server/usage/UsageStatsService.java

/**
 * Copyright (C) 2014 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 com.android.server.usage;

import android.Manifest;
import android.app.ActivityManagerNative;
import android.app.AppGlobals;
import android.app.AppOpsManager;
import android.app.admin.DevicePolicyManager;
import android.app.usage.ConfigurationStats;
import android.app.usage.IUsageStatsManager;
import android.app.usage.UsageEvents;
import android.app.usage.UsageEvents.Event;
import android.app.usage.UsageStats;
import android.app.usage.UsageStatsManagerInternal;
import android.app.usage.UsageStatsManagerInternal.AppIdleStateChangeListener;
import android.appwidget.AppWidgetManager;
import android.content.BroadcastReceiver;
import android.content.ComponentName;
import android.content.ContentResolver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.content.pm.ApplicationInfo;
import android.content.pm.PackageInfo;
import android.content.pm.PackageManager;
import android.content.pm.ParceledListSlice;
import android.content.pm.UserInfo;
import android.content.res.Configuration;
import android.database.ContentObserver;
import android.hardware.display.DisplayManager;
import android.net.NetworkScoreManager;
import android.os.BatteryManager;
import android.os.BatteryStats;
import android.os.Binder;
import android.os.Environment;
import android.os.Handler;
import android.os.IDeviceIdleController;
import android.os.Looper;
import android.os.Message;
import android.os.PowerManager;
import android.os.Process;
import android.os.RemoteException;
import android.os.ServiceManager;
import android.os.SystemClock;
import android.os.UserHandle;
import android.os.UserManager;
import android.provider.Settings;
import android.telephony.TelephonyManager;
import android.util.ArraySet;
import android.util.AtomicFile;
import android.util.KeyValueListParser;
import android.util.Slog;
import android.util.SparseArray;
import android.util.SparseIntArray;
import android.util.TimeUtils;
import android.view.Display;

import com.android.internal.annotations.GuardedBy;
import com.android.internal.app.IBatteryStats;
import com.android.internal.os.BackgroundThread;
import com.android.internal.os.SomeArgs;
import com.android.internal.util.IndentingPrintWriter;
import com.android.server.SystemService;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileDescriptor;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

/**
 * A service that collects, aggregates, and persists application usage data.
 * This data can be queried by apps that have been granted permission by AppOps.
 */
public class UsageStatsService extends SystemService implements
        UserUsageStatsService.StatsUpdatedListener {

    static final String TAG = "UsageStatsService";

    static final boolean DEBUG = false;
    static final boolean COMPRESS_TIME = false;

    private static final long TEN_SECONDS = 10 * 1000;
    private static final long ONE_MINUTE = 60 * 1000;
    private static final long TWENTY_MINUTES = 20 * 60 * 1000;
    private static final long FLUSH_INTERVAL = COMPRESS_TIME ? TEN_SECONDS : TWENTY_MINUTES;
    private static final long TIME_CHANGE_THRESHOLD_MILLIS = 2 * 1000; // Two seconds.

    long mAppIdleDurationMillis;
    long mCheckIdleIntervalMillis;
    long mAppIdleWallclockThresholdMillis;
    long mAppIdleParoleIntervalMillis;
    long mAppIdleParoleDurationMillis;

    // Handler message types.
    static final int MSG_REPORT_EVENT = 0;
    static final int MSG_FLUSH_TO_DISK = 1;
    static final int MSG_REMOVE_USER = 2;
    static final int MSG_INFORM_LISTENERS = 3;
    static final int MSG_FORCE_IDLE_STATE = 4;
    static final int MSG_CHECK_IDLE_STATES = 5;
    static final int MSG_CHECK_PAROLE_TIMEOUT = 6;
    static final int MSG_PAROLE_END_TIMEOUT = 7;
    static final int MSG_REPORT_CONTENT_PROVIDER_USAGE = 8;
    static final int MSG_PAROLE_STATE_CHANGED = 9;

    private final Object mLock = new Object();
    Handler mHandler;
    AppOpsManager mAppOps;
    UserManager mUserManager;
    AppWidgetManager mAppWidgetManager;
    IDeviceIdleController mDeviceIdleController;
    private DisplayManager mDisplayManager;
    private PowerManager mPowerManager;
    private IBatteryStats mBatteryStats;

    private final SparseArray<UserUsageStatsService> mUserState = new SparseArray<>();
    private File mUsageStatsDir;
    long mRealTimeSnapshot;
    long mSystemTimeSnapshot;

    boolean mAppIdleEnabled;
    boolean mAppIdleParoled;
    private boolean mScreenOn;
    private long mLastAppIdleParoledTime;

    long mScreenOnTime;
    long mScreenOnSystemTimeSnapshot;

    @GuardedBy("mLock")
    private AppIdleHistory mAppIdleHistory = new AppIdleHistory();

    private ArrayList<UsageStatsManagerInternal.AppIdleStateChangeListener>
            mPackageAccessListeners = new ArrayList<>();

    public UsageStatsService(Context context) {
        super(context);
    }

    @Override
    public void onStart() {
        mAppOps = (AppOpsManager) getContext().getSystemService(Context.APP_OPS_SERVICE);
        mUserManager = (UserManager) getContext().getSystemService(Context.USER_SERVICE);

        mHandler = new H(BackgroundThread.get().getLooper());

        File systemDataDir = new File(Environment.getDataDirectory(), "system");
        mUsageStatsDir = new File(systemDataDir, "usagestats");
        mUsageStatsDir.mkdirs();
        if (!mUsageStatsDir.exists()) {
            throw new IllegalStateException("Usage stats directory does not exist: "
                    + mUsageStatsDir.getAbsolutePath());
        }

        IntentFilter userActions = new IntentFilter(Intent.ACTION_USER_REMOVED);
        userActions.addAction(Intent.ACTION_USER_STARTED);
        getContext().registerReceiverAsUser(new UserActionsReceiver(), UserHandle.ALL, userActions,
                null, null);

        mAppIdleEnabled = getContext().getResources().getBoolean(
                com.android.internal.R.bool.config_enableAutoPowerModes);
        if (mAppIdleEnabled) {
            IntentFilter deviceStates = new IntentFilter(BatteryManager.ACTION_CHARGING);
            deviceStates.addAction(BatteryManager.ACTION_DISCHARGING);
            deviceStates.addAction(PowerManager.ACTION_DEVICE_IDLE_MODE_CHANGED);
            getContext().registerReceiver(new DeviceStateReceiver(), deviceStates);
        }

        synchronized (mLock) {
            cleanUpRemovedUsersLocked();
        }

        mRealTimeSnapshot = SystemClock.elapsedRealtime();
        mSystemTimeSnapshot = System.currentTimeMillis();

        publishLocalService(UsageStatsManagerInternal.class, new LocalService());
        publishBinderService(Context.USAGE_STATS_SERVICE, new BinderService());
    }

