diff --git a/framework-t/Sources.bp b/framework-t/Sources.bp
index d3d8bba..223bdcd 100644
--- a/framework-t/Sources.bp
+++ b/framework-t/Sources.bp
@@ -129,6 +129,11 @@
         "src/android/net/EthernetNetworkSpecifier.java",
         "src/android/net/IEthernetManager.aidl",
         "src/android/net/IEthernetServiceListener.aidl",
+        "src/android/net/IInternalNetworkManagementListener.aidl",
+        "src/android/net/InternalNetworkUpdateRequest.java",
+        "src/android/net/InternalNetworkUpdateRequest.aidl",
+        "src/android/net/InternalNetworkManagementException.java",
+        "src/android/net/InternalNetworkManagementException.aidl",
         "src/android/net/ITetheredInterfaceCallback.aidl",
     ],
     path: "src",
diff --git a/framework-t/src/android/app/usage/NetworkStatsManager.java b/framework-t/src/android/app/usage/NetworkStatsManager.java
index 683678a..28f930f 100644
--- a/framework-t/src/android/app/usage/NetworkStatsManager.java
+++ b/framework-t/src/android/app/usage/NetworkStatsManager.java
@@ -21,6 +21,7 @@
 import static android.net.NetworkCapabilities.TRANSPORT_WIFI;
 
 import android.Manifest;
+import android.annotation.CallbackExecutor;
 import android.annotation.NonNull;
 import android.annotation.Nullable;
 import android.annotation.RequiresPermission;
@@ -39,14 +40,11 @@
 import android.net.NetworkStateSnapshot;
 import android.net.NetworkTemplate;
 import android.net.UnderlyingNetworkInfo;
+import android.net.netstats.IUsageCallback;
 import android.net.netstats.provider.INetworkStatsProviderCallback;
 import android.net.netstats.provider.NetworkStatsProvider;
-import android.os.Binder;
 import android.os.Build;
 import android.os.Handler;
-import android.os.Looper;
-import android.os.Message;
-import android.os.Messenger;
 import android.os.RemoteException;
 import android.telephony.TelephonyManager;
 import android.text.TextUtils;
@@ -57,6 +55,7 @@
 
 import java.util.List;
 import java.util.Objects;
+import java.util.concurrent.Executor;
 
 /**
  * Provides access to network usage history and statistics. Usage data is collected in
@@ -157,6 +156,11 @@
         setAugmentWithSubscriptionPlan(true);
     }
 
+    /** @hide */
+    public INetworkStatsService getBinder() {
+        return mService;
+    }
+
     /**
      * Set poll on open flag to indicate the poll is needed before service gets statistics
      * result. This is default enabled. However, for any non-privileged caller, the poll might
@@ -718,26 +722,36 @@
         }
     }
 
-    /** @hide */
-    public void registerUsageCallback(NetworkTemplate template, int networkType,
-            long thresholdBytes, UsageCallback callback, @Nullable Handler handler) {
+    /**
+     * Registers to receive notifications about data usage on specified networks.
+     *
+     * <p>The callbacks will continue to be called as long as the process is alive or
+     * {@link #unregisterUsageCallback} is called.
+     *
+     * @param template Template used to match networks. See {@link NetworkTemplate}.
+     * @param thresholdBytes Threshold in bytes to be notified on. The provided value that lower
+     *                       than 2MiB will be clamped for non-privileged callers.
+     * @param executor The executor on which callback will be invoked. The provided {@link Executor}
+     *                 must run callback sequentially, otherwise the order of callbacks cannot be
+     *                 guaranteed.
+     * @param callback The {@link UsageCallback} that the system will call when data usage
+     *                 has exceeded the specified threshold.
+     * @hide
+     */
+    @SystemApi(client = MODULE_LIBRARIES)
+    public void registerUsageCallback(@NonNull NetworkTemplate template, long thresholdBytes,
+            @NonNull @CallbackExecutor Executor executor, @NonNull UsageCallback callback) {
+        Objects.requireNonNull(template, "NetworkTemplate cannot be null");
         Objects.requireNonNull(callback, "UsageCallback cannot be null");
+        Objects.requireNonNull(executor, "Executor cannot be null");
 
-        final Looper looper;
-        if (handler == null) {
-            looper = Looper.myLooper();
-        } else {
-            looper = handler.getLooper();
-        }
-
-        DataUsageRequest request = new DataUsageRequest(DataUsageRequest.REQUEST_ID_UNSET,
+        final DataUsageRequest request = new DataUsageRequest(DataUsageRequest.REQUEST_ID_UNSET,
                 template, thresholdBytes);
         try {
-            CallbackHandler callbackHandler = new CallbackHandler(looper, networkType,
-                    template.getSubscriberId(), callback);
+            final UsageCallbackWrapper callbackWrapper =
+                    new UsageCallbackWrapper(executor, callback);
             callback.request = mService.registerUsageCallback(
-                    mContext.getOpPackageName(), request, new Messenger(callbackHandler),
-                    new Binder());
+                    mContext.getOpPackageName(), request, callbackWrapper);
             if (DBG) Log.d(TAG, "registerUsageCallback returned " + callback.request);
 
             if (callback.request == null) {
@@ -790,12 +804,15 @@
         NetworkTemplate template = createTemplate(networkType, subscriberId);
         if (DBG) {
             Log.d(TAG, "registerUsageCallback called with: {"
-                + " networkType=" + networkType
-                + " subscriberId=" + subscriberId
-                + " thresholdBytes=" + thresholdBytes
-                + " }");
+                    + " networkType=" + networkType
+                    + " subscriberId=" + subscriberId
+                    + " thresholdBytes=" + thresholdBytes
+                    + " }");
         }
-        registerUsageCallback(template, networkType, thresholdBytes, callback, handler);
+
+        final Executor executor = handler == null ? r -> r.run() : r -> handler.post(r);
+
+        registerUsageCallback(template, thresholdBytes, executor, callback);
     }
 
     /**
@@ -820,6 +837,26 @@
      * Base class for usage callbacks. Should be extended by applications wanting notifications.
      */
     public static abstract class UsageCallback {
+        /**
+         * Called when data usage has reached the given threshold.
+         *
+         * Called by {@code NetworkStatsService} when the registered threshold is reached.
+         * If a caller implements {@link #onThresholdReached(NetworkTemplate)}, the system
+         * will not call {@link #onThresholdReached(int, String)}.
+         *
+         * @param template The {@link NetworkTemplate} that associated with this callback.
+         * @hide
+         */
+        @SystemApi(client = MODULE_LIBRARIES)
+        public void onThresholdReached(@NonNull NetworkTemplate template) {
+            // Backward compatibility for those who didn't override this function.
+            final int networkType = networkTypeForTemplate(template);
+            if (networkType != ConnectivityManager.TYPE_NONE) {
+                final String subscriberId = template.getSubscriberIds().isEmpty() ? null
+                        : template.getSubscriberIds().iterator().next();
+                onThresholdReached(networkType, subscriberId);
+            }
+        }
 
         /**
          * Called when data usage has reached the given threshold.
@@ -830,6 +867,25 @@
          * @hide used for internal bookkeeping
          */
         private DataUsageRequest request;
+
+        /**
+         * Get network type from a template if feasible.
+         *
+         * @param template the target {@link NetworkTemplate}.
+         * @return legacy network type, only supports for the types which is already supported in
+         *         {@link #registerUsageCallback(int, String, long, UsageCallback, Handler)}.
+         *         {@link ConnectivityManager#TYPE_NONE} for other types.
+         */
+        private static int networkTypeForTemplate(@NonNull NetworkTemplate template) {
+            switch (template.getMatchRule()) {
+                case NetworkTemplate.MATCH_MOBILE:
+                    return ConnectivityManager.TYPE_MOBILE;
+                case NetworkTemplate.MATCH_WIFI:
+                    return ConnectivityManager.TYPE_WIFI;
+                default:
+                    return ConnectivityManager.TYPE_NONE;
+            }
+        }
     }
 
