Add method to NetworkStatsService for UID stats.

Useful for clients such as BatteryStats which currently rely
on NetworkStatsFactory. Data at that stage is incomplete as
it does not account for tethering, VT data and corresponding
464xlat corrections.

Test: runtest frameworks-net, CTS tests pass.
Change-Id: I763b77f601c827fd2963204694fb5b45425cc791
diff --git a/core/java/android/net/INetworkStatsService.aidl b/core/java/android/net/INetworkStatsService.aidl
index 90e3ffd..eab7041 100644
--- a/core/java/android/net/INetworkStatsService.aidl
+++ b/core/java/android/net/INetworkStatsService.aidl
@@ -44,6 +44,16 @@
 
     /** Return data layer snapshot of UID network usage. */
     NetworkStats getDataLayerSnapshotForUid(int uid);
+
+    /** Get a detailed snapshot of stats since boot for all UIDs.
+    *
+    * <p>Results will not always be limited to stats on requiredIfaces when specified: stats for
+    * interfaces stacked on the specified interfaces, or for interfaces on which the specified
+    * interfaces are stacked on, will also be included.
+    * @param requiredIfaces Interface names to get data for, or {@link NetworkStats#INTERFACES_ALL}.
+    */
+    NetworkStats getDetailedUidStats(in String[] requiredIfaces);
+
     /** Return set of any ifaces associated with mobile networks since boot. */
     String[] getMobileIfaces();
 
diff --git a/core/java/android/net/NetworkStats.java b/core/java/android/net/NetworkStats.java
index 01b2b39..940f985 100644
--- a/core/java/android/net/NetworkStats.java
+++ b/core/java/android/net/NetworkStats.java
@@ -64,6 +64,9 @@
     /** Debug {@link #set} value when the VPN stats are moved out of a vpn UID. */
     public static final int SET_DBG_VPN_OUT = 1002;
 
+    /** Include all interfaces when filtering */
+    public static final String[] INTERFACES_ALL = null;
+
     /** {@link #tag} value for total data across all tags. */
     // TODO: Rename TAG_NONE to TAG_ALL.
     public static final int TAG_NONE = 0;
@@ -359,23 +362,27 @@
             capacity = newLength;
         }
 
-        iface[size] = entry.iface;
-        uid[size] = entry.uid;
-        set[size] = entry.set;
-        tag[size] = entry.tag;
-        metered[size] = entry.metered;
-        roaming[size] = entry.roaming;
-        defaultNetwork[size] = entry.defaultNetwork;
-        rxBytes[size] = entry.rxBytes;
-        rxPackets[size] = entry.rxPackets;
-        txBytes[size] = entry.txBytes;
-        txPackets[size] = entry.txPackets;
-        operations[size] = entry.operations;
+        setValues(size, entry);
         size++;
 
         return this;
     }
 
+    private void setValues(int i, Entry entry) {
+        iface[i] = entry.iface;
+        uid[i] = entry.uid;
+        set[i] = entry.set;
+        tag[i] = entry.tag;
+        metered[i] = entry.metered;
+        roaming[i] = entry.roaming;
+        defaultNetwork[i] = entry.defaultNetwork;
+        rxBytes[i] = entry.rxBytes;
+        rxPackets[i] = entry.rxPackets;
+        txBytes[i] = entry.txBytes;
+        txPackets[i] = entry.txPackets;
+        operations[i] = entry.operations;
+    }
+
     /**
      * Return specific stats entry.
      */
@@ -824,6 +831,39 @@
         return stats;
     }
 
