Dynamically enable/disable watch for RAT type changes

Add ContentObserver to observe the status of
NETSTATS_COMBINE_SUBTYPE_ENABLED to determine that
NetworkStatsSubscriptionsMonitor start or stop
monitoring data usage per RAT type changes.

Bug: 154080515
Test: atest NetworkStatsServiceTest#testDynamicWatchForNetworkRatTypeChanges
Change-Id: I272d589633c9186b45753228b05aa0b40b7c7b89

2 files changed, 154 insertions, 5 deletions

diff --git a/services/core/java/com/android/server/net/NetworkStatsService.java b/services/core/java/com/android/server/net/NetworkStatsService.java
index ba538e1cd826..6e01592c51a0 100644
--- a/services/core/java/com/android/server/net/NetworkStatsService.java
+++ b/services/core/java/com/android/server/net/NetworkStatsService.java
@@ -87,6 +87,7 @@ import android.content.Intent;
 import android.content.IntentFilter;
 import android.content.pm.ApplicationInfo;
 import android.content.pm.PackageManager;
+import android.database.ContentObserver;
 import android.net.DataUsageRequest;
 import android.net.INetworkManagementEventObserver;
 import android.net.INetworkStatsService;
@@ -103,6 +104,7 @@ import android.net.NetworkStats.NonMonotonicObserver;
 import android.net.NetworkStatsHistory;
 import android.net.NetworkTemplate;
 import android.net.TrafficStats;
+import android.net.Uri;
 import android.net.netstats.provider.INetworkStatsProvider;
 import android.net.netstats.provider.INetworkStatsProviderCallback;
 import android.net.netstats.provider.NetworkStatsProvider;
@@ -213,6 +215,9 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
 
     private final boolean mUseBpfTrafficStats;
 
+    private final ContentObserver mContentObserver;
+    private final ContentResolver mContentResolver;
+
     @VisibleForTesting
     public static final String ACTION_NETWORK_STATS_POLL =
             "com.android.server.action.NETWORK_STATS_POLL";
@@ -438,6 +443,9 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
         mHandler = new NetworkStatsHandler(handlerThread.getLooper());
         mNetworkStatsSubscriptionsMonitor = deps.makeSubscriptionsMonitor(mContext,
                 new HandlerExecutor(mHandler), this);
+        mContentResolver = mContext.getContentResolver();
+        mContentObserver = mDeps.makeContentObserver(mHandler, mSettings,
+                mNetworkStatsSubscriptionsMonitor);
     }
 
     /**
@@ -466,6 +474,25 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
             return new NetworkStatsSubscriptionsMonitor(context, executor, (subscriberId, type) ->
                     service.handleOnCollapsedRatTypeChanged());
         }
+
+        /**
+         * Create a ContentObserver instance which is used to observe settings changes,
+         * and dispatch onChange events on handler thread.
+         */
+        public @NonNull ContentObserver makeContentObserver(@NonNull Handler handler,
+                @NonNull NetworkStatsSettings settings,
+                @NonNull NetworkStatsSubscriptionsMonitor monitor) {
+            return new ContentObserver(handler) {
+                @Override
+                public void onChange(boolean selfChange, @NonNull Uri uri) {
+                    if (!settings.getCombineSubtypeEnabled()) {
+                        monitor.start();
+                    } else {
+                        monitor.stop();
+                    }
+                }
+            };
+        }
     }
 
     private void registerLocalService() {
@@ -530,11 +557,14 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
         mAlarmManager.setInexactRepeating(AlarmManager.ELAPSED_REALTIME, currentRealtime,
                 mSettings.getPollInterval(), pollIntent);
 
