Foreground/background network stats using sets.

Teach NetworkStats about "counter sets" coming from kernel, and use
them to track usage in foreground/background.  Add AID_NET_BW_ACCT to
system_server so it can control counter sets.

Move to composite key of NetworkIdentitySet, UID, set, and tag when
recording historical usage.  Persisting still clusters by identity,
since that is heaviest object.

Request async stats poll during systemReady() to bootstrap later
delta calculations. Reset kernel counters when UID removed. Update
various tests.

Bug: 5105592, 5146067
Change-Id: Idabec9e3ffcaf212879821515602ecde0a03de8c

1 files changed, 206 insertions, 142 deletions

diff --git a/services/java/com/android/server/net/NetworkStatsService.java b/services/java/com/android/server/net/NetworkStatsService.java
index deca7a9..c911687 100644
--- a/services/java/com/android/server/net/NetworkStatsService.java
+++ b/services/java/com/android/server/net/NetworkStatsService.java
@@ -26,6 +26,9 @@ import static android.content.Intent.ACTION_UID_REMOVED;
 import static android.content.Intent.EXTRA_UID;
 import static android.net.ConnectivityManager.CONNECTIVITY_ACTION;
 import static android.net.NetworkStats.IFACE_ALL;
+import static android.net.NetworkStats.SET_ALL;
+import static android.net.NetworkStats.SET_DEFAULT;
+import static android.net.NetworkStats.SET_FOREGROUND;
 import static android.net.NetworkStats.TAG_NONE;
 import static android.net.NetworkStats.UID_ALL;
 import static android.net.TrafficStats.UID_REMOVED;
@@ -40,6 +43,8 @@ import static android.text.format.DateUtils.DAY_IN_MILLIS;
 import static android.text.format.DateUtils.HOUR_IN_MILLIS;
 import static android.text.format.DateUtils.MINUTE_IN_MILLIS;
 import static com.android.internal.util.Preconditions.checkNotNull;
+import static com.android.server.NetworkManagementSocketTagger.resetKernelUidStats;
+import static com.android.server.NetworkManagementSocketTagger.setKernelCounterSet;
 
 import android.app.AlarmManager;
 import android.app.IAlarmManager;
@@ -63,17 +68,20 @@ import android.os.Environment;
 import android.os.Handler;
 import android.os.HandlerThread;
 import android.os.INetworkManagementService;
+import android.os.Message;
 import android.os.PowerManager;
 import android.os.RemoteException;
 import android.os.SystemClock;
 import android.provider.Settings;
 import android.telephony.TelephonyManager;
-import android.util.LongSparseArray;
 import android.util.NtpTrustedTime;
 import android.util.Slog;
+import android.util.SparseIntArray;
 import android.util.TrustedTime;
 
 import com.android.internal.os.AtomicFile;
+import com.android.internal.util.Objects;
+import com.google.android.collect.Lists;
 import com.google.android.collect.Maps;
 import com.google.android.collect.Sets;
 
@@ -88,6 +96,8 @@ import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.PrintWriter;
 import java.net.ProtocolException;
+import java.util.ArrayList;
+import java.util.Collections;
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.List;
@@ -109,6 +119,9 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
     private static final int VERSION_UID_INIT = 1;
     private static final int VERSION_UID_WITH_IDENT = 2;
     private static final int VERSION_UID_WITH_TAG = 3;
+    private static final int VERSION_UID_WITH_SET = 4;
+
+    private static final int MSG_FORCE_UPDATE = 0x1;
 
     private final Context mContext;
     private final INetworkManagementService mNetworkManager;
@@ -156,8 +169,7 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
     /** Set of historical network layer stats for known networks. */
     private HashMap<NetworkIdentitySet, NetworkStatsHistory> mNetworkStats = Maps.newHashMap();
     /** Set of historical network layer stats for known UIDs. */
-    private HashMap<NetworkIdentitySet, LongSparseArray<NetworkStatsHistory>> mUidStats =
-            Maps.newHashMap();
+    private HashMap<UidStatsKey, NetworkStatsHistory> mUidStats = Maps.newHashMap();
 
     /** Flag if {@link #mUidStats} have been loaded from disk. */
     private boolean mUidStatsLoaded = false;
@@ -167,6 +179,9 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
 
     private NetworkStats mLastUidSnapshot;
 