+    /**
+     * Only keep entries that match all specified filters.
+     *
+     * <p>This mutates the original structure in place. After this method is called,
+     * size is the number of matching entries, and capacity is the previous capacity.
+     * @param limitUid UID to filter for, or {@link #UID_ALL}.
+     * @param limitIfaces Interfaces to filter for, or {@link #INTERFACES_ALL}.
+     * @param limitTag Tag to filter for, or {@link #TAG_ALL}.
+     */
+    public void filter(int limitUid, String[] limitIfaces, int limitTag) {
+        if (limitUid == UID_ALL && limitTag == TAG_ALL && limitIfaces == INTERFACES_ALL) {
+            return;
+        }
+
+        Entry entry = new Entry();
+        int nextOutputEntry = 0;
+        for (int i = 0; i < size; i++) {
+            entry = getValues(i, entry);
+            final boolean matches =
+                    (limitUid == UID_ALL || limitUid == entry.uid)
+                    && (limitTag == TAG_ALL || limitTag == entry.tag)
+                    && (limitIfaces == INTERFACES_ALL
+                            || ArrayUtils.contains(limitIfaces, entry.iface));
+
+            if (matches) {
+                setValues(nextOutputEntry, entry);
+                nextOutputEntry++;
+            }
+        }
+
+        size = nextOutputEntry;
+    }
+
     public void dump(String prefix, PrintWriter pw) {
         pw.print(prefix);
         pw.print("NetworkStats: elapsedRealtime="); pw.println(elapsedRealtime);
diff --git a/core/java/android/os/INetworkManagementService.aidl b/core/java/android/os/INetworkManagementService.aidl
index a5e1934..9a8f5cb 100644
--- a/core/java/android/os/INetworkManagementService.aidl
+++ b/core/java/android/os/INetworkManagementService.aidl
@@ -268,10 +268,12 @@
     NetworkStats getNetworkStatsDetail();
 
     /**
-     * Return detailed network statistics for the requested UID,
+     * Return detailed network statistics for the requested UID and interfaces,
      * including interface and tag details.
+     * @param uid UID to obtain statistics for, or {@link NetworkStats#UID_ALL}.
+     * @param ifaces Interfaces to obtain statistics for, or {@link NetworkStats#INTERFACES_ALL}.
      */
-    NetworkStats getNetworkStatsUidDetail(int uid);
+    NetworkStats getNetworkStatsUidDetail(int uid, in String[] ifaces);
 
     /**
      * Return summary of network statistics all tethering interfaces.
diff --git a/core/java/com/android/internal/net/NetworkStatsFactory.java b/core/java/com/android/internal/net/NetworkStatsFactory.java
index 902bd12..8172a20 100644
--- a/core/java/com/android/internal/net/NetworkStatsFactory.java
+++ b/core/java/com/android/internal/net/NetworkStatsFactory.java
@@ -22,16 +22,14 @@
 import static android.net.NetworkStats.UID_ALL;
 import static com.android.server.NetworkManagementSocketTagger.kernelToTag;
 
+import android.annotation.Nullable;
 import android.net.NetworkStats;
 import android.os.StrictMode;
 import android.os.SystemClock;
-import android.util.ArrayMap;
 
-import com.android.internal.annotations.GuardedBy;
 import com.android.internal.annotations.VisibleForTesting;
 import com.android.internal.util.ArrayUtils;
 import com.android.internal.util.ProcFileReader;
-import com.google.android.collect.Lists;
 
 import libcore.io.IoUtils;
 
@@ -41,8 +39,10 @@
 import java.io.FileReader;
 import java.io.IOException;
 import java.net.ProtocolException;
-import java.util.ArrayList;
-import java.util.Objects;
+import java.util.Arrays;
+import java.util.HashSet;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
 
 /**
  * Creates {@link NetworkStats} instances by parsing various {@code /proc/}
@@ -70,18 +70,55 @@
 
     private boolean mUseBpfStats;
 
-    // TODO: to improve testability and avoid global state, do not use a static variable.
-    @GuardedBy("sStackedIfaces")
-    private static final ArrayMap<String, String> sStackedIfaces = new ArrayMap<>();
+    // TODO: only do adjustments in NetworkStatsService and remove this.
+    /**
+     * (Stacked interface) -> (base interface) association for all connected ifaces since boot.
+     *
+     * Because counters must never roll backwards, once a given interface is stacked on top of an
+     * underlying interface, the stacked interface can never be stacked on top of
+     * another interface. */
+    private static final ConcurrentHashMap<String, String> sStackedIfaces
+            = new ConcurrentHashMap<>();
 