     /**
@@ -948,43 +1004,32 @@
         }
     }
 
-    private static class CallbackHandler extends Handler {
-        private final int mNetworkType;
-        private final String mSubscriberId;
-        private UsageCallback mCallback;
+    private static class UsageCallbackWrapper extends IUsageCallback.Stub {
+        // Null if unregistered.
+        private volatile UsageCallback mCallback;
 
-        CallbackHandler(Looper looper, int networkType, String subscriberId,
-                UsageCallback callback) {
-            super(looper);
-            mNetworkType = networkType;
-            mSubscriberId = subscriberId;
+        private final Executor mExecutor;
+
+        UsageCallbackWrapper(@NonNull Executor executor, @NonNull UsageCallback callback) {
             mCallback = callback;
+            mExecutor = executor;
         }
 
         @Override
-        public void handleMessage(Message message) {
-            DataUsageRequest request =
-                    (DataUsageRequest) getObject(message, DataUsageRequest.PARCELABLE_KEY);
-
-            switch (message.what) {
-                case CALLBACK_LIMIT_REACHED: {
-                    if (mCallback != null) {
-                        mCallback.onThresholdReached(mNetworkType, mSubscriberId);
-                    } else {
-                        Log.e(TAG, "limit reached with released callback for " + request);
-                    }
-                    break;
-                }
-                case CALLBACK_RELEASED: {
-                    if (DBG) Log.d(TAG, "callback released for " + request);
-                    mCallback = null;
-                    break;
-                }
+        public void onThresholdReached(DataUsageRequest request) {
+            // Copy it to a local variable in case mCallback changed inside the if condition.
+            final UsageCallback callback = mCallback;
+            if (callback != null) {
+                mExecutor.execute(() -> callback.onThresholdReached(request.template));
+            } else {
+                Log.e(TAG, "onThresholdReached with released callback for " + request);
             }
         }
 
-        private static Object getObject(Message msg, String key) {
-            return msg.getData().getParcelable(key);
+        @Override
+        public void onCallbackReleased(DataUsageRequest request) {
+            if (DBG) Log.d(TAG, "callback released for " + request);
+            mCallback = null;
         }
     }
 
diff --git a/framework-t/src/android/net/INetworkStatsService.aidl b/framework-t/src/android/net/INetworkStatsService.aidl
index da0aa99..efe626d 100644
--- a/framework-t/src/android/net/INetworkStatsService.aidl
+++ b/framework-t/src/android/net/INetworkStatsService.aidl
@@ -24,6 +24,7 @@
 import android.net.NetworkStatsHistory;
 import android.net.NetworkTemplate;
 import android.net.UnderlyingNetworkInfo;
+import android.net.netstats.IUsageCallback;
 import android.net.netstats.provider.INetworkStatsProvider;
 import android.net.netstats.provider.INetworkStatsProviderCallback;
 import android.os.IBinder;
@@ -71,7 +72,7 @@
 
     /** Registers a callback on data usage. */
     DataUsageRequest registerUsageCallback(String callingPackage,
-            in DataUsageRequest request, in Messenger messenger, in IBinder binder);
+            in DataUsageRequest request, in IUsageCallback callback);
 
     /** Unregisters a callback on data usage. */
     void unregisterUsageRequest(in DataUsageRequest request);
diff --git a/core/java/android/net/InternalNetworkManagementException.aidl b/framework-t/src/android/net/InternalNetworkManagementException.aidl
similarity index 100%
rename from core/java/android/net/InternalNetworkManagementException.aidl
rename to framework-t/src/android/net/InternalNetworkManagementException.aidl
diff --git a/core/java/android/net/InternalNetworkManagementException.java b/framework-t/src/android/net/InternalNetworkManagementException.java
similarity index 100%
rename from core/java/android/net/InternalNetworkManagementException.java
rename to framework-t/src/android/net/InternalNetworkManagementException.java
diff --git a/core/java/android/net/InternalNetworkUpdateRequest.aidl b/framework-t/src/android/net/InternalNetworkUpdateRequest.aidl
similarity index 100%
rename from core/java/android/net/InternalNetworkUpdateRequest.aidl
rename to framework-t/src/android/net/InternalNetworkUpdateRequest.aidl
diff --git a/core/java/android/net/InternalNetworkUpdateRequest.java b/framework-t/src/android/net/InternalNetworkUpdateRequest.java
similarity index 100%
rename from core/java/android/net/InternalNetworkUpdateRequest.java
rename to framework-t/src/android/net/InternalNetworkUpdateRequest.java
diff --git a/framework-t/src/android/net/NetworkIdentity.java b/framework-t/src/android/net/NetworkIdentity.java
index 9b9d38a..77fc171 100644
--- a/framework-t/src/android/net/NetworkIdentity.java
+++ b/framework-t/src/android/net/NetworkIdentity.java
@@ -16,6 +16,8 @@
 
 package android.net;
 
+import static android.annotation.SystemApi.Client.MODULE_LIBRARIES;
+import static android.net.ConnectivityManager.TYPE_MOBILE;
 import static android.net.ConnectivityManager.TYPE_WIFI;
 import static android.net.NetworkTemplate.NETWORK_TYPE_ALL;
 
@@ -23,6 +25,7 @@
 import android.annotation.NonNull;
 import android.annotation.Nullable;
 import android.annotation.SuppressLint;
+import android.annotation.SystemApi;
 import android.content.Context;
 import android.net.wifi.WifiInfo;
 import android.service.NetworkIdentityProto;
@@ -30,6 +33,7 @@
 import android.telephony.TelephonyManager;
 import android.util.proto.ProtoOutputStream;
 
+import com.android.net.module.util.CollectionUtils;
 import com.android.net.module.util.NetworkCapabilitiesUtils;
 import com.android.net.module.util.NetworkIdentityUtils;
 
@@ -44,8 +48,8 @@
  *
  * @hide
  */
-// @SystemApi(client = MODULE_LIBRARIES)
-public class NetworkIdentity implements Comparable<NetworkIdentity> {
+@SystemApi(client = MODULE_LIBRARIES)
+public class NetworkIdentity {
     private static final String TAG = "NetworkIdentity";
 
     /** @hide */
@@ -55,7 +59,7 @@
 
     /** @hide */
     @Retention(RetentionPolicy.SOURCE)
-    @IntDef(prefix = { "OEM_MANAGED_" }, value = {
+    @IntDef(prefix = { "OEM_MANAGED_" }, flag = true, value = {
             NetworkTemplate.OEM_MANAGED_NO,
             NetworkTemplate.OEM_MANAGED_PAID,
             NetworkTemplate.OEM_MANAGED_PRIVATE
@@ -71,12 +75,14 @@
      * Network has {@link NetworkCapabilities#NET_CAPABILITY_OEM_PAID}.
      * @hide
      */
-    public static final int OEM_PAID = 0x1;
+    public static final int OEM_PAID = 1 << 0;
     /**
      * Network has {@link NetworkCapabilities#NET_CAPABILITY_OEM_PRIVATE}.
      * @hide
      */
-    public static final int OEM_PRIVATE = 0x2;
+    public static final int OEM_PRIVATE = 1 << 1;
+
+    private static final long SUPPORTED_OEM_MANAGED_TYPES = OEM_PAID | OEM_PRIVATE;
 
     final int mType;
     final int mRatType;
@@ -206,7 +212,7 @@
         return mSubscriberId;
     }
 
