1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
|
// Copyright 2023 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "ash/system/scheduled_feature/schedule_utils.h"
#include <sstream>
#include <string>
#include <utility>
#include <vector>
#include "base/check.h"
#include "base/logging.h"
#include "base/notreached.h"
namespace ash::schedule_utils {
namespace {
constexpr base::TimeDelta kOneDay = base::Days(1);
// Pairs together a `ScheduleCheckpoint` and the time at which it's
// hit.
struct Slot {
ScheduleCheckpoint checkpoint;
base::Time time;
};
// For debugging purposes only.
std::string ToString(const std::vector<Slot>& schedule) {
std::stringstream ss;
ss << std::endl;
for (const Slot& slot : schedule) {
ss << static_cast<int>(slot.checkpoint) << ": " << slot.time << std::endl;
}
return ss.str();
}
// Working with null and infinite `base::Time` instances are invalid and cause
// undue complexity to account for. They should never be provided by the caller.
bool IsValidTimestamp(const base::Time t) {
return !t.is_null() && !t.is_inf();
}
// The returned vector has one `Slot` per `ScheduleCheckpoint` and is
// sorted by `Slot::time`. The time at which `Slot` <i> ends is by definition
// `Slot` <i + 1>'s `time`. Also note that:
// * The schedule is cyclic. The next `Slot` after the last one is the first
// `Slot`.
// * The schedule is guaranteed to be centered around "now":
// * `schedule[0].time` <= `now` < `schedule[0].time + kOneDay`
// * `schedule[0].time` <= `schedule[i].time` < `schedule[0].time + kOneDay`
// for all indices <i> in the returned `schedule`.
std::vector<Slot> BuildSchedule(const base::Time now,
base::Time start_time,
base::Time end_time,
const ScheduleType schedule_type) {
DCHECK(!now.is_null());
// The `schedule` could theoretically start with any checkpoint because it's
// cyclic. `end_time` has been picked arbitrarily since it's easiest in the
// case of a `kSunsetToSunrise` to set the rest of the checkpoints relative to
// sunrise (`end_time` for that `ScheduleType`).
//
// `end_time` must first be shifted by a whole number of days such that
// `end_time` <= `now` < `end_time + kOneDay`.
//
// Example with `schedule_type` == `kSunsetToSunrise`:
// Start (sunset): 6:00 PM, End (sunrise): 6:00 AM, Now: 3:00 AM
//
// 3:00 6:00 18:00
// <---------------------------------- + ----- + --------------- + ----->
// | | |
// now end_time start_time
const base::TimeDelta amount_to_advance_end_time =
(now - end_time).FloorToMultiple(kOneDay);
end_time += amount_to_advance_end_time;
// 6:00 3:00 18:00
// <-- + ----------------------------- + ---------------------- + ----->
// | | |
// end_time now start_time
// (previous day)
// Shift `start_time` such that
// `end_time` <= `start_time` < `end_time + kOneDay`.
start_time = ShiftWithinOneDayFrom(end_time, start_time);
// 6:00 18:00 3:00 6:00
// <-- + ----------------- + --------- + ----- + ---------------------->
// | | | |
// end_time start_time now end_time
// (previous day) (current day)
std::vector<Slot> schedule;
switch (schedule_type) {
case ScheduleType::kCustom:
schedule.push_back({ScheduleCheckpoint::kDisabled, end_time});
schedule.push_back({ScheduleCheckpoint::kEnabled, start_time});
break;
case ScheduleType::kSunsetToSunrise: {
const base::TimeDelta daylight_duration = start_time - end_time;
DCHECK_GE(daylight_duration, base::TimeDelta());
schedule.push_back({ScheduleCheckpoint::kSunrise, end_time});
schedule.push_back(
{ScheduleCheckpoint::kMorning, end_time + daylight_duration / 3});
schedule.push_back({ScheduleCheckpoint::kLateAfternoon,
end_time + daylight_duration * 5 / 6});
schedule.push_back({ScheduleCheckpoint::kSunset, start_time});
break;
}
case ScheduleType::kNone:
NOTREACHED() << "kNone ScheduleType does not support any automatic "
"feature changes";
}
// 6:00 10:00 16:00 18:00 3:00 6:00
// <-- + --- + ----- + --- + ---------- + ----- + ---------------------->
// | | | | | |
// end_time morning late sunset now end_time
// (previous day) afternoon (current day)
DVLOG(1) << "Schedule: " << ToString(schedule);
return schedule;
}
// Accounts for the fact that `schedule` is cyclic: When `current_idx`
// refers to the last `Slot`, the next `Slot` is actually the first `Slot` with
// its timestamp advanced by one day.
Slot GetNextSlot(const size_t current_idx, const std::vector<Slot>& schedule) {
DCHECK(!schedule.empty());
DCHECK_LT(current_idx, schedule.size());
for (size_t next_idx = current_idx + 1; next_idx < schedule.size();
++next_idx) {
// Some extremely rare corner cases where the next `Slot`'s time could be
// exactly equal to the current `Slot` instead of greater than it:
// * Sunrise and sunset are exactly the same time in a geolocation where
// there is literally no night or no daylight.
// * Sunrise and sunset are a couple microseconds apart, leaving
// `base::Time` without enough resolution to fit morning and afternoon
// between them at unique times.
// Therefore, this iterates from the current `Slot` until the next `Slot` is
// found with a greater time.
if (schedule[next_idx].time > schedule[current_idx].time) {
return schedule[next_idx];
}
}
return {schedule.front().checkpoint, schedule.front().time + kOneDay};
}
} // namespace
Position GetCurrentPosition(const base::Time now,
const base::Time start_time,
const base::Time end_time,
const ScheduleType schedule_type) {
CHECK(IsValidTimestamp(now));
CHECK(IsValidTimestamp(start_time));
CHECK(IsValidTimestamp(end_time));
const std::vector<Slot> schedule =
BuildSchedule(now, start_time, end_time, schedule_type);
DCHECK(!schedule.empty());
DCHECK_GE(now, schedule.front().time);
DCHECK_LT(now - schedule.front().time, kOneDay);
for (size_t idx = 0; idx < schedule.size(); ++idx) {
const Slot next_slot = GetNextSlot(idx, schedule);
if (now >= schedule[idx].time && now < next_slot.time) {
return {schedule[idx].checkpoint, next_slot.checkpoint,
next_slot.time - now};
}
}
NOTREACHED() << "Failed to find ScheduleCheckpoint for now=" << now
<< " schedule:\n"
<< ToString(schedule);
}
base::Time ShiftWithinOneDayFrom(const base::Time origin,
const base::Time time_in) {
CHECK(IsValidTimestamp(origin));
CHECK(IsValidTimestamp(time_in));
const base::TimeDelta amount_to_advance_time_in =
(origin - time_in).CeilToMultiple(kOneDay);
return time_in + amount_to_advance_time_in;
}
} // namespace ash::schedule_utils
|