-        // TODO: listen to settings changed to support dynamically enable/disable.
-        // watch for networkType changes
-        if (!mSettings.getCombineSubtypeEnabled()) {
-            mNetworkStatsSubscriptionsMonitor.start();
-        }
+        mContentResolver.registerContentObserver(Settings.Global
+                .getUriFor(Settings.Global.NETSTATS_COMBINE_SUBTYPE_ENABLED),
+                        false /* notifyForDescendants */, mContentObserver);
+
+        // Post a runnable on handler thread to call onChange(). It's for getting current value of
+        // NETSTATS_COMBINE_SUBTYPE_ENABLED to decide start or stop monitoring RAT type changes.
+        mHandler.post(() -> mContentObserver.onChange(false, Settings.Global
+                .getUriFor(Settings.Global.NETSTATS_COMBINE_SUBTYPE_ENABLED)));
 
         registerGlobalAlert();
     }
@@ -560,6 +590,8 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
             mNetworkStatsSubscriptionsMonitor.stop();
         }
 
+        mContentResolver.unregisterContentObserver(mContentObserver);
+
         final long currentTime = mClock.millis();
 
         // persist any pending stats
diff --git a/tests/net/java/com/android/server/net/NetworkStatsServiceTest.java b/tests/net/java/com/android/server/net/NetworkStatsServiceTest.java
index a1bb0d586916..9c0d33fe5a37 100644
--- a/tests/net/java/com/android/server/net/NetworkStatsServiceTest.java
+++ b/tests/net/java/com/android/server/net/NetworkStatsServiceTest.java
@@ -41,6 +41,7 @@ import static android.net.NetworkStats.TAG_ALL;
 import static android.net.NetworkStats.TAG_NONE;
 import static android.net.NetworkStats.UID_ALL;
 import static android.net.NetworkStatsHistory.FIELD_ALL;
+import static android.net.NetworkTemplate.NETWORK_TYPE_ALL;
 import static android.net.NetworkTemplate.buildTemplateMobileAll;
 import static android.net.NetworkTemplate.buildTemplateMobileWithRatType;
 import static android.net.NetworkTemplate.buildTemplateWifiWildcard;
@@ -62,6 +63,7 @@ import static org.mockito.ArgumentMatchers.anyInt;
 import static org.mockito.ArgumentMatchers.anyLong;
 import static org.mockito.ArgumentMatchers.anyString;
 import static org.mockito.ArgumentMatchers.eq;
+import static org.mockito.Mockito.reset;
 import static org.mockito.Mockito.times;
 import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.when;
@@ -71,6 +73,7 @@ import android.app.AlarmManager;
 import android.app.usage.NetworkStatsManager;
 import android.content.Context;
 import android.content.Intent;
+import android.database.ContentObserver;
 import android.net.DataUsageRequest;
 import android.net.INetworkManagementEventObserver;
 import android.net.INetworkStatsSession;
@@ -94,6 +97,7 @@ import android.os.Message;
 import android.os.Messenger;
 import android.os.PowerManager;
 import android.os.SimpleClock;
+import android.provider.Settings;
 import android.telephony.TelephonyManager;
 
 import androidx.test.InstrumentationRegistry;
@@ -173,6 +177,8 @@ public class NetworkStatsServiceTest extends NetworkStatsBaseTest {
     private NetworkStatsService mService;
     private INetworkStatsSession mSession;
     private INetworkManagementEventObserver mNetworkObserver;
+    private ContentObserver mContentObserver;
+    private Handler mHandler;
 
     private final Clock mClock = new SimpleClock(ZoneOffset.UTC) {
         @Override
@@ -212,6 +218,12 @@ public class NetworkStatsServiceTest extends NetworkStatsBaseTest {
         mService.systemReady();
         // Verify that system ready fetches realtime stats
         verify(mStatsFactory).readNetworkStatsDetail(UID_ALL, INTERFACES_ALL, TAG_ALL);
+        // Wait for posting onChange() event to handler thread and verify that when system ready,
+        // start monitoring data usage per RAT type because the settings value is mock as false
+        // by default in expectSettings().
+        waitForIdle();
+        verify(mNetworkStatsSubscriptionsMonitor).start();
+        reset(mNetworkStatsSubscriptionsMonitor);
 