     public static void noteStackedIface(String stackedIface, String baseIface) {
-        synchronized (sStackedIfaces) {
-            if (baseIface != null) {
-                sStackedIfaces.put(stackedIface, baseIface);
-            } else {
-                sStackedIfaces.remove(stackedIface);
+        if (stackedIface != null && baseIface != null) {
+            sStackedIfaces.put(stackedIface, baseIface);
+        }
+    }
+
+    /**
+     * Get a set of interfaces containing specified ifaces and stacked interfaces.
+     *
+     * <p>The added stacked interfaces are ifaces stacked on top of the specified ones, or ifaces
+     * on which the specified ones are stacked. Stacked interfaces are those noted with
+     * {@link #noteStackedIface(String, String)}, but only interfaces noted before this method
+     * is called are guaranteed to be included.
+     */
+    public static String[] augmentWithStackedInterfacesLocked(@Nullable String[] requiredIfaces) {
+        if (requiredIfaces == NetworkStats.INTERFACES_ALL) {
+            return null;
+        }
+
+        HashSet<String> relatedIfaces = new HashSet<>(Arrays.asList(requiredIfaces));
+        // ConcurrentHashMap's EntrySet iterators are "guaranteed to traverse
+        // elements as they existed upon construction exactly once, and may
+        // (but are not guaranteed to) reflect any modifications subsequent to construction".
+        // This is enough here.
+        for (Map.Entry<String, String> entry : sStackedIfaces.entrySet()) {
+            if (relatedIfaces.contains(entry.getKey())) {
+                relatedIfaces.add(entry.getValue());
+            } else if (relatedIfaces.contains(entry.getValue())) {
+                relatedIfaces.add(entry.getKey());
             }
         }
+
+        String[] outArray = new String[relatedIfaces.size()];
+        return relatedIfaces.toArray(outArray);
+    }
+
+    @VisibleForTesting
+    public static void clearStackedIfaces() {
+        sStackedIfaces.clear();
     }
 
     public NetworkStatsFactory() {
@@ -250,12 +287,9 @@
             NetworkStats lastStats) throws IOException {
         final NetworkStats stats =
               readNetworkStatsDetailInternal(limitUid, limitIfaces, limitTag, lastStats);
-        final ArrayMap<String, String> stackedIfaces;
-        synchronized (sStackedIfaces) {
-            stackedIfaces = new ArrayMap<>(sStackedIfaces);
-        }
         // Total 464xlat traffic to subtract from uid 0 on all base interfaces.
-        final NetworkStats adjustments = new NetworkStats(0, stackedIfaces.size());
+        // sStackedIfaces may grow afterwards, but NetworkStats will just be resized automatically.
+        final NetworkStats adjustments = new NetworkStats(0, sStackedIfaces.size());
 
         NetworkStats.Entry entry = null; // For recycling
 
@@ -269,7 +303,7 @@
             if (entry.iface == null || !entry.iface.startsWith(CLATD_INTERFACE_PREFIX)) {
                 continue;
             }
-            final String baseIface = stackedIfaces.get(entry.iface);
+            final String baseIface = sStackedIfaces.get(entry.iface);
             if (baseIface == null) {
                 continue;
             }
diff --git a/services/core/java/com/android/server/ConnectivityService.java b/services/core/java/com/android/server/ConnectivityService.java
index 6c24e94..c044242 100644
--- a/services/core/java/com/android/server/ConnectivityService.java
+++ b/services/core/java/com/android/server/ConnectivityService.java
@@ -5268,7 +5268,6 @@
                 for (LinkProperties stacked : newNetwork.linkProperties.getStackedLinks()) {
                     final String stackedIface = stacked.getInterfaceName();
                     bs.noteNetworkInterfaceType(stackedIface, type);
-                    NetworkStatsFactory.noteStackedIface(stackedIface, baseIface);
                 }
             } catch (RemoteException ignored) {
             }
diff --git a/services/core/java/com/android/server/NetworkManagementService.java b/services/core/java/com/android/server/NetworkManagementService.java
index 88ae224..fc4ec11 100644
--- a/services/core/java/com/android/server/NetworkManagementService.java
+++ b/services/core/java/com/android/server/NetworkManagementService.java
@@ -1867,10 +1867,10 @@
     }
 
     @Override
-    public NetworkStats getNetworkStatsUidDetail(int uid) {
+    public NetworkStats getNetworkStatsUidDetail(int uid, String[] ifaces) {
         mContext.enforceCallingOrSelfPermission(CONNECTIVITY_INTERNAL, TAG);
         try {
-            return mStatsFactory.readNetworkStatsDetail(uid, null, TAG_ALL, null);
+            return mStatsFactory.readNetworkStatsDetail(uid, ifaces, TAG_ALL, null);
         } catch (IOException e) {
             throw new IllegalStateException(e);
         }
diff --git a/services/core/java/com/android/server/net/NetworkStatsService.java b/services/core/java/com/android/server/net/NetworkStatsService.java
index 8298127..e0a8643 100644
--- a/services/core/java/com/android/server/net/NetworkStatsService.java
+++ b/services/core/java/com/android/server/net/NetworkStatsService.java
@@ -27,6 +27,7 @@
 import static android.net.ConnectivityManager.isNetworkTypeMobile;
 import static android.net.NetworkStats.DEFAULT_NETWORK_ALL;
 import static android.net.NetworkStats.IFACE_ALL;
+import static android.net.NetworkStats.INTERFACES_ALL;
 import static android.net.NetworkStats.METERED_ALL;
 import static android.net.NetworkStats.ROAMING_ALL;
 import static android.net.NetworkStats.SET_ALL;
@@ -34,6 +35,7 @@
 import static android.net.NetworkStats.SET_FOREGROUND;
 import static android.net.NetworkStats.STATS_PER_IFACE;
 import static android.net.NetworkStats.STATS_PER_UID;
+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;
@@ -128,6 +130,7 @@
 
