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* 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
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* See the License for the specific language governing permissions and
* limitations under the License.
#pragma once
#include <utils/Timers.h>
#include <cinttypes>
#include <numeric>
#include <unordered_map>
#include <vector>
namespace android::scheduler {
// Opaque handle to scheduler connection.
struct ConnectionHandle {
using Id = std::uintptr_t;
static constexpr Id INVALID_ID = static_cast<Id>(-1);
explicit operator bool() const { return id != INVALID_ID; }
inline bool operator==(ConnectionHandle lhs, ConnectionHandle rhs) {
return ==;
// 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) {
// 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);
template <class T, size_t N>
constexpr size_t arrayLen(T (&)[N]) {
return N;
static constexpr size_t max64print = std::numeric_limits<nsecs_t>::digits10 + 1;
template <typename T>
static inline T round(float f) {
return static_cast<T>(std::round(f));
} // namespace android::scheduler
namespace std {
template <>
struct hash<android::scheduler::ConnectionHandle> {
size_t operator()(android::scheduler::ConnectionHandle handle) const {
return hash<android::scheduler::ConnectionHandle::Id>()(;
} // namespace std