+    /** Current counter sets for each UID. */
+    private SparseIntArray mActiveUidCounterSet = new SparseIntArray();
+
     /** Data layer operation counters for splicing into other structures. */
     private NetworkStats mOperations = new NetworkStats(0L, 10);
     private NetworkStats mLastOperationsSnapshot;
@@ -177,11 +192,6 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
     private final AtomicFile mNetworkFile;
     private final AtomicFile mUidFile;
 
-    // TODO: collect detailed uid stats, storing tag-granularity data until next
-    // dropbox, and uid summary for a specific bucket count.
-
-    // TODO: periodically compile statistics and send to dropbox.
-
     public NetworkStatsService(
             Context context, INetworkManagementService networkManager, IAlarmManager alarmManager) {
         this(context, networkManager, alarmManager, NtpTrustedTime.getInstance(context),
@@ -207,7 +217,7 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
 
         mHandlerThread = new HandlerThread(TAG);
         mHandlerThread.start();
-        mHandler = new Handler(mHandlerThread.getLooper());
+        mHandler = new Handler(mHandlerThread.getLooper(), mHandlerCallback);
 
         mNetworkFile = new AtomicFile(new File(systemDir, "netstats.bin"));
         mUidFile = new AtomicFile(new File(systemDir, "netstats_uid.bin"));
@@ -246,6 +256,9 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
         } catch (RemoteException e) {
             Slog.w(TAG, "unable to register poll alarm");
         }
+
+        // kick off background poll to bootstrap deltas
+        mHandler.obtainMessage(MSG_FORCE_UPDATE).sendToTarget();
     }
 
     private void shutdownLocked() {
@@ -302,24 +315,24 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
 
     @Override
     public NetworkStatsHistory getHistoryForUid(
-            NetworkTemplate template, int uid, int tag, int fields) {
+            NetworkTemplate template, int uid, int set, int tag, int fields) {
         mContext.enforceCallingOrSelfPermission(READ_NETWORK_USAGE_HISTORY, TAG);
 
         synchronized (mStatsLock) {
             ensureUidStatsLoadedLocked();
-            final long packed = packUidAndTag(uid, tag);
 
             // combine all interfaces that match template
             final NetworkStatsHistory combined = new NetworkStatsHistory(
                     mSettings.getUidBucketDuration(), estimateUidBuckets(), fields);
-            for (NetworkIdentitySet ident : mUidStats.keySet()) {
-                if (templateMatches(template, ident)) {
-                    final NetworkStatsHistory history = mUidStats.get(ident).get(packed);
-                    if (history != null) {
-                        combined.recordEntireHistory(history);
-                    }
+            for (UidStatsKey key : mUidStats.keySet()) {
+                final boolean setMatches = set == SET_ALL || key.set == set;
+                if (templateMatches(template, key.ident) && key.uid == uid && setMatches
+                        && key.tag == tag) {
+                    final NetworkStatsHistory history = mUidStats.get(key);
+                    combined.recordEntireHistory(history);
                 }
             }
+
             return combined;
         }
     }
@@ -371,33 +384,27 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
             final NetworkStats.Entry entry = new NetworkStats.Entry();
             NetworkStatsHistory.Entry historyEntry = null;
 
