1 /*
2 * Copyright 2018 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #pragma once
18
19 #include <utils/Timers.h>
20 #include <cinttypes>
21 #include <numeric>
22 #include <unordered_map>
23 #include <vector>
24
25 namespace android::scheduler {
26
27 // Opaque handle to scheduler connection.
28 struct ConnectionHandle {
29 using Id = std::uintptr_t;
30 static constexpr Id INVALID_ID = static_cast<Id>(-1);
31
32 Id id = INVALID_ID;
33
34 explicit operator bool() const { return id != INVALID_ID; }
35 };
36
37 inline bool operator==(ConnectionHandle lhs, ConnectionHandle rhs) {
38 return lhs.id == rhs.id;
39 }
40
41 // Calculates the statistical mean (average) in the data structure (array, vector). The
42 // function does not modify the contents of the array.
43 template <typename T>
calculate_mean(const T & v)44 auto calculate_mean(const T& v) {
45 using V = typename T::value_type;
46 V sum = std::accumulate(v.begin(), v.end(), static_cast<V>(0));
47 return sum / static_cast<V>(v.size());
48 }
49
50 // Calculates the statistical median in the vector. Return 0 if the vector is empty. The
51 // function modifies the vector contents.
52 int64_t calculate_median(std::vector<int64_t>* v);
53
54 // Calculates the statistical mode in the vector. Return 0 if the vector is empty.
55 template <typename T>
calculate_mode(const T & v)56 auto calculate_mode(const T& v) {
57 if (v.empty()) {
58 return 0;
59 }
60
61 // Create a map with all the counts for the indivicual values in the vector.
62 std::unordered_map<int64_t, int> counts;
63 for (int64_t value : v) {
64 counts[value]++;
65 }
66
67 // Sort the map, and return the number with the highest count. If two numbers have
68 // the same count, first one is returned.
69 using ValueType = const decltype(counts)::value_type&;
70 const auto compareCounts = [](ValueType l, ValueType r) { return l.second <= r.second; };
71 return static_cast<int>(std::max_element(counts.begin(), counts.end(), compareCounts)->first);
72 }
73
74 template <class T, size_t N>
arrayLen(T (&)[N])75 constexpr size_t arrayLen(T (&)[N]) {
76 return N;
77 }
78
79 static constexpr size_t max64print = std::numeric_limits<nsecs_t>::digits10 + 1;
80
81 template <typename T>
round(float f)82 static inline T round(float f) {
83 return static_cast<T>(std::round(f));
84 }
85
86 } // namespace android::scheduler
87
88 namespace std {
89
90 template <>
91 struct hash<android::scheduler::ConnectionHandle> {
92 size_t operator()(android::scheduler::ConnectionHandle handle) const {
93 return hash<android::scheduler::ConnectionHandle::Id>()(handle.id);
94 }
95 };
96
97 } // namespace std
98