 import com.android.internal.annotations.GuardedBy;
 import com.android.internal.annotations.VisibleForTesting;
+import com.android.internal.net.NetworkStatsFactory;
 import com.android.internal.net.VpnInfo;
 import com.android.internal.util.ArrayUtils;
 import com.android.internal.util.DumpUtils;
@@ -143,6 +146,7 @@
 import java.util.Arrays;
 import java.util.HashSet;
 import java.util.List;
+import java.util.Map;
 
 /**
  * Collect and persist detailed network statistics, and provide this data to
@@ -726,7 +730,8 @@
         final long token = Binder.clearCallingIdentity();
         final NetworkStats networkLayer;
         try {
-            networkLayer = mNetworkManager.getNetworkStatsUidDetail(uid);
+            networkLayer = mNetworkManager.getNetworkStatsUidDetail(uid,
+                    NetworkStats.INTERFACES_ALL);
         } finally {
             Binder.restoreCallingIdentity(token);
         }
@@ -748,6 +753,18 @@
     }
 
     @Override
+    public NetworkStats getDetailedUidStats(String[] requiredIfaces) {
+        try {
+            final String[] ifacesToQuery =
+                    NetworkStatsFactory.augmentWithStackedInterfacesLocked(requiredIfaces);
+            return getNetworkStatsUidDetail(ifacesToQuery);
+        } catch (RemoteException e) {
+            Log.wtf(TAG, "Error compiling UID stats", e);
+            return new NetworkStats(0L, 0);
+        }
+    }
+
+    @Override
     public String[] getMobileIfaces() {
         return mMobileIfaces;
     }
@@ -1109,6 +1126,8 @@
                         if (isMobile) {
                             mobileIfaces.add(stackedIface);
                         }
+
+                        NetworkStatsFactory.noteStackedIface(stackedIface, baseIface);
                     }
                 }
             }
@@ -1130,7 +1149,7 @@
     private void recordSnapshotLocked(long currentTime) throws RemoteException {
         // snapshot and record current counters; read UID stats first to
         // avoid over counting dev stats.
-        final NetworkStats uidSnapshot = getNetworkStatsUidDetail();
+        final NetworkStats uidSnapshot = getNetworkStatsUidDetail(INTERFACES_ALL);
         final NetworkStats xtSnapshot = getNetworkStatsXt();
         final NetworkStats devSnapshot = mNetworkManager.getNetworkStatsSummaryDev();
 
@@ -1464,12 +1483,19 @@
      * Return snapshot of current UID statistics, including any
      * {@link TrafficStats#UID_TETHERING}, video calling data usage, and {@link #mUidOperations}
      * values.
+     *
+     * @param ifaces A list of interfaces the stats should be restricted to, or
+     *               {@link NetworkStats#INTERFACES_ALL}.
      */
-    private NetworkStats getNetworkStatsUidDetail() throws RemoteException {
-        final NetworkStats uidSnapshot = mNetworkManager.getNetworkStatsUidDetail(UID_ALL);
+    private NetworkStats getNetworkStatsUidDetail(String[] ifaces)
+            throws RemoteException {
+
+        final NetworkStats uidSnapshot = mNetworkManager.getNetworkStatsUidDetail(UID_ALL,
+                ifaces);
 
