Vue d'ensemble

UsageStatsService colletce, agrège et stocke les données d'utilisation des applications. Ces données sont accessibles aux applications autorisées via AppOps. Le code source réside dans framework/base/services/usage/java/com/android/server/usage/.

UserUsageStatsService gère spécifiquement les données par utilisateur, créé et démarré par UsageStatsService.

Initilaisation du service

// SystemServer.java
public static void main(String[] args) {
    new SystemServer().launch();
}

private void launch() {
    startCoreServices();
}

private void startCoreServices() {
    mSystemServiceManager.startService(UsageStatsService.class);
    mActivityManager.setUsageStatsManager(
        LocalServices.getService(UsageStatsManagerInternal.class)
    );
}

Cycle de vie du service

@Override
public void onStart() {
    File dataDir = new File(Environment.getDataDirectory(), "system");
    mStatsDirectory = new File(dataDir, "usagestats");
    mStatsDirectory.mkdirs();

    registerLocalService(UsageStatsManagerInternal.class, new InternalHandler());
    publishBinderService(Context.USAGE_STATS_SERVICE, new ServiceBinder());
    
    initializeUserResources(UserHandle.USER_SYSTEM, System.currentTimeMillis());
}

Gestion des utilisateurs

@Override
public void onUserUnlocked(int userId) {
    HashMap<String, Long> packages = fetchInstalledPackages(userId);
    synchronized (mLock) {
        mActiveUsers.add(userId);
        migrateToSystemCe(userId);
        initializeUserService(userId, System.currentTimeMillis(), packages);
    }
}

private void initializeUserService(int userId, long timestamp, 
                                   HashMap<String, Long> packages) {
    File userDir = new File(Environment.getDataSystemCeDirectory(userId), "usagestats");
    UserUsageStatsService service = new UserUsageStatsService(mContext, userId, userDir);
    service.initialize(timestamp, packages);
    mUserServices.put(userId, service);
}

Traitement des données

private static final long FLUSH_DELAY = 20 * 60 * 1000;

void persistData() {
    synchronized (mLock) {
        Event flushEvent = new Event(FLUSH_TO_DISK, SystemClock.elapsedRealtime());
        flushEvent.packageName = SYSTEM_PACKAGE;
        reportGlobalEvent(flushEvent);
        writeToStorage();
    }
}

private void writeToStorage() {
    for (int i = 0; i < mUserServices.size(); i++) {
        int userId = mUserServices.keyAt(i);
        UserUsageStatsService service = mUserServices.get(userId);
        if (service != null) {
            service.commitStats();
        }
    }
}

UsageStatsManager

Interface client pour accéder aux données d'utilisation. Méthodes principales :

• queryUsageStats() : Statistiques agrégées
• queryEventStats() : Événements système

Types d'événements

public static class Event {
    public static final int ACTIVITY_RESUMED = 1;
    public static final int ACTIVITY_PAUSED = 2;
    public static final int DEVICE_SHUTDOWN = 26;
    public static final int DEVICE_STARTUP = 27;
    public static final int SCREEN_INTERACTIVE = 15;
    public static final int SCREEN_NON_INTERACTIVE = 16;
    public static final int KEYGUARD_SHOWN = 17;
    public static final int KEYGUARD_HIDDEN = 18;
}

Stockage des données

public UserUsageStatsService(Context ctx, int uid, File dir) {
    mDatabase = new UsageStatsDatabase(dir);
}

public class UsageStatsDatabase {
    public UsageStatsDatabase(File root) {
        mIntervalDirectories = new File[] {
            new File(root, "daily"),
            new File(root, "weekly"),
            new File(root, "monthly"),
            new File(root, "yearly")
        };
    }
}