-            for (NetworkIdentitySet ident : mUidStats.keySet()) {
-                if (templateMatches(template, ident)) {
-                    final LongSparseArray<NetworkStatsHistory> uidStats = mUidStats.get(ident);
-                    for (int i = 0; i < uidStats.size(); i++) {
-                        final long packed = uidStats.keyAt(i);
-                        final int uid = unpackUid(packed);
-                        final int tag = unpackTag(packed);
-
-                        // always include summary under TAG_NONE, and include
-                        // other tags when requested.
-                        if (tag == TAG_NONE || includeTags) {
-                            final NetworkStatsHistory history = uidStats.valueAt(i);
-                            historyEntry = history.getValues(start, end, now, historyEntry);
-
-                            entry.iface = IFACE_ALL;
-                            entry.uid = uid;
-                            entry.tag = tag;
-                            entry.rxBytes = historyEntry.rxBytes;
-                            entry.rxPackets = historyEntry.rxPackets;
-                            entry.txBytes = historyEntry.txBytes;
-                            entry.txPackets = historyEntry.txPackets;
-                            entry.operations = historyEntry.operations;
-
-                            if (entry.rxBytes > 0 || entry.rxPackets > 0 || entry.txBytes > 0
-                                    || entry.txPackets > 0 || entry.operations > 0) {
-                                stats.combineValues(entry);
-                            }
+            for (UidStatsKey key : mUidStats.keySet()) {
+                if (templateMatches(template, key.ident)) {
+                    // always include summary under TAG_NONE, and include
+                    // other tags when requested.
+                    if (key.tag == TAG_NONE || includeTags) {
+                        final NetworkStatsHistory history = mUidStats.get(key);
+                        historyEntry = history.getValues(start, end, now, historyEntry);
+
+                        entry.iface = IFACE_ALL;
+                        entry.uid = key.uid;
+                        entry.set = key.set;
+                        entry.tag = key.tag;
+                        entry.rxBytes = historyEntry.rxBytes;
+                        entry.rxPackets = historyEntry.rxPackets;
+                        entry.txBytes = historyEntry.txBytes;
+                        entry.txPackets = historyEntry.txPackets;
+                        entry.operations = historyEntry.operations;
+
+                        if (entry.rxBytes > 0 || entry.rxPackets > 0 || entry.txBytes > 0
+                                || entry.txPackets > 0 || entry.operations > 0) {
+                            stats.combineValues(entry);
                         }
                     }
                 }
@@ -437,8 +444,31 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
             mContext.enforceCallingOrSelfPermission(MODIFY_NETWORK_ACCOUNTING, TAG);
         }
 
+        if (operationCount < 0) {
+            throw new IllegalArgumentException("operation count can only be incremented");
+        }
+        if (tag == TAG_NONE) {
+            throw new IllegalArgumentException("operation count must have specific tag");
+        }
+
         synchronized (mStatsLock) {
-            mOperations.combineValues(IFACE_ALL, uid, tag, 0L, 0L, 0L, 0L, operationCount);
+            final int set = mActiveUidCounterSet.get(uid, SET_DEFAULT);
+            mOperations.combineValues(IFACE_ALL, uid, set, tag, 0L, 0L, 0L, 0L, operationCount);
+            mOperations.combineValues(IFACE_ALL, uid, set, TAG_NONE, 0L, 0L, 0L, 0L, operationCount);
+        }
+    }
+
+    @Override
+    public void setUidForeground(int uid, boolean uidForeground) {
+        mContext.enforceCallingOrSelfPermission(MODIFY_NETWORK_ACCOUNTING, TAG);
+
+        synchronized (mStatsLock) {
+            final int set = uidForeground ? SET_FOREGROUND : SET_DEFAULT;
+            final int oldSet = mActiveUidCounterSet.get(uid, SET_DEFAULT);
+            if (oldSet != set) {
+                mActiveUidCounterSet.put(uid, set);
+                setKernelCounterSet(uid, set);
+            }
         }
     }
 
@@ -601,7 +631,7 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
 
         NetworkStats.Entry entry = null;
         for (String iface : persistDelta.getUniqueIfaces()) {
-            final int index = persistDelta.findIndex(iface, UID_ALL, TAG_NONE);
+            final int index = persistDelta.findIndex(iface, UID_ALL, SET_DEFAULT, TAG_NONE);
             entry = persistDelta.getValues(index, entry);
             if (forcePersist || entry.rxBytes > persistThreshold
                     || entry.txBytes > persistThreshold) {
@@ -676,31 +706,28 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
             }
 
             // splice in operation counts since last poll
-            final int j = operationsDelta.findIndex(IFACE_ALL, entry.uid, entry.tag);
+            final int j = operationsDelta.findIndex(IFACE_ALL, entry.uid, entry.set, entry.tag);
             if (j != -1) {
                 operationsEntry = operationsDelta.getValues(j, operationsEntry);
                 entry.operations = operationsEntry.operations;
             }
 
             final NetworkStatsHistory history = findOrCreateUidStatsLocked(
-                    ident, entry.uid, entry.tag);
+                    ident, entry.uid, entry.set, entry.tag);
             history.recordData(timeStart, currentTime, entry);
         }
 