         // fold tethering stats and operations into uid snapshot
         final NetworkStats tetherSnapshot = getNetworkStatsTethering(STATS_PER_UID);
+        tetherSnapshot.filter(UID_ALL, ifaces, TAG_ALL);
         uidSnapshot.combineAllValues(tetherSnapshot);
 
         final TelephonyManager telephonyManager = (TelephonyManager) mContext.getSystemService(
@@ -1478,10 +1504,14 @@
         // fold video calling data usage stats into uid snapshot
         final NetworkStats vtStats = telephonyManager.getVtDataUsage(STATS_PER_UID);
         if (vtStats != null) {
+            vtStats.filter(UID_ALL, ifaces, TAG_ALL);
             uidSnapshot.combineAllValues(vtStats);
         }
+
         uidSnapshot.combineAllValues(mUidOperations);
 
+        // TODO: apply tethering & VC 464xlat adjustments here
+
         return uidSnapshot;
     }
 
diff --git a/tests/net/java/android/net/NetworkStatsTest.java b/tests/net/java/android/net/NetworkStatsTest.java
index 035a4cd7..0530a86 100644
--- a/tests/net/java/android/net/NetworkStatsTest.java
+++ b/tests/net/java/android/net/NetworkStatsTest.java
@@ -19,6 +19,7 @@
 import static android.net.NetworkStats.DEFAULT_NETWORK_ALL;
 import static android.net.NetworkStats.DEFAULT_NETWORK_NO;
 import static android.net.NetworkStats.DEFAULT_NETWORK_YES;
+import static android.net.NetworkStats.INTERFACES_ALL;
 import static android.net.NetworkStats.METERED_ALL;
 import static android.net.NetworkStats.METERED_NO;
 import static android.net.NetworkStats.METERED_YES;
@@ -31,6 +32,7 @@
 import static android.net.NetworkStats.SET_DBG_VPN_OUT;
 import static android.net.NetworkStats.SET_ALL;
 import static android.net.NetworkStats.IFACE_ALL;
+import static android.net.NetworkStats.TAG_ALL;
 import static android.net.NetworkStats.TAG_NONE;
 import static android.net.NetworkStats.UID_ALL;
 import static org.junit.Assert.assertEquals;
@@ -641,6 +643,136 @@
                 ROAMING_ALL, DEFAULT_NETWORK_ALL, 50500L, 27L, 100200L, 55, 0);
     }
 
