1// Copyright 2013 The Flutter Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#ifndef FLUTTER_FML_TIME_TIME_POINT_H_
6#define FLUTTER_FML_TIME_TIME_POINT_H_
7
8#include <cstdint>
9#include <functional>
10#include <iosfwd>
11
12#include "flutter/fml/time/time_delta.h"
13
14namespace fml {
15
16// A TimePoint represents a point in time represented as an integer number of
17// nanoseconds elapsed since an arbitrary point in the past.
18//
19// WARNING: This class should not be serialized across reboots, or across
20// devices: the reference point is only stable for a given device between
21// reboots.
22class TimePoint {
23 public:
24 using ClockSource = TimePoint (*)();
25
26 // Default TimePoint with internal value 0 (epoch).
27 constexpr TimePoint() = default;
28
29 static void SetClockSource(ClockSource source);
30
31 static TimePoint Now();
32
33 static TimePoint CurrentWallTime();
34
35 static constexpr TimePoint Min() {
36 return TimePoint(std::numeric_limits<int64_t>::min());
37 }
38
39 static constexpr TimePoint Max() {
40 return TimePoint(std::numeric_limits<int64_t>::max());
41 }
42
43 static constexpr TimePoint FromEpochDelta(TimeDelta ticks) {
44 return TimePoint(ticks.ToNanoseconds());
45 }
46
47 // Expects ticks in nanos.
48 static constexpr TimePoint FromTicks(int64_t ticks) {
49 return TimePoint(ticks);
50 }
51
52 TimeDelta ToEpochDelta() const { return TimeDelta::FromNanoseconds(nanos: ticks_); }
53
54 // Compute the difference between two time points.
55 TimeDelta operator-(TimePoint other) const {
56 return TimeDelta::FromNanoseconds(nanos: ticks_ - other.ticks_);
57 }
58
59 TimePoint operator+(TimeDelta duration) const {
60 return TimePoint(ticks_ + duration.ToNanoseconds());
61 }
62 TimePoint operator-(TimeDelta duration) const {
63 return TimePoint(ticks_ - duration.ToNanoseconds());
64 }
65
66 bool operator==(TimePoint other) const { return ticks_ == other.ticks_; }
67 bool operator!=(TimePoint other) const { return ticks_ != other.ticks_; }
68 bool operator<(TimePoint other) const { return ticks_ < other.ticks_; }
69 bool operator<=(TimePoint other) const { return ticks_ <= other.ticks_; }
70 bool operator>(TimePoint other) const { return ticks_ > other.ticks_; }
71 bool operator>=(TimePoint other) const { return ticks_ >= other.ticks_; }
72
73 private:
74 explicit constexpr TimePoint(int64_t ticks) : ticks_(ticks) {}
75
76 int64_t ticks_ = 0;
77};
78
79} // namespace fml
80
81#endif // FLUTTER_FML_TIME_TIME_POINT_H_
82

source code of flutter_engine/flutter/fml/time/time_point.h