    @Override
    public void onBootPhase(int phase) {
        if (phase == PHASE_SYSTEM_SERVICES_READY) {
            // Observe changes to the threshold
            SettingsObserver settingsObserver = new SettingsObserver(mHandler);
            settingsObserver.registerObserver();
            settingsObserver.updateSettings();

            mAppWidgetManager = getContext().getSystemService(AppWidgetManager.class);
            mDeviceIdleController = IDeviceIdleController.Stub.asInterface(
                    ServiceManager.getService(Context.DEVICE_IDLE_CONTROLLER));
            mBatteryStats = IBatteryStats.Stub.asInterface(
                    ServiceManager.getService(BatteryStats.SERVICE_NAME));
            mDisplayManager = (DisplayManager) getContext().getSystemService(
                    Context.DISPLAY_SERVICE);
            mPowerManager = getContext().getSystemService(PowerManager.class);

            mScreenOnSystemTimeSnapshot = System.currentTimeMillis();
            synchronized (this) {
                mScreenOnTime = readScreenOnTimeLocked();
            }
            mDisplayManager.registerDisplayListener(mDisplayListener, null);
            synchronized (this) {
                updateDisplayLocked();
            }
        } else if (phase == PHASE_BOOT_COMPLETED) {
            setAppIdleParoled(getContext().getSystemService(BatteryManager.class).isCharging());
        }
    }

    private class UserActionsReceiver extends BroadcastReceiver {

        @Override
        public void onReceive(Context context, Intent intent) {
            final int userId = intent.getIntExtra(Intent.EXTRA_USER_HANDLE, -1);
            if (Intent.ACTION_USER_REMOVED.equals(intent.getAction())) {
                if (userId >= 0) {
                    mHandler.obtainMessage(MSG_REMOVE_USER, userId, 0).sendToTarget();
                }
            } else if (Intent.ACTION_USER_STARTED.equals(intent.getAction())) {
                if (userId >=0) {
                    postCheckIdleStates(userId);
                }
            }
        }
    }

    private class DeviceStateReceiver extends BroadcastReceiver {
        @Override
        public void onReceive(Context context, Intent intent) {
            final String action = intent.getAction();
            if (BatteryManager.ACTION_CHARGING.equals(action)
                    || BatteryManager.ACTION_DISCHARGING.equals(action)) {
                setAppIdleParoled(BatteryManager.ACTION_CHARGING.equals(action));
            } else if (PowerManager.ACTION_DEVICE_IDLE_MODE_CHANGED.equals(action)) {
                onDeviceIdleModeChanged();
            }
        }
    }

    private final DisplayManager.DisplayListener mDisplayListener
            = new DisplayManager.DisplayListener() {

        @Override public void onDisplayAdded(int displayId) {
        }

        @Override public void onDisplayRemoved(int displayId) {
        }

        @Override public void onDisplayChanged(int displayId) {
            if (displayId == Display.DEFAULT_DISPLAY) {
                synchronized (UsageStatsService.this.mLock) {
                    updateDisplayLocked();
                }
            }
        }
    };

    @Override
    public void onStatsUpdated() {
        mHandler.sendEmptyMessageDelayed(MSG_FLUSH_TO_DISK, FLUSH_INTERVAL);
    }

    private void cleanUpRemovedUsersLocked() {
        final List<UserInfo> users = mUserManager.getUsers(true);
        if (users == null || users.size() == 0) {
            throw new IllegalStateException("There can't be no users");
        }

        ArraySet<String> toDelete = new ArraySet<>();
        String[] fileNames = mUsageStatsDir.list();
        if (fileNames == null) {
            // No users to delete.
            return;
        }

        toDelete.addAll(Arrays.asList(fileNames));

        final int userCount = users.size();
        for (int i = 0; i < userCount; i++) {
            final UserInfo userInfo = users.get(i);
            toDelete.remove(Integer.toString(userInfo.id));
        }

        final int deleteCount = toDelete.size();
        for (int i = 0; i < deleteCount; i++) {
            deleteRecursively(new File(mUsageStatsDir, toDelete.valueAt(i)));
        }
    }

    /** Paroled here means temporary pardon from being inactive */
    void setAppIdleParoled(boolean paroled) {
        synchronized (mLock) {
            if (mAppIdleParoled != paroled) {
                mAppIdleParoled = paroled;
                if (DEBUG) Slog.d(TAG, "Changing paroled to " + mAppIdleParoled);
                if (paroled) {
                    postParoleEndTimeout();
                } else {
                    mLastAppIdleParoledTime = checkAndGetTimeLocked();
                    postNextParoleTimeout();
                }
                postParoleStateChanged();
            }
        }
    }

    private void postNextParoleTimeout() {
        if (DEBUG) Slog.d(TAG, "Posting MSG_CHECK_PAROLE_TIMEOUT");
        mHandler.removeMessages(MSG_CHECK_PAROLE_TIMEOUT);
        // Compute when the next parole needs to happen. We check more frequently than necessary
        // since the message handler delays are based on elapsedRealTime and not wallclock time.
        // The comparison is done in wallclock time.
        long timeLeft = (mLastAppIdleParoledTime + mAppIdleParoleIntervalMillis)
                - checkAndGetTimeLocked();
        if (timeLeft < 0) {
            timeLeft = 0;
        }
        mHandler.sendEmptyMessageDelayed(MSG_CHECK_PAROLE_TIMEOUT, timeLeft / 10);
    }

    private void postParoleEndTimeout() {
        if (DEBUG) Slog.d(TAG, "Posting MSG_PAROLE_END_TIMEOUT");
        mHandler.removeMessages(MSG_PAROLE_END_TIMEOUT);
        mHandler.sendEmptyMessageDelayed(MSG_PAROLE_END_TIMEOUT, mAppIdleParoleDurationMillis);
    }

    private void postParoleStateChanged() {
        if (DEBUG) Slog.d(TAG, "Posting MSG_PAROLE_STATE_CHANGED");
        mHandler.removeMessages(MSG_PAROLE_STATE_CHANGED);
        mHandler.sendEmptyMessage(MSG_PAROLE_STATE_CHANGED);
    }

    void postCheckIdleStates(int userId) {
        mHandler.sendMessage(mHandler.obtainMessage(MSG_CHECK_IDLE_STATES, userId, 0));
    }