         // trim any history beyond max
         final long maxUidHistory = mSettings.getUidMaxHistory();
         final long maxTagHistory = mSettings.getTagMaxHistory();
-        for (LongSparseArray<NetworkStatsHistory> uidStats : mUidStats.values()) {
-            for (int i = 0; i < uidStats.size(); i++) {
-                final long packed = uidStats.keyAt(i);
-                final NetworkStatsHistory history = uidStats.valueAt(i);
-
-                // detailed tags are trimmed sooner than summary in TAG_NONE
-                if (unpackTag(packed) == TAG_NONE) {
-                    history.removeBucketsBefore(currentTime - maxUidHistory);
-                } else {
-                    history.removeBucketsBefore(currentTime - maxTagHistory);
-                }
+        for (UidStatsKey key : mUidStats.keySet()) {
+            final NetworkStatsHistory history = mUidStats.get(key);
+
+            // detailed tags are trimmed sooner than summary in TAG_NONE
+            if (key.tag == TAG_NONE) {
+                history.removeBucketsBefore(currentTime - maxUidHistory);
+            } else {
+                history.removeBucketsBefore(currentTime - maxTagHistory);
             }
         }
 
@@ -715,26 +742,25 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
     private void removeUidLocked(int uid) {
         ensureUidStatsLoadedLocked();
 
+        final ArrayList<UidStatsKey> knownKeys = Lists.newArrayList();
+        knownKeys.addAll(mUidStats.keySet());
+
         // migrate all UID stats into special "removed" bucket
-        for (NetworkIdentitySet ident : mUidStats.keySet()) {
-            final LongSparseArray<NetworkStatsHistory> uidStats = mUidStats.get(ident);
-            for (int i = 0; i < uidStats.size(); i++) {
-                final long packed = uidStats.keyAt(i);
-                if (unpackUid(packed) == uid) {
-                    // only migrate combined TAG_NONE history
-                    if (unpackTag(packed) == TAG_NONE) {
-                        final NetworkStatsHistory uidHistory = uidStats.valueAt(i);
-                        final NetworkStatsHistory removedHistory = findOrCreateUidStatsLocked(
-                                ident, UID_REMOVED, TAG_NONE);
-                        removedHistory.recordEntireHistory(uidHistory);
-                    }
-                    uidStats.remove(packed);
+        for (UidStatsKey key : knownKeys) {
+            if (key.uid == uid) {
+                // only migrate combined TAG_NONE history
+                if (key.tag == TAG_NONE) {
+                    final NetworkStatsHistory uidHistory = mUidStats.get(key);
+                    final NetworkStatsHistory removedHistory = findOrCreateUidStatsLocked(
+                            key.ident, UID_REMOVED, SET_DEFAULT, TAG_NONE);
+                    removedHistory.recordEntireHistory(uidHistory);
                 }
+                mUidStats.remove(key);
             }
         }
 
-        // TODO: push kernel event to wipe stats for UID, otherwise we risk
-        // picking them up again during next poll.
+        // clear kernel stats associated with UID
+        resetKernelUidStats(uid);
 
         // since this was radical rewrite, push to disk
         writeUidStatsLocked();
@@ -763,17 +789,11 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
     }
 
     private NetworkStatsHistory findOrCreateUidStatsLocked(
-            NetworkIdentitySet ident, int uid, int tag) {
+            NetworkIdentitySet ident, int uid, int set, int tag) {
         ensureUidStatsLoadedLocked();
 
-        LongSparseArray<NetworkStatsHistory> uidStats = mUidStats.get(ident);
-        if (uidStats == null) {
-            uidStats = new LongSparseArray<NetworkStatsHistory>();
-            mUidStats.put(ident, uidStats);
-        }
-
-        final long packed = packUidAndTag(uid, tag);
-        final NetworkStatsHistory existing = uidStats.get(packed);
+        final UidStatsKey key = new UidStatsKey(ident, uid, set, tag);
+        final NetworkStatsHistory existing = mUidStats.get(key);
 
         // update when no existing, or when bucket duration changed
         final long bucketDuration = mSettings.getUidBucketDuration();
@@ -787,7 +807,7 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
         }
 
         if (updated != null) {
-            uidStats.put(packed, updated);
+            mUidStats.put(key, updated);
             return updated;
         } else {
             return existing;
@@ -874,25 +894,24 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
                     // for a short time.
                     break;
                 }
-                case VERSION_UID_WITH_TAG: {
-                    // uid := size *(NetworkIdentitySet size *(UID tag NetworkStatsHistory))
-                    final int ifaceSize = in.readInt();
-                    for (int i = 0; i < ifaceSize; i++) {
+                case VERSION_UID_WITH_TAG:
+                case VERSION_UID_WITH_SET: {
+                    // uid := size *(NetworkIdentitySet size *(uid set tag NetworkStatsHistory))
+                    final int identSize = in.readInt();
+                    for (int i = 0; i < identSize; i++) {
                         final NetworkIdentitySet ident = new NetworkIdentitySet(in);
 