+    @Test
+    public void testFilter_NoFilter() {
+        NetworkStats.Entry entry1 = new NetworkStats.Entry(
+                "test1", 10100, SET_DEFAULT, TAG_NONE, METERED_NO, ROAMING_NO,
+                DEFAULT_NETWORK_NO, 50000L, 25L, 100000L, 50L, 0L);
+
+        NetworkStats.Entry entry2 = new NetworkStats.Entry(
+                "test2", 10101, SET_DEFAULT, TAG_NONE, METERED_NO, ROAMING_NO,
+                DEFAULT_NETWORK_NO, 50000L, 25L, 100000L, 50L, 0L);
+
+        NetworkStats.Entry entry3 = new NetworkStats.Entry(
+                "test2", 10101, SET_DEFAULT, 123, METERED_NO, ROAMING_NO,
+                DEFAULT_NETWORK_NO, 50000L, 25L, 100000L, 50L, 0L);
+
+        NetworkStats stats = new NetworkStats(TEST_START, 3)
+                .addValues(entry1)
+                .addValues(entry2)
+                .addValues(entry3);
+
+        stats.filter(UID_ALL, INTERFACES_ALL, TAG_ALL);
+        assertEquals(3, stats.size());
+        assertEquals(entry1, stats.getValues(0, null));
+        assertEquals(entry2, stats.getValues(1, null));
+        assertEquals(entry3, stats.getValues(2, null));
+    }
+
+    @Test
+    public void testFilter_UidFilter() {
+        final int testUid = 10101;
+        NetworkStats.Entry entry1 = new NetworkStats.Entry(
+                "test1", 10100, SET_DEFAULT, TAG_NONE, METERED_NO, ROAMING_NO,
+                DEFAULT_NETWORK_NO, 50000L, 25L, 100000L, 50L, 0L);
+
+        NetworkStats.Entry entry2 = new NetworkStats.Entry(
+                "test2", testUid, SET_DEFAULT, TAG_NONE, METERED_NO, ROAMING_NO,
+                DEFAULT_NETWORK_NO, 50000L, 25L, 100000L, 50L, 0L);
+
+        NetworkStats.Entry entry3 = new NetworkStats.Entry(
+                "test2", testUid, SET_DEFAULT, 123, METERED_NO, ROAMING_NO,
+                DEFAULT_NETWORK_NO, 50000L, 25L, 100000L, 50L, 0L);
+
+        NetworkStats stats = new NetworkStats(TEST_START, 3)
+                .addValues(entry1)
+                .addValues(entry2)
+                .addValues(entry3);
+
+        stats.filter(testUid, INTERFACES_ALL, TAG_ALL);
+        assertEquals(2, stats.size());
+        assertEquals(entry2, stats.getValues(0, null));
+        assertEquals(entry3, stats.getValues(1, null));
+    }
+
+    @Test
+    public void testFilter_InterfaceFilter() {
+        final String testIf1 = "testif1";
+        final String testIf2 = "testif2";
+        NetworkStats.Entry entry1 = new NetworkStats.Entry(
+                testIf1, 10100, SET_DEFAULT, TAG_NONE, METERED_NO, ROAMING_NO,
+                DEFAULT_NETWORK_NO, 50000L, 25L, 100000L, 50L, 0L);
+
+        NetworkStats.Entry entry2 = new NetworkStats.Entry(
+                "otherif", 10101, SET_DEFAULT, TAG_NONE, METERED_NO, ROAMING_NO,
+                DEFAULT_NETWORK_NO, 50000L, 25L, 100000L, 50L, 0L);
+
+        NetworkStats.Entry entry3 = new NetworkStats.Entry(
+                testIf1, 10101, SET_DEFAULT, 123, METERED_NO, ROAMING_NO,
+                DEFAULT_NETWORK_NO, 50000L, 25L, 100000L, 50L, 0L);
+
+        NetworkStats.Entry entry4 = new NetworkStats.Entry(
+                testIf2, 10101, SET_DEFAULT, 123, METERED_NO, ROAMING_NO,
+                DEFAULT_NETWORK_NO, 50000L, 25L, 100000L, 50L, 0L);
+
+        NetworkStats stats = new NetworkStats(TEST_START, 4)
+                .addValues(entry1)
+                .addValues(entry2)
+                .addValues(entry3)
+                .addValues(entry4);
+
+        stats.filter(UID_ALL, new String[] { testIf1, testIf2 }, TAG_ALL);
+        assertEquals(3, stats.size());
+        assertEquals(entry1, stats.getValues(0, null));
+        assertEquals(entry3, stats.getValues(1, null));
+        assertEquals(entry4, stats.getValues(2, null));
+    }
+
+    @Test
+    public void testFilter_EmptyInterfaceFilter() {
+        NetworkStats.Entry entry1 = new NetworkStats.Entry(
+                "if1", 10100, SET_DEFAULT, TAG_NONE, METERED_NO, ROAMING_NO,
+                DEFAULT_NETWORK_NO, 50000L, 25L, 100000L, 50L, 0L);
+
+        NetworkStats.Entry entry2 = new NetworkStats.Entry(
+                "if2", 10101, SET_DEFAULT, TAG_NONE, METERED_NO, ROAMING_NO,
+                DEFAULT_NETWORK_NO, 50000L, 25L, 100000L, 50L, 0L);
+
+        NetworkStats stats = new NetworkStats(TEST_START, 3)
+                .addValues(entry1)
+                .addValues(entry2);
+
+        stats.filter(UID_ALL, new String[] { }, TAG_ALL);
+        assertEquals(0, stats.size());
+    }
+
+    @Test
+    public void testFilter_TagFilter() {
+        final int testTag = 123;
+        final int otherTag = 456;
+        NetworkStats.Entry entry1 = new NetworkStats.Entry(
+                "test1", 10100, SET_DEFAULT, testTag, METERED_NO, ROAMING_NO,
+                DEFAULT_NETWORK_NO, 50000L, 25L, 100000L, 50L, 0L);
+
+        NetworkStats.Entry entry2 = new NetworkStats.Entry(
+                "test2", 10101, SET_DEFAULT, testTag, METERED_NO, ROAMING_NO,
+                DEFAULT_NETWORK_NO, 50000L, 25L, 100000L, 50L, 0L);
+
+        NetworkStats.Entry entry3 = new NetworkStats.Entry(
+                "test2", 10101, SET_DEFAULT, otherTag, METERED_NO, ROAMING_NO,
+                DEFAULT_NETWORK_NO, 50000L, 25L, 100000L, 50L, 0L);
+
+        NetworkStats stats = new NetworkStats(TEST_START, 3)
+                .addValues(entry1)
+                .addValues(entry2)
+                .addValues(entry3);
+
+        stats.filter(UID_ALL, INTERFACES_ALL, testTag);
+        assertEquals(2, stats.size());
+        assertEquals(entry1, stats.getValues(0, null));
+        assertEquals(entry2, stats.getValues(1, null));
+    }
+
     private static void assertContains(NetworkStats stats,  String iface, int uid, int set,
             int tag, int metered, int roaming, int defaultNetwork, long rxBytes, long rxPackets,
             long txBytes, long txPackets, long operations) {
diff --git a/tests/net/java/com/android/internal/net/NetworkStatsFactoryTest.java b/tests/net/java/com/android/internal/net/NetworkStatsFactoryTest.java
index b14f550..fc46b9c 100644
--- a/tests/net/java/com/android/internal/net/NetworkStatsFactoryTest.java
+++ b/tests/net/java/com/android/internal/net/NetworkStatsFactoryTest.java
@@ -184,7 +184,7 @@
         assertStatsEntry(stats, "dummy0", 0, SET_DEFAULT, 0x0, 0L, 168L);
         assertStatsEntry(stats, "lo", 0, SET_DEFAULT, 0x0, 1288L, 1288L);
 