    /** Check all running users' or specified user's apps to see if they enter an idle state. */
    void checkIdleStates(int checkUserId) {
        if (!mAppIdleEnabled) {
            return;
        }

        final int[] userIds;
        try {
            if (checkUserId == UserHandle.USER_ALL) {
                userIds = ActivityManagerNative.getDefault().getRunningUserIds();
            } else {
                userIds = new int[] { checkUserId };
            }
        } catch (RemoteException re) {
            return;
        }

        for (int i = 0; i < userIds.length; i++) {
            final int userId = userIds[i];
            List<PackageInfo> packages =
                    getContext().getPackageManager().getInstalledPackages(
                            PackageManager.GET_DISABLED_COMPONENTS
                                | PackageManager.GET_UNINSTALLED_PACKAGES,
                            userId);
            synchronized (mLock) {
                final long timeNow = checkAndGetTimeLocked();
                final long screenOnTime = getScreenOnTimeLocked(timeNow);
                UserUsageStatsService service = getUserDataAndInitializeIfNeededLocked(userId,
                        timeNow);
                final int packageCount = packages.size();
                for (int p = 0; p < packageCount; p++) {
                    final String packageName = packages.get(p).packageName;
                    final boolean isIdle = isAppIdleFiltered(packageName, userId, service, timeNow,
                            screenOnTime);
                    mHandler.sendMessage(mHandler.obtainMessage(MSG_INFORM_LISTENERS,
                            userId, isIdle ? 1 : 0, packageName));
                    mAppIdleHistory.addEntry(packageName, userId, isIdle, timeNow);
                }
            }
        }
        mHandler.sendMessageDelayed(mHandler.obtainMessage(MSG_CHECK_IDLE_STATES, checkUserId, 0),
                mCheckIdleIntervalMillis);
    }

    /** Check if it's been a while since last parole and let idle apps do some work */
    void checkParoleTimeout() {
        synchronized (mLock) {
            if (!mAppIdleParoled) {
                final long timeSinceLastParole = checkAndGetTimeLocked() - mLastAppIdleParoledTime;
                if (timeSinceLastParole > mAppIdleParoleIntervalMillis) {
                    if (DEBUG) Slog.d(TAG, "Crossed default parole interval");
                    setAppIdleParoled(true);
                } else {
                    if (DEBUG) Slog.d(TAG, "Not long enough to go to parole");
                    postNextParoleTimeout();
                }
            }
        }
    }

    private void notifyBatteryStats(String packageName, int userId, boolean idle) {
        try {
            int uid = AppGlobals.getPackageManager().getPackageUid(packageName, userId);
            if (idle) {
                mBatteryStats.noteEvent(BatteryStats.HistoryItem.EVENT_PACKAGE_INACTIVE,
                        packageName, uid);
            } else {
                mBatteryStats.noteEvent(BatteryStats.HistoryItem.EVENT_PACKAGE_ACTIVE,
                        packageName, uid);
            }
        } catch (RemoteException re) {
        }
    }

    void updateDisplayLocked() {
        boolean screenOn = mDisplayManager.getDisplay(Display.DEFAULT_DISPLAY).getState()
                == Display.STATE_ON;

        if (screenOn == mScreenOn) return;

        mScreenOn = screenOn;
        long now = System.currentTimeMillis();
        if (mScreenOn) {
            mScreenOnSystemTimeSnapshot = now;
        } else {
            mScreenOnTime += now - mScreenOnSystemTimeSnapshot;
            writeScreenOnTimeLocked(mScreenOnTime);
        }
    }

    private long getScreenOnTimeLocked(long now) {
        if (mScreenOn) {
            return now - mScreenOnSystemTimeSnapshot + mScreenOnTime;
        } else {
            return mScreenOnTime;
        }
    }

    private File getScreenOnTimeFile() {
        return new File(mUsageStatsDir, UserHandle.USER_OWNER + "/screen_on_time");
    }

    private long readScreenOnTimeLocked() {
        long screenOnTime = 0;
        File screenOnTimeFile = getScreenOnTimeFile();
        if (screenOnTimeFile.exists()) {
            try {
                BufferedReader reader = new BufferedReader(new FileReader(screenOnTimeFile));
                screenOnTime = Long.parseLong(reader.readLine());
                reader.close();
            } catch (IOException | NumberFormatException e) {
            }
        } else {
            writeScreenOnTimeLocked(screenOnTime);
        }
        return screenOnTime;
    }

    private void writeScreenOnTimeLocked(long screenOnTime) {
        AtomicFile screenOnTimeFile = new AtomicFile(getScreenOnTimeFile());
        FileOutputStream fos = null;
        try {
            fos = screenOnTimeFile.startWrite();
            fos.write(Long.toString(screenOnTime).getBytes());
            screenOnTimeFile.finishWrite(fos);
        } catch (IOException ioe) {
            screenOnTimeFile.failWrite(fos);
        }
    }

    void onDeviceIdleModeChanged() {
        final boolean deviceIdle = mPowerManager.isDeviceIdleMode();
        if (DEBUG) Slog.i(TAG, "DeviceIdleMode changed to " + deviceIdle);
        synchronized (mLock) {
            final long timeSinceLastParole = checkAndGetTimeLocked() - mLastAppIdleParoledTime;
            if (!deviceIdle
                    && timeSinceLastParole >= mAppIdleParoleIntervalMillis) {
                if (DEBUG) Slog.i(TAG, "Bringing idle apps out of inactive state due to deviceIdleMode=false");
                setAppIdleParoled(true);
            } else if (deviceIdle) {
                if (DEBUG) Slog.i(TAG, "Device idle, back to prison");
                setAppIdleParoled(false);
            }
        }
    }

    private static void deleteRecursively(File f) {
        File[] files = f.listFiles();
        if (files != null) {
            for (File subFile : files) {
                deleteRecursively(subFile);
            }
        }

        if (!f.delete()) {
            Slog.e(TAG, "Failed to delete " + f);
        }
    }

    private UserUsageStatsService getUserDataAndInitializeIfNeededLocked(int userId,
            long currentTimeMillis) {
        UserUsageStatsService service = mUserState.get(userId);
        if (service == null) {
            service = new UserUsageStatsService(getContext(), userId,
                    new File(mUsageStatsDir, Integer.toString(userId)), this);
            service.init(currentTimeMillis, getScreenOnTimeLocked(currentTimeMillis));
            mUserState.put(userId, service);
        }
        return service;
    }