-                        final int childSize = in.readInt();
-                        final LongSparseArray<NetworkStatsHistory> uidStats = new LongSparseArray<
-                                NetworkStatsHistory>(childSize);
-                        for (int j = 0; j < childSize; j++) {
+                        final int size = in.readInt();
+                        for (int j = 0; j < size; j++) {
                             final int uid = in.readInt();
+                            final int set = (version >= VERSION_UID_WITH_SET) ? in.readInt()
+                                    : SET_DEFAULT;
                             final int tag = in.readInt();
-                            final long packed = packUidAndTag(uid, tag);
 
+                            final UidStatsKey key = new UidStatsKey(ident, uid, set, tag);
                             final NetworkStatsHistory history = new NetworkStatsHistory(in);
-                            uidStats.put(packed, history);
+                            mUidStats.put(key, history);
                         }
-
-                        mUidStats.put(ident, uidStats);
                     }
                     break;
                 }
@@ -949,29 +968,36 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
 
         // TODO: consider duplicating stats and releasing lock while writing
 
+        // build UidStatsKey lists grouped by ident
+        final HashMap<NetworkIdentitySet, ArrayList<UidStatsKey>> keysByIdent = Maps.newHashMap();
+        for (UidStatsKey key : mUidStats.keySet()) {
+            ArrayList<UidStatsKey> keys = keysByIdent.get(key.ident);
+            if (keys == null) {
+                keys = Lists.newArrayList();
+                keysByIdent.put(key.ident, keys);
+            }
+            keys.add(key);
+        }
+
         FileOutputStream fos = null;
         try {
             fos = mUidFile.startWrite();
             final DataOutputStream out = new DataOutputStream(new BufferedOutputStream(fos));
 
             out.writeInt(FILE_MAGIC);
-            out.writeInt(VERSION_UID_WITH_TAG);
+            out.writeInt(VERSION_UID_WITH_SET);
 
-            final int size = mUidStats.size();
-            out.writeInt(size);
-            for (NetworkIdentitySet ident : mUidStats.keySet()) {
-                final LongSparseArray<NetworkStatsHistory> uidStats = mUidStats.get(ident);
+            out.writeInt(keysByIdent.size());
+            for (NetworkIdentitySet ident : keysByIdent.keySet()) {
+                final ArrayList<UidStatsKey> keys = keysByIdent.get(ident);
                 ident.writeToStream(out);
 
-                final int childSize = uidStats.size();
-                out.writeInt(childSize);
-                for (int i = 0; i < childSize; i++) {
-                    final long packed = uidStats.keyAt(i);
-                    final int uid = unpackUid(packed);
-                    final int tag = unpackTag(packed);
-                    final NetworkStatsHistory history = uidStats.valueAt(i);
-                    out.writeInt(uid);
-                    out.writeInt(tag);
+                out.writeInt(keys.size());
+                for (UidStatsKey key : keys) {
+                    final NetworkStatsHistory history = mUidStats.get(key);
+                    out.writeInt(key.uid);
+                    out.writeInt(key.set);
+                    out.writeInt(key.tag);
                     history.writeToStream(out);
                 }
             }
@@ -1030,20 +1056,19 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
                 // from disk if not already in memory.
                 ensureUidStatsLoadedLocked();
 