         mSession = mService.openSession();
         assertNotNull("openSession() failed", mSession);
@@ -238,6 +250,14 @@ public class NetworkStatsServiceTest extends NetworkStatsBaseTest {
 
                 return mNetworkStatsSubscriptionsMonitor;
             }
+
+            @Override
+            public ContentObserver makeContentObserver(Handler handler,
+                    NetworkStatsSettings settings, NetworkStatsSubscriptionsMonitor monitor) {
+                mHandler = handler;
+                return mContentObserver = super.makeContentObserver(handler, settings, monitor);
+            }
+
         };
     }
 
@@ -1191,6 +1211,99 @@ public class NetworkStatsServiceTest extends NetworkStatsBaseTest {
         provider.expectOnSetAlert(MB_IN_BYTES);
     }
 
+    private void setCombineSubtypeEnabled(boolean enable) {
+        when(mSettings.getCombineSubtypeEnabled()).thenReturn(enable);
+        mHandler.post(() -> mContentObserver.onChange(false, Settings.Global
+                    .getUriFor(Settings.Global.NETSTATS_COMBINE_SUBTYPE_ENABLED)));
+        waitForIdle();
+        if (enable) {
+            verify(mNetworkStatsSubscriptionsMonitor).stop();
+        } else {
+            verify(mNetworkStatsSubscriptionsMonitor).start();
+        }
+    }
+
+    @Test
+    public void testDynamicWatchForNetworkRatTypeChanges() throws Exception {
+        // Build 3G template, type unknown template to get stats while network type is unknown
+        // and type all template to get the sum of all network type stats.
+        final NetworkTemplate template3g =
+                buildTemplateMobileWithRatType(null, TelephonyManager.NETWORK_TYPE_UMTS);
+        final NetworkTemplate templateUnknown =
+                buildTemplateMobileWithRatType(null, TelephonyManager.NETWORK_TYPE_UNKNOWN);
+        final NetworkTemplate templateAll =
+                buildTemplateMobileWithRatType(null, NETWORK_TYPE_ALL);
+        final NetworkState[] states = new NetworkState[]{buildMobile3gState(IMSI_1)};
+
+        expectNetworkStatsSummary(buildEmptyStats());
+        expectNetworkStatsUidDetail(buildEmptyStats());
+
+        // 3G network comes online.
+        setMobileRatTypeAndWaitForIdle(TelephonyManager.NETWORK_TYPE_UMTS);
+        mService.forceUpdateIfaces(NETWORKS_MOBILE, states, getActiveIface(states),
+                new VpnInfo[0]);
+
+        // Create some traffic.
+        incrementCurrentTime(MINUTE_IN_MILLIS);
+        expectNetworkStatsUidDetail(new NetworkStats(getElapsedRealtime(), 1)
+                .addEntry(new NetworkStats.Entry(TEST_IFACE, UID_RED, SET_DEFAULT, TAG_NONE,
+                        12L, 18L, 14L, 1L, 0L)));
+        forcePollAndWaitForIdle();
+
+        // Since CombineSubtypeEnabled is false by default in unit test, the generated traffic
+        // will be split by RAT type. Verify 3G templates gets stats, while template with unknown
+        // RAT type gets nothing, and template with NETWORK_TYPE_ALL gets all stats.
+        assertUidTotal(template3g, UID_RED, 12L, 18L, 14L, 1L, 0);
+        assertUidTotal(templateUnknown, UID_RED, 0L, 0L, 0L, 0L, 0);
+        assertUidTotal(templateAll, UID_RED, 12L, 18L, 14L, 1L, 0);
+
