Add perf tests for LooperStats

/*

 * Copyright (C) 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.

 */

package android.os;

import android.perftests.utils.BenchmarkState;

import android.perftests.utils.PerfStatusReporter;

import android.support.test.filters.LargeTest;

import android.support.test.runner.AndroidJUnit4;

import com.android.internal.os.CachedDeviceState;

import com.android.internal.os.LooperStats;

import org.junit.After;

import org.junit.Before;

import org.junit.Rule;

import org.junit.Test;

import org.junit.runner.RunWith;

/**

 * Performance tests for {@link LooperStats}.

 */

@RunWith(AndroidJUnit4.class)

@LargeTest

public class LooperStatsPerfTest {

    private static final int DISTINCT_MESSAGE_COUNT = 1000;

    @Rule

    public PerfStatusReporter mPerfStatusReporter = new PerfStatusReporter();

    private LooperStats mStats;

    private CachedDeviceState mDeviceState;

    private HandlerThread mThread;

    private Message[] mMessages = new Message[DISTINCT_MESSAGE_COUNT];

    @Before

    public void setUp() {

        mStats = new LooperStats(1, DISTINCT_MESSAGE_COUNT - 1);

        mDeviceState = new CachedDeviceState(false, false);

        mStats.setDeviceState(mDeviceState.getReadonlyClient());

        // The tests are all single-threaded. HandlerThread is created to allow creating Handlers.

        mThread = new HandlerThread("UnusedThread");

        mThread.start();

        for (int i = 0; i < DISTINCT_MESSAGE_COUNT; i++) {

            mMessages[i] = mThread.getThreadHandler().obtainMessage(i);

        }

    }

    @After

    public void tearDown() {

        mThread.quit();

    }

    @Test

    public void timeHundredPercentSampling() {

        mStats.setSamplingInterval(1);

        runScenario();

    }

    @Test

    public void timeOnePercentSampling() {

        mStats.setSamplingInterval(100);

        runScenario();

    }

    @Test

    public void timeCollectionDisabled() {

        // We do not collect data on charger.

        mDeviceState.setCharging(true);

        runScenario();

    }

    private void runScenario() {

        final BenchmarkState state = mPerfStatusReporter.getBenchmarkState();

        while (state.keepRunning()) {

            for (int i = 0; i < DISTINCT_MESSAGE_COUNT; i++) {

                Object token = mStats.messageDispatchStarting();

                mStats.messageDispatched(token, mMessages[i]);

            }

        }

    }

}