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Commit dbe15f0b authored by Alex Salo's avatar Alex Salo
Browse files

Cache DeviceConfig's values in Attention 

AttentionManagerService might be called on a critical system path, and
DeviceConfig calls have some costs. To reduce these cost - cache the
values for at least 4 hours.

Bug: 169427927
Test: manually
Change-Id: I7bfb564701e604ae2fa7544826526ef060552e56
parent 82bc48af

services/core/java/com/android/server/attention/AttentionManagerService.java

+41 −6
Original line number Diff line number Diff line
@@ -81,12 +81,22 @@ public class AttentionManagerService extends SystemService { 
    /** Service will unbind if connection is not used for that amount of time. */

    private static final long CONNECTION_TTL_MILLIS = 60_000;



    /**

     * We cache the DeviceConfig values to avoid frequent ashmem-related checks; if the cached

     * values are stale for more than this duration we will update the cache.

     */

    @VisibleForTesting static final long DEVICE_CONFIG_MAX_STALENESS_MILLIS = 4 * 60 * 60 * 1000L;



    @VisibleForTesting long mLastReadDeviceConfigMillis = Long.MIN_VALUE;



    /** DeviceConfig flag name, if {@code true}, enables AttentionManagerService features. */

    private static final String KEY_SERVICE_ENABLED = "service_enabled";



    /** Default value in absence of {@link DeviceConfig} override. */

    private static final boolean DEFAULT_SERVICE_ENABLED = true;



    private boolean mIsServiceEnabledCached;



    /**

     * DeviceConfig flag name, describes how much time we consider a result fresh; if the check

     * attention called within that period - cached value will be returned.
@@ -98,6 +108,8 @@ public class AttentionManagerService extends SystemService { 
    @VisibleForTesting

    static final long DEFAULT_STALE_AFTER_MILLIS = 1_000;



    private long mStaleAfterMillisCached;



    /** The size of the buffer that stores recent attention check results. */

    @VisibleForTesting

    protected static final int ATTENTION_CACHE_BUFFER_SIZE = 5;
@@ -172,12 +184,12 @@ public class AttentionManagerService extends SystemService { 
     */

    @VisibleForTesting

    protected boolean isAttentionServiceSupported() {

        return isServiceEnabled() && isServiceConfigured(mContext);

        return isServiceEnabled();

    }



    private boolean isServiceEnabled() {

        return DeviceConfig.getBoolean(NAMESPACE_ATTENTION_MANAGER_SERVICE, KEY_SERVICE_ENABLED,

                DEFAULT_SERVICE_ENABLED);

        ensureDeviceConfigCachedValuesFreshness();

        return mIsServiceEnabledCached;

    }



    /**
@@ -186,16 +198,39 @@ public class AttentionManagerService extends SystemService { 
     */

    @VisibleForTesting

    protected long getStaleAfterMillis() {

        ensureDeviceConfigCachedValuesFreshness();

        return mStaleAfterMillisCached;

    }



    @VisibleForTesting

    protected void ensureDeviceConfigCachedValuesFreshness() {

        final long now = SystemClock.elapsedRealtime();

        final long whenBecomesStale =

                mLastReadDeviceConfigMillis + DEVICE_CONFIG_MAX_STALENESS_MILLIS;

        if (now < whenBecomesStale) {

            if (DEBUG) {

                Slog.d(LOG_TAG,

                        "Cached values are still fresh. Refreshed at=" + mLastReadDeviceConfigMillis

                                + ", now=" + now);

            }

            return;

        }



        mIsServiceEnabledCached = DeviceConfig.getBoolean(NAMESPACE_ATTENTION_MANAGER_SERVICE,

