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/*
* Copyright (C) 2019 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.
*/
#include <input/LatencyStatistics.h>
#include <android-base/chrono_utils.h>
#include <cmath>
#include <limits>
namespace android {
LatencyStatistics::LatencyStatistics(std::chrono::seconds period) : mReportPeriod(period) {
reset();
}
/**
* Add a raw value to the statistics
*/
void LatencyStatistics::addValue(float value) {
if (value < mMin) {
mMin = value;
}
if (value > mMax) {
mMax = value;
}
mSum += value;
mSum2 += value * value;
mCount++;
}
/**
* Get the mean. Should not be called if no samples have been added.
*/
float LatencyStatistics::getMean() {
return mSum / mCount;
}
/**
* Get the standard deviation. Should not be called if no samples have been added.
*/
float LatencyStatistics::getStDev() {
float mean = getMean();
return sqrt(mSum2 / mCount - mean * mean);
}
float LatencyStatistics::getMin() {
return mMin;
}
float LatencyStatistics::getMax() {
return mMax;
}
size_t LatencyStatistics::getCount() {
return mCount;
}
/**
* Reset internal state. The variable 'when' is the time when the data collection started.
* Call this to start a new data collection window.
*/
void LatencyStatistics::reset() {
mMax = std::numeric_limits<float>::lowest();
mMin = std::numeric_limits<float>::max();
mSum = 0;
mSum2 = 0;
mCount = 0;
mLastReportTime = std::chrono::steady_clock::now();
}
bool LatencyStatistics::shouldReport() {
std::chrono::duration timeSinceReport = std::chrono::steady_clock::now() - mLastReportTime;
return mCount != 0 && timeSinceReport >= mReportPeriod;
}
} // namespace android
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