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
|
/*
* Copyright 2018 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#pragma once
#include <chrono>
#include <cinttypes>
#include <numeric>
#include <unordered_map>
#include <vector>
namespace android {
namespace scheduler {
using namespace std::chrono_literals;
// This number is used to set the size of the arrays in scheduler that hold information
// about layers.
static constexpr size_t ARRAY_SIZE = 30;
// This number is used when we try to determine how long do we keep layer information around
// before we remove it. It is also used to determine how long the layer stays relevant.
// This time period captures infrequent updates when playing YouTube video with static image,
// or waiting idle in messaging app, when cursor is blinking.
static constexpr std::chrono::nanoseconds OBSOLETE_TIME_EPSILON_NS = 1200ms;
// Layer is considered low activity if the LOW_ACTIVITY_BUFFERS buffers come more than
// LOW_ACTIVITY_EPSILON_NS apart.
// This is helping SF to vote for lower refresh rates when there is not activity
// in screen.
static constexpr int LOW_ACTIVITY_BUFFERS = 2;
static constexpr std::chrono::nanoseconds LOW_ACTIVITY_EPSILON_NS = 250ms;
// Calculates the statistical mean (average) in the data structure (array, vector). The
// function does not modify the contents of the array.
template <typename T>
auto calculate_mean(const T& v) {
using V = typename T::value_type;
V sum = std::accumulate(v.begin(), v.end(), static_cast<V>(0));
return sum / static_cast<V>(v.size());
}
// Calculates the statistical median in the vector. Return 0 if the vector is empty. The
// function modifies the vector contents.
int64_t calculate_median(std::vector<int64_t>* v);
// Calculates the statistical mode in the vector. Return 0 if the vector is empty.
template <typename T>
auto calculate_mode(const T& v) {
if (v.empty()) {
return 0;
}
// Create a map with all the counts for the indivicual values in the vector.
std::unordered_map<int64_t, int> counts;
for (int64_t value : v) {
counts[value]++;
}
// Sort the map, and return the number with the highest count. If two numbers have
// the same count, first one is returned.
using ValueType = const decltype(counts)::value_type&;
const auto compareCounts = [](ValueType l, ValueType r) { return l.second <= r.second; };
return static_cast<int>(std::max_element(counts.begin(), counts.end(), compareCounts)->first);
}
} // namespace scheduler
} // namespace android
|
