Seperate LatencyStatistics from InputReader (8384682f) · Commits · e / os / platform_frameworks_native

include/input/LatencyStatistics.h

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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.
		*/

		#ifndef _UI_INPUT_STATISTICS_H
		#define _UI_INPUT_STATISTICS_H

		#include <android-base/chrono_utils.h>

		#include <stddef.h>

		namespace android {

		class LatencyStatistics {
		private:
		/* Minimum sample recorded */
		float mMin;
		/* Maximum sample recorded */
		float mMax;
		/* Sum of all samples recorded */
		float mSum;
		/* Sum of all the squares of samples recorded */
		float mSum2;
		/* Count of all samples recorded */
		size_t mCount;
		/* The last time statistics were reported */
		std::chrono::steady_clock::time_point mLastReportTime;
		/* Statistics Report Frequency */
		const std::chrono::seconds mReportPeriod;

		public:
		LatencyStatistics(std::chrono::seconds period);

		void addValue(float);
		void reset();
		bool shouldReport();

		float getMean();
		float getMin();
		float getMax();
		float getStDev();
		size_t getCount();
		};

		} // namespace android

		#endif // _UI_INPUT_STATISTICS_H

libs/input/Android.bp

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		@@ -48,6 +48,7 @@ cc_library {
		"InputTransport.cpp",
		"InputWindow.cpp",
		"ISetInputWindowsListener.cpp",
		"LatencyStatistics.cpp",
		"VelocityControl.cpp",
		"VelocityTracker.cpp",
		],

libs/input/LatencyStatistics.cpp

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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

libs/input/tests/Android.bp

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		@@ -7,6 +7,7 @@ cc_test {
		"InputEvent_test.cpp",
		"InputPublisherAndConsumer_test.cpp",
		"InputWindow_test.cpp",
		"LatencyStatistics_test.cpp",
		"TouchVideoFrame_test.cpp",
		"VelocityTracker_test.cpp",
		],

libs/input/tests/LatencyStatistics_test.cpp

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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 <gtest/gtest.h>
		#include <input/LatencyStatistics.h>
		#include <cmath>
		#include <limits>

		namespace android {
		namespace test {

		TEST(LatencyStatisticsTest, ResetStats) {
		LatencyStatistics stats{5min};
		stats.addValue(5.0);
		stats.addValue(19.3);
		stats.addValue(20);
		stats.reset();

		ASSERT_EQ(stats.getCount(), 0u);
		ASSERT_EQ(std::isnan(stats.getStDev()), true);
		ASSERT_EQ(std::isnan(stats.getMean()), true);
		}

		TEST(LatencyStatisticsTest, AddStatsValue) {
		LatencyStatistics stats{5min};
		stats.addValue(5.0);

		ASSERT_EQ(stats.getMin(), 5.0);
		ASSERT_EQ(stats.getMax(), 5.0);
		ASSERT_EQ(stats.getCount(), 1u);
		ASSERT_EQ(stats.getMean(), 5.0);
		ASSERT_EQ(stats.getStDev(), 0.0);
		}

		TEST(LatencyStatisticsTest, AddMultipleStatsValue) {
		LatencyStatistics stats{5min};
		stats.addValue(4.0);
		stats.addValue(6.0);
		stats.addValue(8.0);
		stats.addValue(10.0);

		float stdev = stats.getStDev();

		ASSERT_EQ(stats.getMin(), 4.0);
		ASSERT_EQ(stats.getMax(), 10.0);
		ASSERT_EQ(stats.getCount(), 4u);
		ASSERT_EQ(stats.getMean(), 7.0);
		ASSERT_EQ(stdev * stdev, 5.0);
		}

		TEST(LatencyStatisticsTest, ShouldReportStats) {
		LatencyStatistics stats{0min};
		stats.addValue(5.0);

		ASSERT_EQ(stats.shouldReport(), true);
		}

		} // namespace test
		} // namespace android
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