-    /** Get the Wifi Network Key of this instance. See {@link WifiInfo#getCurrentNetworkKey()}. */
+    /** Get the Wifi Network Key of this instance. See {@link WifiInfo#getNetworkKey()}. */
     @Nullable
     public String getWifiNetworkKey() {
         return mWifiNetworkKey;
@@ -218,7 +224,7 @@
         return mRoaming;
     }
 
-    /** Return the roaming status of this instance. */
+    /** Return whether this network is roaming. */
     public boolean isRoaming() {
         return mRoaming;
     }
@@ -229,7 +235,7 @@
         return mMetered;
     }
 
-    /** Return the meteredness of this instance. */
+    /** Return whether this network is metered. */
     public boolean isMetered() {
         return mMetered;
     }
@@ -240,7 +246,7 @@
         return mDefaultNetwork;
     }
 
-    /** Return the default network status of this instance. */
+    /** Return whether this network is the default network. */
     public boolean isDefaultNetwork() {
         return mDefaultNetwork;
     }
@@ -262,7 +268,7 @@
      *                {@link TelephonyManager#NETWORK_TYPE_UNKNOWN} if not applicable.
      *                See {@code TelephonyManager.NETWORK_TYPE_*}.
      * @hide
-     * @deprecated See {@link NetworkIdentity#Builder}.
+     * @deprecated See {@link NetworkIdentity.Builder}.
      */
     // TODO: Remove this after all callers are migrated to use new Api.
     @Deprecated
@@ -270,8 +276,12 @@
     public static NetworkIdentity buildNetworkIdentity(Context context,
             @NonNull NetworkStateSnapshot snapshot,
             boolean defaultNetwork, @Annotation.NetworkType int ratType) {
-        return new NetworkIdentity.Builder().setNetworkStateSnapshot(snapshot)
-                .setDefaultNetwork(defaultNetwork).setRatType(ratType).build();
+        final NetworkIdentity.Builder builder = new NetworkIdentity.Builder()
+                .setNetworkStateSnapshot(snapshot).setDefaultNetwork(defaultNetwork);
+        if (snapshot.getLegacyType() == TYPE_MOBILE && ratType != NETWORK_TYPE_ALL) {
+            builder.setRatType(ratType);
+        }
+        return builder.build();
     }
 
     /**
@@ -291,30 +301,30 @@
         return oemManaged;
     }
 
-    @Override
-    public int compareTo(@NonNull NetworkIdentity another) {
-        Objects.requireNonNull(another);
-        int res = Integer.compare(mType, another.mType);
+    /** @hide */
+    public static int compare(@NonNull NetworkIdentity left, @NonNull NetworkIdentity right) {
+        Objects.requireNonNull(right);
+        int res = Integer.compare(left.mType, right.mType);
         if (res == 0) {
-            res = Integer.compare(mRatType, another.mRatType);
+            res = Integer.compare(left.mRatType, right.mRatType);
         }
-        if (res == 0 && mSubscriberId != null && another.mSubscriberId != null) {
-            res = mSubscriberId.compareTo(another.mSubscriberId);
+        if (res == 0 && left.mSubscriberId != null && right.mSubscriberId != null) {
+            res = left.mSubscriberId.compareTo(right.mSubscriberId);
         }
-        if (res == 0 && mWifiNetworkKey != null && another.mWifiNetworkKey != null) {
-            res = mWifiNetworkKey.compareTo(another.mWifiNetworkKey);
+        if (res == 0 && left.mWifiNetworkKey != null && right.mWifiNetworkKey != null) {
+            res = left.mWifiNetworkKey.compareTo(right.mWifiNetworkKey);
         }
         if (res == 0) {
-            res = Boolean.compare(mRoaming, another.mRoaming);
+            res = Boolean.compare(left.mRoaming, right.mRoaming);
         }
         if (res == 0) {
-            res = Boolean.compare(mMetered, another.mMetered);
+            res = Boolean.compare(left.mMetered, right.mMetered);
         }
         if (res == 0) {
-            res = Boolean.compare(mDefaultNetwork, another.mDefaultNetwork);
+            res = Boolean.compare(left.mDefaultNetwork, right.mDefaultNetwork);
         }
         if (res == 0) {
-            res = Integer.compare(mOemManaged, another.mOemManaged);
+            res = Integer.compare(left.mOemManaged, right.mOemManaged);
         }
         return res;
     }
@@ -323,6 +333,11 @@
      * Builder class for {@link NetworkIdentity}.
      */
     public static final class Builder {
+        // Need to be synchronized with ConnectivityManager.
+        // TODO: Use {@link ConnectivityManager#MAX_NETWORK_TYPE} when this file is in the module.
+        private static final int MAX_NETWORK_TYPE = 18; // TYPE_TEST
+        private static final int MIN_NETWORK_TYPE = TYPE_MOBILE;
+
         private int mType;
         private int mRatType;
         private String mSubscriberId;
@@ -349,7 +364,14 @@
 
         /**
          * Add an {@link NetworkStateSnapshot} into the {@link NetworkIdentity} instance.
-         * This is to read roaming, metered, wifikey... from the snapshot for convenience.
+         * This is a useful shorthand that will read from the snapshot and set the
+         * following fields, if they are set in the snapshot :
+         *  - type
+         *  - subscriberId
+         *  - roaming
+         *  - metered
+         *  - oemManaged
+         *  - wifiNetworkKey
          *
          * @param snapshot The target {@link NetworkStateSnapshot} object.
          * @return The builder object.
@@ -374,9 +396,7 @@
                         .getTransportInfo();
                 if (transportInfo instanceof WifiInfo) {
                     final WifiInfo info = (WifiInfo) transportInfo;
-                    if (info != null) {
-                        setWifiNetworkKey(info.getCurrentNetworkKey());
-                    }
+                    setWifiNetworkKey(info.getNetworkKey());
                 }
             }
             return this;
@@ -391,6 +411,12 @@
          */
         @NonNull
         public Builder setType(int type) {
+            // Include TYPE_NONE for compatibility, type field might not be filled by some
+            // networks such as test networks.
+            if ((type < MIN_NETWORK_TYPE || MAX_NETWORK_TYPE < type)
+                    && type != ConnectivityManager.TYPE_NONE) {
+                throw new IllegalArgumentException("Invalid network type: " + type);
+            }
             mType = type;
             return this;
         }
@@ -398,6 +424,8 @@
         /**
          * Set the Radio Access Technology(RAT) type of the network.
          *
+         * No RAT type is specified by default. Call clearRatType to reset.
+         *
          * @param ratType the Radio Access Technology(RAT) type if applicable. See
          *                {@code TelephonyManager.NETWORK_TYPE_*}.
          *
@@ -405,6 +433,11 @@
          */
         @NonNull
         public Builder setRatType(@Annotation.NetworkType int ratType) {
+            if (!CollectionUtils.contains(TelephonyManager.getAllNetworkTypes(), ratType)
+                    && ratType != TelephonyManager.NETWORK_TYPE_UNKNOWN
+                    && ratType != NetworkTemplate.NETWORK_TYPE_5G_NSA) {
+                throw new IllegalArgumentException("Invalid ratType " + ratType);
+            }
             mRatType = ratType;
             return this;
         }
@@ -436,7 +469,7 @@
          * Set the Wifi Network Key.
          *
          * @param wifiNetworkKey Wifi Network Key of the network,
-         *                        see {@link WifiInfo#getCurrentNetworkKey()}.
+         *                        see {@link WifiInfo#getNetworkKey()}.
          *                        Or null if not applicable.
          * @return this builder.
          */
@@ -447,7 +480,9 @@
         }
 
