalSleepFor(duration);
70}
71
72#endif // ABSL_TIME_CLOCK_H_
73