-        NetworkStatsFactory.noteStackedIface("v4-wlan0", null);
+        NetworkStatsFactory.clearStackedIfaces();
     }
 
     @Test
@@ -212,7 +212,7 @@
         assertStatsEntry(stats, "v4-wlan0", 10106, SET_FOREGROUND, 0x0, appRxBytesAfter, 7867488L);
         assertStatsEntry(stats, "wlan0", 0, SET_DEFAULT, 0x0, rootRxBytesAfter, 647587L);
 
-        NetworkStatsFactory.noteStackedIface("v4-wlan0", null);
+        NetworkStatsFactory.clearStackedIfaces();
     }
 
     /**
diff --git a/tests/net/java/com/android/server/net/NetworkStatsServiceTest.java b/tests/net/java/com/android/server/net/NetworkStatsServiceTest.java
index 47c3455..17ca651 100644
--- a/tests/net/java/com/android/server/net/NetworkStatsServiceTest.java
+++ b/tests/net/java/com/android/server/net/NetworkStatsServiceTest.java
@@ -25,6 +25,7 @@
 import static android.net.NetworkStats.DEFAULT_NETWORK_NO;
 import static android.net.NetworkStats.DEFAULT_NETWORK_YES;
 import static android.net.NetworkStats.IFACE_ALL;
+import static android.net.NetworkStats.INTERFACES_ALL;
 import static android.net.NetworkStats.METERED_ALL;
 import static android.net.NetworkStats.METERED_NO;
 import static android.net.NetworkStats.METERED_YES;
@@ -58,6 +59,9 @@
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.ArgumentMatchers.anyInt;
 import static org.mockito.ArgumentMatchers.anyLong;
+import static org.mockito.ArgumentMatchers.argThat;
+import static org.mockito.ArgumentMatchers.eq;
+import static org.mockito.Mockito.times;
 import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.when;
 
@@ -95,6 +99,7 @@
 import android.util.TrustedTime;
 
 import com.android.internal.net.VpnInfo;
+import com.android.internal.util.ArrayUtils;
 import com.android.internal.util.test.BroadcastInterceptingContext;
 import com.android.server.net.NetworkStatsService.NetworkStatsSettings;
 import com.android.server.net.NetworkStatsService.NetworkStatsSettings.Config;
@@ -668,6 +673,94 @@
     }
 