         /**
-         * Set the roaming.
+         * Set whether this network is roaming.
+         *
+         * This field is false by default. Call with false to reset.
          *
          * @param roaming the roaming status of the network.
          * @return this builder.
@@ -459,7 +494,9 @@
         }
 
         /**
-         * Set the meteredness.
+         * Set whether this network is metered.
+         *
+         * This field is false by default. Call with false to reset.
          *
          * @param metered the meteredness of the network.
          * @return this builder.
@@ -471,7 +508,9 @@
         }
 
         /**
-         * Set the default network status.
+         * Set whether this network is the default network.
+         *
+         * This field is false by default. Call with false to reset.
          *
          * @param defaultNetwork the default network status of the network.
          * @return this builder.
@@ -491,10 +530,27 @@
          */
         @NonNull
         public Builder setOemManaged(@OemManaged int oemManaged) {
+            // Assert input does not contain illegal oemManage bits.
+            if ((~SUPPORTED_OEM_MANAGED_TYPES & oemManaged) != 0) {
+                throw new IllegalArgumentException("Invalid value for OemManaged : " + oemManaged);
+            }
             mOemManaged = oemManaged;
             return this;
         }
 
+        private void ensureValidParameters() {
+            // Assert non-mobile network cannot have a ratType.
+            if (mType != TYPE_MOBILE && mRatType != NetworkTemplate.NETWORK_TYPE_ALL) {
+                throw new IllegalArgumentException(
+                        "Invalid ratType " + mRatType + " for type " + mType);
+            }
+
+            // Assert non-wifi network cannot have a wifi network key.
+            if (mType != TYPE_WIFI && mWifiNetworkKey != null) {
+                throw new IllegalArgumentException("Invalid wifi network key for type " + mType);
+            }
+        }
+
         /**
          * Builds the instance of the {@link NetworkIdentity}.
          *
@@ -502,6 +558,7 @@
          */
         @NonNull
         public NetworkIdentity build() {
+            ensureValidParameters();
             return new NetworkIdentity(mType, mRatType, mSubscriberId, mWifiNetworkKey,
                     mRoaming, mMetered, mDefaultNetwork, mOemManaged);
         }
diff --git a/framework-t/src/android/net/NetworkIdentitySet.java b/framework-t/src/android/net/NetworkIdentitySet.java
index 041f070..dfa347f 100644
--- a/framework-t/src/android/net/NetworkIdentitySet.java
+++ b/framework-t/src/android/net/NetworkIdentitySet.java
@@ -27,6 +27,7 @@
 import java.io.IOException;
 import java.util.HashSet;
 import java.util.Objects;
+import java.util.Set;
 
 /**
  * Identity of a {@code iface}, defined by the set of {@link NetworkIdentity}
@@ -34,9 +35,7 @@
  *
  * @hide
  */
-// @SystemApi(client = MODULE_LIBRARIES)
-public class NetworkIdentitySet extends HashSet<NetworkIdentity> implements
-        Comparable<NetworkIdentitySet> {
+public class NetworkIdentitySet extends HashSet<NetworkIdentity> {
     private static final int VERSION_INIT = 1;
     private static final int VERSION_ADD_ROAMING = 2;
     private static final int VERSION_ADD_NETWORK_ID = 3;
@@ -52,6 +51,11 @@
     }
 
     /** @hide */
+    public NetworkIdentitySet(@NonNull Set<NetworkIdentity> ident) {
+        super(ident);
+    }
+
+    /** @hide */
     public NetworkIdentitySet(DataInput in) throws IOException {
         final int version = in.readInt();
         final int size = in.readInt();
@@ -189,15 +193,15 @@
         }
     }
 
-    @Override
-    public int compareTo(@NonNull NetworkIdentitySet another) {
-        Objects.requireNonNull(another);
-        if (isEmpty()) return -1;
-        if (another.isEmpty()) return 1;
+    public static int compare(@NonNull NetworkIdentitySet left, @NonNull NetworkIdentitySet right) {
+        Objects.requireNonNull(left);
+        Objects.requireNonNull(right);
+        if (left.isEmpty()) return -1;
+        if (right.isEmpty()) return 1;
 
-        final NetworkIdentity ident = iterator().next();
-        final NetworkIdentity anotherIdent = another.iterator().next();
-        return ident.compareTo(anotherIdent);
+        final NetworkIdentity leftIdent = left.iterator().next();
+        final NetworkIdentity rightIdent = right.iterator().next();
+        return NetworkIdentity.compare(leftIdent, rightIdent);
     }
 
     /**
diff --git a/framework-t/src/android/net/NetworkStatsCollection.java b/framework-t/src/android/net/NetworkStatsCollection.java
index f169fed..735c44d 100644
--- a/framework-t/src/android/net/NetworkStatsCollection.java
+++ b/framework-t/src/android/net/NetworkStatsCollection.java
@@ -16,6 +16,7 @@
 
 package android.net;
 
+import static android.annotation.SystemApi.Client.MODULE_LIBRARIES;
 import static android.net.NetworkStats.DEFAULT_NETWORK_NO;
 import static android.net.NetworkStats.DEFAULT_NETWORK_YES;
 import static android.net.NetworkStats.IFACE_ALL;
@@ -34,6 +35,8 @@
 
 import android.annotation.NonNull;
 import android.annotation.Nullable;
+import android.annotation.SystemApi;
+import android.net.NetworkStatsHistory.Entry;
 import android.os.Binder;
 import android.service.NetworkStatsCollectionKeyProto;
 import android.service.NetworkStatsCollectionProto;
@@ -71,7 +74,10 @@
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.Iterator;
+import java.util.List;
+import java.util.Map;
 import java.util.Objects;
+import java.util.Set;
 
 /**
  * Collection of {@link NetworkStatsHistory}, stored based on combined key of
@@ -79,7 +85,7 @@
  *
  * @hide
  */
-// @SystemApi(client = MODULE_LIBRARIES)
+@SystemApi(client = MODULE_LIBRARIES)
 public class NetworkStatsCollection implements FileRotator.Reader, FileRotator.Writer {
     private static final String TAG = NetworkStatsCollection.class.getSimpleName();
     /** File header magic number: "ANET" */
@@ -702,7 +708,7 @@
     private ArrayList<Key> getSortedKeys() {
         final ArrayList<Key> keys = new ArrayList<>();
         keys.addAll(mStats.keySet());
-        Collections.sort(keys);
+        Collections.sort(keys, (left, right) -> Key.compare(left, right));
         return keys;
     }
 