    /**
     * This should be the only way to get the time from the system.
     */
    private long checkAndGetTimeLocked() {
        final long actualSystemTime = System.currentTimeMillis();
        final long actualRealtime = SystemClock.elapsedRealtime();
        final long expectedSystemTime = (actualRealtime - mRealTimeSnapshot) + mSystemTimeSnapshot;
        boolean resetBeginIdleTime = false;
        if (Math.abs(actualSystemTime - expectedSystemTime) > TIME_CHANGE_THRESHOLD_MILLIS) {
            // The time has changed.

            // Check if it's severe enough a change to reset screenOnTime
            if (Math.abs(actualSystemTime - expectedSystemTime) > mAppIdleDurationMillis) {
                mScreenOnSystemTimeSnapshot = actualSystemTime;
                mScreenOnTime = 0;
                resetBeginIdleTime = true;
            }
            final int userCount = mUserState.size();
            for (int i = 0; i < userCount; i++) {
                final UserUsageStatsService service = mUserState.valueAt(i);
                service.onTimeChanged(expectedSystemTime, actualSystemTime, resetBeginIdleTime);
            }
            mRealTimeSnapshot = actualRealtime;
            mSystemTimeSnapshot = actualSystemTime;
        }
        return actualSystemTime;
    }

    /**
     * Assuming the event's timestamp is measured in milliseconds since boot,
     * convert it to a system wall time.
     */
    private void convertToSystemTimeLocked(UsageEvents.Event event) {
        event.mTimeStamp = Math.max(0, event.mTimeStamp - mRealTimeSnapshot) + mSystemTimeSnapshot;
    }

    /**
     * Called by the Binder stub
     */
    void shutdown() {
        synchronized (mLock) {
            mHandler.removeMessages(MSG_REPORT_EVENT);
            flushToDiskLocked();
        }
    }

    /**
     * Called by the Binder stub.
     */
    void reportEvent(UsageEvents.Event event, int userId) {
        synchronized (mLock) {
            final long timeNow = checkAndGetTimeLocked();
            final long screenOnTime = getScreenOnTimeLocked(timeNow);
            convertToSystemTimeLocked(event);

            final UserUsageStatsService service =
                    getUserDataAndInitializeIfNeededLocked(userId, timeNow);
            final long beginIdleTime = service.getBeginIdleTime(event.mPackage);
            final long lastUsedTime = service.getSystemLastUsedTime(event.mPackage);
            final boolean previouslyIdle = hasPassedIdleTimeoutLocked(beginIdleTime,
                    lastUsedTime, screenOnTime, timeNow);
            service.reportEvent(event, screenOnTime);
            // Inform listeners if necessary
            if ((event.mEventType == Event.MOVE_TO_FOREGROUND
                    || event.mEventType == Event.MOVE_TO_BACKGROUND
                    || event.mEventType == Event.SYSTEM_INTERACTION
                    || event.mEventType == Event.USER_INTERACTION)) {
                if (previouslyIdle) {
                    // Slog.d(TAG, "Informing listeners of out-of-idle " + event.mPackage);
                    mHandler.sendMessage(mHandler.obtainMessage(MSG_INFORM_LISTENERS, userId,
                            /* idle = */ 0, event.mPackage));
                    notifyBatteryStats(event.mPackage, userId, false);
                    mAppIdleHistory.addEntry(event.mPackage, userId, false, timeNow);
                }
            }
        }
    }

    void reportContentProviderUsage(String authority, String providerPkgName, int userId) {
        // Get sync adapters for the authority
        String[] packages = ContentResolver.getSyncAdapterPackagesForAuthorityAsUser(
                authority, userId);
        for (String packageName: packages) {
            // Only force the sync adapters to active if the provider is not in the same package and
            // the sync adapter is a system package.
            try {
                PackageInfo pi = AppGlobals.getPackageManager().getPackageInfo(
                        packageName, 0, userId);
                if (pi == null || pi.applicationInfo == null
                        || !pi.applicationInfo.isSystemApp()) {
                    continue;
                }
                if (!packageName.equals(providerPkgName)) {
                    forceIdleState(packageName, userId, false);
                }
            } catch (RemoteException re) {
                // Shouldn't happen
            }
        }
    }

    /**
     * Forces the app's beginIdleTime and lastUsedTime to reflect idle or active. If idle,
     * then it rolls back the beginIdleTime and lastUsedTime to a point in time that's behind
     * the threshold for idle.
     */
    void forceIdleState(String packageName, int userId, boolean idle) {
        synchronized (mLock) {
            final long timeNow = checkAndGetTimeLocked();
            final long screenOnTime = getScreenOnTimeLocked(timeNow);
            final long deviceUsageTime = screenOnTime - (idle ? mAppIdleDurationMillis : 0) - 5000;

            final UserUsageStatsService service =
                    getUserDataAndInitializeIfNeededLocked(userId, timeNow);
            final long beginIdleTime = service.getBeginIdleTime(packageName);
            final long lastUsedTime = service.getSystemLastUsedTime(packageName);
            final boolean previouslyIdle = hasPassedIdleTimeoutLocked(beginIdleTime,
                    lastUsedTime, screenOnTime, timeNow);
            service.setBeginIdleTime(packageName, deviceUsageTime);
            service.setSystemLastUsedTime(packageName,
                    timeNow - (idle ? mAppIdleWallclockThresholdMillis : 0) - 5000);
            // Inform listeners if necessary
            if (previouslyIdle != idle) {
                // Slog.d(TAG, "Informing listeners of out-of-idle " + packageName);
                mHandler.sendMessage(mHandler.obtainMessage(MSG_INFORM_LISTENERS, userId,
                        /* idle = */ idle ? 1 : 0, packageName));
                if (!idle) {
                    notifyBatteryStats(packageName, userId, idle);
                }
                mAppIdleHistory.addEntry(packageName, userId, idle, timeNow);
            }
        }
    }