+        // Stop monitoring data usage per RAT type changes NetworkStatsService records data
+        // to {@link TelephonyManager#NETWORK_TYPE_UNKNOWN}.
+        setCombineSubtypeEnabled(true);
+
+        // Call handleOnCollapsedRatTypeChanged manually to simulate the callback fired
+        // when stopping monitor, this is needed by NetworkStatsService to trigger updateIfaces.
+        mService.handleOnCollapsedRatTypeChanged();
+        HandlerUtilsKt.waitForIdle(mHandlerThread, WAIT_TIMEOUT);
+        // Create some traffic.
+        incrementCurrentTime(MINUTE_IN_MILLIS);
+        // Append more traffic on existing snapshot.
+        expectNetworkStatsUidDetail(new NetworkStats(getElapsedRealtime(), 1)
+                .addEntry(new NetworkStats.Entry(TEST_IFACE, UID_RED, SET_DEFAULT, TAG_NONE,
+                        12L + 4L, 18L + 4L, 14L + 3L, 1L + 1L, 0L))
+                .addEntry(new NetworkStats.Entry(TEST_IFACE, UID_RED, SET_FOREGROUND, TAG_NONE,
+                        35L, 29L, 7L, 11L, 1L)));
+        forcePollAndWaitForIdle();
+
+        // Verify 3G counters do not increase, while template with unknown RAT type gets new
+        // traffic and template with NETWORK_TYPE_ALL gets all stats.
+        assertUidTotal(template3g, UID_RED, 12L, 18L, 14L, 1L, 0);
+        assertUidTotal(templateUnknown, UID_RED, 4L + 35L, 4L + 29L, 3L + 7L, 1L + 11L, 1);
+        assertUidTotal(templateAll, UID_RED, 16L + 35L, 22L + 29L, 17L + 7L, 2L + 11L, 1);
+
+        // Start monitoring data usage per RAT type changes and NetworkStatsService records data
+        // by a granular subtype representative of the actual subtype
+        setCombineSubtypeEnabled(false);
+
+        mService.handleOnCollapsedRatTypeChanged();
+        HandlerUtilsKt.waitForIdle(mHandlerThread, WAIT_TIMEOUT);
+        // Create some traffic.
+        incrementCurrentTime(MINUTE_IN_MILLIS);
+        // Append more traffic on existing snapshot.
+        expectNetworkStatsUidDetail(new NetworkStats(getElapsedRealtime(), 1)
+                .addEntry(new NetworkStats.Entry(TEST_IFACE, UID_RED, SET_DEFAULT, TAG_NONE,
+                        22L, 26L, 19L, 5L, 0L))
+                .addEntry(new NetworkStats.Entry(TEST_IFACE, UID_RED, SET_FOREGROUND, TAG_NONE,
+                        35L, 29L, 7L, 11L, 1L)));
+        forcePollAndWaitForIdle();
+
+        // Verify traffic is split by RAT type, no increase on template with unknown RAT type
+        // and template with NETWORK_TYPE_ALL gets all stats.
+        assertUidTotal(template3g, UID_RED, 6L + 12L , 4L + 18L, 2L + 14L, 3L + 1L, 0);
+        assertUidTotal(templateUnknown, UID_RED, 4L + 35L, 4L + 29L, 3L + 7L, 1L + 11L, 1);
+        assertUidTotal(templateAll, UID_RED, 22L + 35L, 26L + 29L, 19L + 7L, 5L + 11L, 1);
+    }
+
     private static File getBaseDir(File statsDir) {
         File baseDir = new File(statsDir, "netstats");
         baseDir.mkdirs();
@@ -1403,6 +1516,10 @@ public class NetworkStatsServiceTest extends NetworkStatsBaseTest {
 
     private void forcePollAndWaitForIdle() {
         mServiceContext.sendBroadcast(new Intent(ACTION_NETWORK_STATS_POLL));
+        waitForIdle();
+    }
+
+    private void waitForIdle() {
         HandlerUtilsKt.waitForIdle(mHandlerThread, WAIT_TIMEOUT);
     }