@@ -809,10 +815,75 @@
     }
 
     /**
+     * Get the all historical stats of the collection {@link NetworkStatsCollection}.
+     *
+     * @return All {@link NetworkStatsHistory} in this collection.
+     */
+    @NonNull
+    public Map<Key, NetworkStatsHistory> getEntries() {
+        return new ArrayMap(mStats);
+    }
+
+    /**
+     * Builder class for {@link NetworkStatsCollection}.
+     */
+    public static final class Builder {
+        private final long mBucketDuration;
+        private final ArrayMap<Key, NetworkStatsHistory> mEntries = new ArrayMap<>();
+
+        /**
+         * Creates a new Builder with given bucket duration.
+         *
+         * @param bucketDuration Duration of the buckets of the object, in milliseconds.
+         */
+        public Builder(long bucketDuration) {
+            mBucketDuration = bucketDuration;
+        }
+
+        /**
+         * Add association of the history with the specified key in this map.
+         *
+         * @param key The object used to identify a network, see {@link Key}.
+         * @param history {@link NetworkStatsHistory} instance associated to the given {@link Key}.
+         * @return The builder object.
+         */
+        @NonNull
+        public NetworkStatsCollection.Builder addEntry(@NonNull Key key,
+                @NonNull NetworkStatsHistory history) {
+            Objects.requireNonNull(key);
+            Objects.requireNonNull(history);
+            final List<Entry> historyEntries = history.getEntries();
+
+            final NetworkStatsHistory.Builder historyBuilder =
+                    new NetworkStatsHistory.Builder(mBucketDuration, historyEntries.size());
+            for (Entry entry : historyEntries) {
+                historyBuilder.addEntry(entry);
+            }
+
+            mEntries.put(key, historyBuilder.build());
+            return this;
+        }
+
+        /**
+         * Builds the instance of the {@link NetworkStatsCollection}.
+         *
+         * @return the built instance of {@link NetworkStatsCollection}.
+         */
+        @NonNull
+        public NetworkStatsCollection build() {
+            final NetworkStatsCollection collection = new NetworkStatsCollection(mBucketDuration);
+            for (int i = 0; i < mEntries.size(); i++) {
+                collection.recordHistory(mEntries.keyAt(i), mEntries.valueAt(i));
+            }
+            return collection;
+        }
+    }
+
+    /**
      * the identifier that associate with the {@link NetworkStatsHistory} object to identify
      * a certain record in the {@link NetworkStatsCollection} object.
      */
-    public static class Key implements Comparable<Key> {
+    public static class Key {
         /** @hide */
         public final NetworkIdentitySet ident;
         /** @hide */
@@ -832,6 +903,11 @@
          * @param set Set of the record, see {@code NetworkStats#SET_*}.
          * @param tag Tag of the record, see {@link TrafficStats#setThreadStatsTag(int)}.
          */
+        public Key(@NonNull Set<NetworkIdentity> ident, int uid, int set, int tag) {
+            this(new NetworkIdentitySet(Objects.requireNonNull(ident)), uid, set, tag);
+        }
+
+        /** @hide */
         public Key(@NonNull NetworkIdentitySet ident, int uid, int set, int tag) {
             this.ident = Objects.requireNonNull(ident);
             this.uid = uid;
@@ -855,21 +931,22 @@
             return false;
         }
 
-        @Override
-        public int compareTo(@NonNull Key another) {
-            Objects.requireNonNull(another);
+        /** @hide */
+        public static int compare(@NonNull Key left, @NonNull Key right) {
+            Objects.requireNonNull(left);
+            Objects.requireNonNull(right);
             int res = 0;
-            if (ident != null && another.ident != null) {
-                res = ident.compareTo(another.ident);
+            if (left.ident != null && right.ident != null) {
+                res = NetworkIdentitySet.compare(left.ident, right.ident);
             }
             if (res == 0) {
-                res = Integer.compare(uid, another.uid);
+                res = Integer.compare(left.uid, right.uid);
             }
             if (res == 0) {
-                res = Integer.compare(set, another.set);
+                res = Integer.compare(left.set, right.set);
             }
             if (res == 0) {
-                res = Integer.compare(tag, another.tag);
+                res = Integer.compare(left.tag, right.tag);
             }
             return res;
         }
diff --git a/framework-t/src/android/net/NetworkStatsHistory.java b/framework-t/src/android/net/NetworkStatsHistory.java
index 90054c6..78c1370 100644
--- a/framework-t/src/android/net/NetworkStatsHistory.java
+++ b/framework-t/src/android/net/NetworkStatsHistory.java
@@ -16,6 +16,7 @@
 
 package android.net;
 
+import static android.annotation.SystemApi.Client.MODULE_LIBRARIES;
 import static android.net.NetworkStats.IFACE_ALL;
 import static android.net.NetworkStats.SET_DEFAULT;
 import static android.net.NetworkStats.TAG_NONE;
@@ -31,6 +32,7 @@
 import static com.android.net.module.util.NetworkStatsUtils.multiplySafeByRational;
 
 import android.annotation.NonNull;
+import android.annotation.SystemApi;
 import android.compat.annotation.UnsupportedAppUsage;
 import android.os.Build;
 import android.os.Parcel;
@@ -51,7 +53,9 @@
 import java.io.IOException;
 import java.io.PrintWriter;
 import java.net.ProtocolException;
+import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.List;
 import java.util.Random;
 
 /**
@@ -65,7 +69,7 @@
  *
  * @hide
  */
-// @SystemApi(client = MODULE_LIBRARIES)
+@SystemApi(client = MODULE_LIBRARIES)
 public final class NetworkStatsHistory implements Parcelable {
     private static final int VERSION_INIT = 1;
     private static final int VERSION_ADD_PACKETS = 2;
@@ -97,23 +101,157 @@
     private long[] operations;
     private long totalBytes;
 
-    public static class Entry {
+    /** @hide */
+    public NetworkStatsHistory(long bucketDuration, long[] bucketStart, long[] activeTime,
+            long[] rxBytes, long[] rxPackets, long[] txBytes, long[] txPackets,
+            long[] operations, int bucketCount, long totalBytes) {
+        this.bucketDuration = bucketDuration;
+        this.bucketStart = bucketStart;
+        this.activeTime = activeTime;
+        this.rxBytes = rxBytes;
+        this.rxPackets = rxPackets;
+        this.txBytes = txBytes;
+        this.txPackets = txPackets;
+        this.operations = operations;
+        this.bucketCount = bucketCount;
+        this.totalBytes = totalBytes;
+    }
+
+    /**
+     * An instance to represent a single record in a {@link NetworkStatsHistory} object.
+     */
+    public static final class Entry {
+        /** @hide */
         public static final long UNKNOWN = -1;
 