    /**
     * Called by the Binder stub.
     */
    void flushToDisk() {
        synchronized (mLock) {
            flushToDiskLocked();
        }
    }

    /**
     * Called by the Binder stub.
     */
    void removeUser(int userId) {
        synchronized (mLock) {
            Slog.i(TAG, "Removing user " + userId + " and all data.");
            mUserState.remove(userId);
            cleanUpRemovedUsersLocked();
        }
    }

    /**
     * Called by the Binder stub.
     */
    List<UsageStats> queryUsageStats(int userId, int bucketType, long beginTime, long endTime) {
        synchronized (mLock) {
            final long timeNow = checkAndGetTimeLocked();
            if (!validRange(timeNow, beginTime, endTime)) {
                return null;
            }

            final UserUsageStatsService service =
                    getUserDataAndInitializeIfNeededLocked(userId, timeNow);
            return service.queryUsageStats(bucketType, beginTime, endTime);
        }
    }

    /**
     * Called by the Binder stub.
     */
    List<ConfigurationStats> queryConfigurationStats(int userId, int bucketType, long beginTime,
            long endTime) {
        synchronized (mLock) {
            final long timeNow = checkAndGetTimeLocked();
            if (!validRange(timeNow, beginTime, endTime)) {
                return null;
            }

            final UserUsageStatsService service =
                    getUserDataAndInitializeIfNeededLocked(userId, timeNow);
            return service.queryConfigurationStats(bucketType, beginTime, endTime);
        }
    }

    /**
     * Called by the Binder stub.
     */
    UsageEvents queryEvents(int userId, long beginTime, long endTime) {
        synchronized (mLock) {
            final long timeNow = checkAndGetTimeLocked();
            if (!validRange(timeNow, beginTime, endTime)) {
                return null;
            }

            final UserUsageStatsService service =
                    getUserDataAndInitializeIfNeededLocked(userId, timeNow);
            return service.queryEvents(beginTime, endTime);
        }
    }

    private boolean isAppIdleUnfiltered(String packageName, UserUsageStatsService userService,
            long timeNow, long screenOnTime) {
        synchronized (mLock) {
            long beginIdleTime = userService.getBeginIdleTime(packageName);
            long lastUsedTime = userService.getSystemLastUsedTime(packageName);
            return hasPassedIdleTimeoutLocked(beginIdleTime, lastUsedTime, screenOnTime,
                    timeNow);
        }
    }

    /**
     * @param beginIdleTime when the app was last used in device usage timebase
     * @param lastUsedTime wallclock time of when the app was last used
     * @param screenOnTime screen-on timebase time
     * @param currentTime current time in device usage timebase
     * @return whether it's been used far enough in the past to be considered inactive
     */
    boolean hasPassedIdleTimeoutLocked(long beginIdleTime, long lastUsedTime,
            long screenOnTime, long currentTime) {
        return (beginIdleTime <= screenOnTime - mAppIdleDurationMillis)
                && (lastUsedTime <= currentTime - mAppIdleWallclockThresholdMillis);
    }

    void addListener(AppIdleStateChangeListener listener) {
        synchronized (mLock) {
            if (!mPackageAccessListeners.contains(listener)) {
                mPackageAccessListeners.add(listener);
            }
        }
    }

    void removeListener(AppIdleStateChangeListener listener) {
        synchronized (mLock) {
            mPackageAccessListeners.remove(listener);
        }
    }

    boolean isAppIdleFilteredOrParoled(String packageName, int userId, long timeNow) {
        if (mAppIdleParoled) {
            return false;
        }
        return isAppIdleFiltered(packageName, userId, timeNow);
    }

    boolean isAppIdleFiltered(String packageName, int userId, long timeNow) {
        final UserUsageStatsService userService;
        final long screenOnTime;
        synchronized (mLock) {
            if (timeNow == -1) {
                timeNow = checkAndGetTimeLocked();
            }
            userService = getUserDataAndInitializeIfNeededLocked(userId, timeNow);
            screenOnTime = getScreenOnTimeLocked(timeNow);
        }
        return isAppIdleFiltered(packageName, userId, userService, timeNow, screenOnTime);
    }

    /**
     * Checks if an app has been idle for a while and filters out apps that are excluded.
     * It returns false if the current system state allows all apps to be considered active.
     * This happens if the device is plugged in or temporarily allowed to make exceptions.
     * Called by interface impls.
     */
    private boolean isAppIdleFiltered(String packageName, int userId,
            UserUsageStatsService userService, long timeNow, long screenOnTime) {
        if (packageName == null) return false;
        // If not enabled at all, of course nobody is ever idle.
        if (!mAppIdleEnabled) {
            return false;
        }
        if (packageName.equals("android")) return false;
        try {
            // We allow all whitelisted apps, including those that don't want to be whitelisted
            // for idle mode, because app idle (aka app standby) is really not as big an issue
            // for controlling who participates vs. doze mode.
            if (mDeviceIdleController.isPowerSaveWhitelistExceptIdleApp(packageName)) {
                return false;
            }
        } catch (RemoteException re) {
        }
        // TODO: Optimize this check
        if (isActiveDeviceAdmin(packageName, userId)) {
            return false;
        }

        if (isCarrierApp(packageName)) {
            return false;
        }

        if (isActiveNetworkScorer(packageName)) {
            return false;
        }

        if (mAppWidgetManager != null
                && mAppWidgetManager.isBoundWidgetPackage(packageName, userId)) {
            return false;
        }

        return isAppIdleUnfiltered(packageName, userService, timeNow, screenOnTime);
    }

    int[] getIdleUidsForUser(int userId) {
        if (!mAppIdleEnabled) {
            return new int[0];
        }

        final long timeNow;
        final UserUsageStatsService userService;
        final long screenOnTime;
        synchronized (mLock) {
            timeNow = checkAndGetTimeLocked();
            userService = getUserDataAndInitializeIfNeededLocked(userId, timeNow);
            screenOnTime = getScreenOnTimeLocked(timeNow);
        }

        List<ApplicationInfo> apps;
        try {
            ParceledListSlice<ApplicationInfo> slice
                    = AppGlobals.getPackageManager().getInstalledApplications(0, userId);
            if (slice == null) {
                return new int[0];
            }
            apps = slice.getList();
        } catch (RemoteException e) {
            return new int[0];
        }