                KEY_SERVICE_ENABLED,

                DEFAULT_SERVICE_ENABLED);



        final long millis = DeviceConfig.getLong(NAMESPACE_ATTENTION_MANAGER_SERVICE,

                KEY_STALE_AFTER_MILLIS,

                DEFAULT_STALE_AFTER_MILLIS);



        if (millis < 0 || millis > 10_000) {

            Slog.w(LOG_TAG, "Bad flag value supplied for: " + KEY_STALE_AFTER_MILLIS);

            return DEFAULT_STALE_AFTER_MILLIS;

            mStaleAfterMillisCached = DEFAULT_STALE_AFTER_MILLIS;

        } else {

            mStaleAfterMillisCached = millis;

        }



        return millis;

        mLastReadDeviceConfigMillis = now;

    }



    /**

services/tests/servicestests/src/com/android/server/attention/AttentionManagerServiceTest.java

+34 −0
Original line number Diff line number Diff line
@@ -20,6 +20,7 @@ import static android.provider.DeviceConfig.NAMESPACE_ATTENTION_MANAGER_SERVICE; 


import static com.android.server.attention.AttentionManagerService.ATTENTION_CACHE_BUFFER_SIZE;

import static com.android.server.attention.AttentionManagerService.DEFAULT_STALE_AFTER_MILLIS;

import static com.android.server.attention.AttentionManagerService.DEVICE_CONFIG_MAX_STALENESS_MILLIS;

import static com.android.server.attention.AttentionManagerService.KEY_STALE_AFTER_MILLIS;



import static com.google.common.truth.Truth.assertThat;
@@ -39,6 +40,7 @@ import android.os.IPowerManager; 
import android.os.IThermalService;

import android.os.PowerManager;

import android.os.RemoteException;

import android.os.SystemClock;

import android.provider.DeviceConfig;

import android.service.attention.IAttentionCallback;

import android.service.attention.IAttentionService;
@@ -205,6 +207,38 @@ public class AttentionManagerServiceTest { 
                DEFAULT_STALE_AFTER_MILLIS);

    }



    @Test

    public void testEnsureDeviceConfigCachedValuesFreshness_doesNotCallDeviceConfigTooFrequently() {

        DeviceConfig.setProperty(NAMESPACE_ATTENTION_MANAGER_SERVICE,

                KEY_STALE_AFTER_MILLIS, String.valueOf(DEFAULT_STALE_AFTER_MILLIS), false);

        assertThat(mSpyAttentionManager.getStaleAfterMillis()).isEqualTo(

                DEFAULT_STALE_AFTER_MILLIS);



        DeviceConfig.setProperty(NAMESPACE_ATTENTION_MANAGER_SERVICE,

                KEY_STALE_AFTER_MILLIS, "123", false);



        // New value is ignored

        assertThat(mSpyAttentionManager.getStaleAfterMillis()).isEqualTo(

                DEFAULT_STALE_AFTER_MILLIS);

    }





    @Test

    public void testEnsureDeviceConfigCachedValuesFreshness_refreshesWhenStale() {

        DeviceConfig.setProperty(NAMESPACE_ATTENTION_MANAGER_SERVICE,

                KEY_STALE_AFTER_MILLIS, String.valueOf(DEFAULT_STALE_AFTER_MILLIS), false);

        assertThat(mSpyAttentionManager.getStaleAfterMillis()).isEqualTo(

                DEFAULT_STALE_AFTER_MILLIS);



        DeviceConfig.setProperty(NAMESPACE_ATTENTION_MANAGER_SERVICE,

                KEY_STALE_AFTER_MILLIS, "123", false);

        mSpyAttentionManager.mLastReadDeviceConfigMillis =

                SystemClock.elapsedRealtime() - (DEVICE_CONFIG_MAX_STALENESS_MILLIS + 1);



        // Values are refreshed

        assertThat(mSpyAttentionManager.getStaleAfterMillis()).isEqualTo(123);

    }



    private class MockIAttentionService implements IAttentionService {

        public void checkAttention(IAttentionCallback callback) throws RemoteException {

            callback.onSuccess(0, 0);