+        /** @hide */
+        // TODO: Migrate all callers to get duration from the history object and remove this field.
         @UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.R, trackingBug = 170729553)
         public long bucketDuration;
+        /** @hide */
         @UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.R, trackingBug = 170729553)
         public long bucketStart;
+        /** @hide */
         public long activeTime;
+        /** @hide */
         @UnsupportedAppUsage
         public long rxBytes;
+        /** @hide */
         @UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.R, trackingBug = 170729553)
         public long rxPackets;
+        /** @hide */
         @UnsupportedAppUsage
         public long txBytes;
+        /** @hide */
         @UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.R, trackingBug = 170729553)
         public long txPackets;
+        /** @hide */
         public long operations;
+        /** @hide */
+        Entry() {}
+
+        /**
+         * Construct a {@link Entry} instance to represent a single record in a
+         * {@link NetworkStatsHistory} object.
+         *
+         * @param bucketStart Start of period for this {@link Entry}, in milliseconds since the
+         *                    Unix epoch, see {@link java.lang.System#currentTimeMillis}.
+         * @param activeTime Active time for this {@link Entry}, in milliseconds.
+         * @param rxBytes Number of bytes received for this {@link Entry}. Statistics should
+         *                represent the contents of IP packets, including IP headers.
+         * @param rxPackets Number of packets received for this {@link Entry}. Statistics should
+         *                  represent the contents of IP packets, including IP headers.
+         * @param txBytes Number of bytes transmitted for this {@link Entry}. Statistics should
+         *                represent the contents of IP packets, including IP headers.
+         * @param txPackets Number of bytes transmitted for this {@link Entry}. Statistics should
+         *                  represent the contents of IP packets, including IP headers.
+         * @param operations count of network operations performed for this {@link Entry}. This can
+         *                   be used to derive bytes-per-operation.
+         */
+        public Entry(long bucketStart, long activeTime, long rxBytes,
+                long rxPackets, long txBytes, long txPackets, long operations) {
+            this.bucketStart = bucketStart;
+            this.activeTime = activeTime;
+            this.rxBytes = rxBytes;
+            this.rxPackets = rxPackets;
+            this.txBytes = txBytes;
+            this.txPackets = txPackets;
+            this.operations = operations;
+        }
+
+        /**
+         * Get start timestamp of the bucket's time interval, in milliseconds since the Unix epoch.
+         */
+        public long getBucketStart() {
+            return bucketStart;
+        }
+
+        /**
+         * Get active time of the bucket's time interval, in milliseconds.
+         */
+        public long getActiveTime() {
+            return activeTime;
+        }
+
+        /** Get number of bytes received for this {@link Entry}. */
+        public long getRxBytes() {
+            return rxBytes;
+        }
+
+        /** Get number of packets received for this {@link Entry}. */
+        public long getRxPackets() {
+            return rxPackets;
+        }
+
+        /** Get number of bytes transmitted for this {@link Entry}. */
+        public long getTxBytes() {
+            return txBytes;
+        }
+
+        /** Get number of packets transmitted for this {@link Entry}. */
+        public long getTxPackets() {
+            return txPackets;
+        }
+
+        /** Get count of network operations performed for this {@link Entry}. */
+        public long getOperations() {
+            return operations;
+        }
+
+        @Override
+        public boolean equals(Object o) {
+            if (this == o) return true;
+            if (o.getClass() != getClass()) return false;
+            Entry entry = (Entry) o;
+            return bucketStart == entry.bucketStart
+                    && activeTime == entry.activeTime && rxBytes == entry.rxBytes
+                    && rxPackets == entry.rxPackets && txBytes == entry.txBytes
+                    && txPackets == entry.txPackets && operations == entry.operations;
+        }
+
+        @Override
+        public int hashCode() {
+            return (int) (bucketStart * 2
+                    + activeTime * 3
+                    + rxBytes * 5
+                    + rxPackets * 7
+                    + txBytes * 11
+                    + txPackets * 13
+                    + operations * 17);
+        }
+
+        @Override
+        public String toString() {
+            return "Entry{"
+                    + "bucketStart=" + bucketStart
+                    + ", activeTime=" + activeTime
+                    + ", rxBytes=" + rxBytes
+                    + ", rxPackets=" + rxPackets
+                    + ", txBytes=" + txBytes
+                    + ", txPackets=" + txPackets
+                    + ", operations=" + operations
+                    + "}";
+        }
     }
 
     /** @hide */
@@ -324,6 +462,22 @@
         return entry;
     }
 
+    /**
+     * Get List of {@link Entry} of the {@link NetworkStatsHistory} instance.
+     *
+     * @return
+     */
+    @NonNull
+    public List<Entry> getEntries() {
+        // TODO: Return a wrapper that uses this list instead, to prevent the returned result
+        //  from being changed.
+        final ArrayList<Entry> ret = new ArrayList<>(size());
+        for (int i = 0; i < size(); i++) {
+            ret.add(getValues(i, null /* recycle */));
+        }
+        return ret;
+    }
+
     /** @hide */
     public void setValues(int i, Entry entry) {
         // Unwind old values
@@ -928,4 +1082,80 @@
         }
     }
 
+    /**
+     * Builder class for {@link NetworkStatsHistory}.
+     */
+    public static final class Builder {
+        private final long mBucketDuration;
+        private final List<Long> mBucketStart;
+        private final List<Long> mActiveTime;
+        private final List<Long> mRxBytes;
+        private final List<Long> mRxPackets;
+        private final List<Long> mTxBytes;
+        private final List<Long> mTxPackets;
+        private final List<Long> mOperations;
+
+        /**
+         * Creates a new Builder with given bucket duration and initial capacity to construct
+         * {@link NetworkStatsHistory} objects.
+         *
+         * @param bucketDuration Duration of the buckets of the object, in milliseconds.
+         * @param initialCapacity Estimated number of records.
+         */
+        public Builder(long bucketDuration, int initialCapacity) {
+            mBucketDuration = bucketDuration;
+            mBucketStart = new ArrayList<>(initialCapacity);
+            mActiveTime = new ArrayList<>(initialCapacity);
+            mRxBytes = new ArrayList<>(initialCapacity);
+            mRxPackets = new ArrayList<>(initialCapacity);
+            mTxBytes = new ArrayList<>(initialCapacity);
+            mTxPackets = new ArrayList<>(initialCapacity);
+            mOperations = new ArrayList<>(initialCapacity);
+        }
+
+        /**
+         * Add an {@link Entry} into the {@link NetworkStatsHistory} instance.
+         *
+         * @param entry The target {@link Entry} object.
+         * @return The builder object.
+         */
+        @NonNull
+        public Builder addEntry(@NonNull Entry entry) {
+            mBucketStart.add(entry.bucketStart);
+            mActiveTime.add(entry.activeTime);
+            mRxBytes.add(entry.rxBytes);
+            mRxPackets.add(entry.rxPackets);
+            mTxBytes.add(entry.txBytes);
+            mTxPackets.add(entry.txPackets);
+            mOperations.add(entry.operations);
+            return this;
+        }
+
+        private static long sum(@NonNull List<Long> list) {
+            long sum = 0;
+            for (long entry : list) {
+                sum += entry;
+            }
+            return sum;
+        }
+
+        /**
+         * Builds the instance of the {@link NetworkStatsHistory}.
+         *
+         * @return the built instance of {@link NetworkStatsHistory}.
+         */
+        @NonNull
+        public NetworkStatsHistory build() {
+            return new NetworkStatsHistory(mBucketDuration,
+                    CollectionUtils.toLongArray(mBucketStart),
+                    CollectionUtils.toLongArray(mActiveTime),
+                    CollectionUtils.toLongArray(mRxBytes),
+                    CollectionUtils.toLongArray(mRxPackets),
+                    CollectionUtils.toLongArray(mTxBytes),
+                    CollectionUtils.toLongArray(mTxPackets),
+                    CollectionUtils.toLongArray(mOperations),
+                    mBucketStart.size(),
+                    sum(mRxBytes) + sum(mTxBytes));
+        }
+    }
 }
diff --git a/framework-t/src/android/net/NetworkTemplate.java b/framework-t/src/android/net/NetworkTemplate.java
index a7e48d4..dba3991 100644
--- a/framework-t/src/android/net/NetworkTemplate.java
+++ b/framework-t/src/android/net/NetworkTemplate.java
@@ -263,7 +263,7 @@
      * Template to match {@link ConnectivityManager#TYPE_WIFI} networks with the
      * given key of the wifi network.
      *
-     * @param wifiNetworkKey key of the wifi network. see {@link WifiInfo#getCurrentNetworkKey()}
+     * @param wifiNetworkKey key of the wifi network. see {@link WifiInfo#getNetworkKey()}
      *                  to know details about the key.
      * @hide
      */
@@ -283,7 +283,7 @@
      * Call with {@link #WIFI_NETWORK_KEY_ALL} for {@code wifiNetworkKey} to get result regardless
      * of key of the wifi network.
      *
-     * @param wifiNetworkKey key of the wifi network. see {@link WifiInfo#getCurrentNetworkKey()}
+     * @param wifiNetworkKey key of the wifi network. see {@link WifiInfo#getNetworkKey()}
      *                  to know details about the key.
      * @param subscriberId the IMSI associated to this wifi network.
      *
@@ -593,7 +593,7 @@
 