        // State of each uid.  Key is the uid.  Value lower 16 bits is the number of apps
        // associated with that uid, upper 16 bits is the number of those apps that is idle.
        SparseIntArray uidStates = new SparseIntArray();

        // Now resolve all app state.  Iterating over all apps, keeping track of how many
        // we find for each uid and how many of those are idle.
        for (int i = apps.size()-1; i >= 0; i--) {
            ApplicationInfo ai = apps.get(i);

            // Check whether this app is idle.
            boolean idle = isAppIdleFiltered(ai.packageName, userId, userService, timeNow,
                    screenOnTime);

            int index = uidStates.indexOfKey(ai.uid);
            if (index < 0) {
                uidStates.put(ai.uid, 1 + (idle ? 1<<16 : 0));
            } else {
                int value = uidStates.valueAt(index);
                uidStates.setValueAt(index, value + 1 + (idle ? 1<<16 : 0));
            }
        }

        int numIdle = 0;
        for (int i = uidStates.size() - 1; i >= 0; i--) {
            int value = uidStates.valueAt(i);
            if ((value&0x7fff) == (value>>16)) {
                numIdle++;
            }
        }

        int[] res = new int[numIdle];
        numIdle = 0;
        for (int i = uidStates.size() - 1; i >= 0; i--) {
            int value = uidStates.valueAt(i);
            if ((value&0x7fff) == (value>>16)) {
                res[numIdle] = uidStates.keyAt(i);
                numIdle++;
            }
        }

        return res;
    }

    void setAppIdle(String packageName, boolean idle, int userId) {
        if (packageName == null) return;

        mHandler.obtainMessage(MSG_FORCE_IDLE_STATE, userId, idle ? 1 : 0, packageName)
                .sendToTarget();
    }

    private boolean isActiveDeviceAdmin(String packageName, int userId) {
        DevicePolicyManager dpm = getContext().getSystemService(DevicePolicyManager.class);
        if (dpm == null) return false;
        List<ComponentName> components = dpm.getActiveAdminsAsUser(userId);
        if (components == null) return false;
        final int size = components.size();
        for (int i = 0; i < size; i++) {
            if (components.get(i).getPackageName().equals(packageName)) {
                return true;
            }
        }
        return false;
    }

    private boolean isCarrierApp(String packageName) {
        TelephonyManager telephonyManager = getContext().getSystemService(TelephonyManager.class);
        return telephonyManager.checkCarrierPrivilegesForPackageAnyPhone(packageName)
                    == TelephonyManager.CARRIER_PRIVILEGE_STATUS_HAS_ACCESS;
    }

    private boolean isActiveNetworkScorer(String packageName) {
        NetworkScoreManager nsm = (NetworkScoreManager) getContext().getSystemService(
                Context.NETWORK_SCORE_SERVICE);
        return packageName != null && packageName.equals(nsm.getActiveScorerPackage());
    }

    void informListeners(String packageName, int userId, boolean isIdle) {
        for (AppIdleStateChangeListener listener : mPackageAccessListeners) {
            listener.onAppIdleStateChanged(packageName, userId, isIdle);
        }
    }

    void informParoleStateChanged() {
        for (AppIdleStateChangeListener listener : mPackageAccessListeners) {
            listener.onParoleStateChanged(mAppIdleParoled);
        }
    }

    private static boolean validRange(long currentTime, long beginTime, long endTime) {
        return beginTime <= currentTime && beginTime < endTime;
    }

    private void flushToDiskLocked() {
        final int userCount = mUserState.size();
        for (int i = 0; i < userCount; i++) {
            UserUsageStatsService service = mUserState.valueAt(i);
            service.persistActiveStats();
        }

        mHandler.removeMessages(MSG_FLUSH_TO_DISK);
    }

    /**
     * Called by the Binder stub.
     */
    void dump(String[] args, PrintWriter pw) {
        synchronized (mLock) {
            final long screenOnTime = getScreenOnTimeLocked(checkAndGetTimeLocked());
            IndentingPrintWriter idpw = new IndentingPrintWriter(pw, "  ");
            ArraySet<String> argSet = new ArraySet<>();
            argSet.addAll(Arrays.asList(args));

            final int userCount = mUserState.size();
            for (int i = 0; i < userCount; i++) {
                idpw.printPair("user", mUserState.keyAt(i));
                idpw.println();
                idpw.increaseIndent();
                if (argSet.contains("--checkin")) {
                    mUserState.valueAt(i).checkin(idpw, screenOnTime);
                } else {
                    mUserState.valueAt(i).dump(idpw, screenOnTime);
                    idpw.println();
                    if (args.length > 0 && "history".equals(args[0])) {
                        mAppIdleHistory.dump(idpw, mUserState.keyAt(i));
                    }
                }
                idpw.decreaseIndent();
            }
            pw.println("Screen On Timebase:" + mScreenOnTime);

            pw.println();
            pw.println("Settings:");

            pw.print("  mAppIdleDurationMillis=");
            TimeUtils.formatDuration(mAppIdleDurationMillis, pw);
            pw.println();

            pw.print("  mAppIdleWallclockThresholdMillis=");
            TimeUtils.formatDuration(mAppIdleWallclockThresholdMillis, pw);
            pw.println();

            pw.print("  mCheckIdleIntervalMillis=");
            TimeUtils.formatDuration(mCheckIdleIntervalMillis, pw);
            pw.println();

            pw.print("  mAppIdleParoleIntervalMillis=");
            TimeUtils.formatDuration(mAppIdleParoleIntervalMillis, pw);
            pw.println();

            pw.print("  mAppIdleParoleDurationMillis=");
            TimeUtils.formatDuration(mAppIdleParoleDurationMillis, pw);
            pw.println();

            pw.println();
            pw.print("mAppIdleEnabled="); pw.print(mAppIdleEnabled);
            pw.print(" mAppIdleParoled="); pw.print(mAppIdleParoled);
            pw.print(" mScreenOn="); pw.println(mScreenOn);
            pw.print("mLastAppIdleParoledTime=");
            TimeUtils.formatDuration(mLastAppIdleParoledTime, pw);
            pw.println();
            pw.print("mScreenOnTime="); TimeUtils.formatDuration(mScreenOnTime, pw);
            pw.println();
            pw.print("mScreenOnSystemTimeSnapshot=");
            TimeUtils.formatDuration(mScreenOnSystemTimeSnapshot, pw);
            pw.println();
        }
    }

    class H extends Handler {
        public H(Looper looper) {
            super(looper);
        }