     @Test
+    public void testDetailedUidStats() throws Exception {
+        // pretend that network comes online
+        expectDefaultSettings();
+        expectNetworkState(buildWifiState());
+        expectNetworkStatsSummary(buildEmptyStats());
+        expectNetworkStatsUidDetail(buildEmptyStats());
+        expectBandwidthControlCheck();
+
+        mService.forceUpdateIfaces(NETWORKS_WIFI);
+
+        NetworkStats.Entry entry1 = new NetworkStats.Entry(
+                TEST_IFACE, UID_RED, SET_DEFAULT, TAG_NONE, 50L, 5L, 50L, 5L, 0L);
+        NetworkStats.Entry entry2 = new NetworkStats.Entry(
+                TEST_IFACE, UID_RED, SET_DEFAULT, 0xF00D, 50L, 5L, 50L, 5L, 0L);
+        NetworkStats.Entry entry3 = new NetworkStats.Entry(
+                TEST_IFACE, UID_BLUE, SET_DEFAULT, 0xBEEF, 1024L, 8L, 512L, 4L, 0L);
+
+        incrementCurrentTime(HOUR_IN_MILLIS);
+        expectDefaultSettings();
+        expectNetworkStatsSummary(buildEmptyStats());
+        expectNetworkStatsUidDetail(new NetworkStats(getElapsedRealtime(), 3)
+                .addValues(entry1)
+                .addValues(entry2)
+                .addValues(entry3));
+        mService.incrementOperationCount(UID_RED, 0xF00D, 1);
+
+        NetworkStats stats = mService.getDetailedUidStats(INTERFACES_ALL);
+
+        assertEquals(3, stats.size());
+        entry1.operations = 1;
+        assertEquals(entry1, stats.getValues(0, null));
+        entry2.operations = 1;
+        assertEquals(entry2, stats.getValues(1, null));
+        assertEquals(entry3, stats.getValues(2, null));
+    }
+
+    @Test
+    public void testDetailedUidStats_Filtered() throws Exception {
+        // pretend that network comes online
+        expectDefaultSettings();
+
+        final String stackedIface = "stacked-test0";
+        final LinkProperties stackedProp = new LinkProperties();
+        stackedProp.setInterfaceName(stackedIface);
+        final NetworkState wifiState = buildWifiState();
+        wifiState.linkProperties.addStackedLink(stackedProp);
+        expectNetworkState(wifiState);
+
+        expectNetworkStatsSummary(buildEmptyStats());
+        expectNetworkStatsUidDetail(buildEmptyStats());
+        expectBandwidthControlCheck();
+
+        mService.forceUpdateIfaces(NETWORKS_WIFI);
+
+        NetworkStats.Entry uidStats = new NetworkStats.Entry(
+                TEST_IFACE, UID_BLUE, SET_DEFAULT, 0xF00D, 1024L, 8L, 512L, 4L, 0L);
+        // Stacked on matching interface
+        NetworkStats.Entry tetheredStats1 = new NetworkStats.Entry(
+                stackedIface, UID_BLUE, SET_DEFAULT, 0xF00D, 1024L, 8L, 512L, 4L, 0L);
+        // Different interface
+        NetworkStats.Entry tetheredStats2 = new NetworkStats.Entry(
+                "otherif", UID_BLUE, SET_DEFAULT, 0xF00D, 1024L, 8L, 512L, 4L, 0L);
+
+        final String[] ifaceFilter = new String[] { TEST_IFACE };
+        incrementCurrentTime(HOUR_IN_MILLIS);
+        expectDefaultSettings();
+        expectNetworkStatsSummary(buildEmptyStats());
+        when(mNetManager.getNetworkStatsUidDetail(eq(UID_ALL), any()))
+                .thenReturn(new NetworkStats(getElapsedRealtime(), 1)
+                        .addValues(uidStats));
+        when(mNetManager.getNetworkStatsTethering(STATS_PER_UID))
+                .thenReturn(new NetworkStats(getElapsedRealtime(), 2)
+                        .addValues(tetheredStats1)
+                        .addValues(tetheredStats2));
+
+        NetworkStats stats = mService.getDetailedUidStats(ifaceFilter);
+
+        verify(mNetManager, times(1)).getNetworkStatsUidDetail(eq(UID_ALL), argThat(ifaces ->
+                ifaces != null && ifaces.length == 2
+                        && ArrayUtils.contains(ifaces, TEST_IFACE)
+                        && ArrayUtils.contains(ifaces, stackedIface)));
+
+        assertEquals(2, stats.size());
+        assertEquals(uidStats, stats.getValues(0, null));
+        assertEquals(tetheredStats1, stats.getValues(1, null));
+    }
+
+    @Test
     public void testForegroundBackground() throws Exception {
         // pretend that network comes online
         expectCurrentTime();
@@ -1056,7 +1149,7 @@
 
     private void expectNetworkStatsUidDetail(NetworkStats detail, NetworkStats tetherStats)
             throws Exception {
-        when(mNetManager.getNetworkStatsUidDetail(UID_ALL)).thenReturn(detail);
+        when(mNetManager.getNetworkStatsUidDetail(UID_ALL, INTERFACES_ALL)).thenReturn(detail);
 
         // also include tethering details, since they are folded into UID
         when(mNetManager.getNetworkStatsTethering(STATS_PER_UID)).thenReturn(tetherStats);