     /**
      * Get the set of Wifi Network Keys of the template.
-     * See {@link WifiInfo#getCurrentNetworkKey()}.
+     * See {@link WifiInfo#getNetworkKey()}.
      */
     @NonNull
     public Set<String> getWifiNetworkKeys() {
@@ -652,7 +652,9 @@
      *
      * @hide
      */
-    public boolean matches(NetworkIdentity ident) {
+    @SystemApi(client = MODULE_LIBRARIES)
+    public boolean matches(@NonNull NetworkIdentity ident) {
+        Objects.requireNonNull(ident);
         if (!matchesMetered(ident)) return false;
         if (!matchesRoaming(ident)) return false;
         if (!matchesDefaultNetwork(ident)) return false;
@@ -729,7 +731,7 @@
      * Returns true when the key matches, or when {@code mMatchWifiNetworkKeys} is
      * empty.
      *
-     * @param wifiNetworkKey key of the wifi network. see {@link WifiInfo#getCurrentNetworkKey()}
+     * @param wifiNetworkKey key of the wifi network. see {@link WifiInfo#getNetworkKey()}
      *                  to know details about the key.
      */
     private boolean matchesWifiNetworkKey(@NonNull String wifiNetworkKey) {
@@ -1059,9 +1061,9 @@
          * the intention of matching any Wifi Network Key.
          *
          * @param wifiNetworkKeys the list of Wifi Network Key,
-         *                        see {@link WifiInfo#getCurrentNetworkKey()}.
+         *                        see {@link WifiInfo#getNetworkKey()}.
          *                        Or an empty list to match all networks.
-         *                        Note that {@code getCurrentNetworkKey()} might get null key
+         *                        Note that {@code getNetworkKey()} might get null key
          *                        when wifi disconnects. However, the caller should never invoke
          *                        this function with a null Wifi Network Key since such statistics
          *                        never exists.
diff --git a/framework-t/src/android/net/TrafficStats.java b/framework-t/src/android/net/TrafficStats.java
index 1af32bf..c2f0cdf 100644
--- a/framework-t/src/android/net/TrafficStats.java
+++ b/framework-t/src/android/net/TrafficStats.java
@@ -16,8 +16,9 @@
 
 package android.net;
 
+import static android.annotation.SystemApi.Client.MODULE_LIBRARIES;
+
 import android.annotation.NonNull;
-import android.annotation.Nullable;
 import android.annotation.SuppressLint;
 import android.annotation.SystemApi;
 import android.annotation.TestApi;
@@ -27,9 +28,10 @@
 import android.compat.annotation.UnsupportedAppUsage;
 import android.content.Context;
 import android.media.MediaPlayer;
+import android.os.Binder;
 import android.os.Build;
-import android.os.IBinder;
 import android.os.RemoteException;
+import android.util.Log;
 
 import com.android.server.NetworkManagementSocketTagger;
 
@@ -37,8 +39,6 @@
 
 import java.io.FileDescriptor;
 import java.io.IOException;
-import java.lang.reflect.InvocationTargetException;
-import java.lang.reflect.Method;
 import java.net.DatagramSocket;
 import java.net.Socket;
 import java.net.SocketException;
@@ -177,25 +177,12 @@
     @UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.P, trackingBug = 130143562)
     private synchronized static INetworkStatsService getStatsService() {
         if (sStatsService == null) {
-            sStatsService = getStatsBinder();
+            throw new IllegalStateException("TrafficStats not initialized, uid="
+                    + Binder.getCallingUid());
         }
         return sStatsService;
     }
 
-    @Nullable
-    private static INetworkStatsService getStatsBinder() {
-        try {
-            final Method getServiceMethod = Class.forName("android.os.ServiceManager")
-                    .getDeclaredMethod("getService", new Class[]{String.class});
-            final IBinder binder = (IBinder) getServiceMethod.invoke(
-                    null, Context.NETWORK_STATS_SERVICE);
-            return INetworkStatsService.Stub.asInterface(binder);
-        } catch (NoSuchMethodException | ClassNotFoundException | IllegalAccessException
-                | InvocationTargetException e) {
-            throw new NullPointerException("Cannot get INetworkStatsService: " + e);
-        }
-    }
-
     /**
      * Snapshot of {@link NetworkStats} when the currently active profiling
      * session started, or {@code null} if no session active.
@@ -210,6 +197,45 @@
     private static final String LOOPBACK_IFACE = "lo";
 