        @Override
        public void handleMessage(Message msg) {
            switch (msg.what) {
                case MSG_REPORT_EVENT:
                    reportEvent((UsageEvents.Event) msg.obj, msg.arg1);
                    break;

                case MSG_FLUSH_TO_DISK:
                    flushToDisk();
                    break;

                case MSG_REMOVE_USER:
                    removeUser(msg.arg1);
                    break;

                case MSG_INFORM_LISTENERS:
                    informListeners((String) msg.obj, msg.arg1, msg.arg2 == 1);
                    break;

                case MSG_FORCE_IDLE_STATE:
                    forceIdleState((String) msg.obj, msg.arg1, msg.arg2 == 1);
                    break;

                case MSG_CHECK_IDLE_STATES:
                    checkIdleStates(msg.arg1);
                    break;

                case MSG_CHECK_PAROLE_TIMEOUT:
                    checkParoleTimeout();
                    break;

                case MSG_PAROLE_END_TIMEOUT:
                    if (DEBUG) Slog.d(TAG, "Ending parole");
                    setAppIdleParoled(false);
                    break;

                case MSG_REPORT_CONTENT_PROVIDER_USAGE:
                    SomeArgs args = (SomeArgs) msg.obj;
                    reportContentProviderUsage((String) args.arg1, // authority name
                            (String) args.arg2, // package name
                            (int) args.arg3); // userId
                    args.recycle();
                    break;

                case MSG_PAROLE_STATE_CHANGED:
                    if (DEBUG) Slog.d(TAG, "Parole state changed: " + mAppIdleParoled);
                    informParoleStateChanged();
                    break;

                default:
                    super.handleMessage(msg);
                    break;
            }
        }
    }

    /**
     * Observe settings changes for {@link Settings.Global#APP_IDLE_CONSTANTS}.
     */
    private class SettingsObserver extends ContentObserver {
        private static final String KEY_IDLE_DURATION = "idle_duration";
        private static final String KEY_WALLCLOCK_THRESHOLD = "wallclock_threshold";
        private static final String KEY_PAROLE_INTERVAL = "parole_interval";
        private static final String KEY_PAROLE_DURATION = "parole_duration";

        private final KeyValueListParser mParser = new KeyValueListParser(',');

        SettingsObserver(Handler handler) {
            super(handler);
        }

        void registerObserver() {
            getContext().getContentResolver().registerContentObserver(Settings.Global.getUriFor(
                    Settings.Global.APP_IDLE_CONSTANTS), false, this);
        }

        @Override
        public void onChange(boolean selfChange) {
            updateSettings();
            postCheckIdleStates(UserHandle.USER_ALL);
        }

        void updateSettings() {
            synchronized (mLock) {
                // Look at global settings for this.
                // TODO: Maybe apply different thresholds for different users.
                try {
                    mParser.setString(Settings.Global.getString(getContext().getContentResolver(),
                            Settings.Global.APP_IDLE_CONSTANTS));
                } catch (IllegalArgumentException e) {
                    Slog.e(TAG, "Bad value for app idle settings: " + e.getMessage());
                    // fallthrough, mParser is empty and all defaults will be returned.
                }

                // Default: 12 hours of screen-on time sans dream-time
                mAppIdleDurationMillis = mParser.getLong(KEY_IDLE_DURATION,
                       COMPRESS_TIME ? ONE_MINUTE * 4 : 12 * 60 * ONE_MINUTE);

                mAppIdleWallclockThresholdMillis = mParser.getLong(KEY_WALLCLOCK_THRESHOLD,
                        COMPRESS_TIME ? ONE_MINUTE * 8 : 2L * 24 * 60 * ONE_MINUTE); // 2 days

                mCheckIdleIntervalMillis = Math.min(mAppIdleDurationMillis / 4,
                        COMPRESS_TIME ? ONE_MINUTE : 8 * 60 * ONE_MINUTE); // 8 hours

                // Default: 24 hours between paroles
                mAppIdleParoleIntervalMillis = mParser.getLong(KEY_PAROLE_INTERVAL,
                        COMPRESS_TIME ? ONE_MINUTE * 10 : 24 * 60 * ONE_MINUTE);

                mAppIdleParoleDurationMillis = mParser.getLong(KEY_PAROLE_DURATION,
                        COMPRESS_TIME ? ONE_MINUTE : 10 * ONE_MINUTE); // 10 minutes
            }
        }
    }

    private final class BinderService extends IUsageStatsManager.Stub {

        private boolean hasPermission(String callingPackage) {
            final int callingUid = Binder.getCallingUid();
            if (callingUid == Process.SYSTEM_UID) {
                return true;
            }
            final int mode = mAppOps.checkOp(AppOpsManager.OP_GET_USAGE_STATS,
                    callingUid, callingPackage);
            if (mode == AppOpsManager.MODE_DEFAULT) {
                // The default behavior here is to check if PackageManager has given the app
                // permission.
                return getContext().checkCallingPermission(Manifest.permission.PACKAGE_USAGE_STATS)
                        == PackageManager.PERMISSION_GRANTED;
            }
            return mode == AppOpsManager.MODE_ALLOWED;
        }

        @Override
        public ParceledListSlice<UsageStats> queryUsageStats(int bucketType, long beginTime,
                long endTime, String callingPackage) {
            if (!hasPermission(callingPackage)) {
                return null;
            }

            final int userId = UserHandle.getCallingUserId();
            final long token = Binder.clearCallingIdentity();
            try {
                final List<UsageStats> results = UsageStatsService.this.queryUsageStats(
                        userId, bucketType, beginTime, endTime);
                if (results != null) {
                    return new ParceledListSlice<>(results);
                }
            } finally {
                Binder.restoreCallingIdentity(token);
            }
            return null;
        }

        @Override
        public ParceledListSlice<ConfigurationStats> queryConfigurationStats(int bucketType,
                long beginTime, long endTime, String callingPackage) throws RemoteException {
            if (!hasPermission(callingPackage)) {
                return null;
            }

            final int userId = UserHandle.getCallingUserId();
            final long token = Binder.clearCallingIdentity();
            try {
                final List<ConfigurationStats> results =
                        UsageStatsService.this.queryConfigurationStats(userId, bucketType,
                                beginTime, endTime);
                if (results != null) {
                    return new ParceledListSlice<>(results);
                }
            } finally {
                Binder.restoreCallingIdentity(token);
            }
            return null;
        }