+                final ArrayList<UidStatsKey> keys = Lists.newArrayList();
+                keys.addAll(mUidStats.keySet());
+                Collections.sort(keys);
+
                 pw.println("Detailed UID stats:");
-                for (NetworkIdentitySet ident : mUidStats.keySet()) {
-                    pw.print("  ident="); pw.println(ident.toString());
-
-                    final LongSparseArray<NetworkStatsHistory> uidStats = mUidStats.get(ident);
-                    for (int i = 0; i < uidStats.size(); i++) {
-                        final long packed = uidStats.keyAt(i);
-                        final int uid = unpackUid(packed);
-                        final int tag = unpackTag(packed);
-                        final NetworkStatsHistory history = uidStats.valueAt(i);
-                        pw.print("    UID="); pw.print(uid);
-                        pw.print(" tag=0x"); pw.println(Integer.toHexString(tag));
-                        history.dump("    ", pw, fullHistory);
-                    }
+                for (UidStatsKey key : keys) {
+                    pw.print("  ident="); pw.print(key.ident.toString());
+                    pw.print(" uid="); pw.print(key.uid);
+                    pw.print(" set="); pw.print(NetworkStats.setToString(key.set));
+                    pw.print(" tag="); pw.println(NetworkStats.tagToString(key.tag));
+
+                    final NetworkStatsHistory history = mUidStats.get(key);
+                    history.dump("    ", pw, fullHistory);
                 }
             }
         }
@@ -1080,8 +1105,12 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
 
             for (ApplicationInfo info : installedApps) {
                 final int uid = info.uid;
-                findOrCreateUidStatsLocked(ident, uid, TAG_NONE).generateRandom(UID_START, UID_END,
-                        UID_RX_BYTES, UID_RX_PACKETS, UID_TX_BYTES, UID_TX_PACKETS, UID_OPERATIONS);
+                findOrCreateUidStatsLocked(ident, uid, SET_DEFAULT, TAG_NONE).generateRandom(
+                        UID_START, UID_END, UID_RX_BYTES, UID_RX_PACKETS, UID_TX_BYTES,
+                        UID_TX_PACKETS, UID_OPERATIONS);
+                findOrCreateUidStatsLocked(ident, uid, SET_FOREGROUND, TAG_NONE).generateRandom(
+                        UID_START, UID_END, UID_RX_BYTES, UID_RX_PACKETS, UID_TX_BYTES,
+                        UID_TX_PACKETS, UID_OPERATIONS);
             }
         }
     }
@@ -1116,23 +1145,6 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
         return (int) (existing.size() * existing.getBucketDuration() / newBucketDuration);
     }
 
-    // @VisibleForTesting
-    public static long packUidAndTag(int uid, int tag) {
-        final long uidLong = uid;
-        final long tagLong = tag;
-        return (uidLong << 32) | (tagLong & 0xFFFFFFFFL);
-    }
-
-    // @VisibleForTesting
-    public static int unpackUid(long packed) {
-        return (int) (packed >> 32);
-    }
-
-    // @VisibleForTesting
-    public static int unpackTag(long packed) {
-        return (int) (packed & 0xFFFFFFFFL);
-    }
-
     /**
      * Test if given {@link NetworkTemplate} matches any {@link NetworkIdentity}
      * in the given {@link NetworkIdentitySet}.
@@ -1146,6 +1158,58 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
         return false;
     }
 
+    private Handler.Callback mHandlerCallback = new Handler.Callback() {
+        /** {@inheritDoc} */
+        public boolean handleMessage(Message msg) {
+            switch (msg.what) {
+                case MSG_FORCE_UPDATE: {
+                    forceUpdate();
+                    return true;
+                }
+                default: {
+                    return false;
+                }
+            }
+        }
+    };
+
+    /**
+     * Key uniquely identifying a {@link NetworkStatsHistory} for a UID.
+     */
+    private static class UidStatsKey implements Comparable<UidStatsKey> {
+        public final NetworkIdentitySet ident;
+        public final int uid;
+        public final int set;
+        public final int tag;
+
+        public UidStatsKey(NetworkIdentitySet ident, int uid, int set, int tag) {
+            this.ident = ident;
+            this.uid = uid;
+            this.set = set;
+            this.tag = tag;
+        }
+
+        @Override
+        public int hashCode() {
+            return Objects.hashCode(ident, uid, set, tag);
+        }
+
+        @Override
+        public boolean equals(Object obj) {
+            if (obj instanceof UidStatsKey) {
+                final UidStatsKey key = (UidStatsKey) obj;
+                return Objects.equal(ident, key.ident) && uid == key.uid && set == key.set
+                        && tag == key.tag;
+            }
+            return false;
+        }
+
+        /** {@inheritDoc} */
+        public int compareTo(UidStatsKey another) {
+            return Integer.compare(uid, another.uid);
+        }
+    }
+
     /**
      * Default external settings that read from {@link Settings.Secure}.
      */