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.
Bug: b/72107146
Merged-In: I31c5b9b4a7c6e72910152415894a137f000a5858
Merged-In: I2527d95000c7500c824ede70f87ecb38e21ed323
(cherry picked from aosp 088ff6824f13145ea52207bdead0d7e454a6f3ce)

Change-Id: Ie80f1bb21124241f3414f9be77aceac9a44ec6d1

core/java/android/net/INetworkStatsService.aidl

@@ -41,6 +41,16 @@ interface INetworkStatsService {
 
     /** 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();
 

core/java/android/net/NetworkStats.java

@@ -64,6 +64,9 @@ public class NetworkStats implements Parcelable {
     /** 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;
@@ -366,23 +369,27 @@ public class NetworkStats implements Parcelable {
             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.
      */
@@ -831,6 +838,39 @@ public class NetworkStats implements Parcelable {
         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);