        @Override
        public UsageEvents queryEvents(long beginTime, long endTime, String callingPackage) {
            if (!hasPermission(callingPackage)) {
                return null;
            }

            final int userId = UserHandle.getCallingUserId();
            final long token = Binder.clearCallingIdentity();
            try {
                return UsageStatsService.this.queryEvents(userId, beginTime, endTime);
            } finally {
                Binder.restoreCallingIdentity(token);
            }
        }

        @Override
        public boolean isAppInactive(String packageName, int userId) {
            try {
                userId = ActivityManagerNative.getDefault().handleIncomingUser(Binder.getCallingPid(),
                        Binder.getCallingUid(), userId, false, true, "isAppInactive", null);
            } catch (RemoteException re) {
                return false;
            }
            final long token = Binder.clearCallingIdentity();
            try {
                return UsageStatsService.this.isAppIdleFilteredOrParoled(packageName, userId, -1);
            } finally {
                Binder.restoreCallingIdentity(token);
            }
        }

        @Override
        public void setAppInactive(String packageName, boolean idle, int userId) {
            final int callingUid = Binder.getCallingUid();
            try {
                userId = ActivityManagerNative.getDefault().handleIncomingUser(
                        Binder.getCallingPid(), callingUid, userId, false, true,
                        "setAppIdle", null);
            } catch (RemoteException re) {
                return;
            }
            getContext().enforceCallingPermission(Manifest.permission.CHANGE_APP_IDLE_STATE,
                    "No permission to change app idle state");
            final long token = Binder.clearCallingIdentity();
            try {
                PackageInfo pi = AppGlobals.getPackageManager()
                        .getPackageInfo(packageName, 0, userId);
                if (pi == null) return;
                UsageStatsService.this.setAppIdle(packageName, idle, userId);
            } catch (RemoteException re) {
            } finally {
                Binder.restoreCallingIdentity(token);
            }
        }

        @Override
        public void whitelistAppTemporarily(String packageName, long duration, int userId)
                throws RemoteException {
            StringBuilder reason = new StringBuilder(32);
            reason.append("from:");
            UserHandle.formatUid(reason, Binder.getCallingUid());
            mDeviceIdleController.addPowerSaveTempWhitelistApp(packageName, duration, userId,
                    reason.toString());
        }

        @Override
        protected void dump(FileDescriptor fd, PrintWriter pw, String[] args) {
            if (getContext().checkCallingOrSelfPermission(android.Manifest.permission.DUMP)
                    != PackageManager.PERMISSION_GRANTED) {
                pw.println("Permission Denial: can't dump UsageStats from pid="
                        + Binder.getCallingPid() + ", uid=" + Binder.getCallingUid()
                        + " without permission " + android.Manifest.permission.DUMP);
                return;
            }
            UsageStatsService.this.dump(args, pw);
        }
    }

    /**
     * This local service implementation is primarily used by ActivityManagerService.
     * ActivityManagerService will call these methods holding the 'am' lock, which means we
     * shouldn't be doing any IO work or other long running tasks in these methods.
     */
    private final class LocalService extends UsageStatsManagerInternal {

        @Override
        public void reportEvent(ComponentName component, int userId, int eventType) {
            if (component == null) {
                Slog.w(TAG, "Event reported without a component name");
                return;
            }

            UsageEvents.Event event = new UsageEvents.Event();
            event.mPackage = component.getPackageName();
            event.mClass = component.getClassName();

            // This will later be converted to system time.
            event.mTimeStamp = SystemClock.elapsedRealtime();

            event.mEventType = eventType;
            mHandler.obtainMessage(MSG_REPORT_EVENT, userId, 0, event).sendToTarget();
        }

        @Override
        public void reportEvent(String packageName, int userId, int eventType) {
            if (packageName == null) {
                Slog.w(TAG, "Event reported without a package name");
                return;
            }

            UsageEvents.Event event = new UsageEvents.Event();
            event.mPackage = packageName;

            // This will later be converted to system time.
            event.mTimeStamp = SystemClock.elapsedRealtime();

            event.mEventType = eventType;
            mHandler.obtainMessage(MSG_REPORT_EVENT, userId, 0, event).sendToTarget();
        }

        @Override
        public void reportConfigurationChange(Configuration config, int userId) {
            if (config == null) {
                Slog.w(TAG, "Configuration event reported with a null config");
                return;
            }

            UsageEvents.Event event = new UsageEvents.Event();
            event.mPackage = "android";

            // This will later be converted to system time.
            event.mTimeStamp = SystemClock.elapsedRealtime();

            event.mEventType = UsageEvents.Event.CONFIGURATION_CHANGE;
            event.mConfiguration = new Configuration(config);
            mHandler.obtainMessage(MSG_REPORT_EVENT, userId, 0, event).sendToTarget();
        }

        @Override
        public void reportContentProviderUsage(String name, String packageName, int userId) {
            SomeArgs args = SomeArgs.obtain();
            args.arg1 = name;
            args.arg2 = packageName;
            args.arg3 = userId;
            mHandler.obtainMessage(MSG_REPORT_CONTENT_PROVIDER_USAGE, args)
                    .sendToTarget();
        }

        @Override
        public boolean isAppIdle(String packageName, int userId) {
            return UsageStatsService.this.isAppIdleFiltered(packageName, userId, -1);
        }

        @Override
        public int[] getIdleUidsForUser(int userId) {
            return UsageStatsService.this.getIdleUidsForUser(userId);
        }

        @Override
        public boolean isAppIdleParoleOn() {
            return mAppIdleParoled;
        }

        @Override
        public void prepareShutdown() {
            // This method *WILL* do IO work, but we must block until it is finished or else
            // we might not shutdown cleanly. This is ok to do with the 'am' lock held, because
            // we are shutting down.
            shutdown();
        }

        @Override
        public void addAppIdleStateChangeListener(AppIdleStateChangeListener listener) {
            UsageStatsService.this.addListener(listener);
            listener.onParoleStateChanged(isAppIdleParoleOn());
        }

        @Override
        public void removeAppIdleStateChangeListener(
                AppIdleStateChangeListener listener) {
            UsageStatsService.this.removeListener(listener);
        }
    }
}