     /**
+     * Initialization {@link TrafficStats} with the context, to
+     * allow {@link TrafficStats} to fetch the needed binder.
+     *
+     * @param context a long-lived context, such as the application context or system
+     *                server context.
+     * @hide
+     */
+    @SystemApi(client = SystemApi.Client.MODULE_LIBRARIES)
+    @SuppressLint("VisiblySynchronized")
+    public static synchronized void init(@NonNull final Context context) {
+        if (sStatsService != null) {
+            throw new IllegalStateException("TrafficStats is already initialized, uid="
+                    + Binder.getCallingUid());
+        }
+        final NetworkStatsManager statsManager =
+                context.getSystemService(NetworkStatsManager.class);
+        if (statsManager == null) {
+            // TODO: Currently Process.isSupplemental is not working yet, because it depends on
+            //  process to run in a certain UID range, which is not true for now. Change this
+            //  to Log.wtf once Process.isSupplemental is ready.
+            Log.e(TAG, "TrafficStats not initialized, uid=" + Binder.getCallingUid());
+            return;
+        }
+        sStatsService = statsManager.getBinder();
+    }
+
+    /**
+     * Attach the socket tagger implementation to the current process, to
+     * get notified when a socket's {@link FileDescriptor} is assigned to
+     * a thread. See {@link SocketTagger#set(SocketTagger)}.
+     *
+     * @hide
+     */
+    @SystemApi(client = MODULE_LIBRARIES)
+    public static void attachSocketTagger() {
+        NetworkManagementSocketTagger.install();
+    }
+
+    /**
      * Set active tag to use when accounting {@link Socket} traffic originating
      * from the current thread. Only one active tag per thread is supported.
      * <p>
diff --git a/framework-t/src/android/net/netstats/IUsageCallback.aidl b/framework-t/src/android/net/netstats/IUsageCallback.aidl
new file mode 100644
index 0000000..4e8a5b2
--- /dev/null
+++ b/framework-t/src/android/net/netstats/IUsageCallback.aidl
@@ -0,0 +1,29 @@
+/*
+ * Copyright (C) 2022 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package android.net.netstats;
+
+import android.net.DataUsageRequest;
+
+/**
+ * Interface for NetworkStatsService to notify events to the callers of registerUsageCallback.
+ *
+ * @hide
+ */
+oneway interface IUsageCallback {
+    void onThresholdReached(in DataUsageRequest request);
+    void onCallbackReleased(in DataUsageRequest request);
+}
diff --git a/service-t/Sources.bp b/service-t/Sources.bp
index b261e16..24bc91d 100644
--- a/service-t/Sources.bp
+++ b/service-t/Sources.bp
@@ -26,6 +26,8 @@
     srcs: [
         "src/com/android/server/net/NetworkIdentity*.java",
         "src/com/android/server/net/NetworkStats*.java",
+        "src/com/android/server/net/BpfInterfaceMapUpdater.java",
+        "src/com/android/server/net/InterfaceMapValue.java",
     ],
     path: "src",
     visibility: [
@@ -66,6 +68,7 @@
 filegroup {
     name: "services.connectivity-ethernet-sources",
     srcs: [
+        "src/com/android/server/net/DelayedDiskWrite.java",
         "src/com/android/server/net/IpConfigStore.java",
     ],
     path: "src",
@@ -97,3 +100,28 @@
         "//packages/modules/Connectivity:__subpackages__",
     ],
 }
+
+cc_library_shared {
+    name: "libcom_android_net_module_util_jni",
+    min_sdk_version: "30",
+    cflags: [
+        "-Wall",
+        "-Werror",
+        "-Wno-unused-parameter",
+        "-Wthread-safety",
+    ],
+    srcs: [
+        "jni/onload.cpp",
+    ],
+    stl: "libc++_static",
+    static_libs: [
+        "libnet_utils_device_common_bpfjni",
+    ],
+    shared_libs: [
+        "liblog",
+        "libnativehelper",
+    ],
+    apex_available: [
+        "//apex_available:platform",
+    ],
+}
diff --git a/service-t/jni/onload.cpp b/service-t/jni/onload.cpp
new file mode 100644
index 0000000..bca4697
--- /dev/null
+++ b/service-t/jni/onload.cpp
@@ -0,0 +1,38 @@
+/*
+ * Copyright (C) 2022 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <nativehelper/JNIHelp.h>
+#include <log/log.h>
+
+namespace android {
+
+int register_com_android_net_module_util_BpfMap(JNIEnv* env, char const* class_name);
+
+extern "C" jint JNI_OnLoad(JavaVM* vm, void*) {
+    JNIEnv *env;
+    if (vm->GetEnv(reinterpret_cast<void**>(&env), JNI_VERSION_1_6) != JNI_OK) {
+        ALOGE("GetEnv failed");
+        return JNI_ERR;
+    }
+
+    if (register_com_android_net_module_util_BpfMap(env,
+            "com/android/net/module/util/BpfMap") < 0) return JNI_ERR;
+
+    return JNI_VERSION_1_6;
+}
+
+};
+
diff --git a/service-t/src/com/android/server/net/BpfInterfaceMapUpdater.java b/service-t/src/com/android/server/net/BpfInterfaceMapUpdater.java
new file mode 100644
index 0000000..25c88eb
--- /dev/null
+++ b/service-t/src/com/android/server/net/BpfInterfaceMapUpdater.java
@@ -0,0 +1,139 @@
+/*
+ * Copyright (C) 2022 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.android.server.net;
+
+import android.content.Context;
+import android.net.INetd;
+import android.os.Handler;
+import android.os.IBinder;
+import android.os.RemoteException;
+import android.os.ServiceSpecificException;
+import android.system.ErrnoException;
+import android.util.Log;
+
+import com.android.internal.annotations.VisibleForTesting;
+import com.android.net.module.util.BaseNetdUnsolicitedEventListener;
+import com.android.net.module.util.BpfMap;
+import com.android.net.module.util.IBpfMap;
+import com.android.net.module.util.InterfaceParams;
+import com.android.net.module.util.Struct.U32;
+
+/**
+ * Monitor interface added (without removed) and right interface name and its index to bpf map.
+ */
+public class BpfInterfaceMapUpdater {
+    private static final String TAG = BpfInterfaceMapUpdater.class.getSimpleName();
+    // This is current path but may be changed soon.
+    private static final String IFACE_INDEX_NAME_MAP_PATH =
+            "/sys/fs/bpf/map_netd_iface_index_name_map";
+    private final IBpfMap<U32, InterfaceMapValue> mBpfMap;
+    private final INetd mNetd;
+    private final Handler mHandler;
+    private final Dependencies mDeps;
+
+    public BpfInterfaceMapUpdater(Context ctx, Handler handler) {
+        this(ctx, handler, new Dependencies());
+    }
+
+    @VisibleForTesting
+    public BpfInterfaceMapUpdater(Context ctx, Handler handler, Dependencies deps) {
+        mDeps = deps;
+        mBpfMap = deps.getInterfaceMap();
+        mNetd = deps.getINetd(ctx);
+        mHandler = handler;
+    }
+
+    /**
+     * Dependencies of BpfInerfaceMapUpdater, for injection in tests.
+     */
+    @VisibleForTesting
+    public static class Dependencies {
+        /** Create BpfMap for updating interface and index mapping. */
+        public IBpfMap<U32, InterfaceMapValue> getInterfaceMap() {
+            try {
+                return new BpfMap<>(IFACE_INDEX_NAME_MAP_PATH, BpfMap.BPF_F_RDWR,
+                    U32.class, InterfaceMapValue.class);
+            } catch (ErrnoException e) {
+                Log.e(TAG, "Cannot create interface map: " + e);
+                return null;
+            }
+        }
+
+        /** Get InterfaceParams for giving interface name. */
+        public InterfaceParams getInterfaceParams(String ifaceName) {
+            return InterfaceParams.getByName(ifaceName);
+        }
+
+        /** Get INetd binder object. */
+        public INetd getINetd(Context ctx) {
+            return INetd.Stub.asInterface((IBinder) ctx.getSystemService(Context.NETD_SERVICE));
+        }
+    }
+
+    /**
+     * Start listening interface update event.
+     * Query current interface names before listening.
+     */
+    public void start() {
+        mHandler.post(() -> {
+            if (mBpfMap == null) {
+                Log.wtf(TAG, "Fail to start: Null bpf map");
+                return;
+            }
+
+            try {
+                // TODO: use a NetlinkMonitor and listen for RTM_NEWLINK messages instead.
+                mNetd.registerUnsolicitedEventListener(new InterfaceChangeObserver());
+            } catch (RemoteException e) {
+                Log.wtf(TAG, "Unable to register netd UnsolicitedEventListener, " + e);
+            }
+
+            final String[] ifaces;
+            try {
+                // TODO: use a netlink dump to get the current interface list.
+                ifaces = mNetd.interfaceGetList();
+            } catch (RemoteException | ServiceSpecificException e) {
+                Log.wtf(TAG, "Unable to query interface names by netd, " + e);
+                return;
+            }
+
+            for (String ifaceName : ifaces) {
+                addInterface(ifaceName);
+            }
+        });
+    }
+
+    private void addInterface(String ifaceName) {
+        final InterfaceParams iface = mDeps.getInterfaceParams(ifaceName);
+        if (iface == null) {
+            Log.e(TAG, "Unable to get InterfaceParams for " + ifaceName);
+            return;
+        }
+
+        try {
+            mBpfMap.updateEntry(new U32(iface.index), new InterfaceMapValue(ifaceName));
+        } catch (ErrnoException e) {
+            Log.e(TAG, "Unable to update entry for " + ifaceName + ", " + e);
+        }
+    }
+
+    private class InterfaceChangeObserver extends BaseNetdUnsolicitedEventListener {
+        @Override
+        public void onInterfaceAdded(String ifName) {
+            mHandler.post(() -> addInterface(ifName));
+        }
+    }
+}
diff --git a/services/core/java/com/android/server/net/DelayedDiskWrite.java b/service-t/src/com/android/server/net/DelayedDiskWrite.java
similarity index 82%
rename from services/core/java/com/android/server/net/DelayedDiskWrite.java
rename to service-t/src/com/android/server/net/DelayedDiskWrite.java
index 8f09eb7..35dc455 100644
--- a/services/core/java/com/android/server/net/DelayedDiskWrite.java
+++ b/service-t/src/com/android/server/net/DelayedDiskWrite.java
@@ -26,21 +26,37 @@
 import java.io.FileOutputStream;
 import java.io.IOException;
 
+/**
+ * This class provides APIs to do a delayed data write to a given {@link OutputStream}.
+ */
 public class DelayedDiskWrite {
+    private static final String TAG = "DelayedDiskWrite";
+
     private HandlerThread mDiskWriteHandlerThread;
     private Handler mDiskWriteHandler;
     /* Tracks multiple writes on the same thread */
     private int mWriteSequence = 0;
-    private final String TAG = "DelayedDiskWrite";
 
+    /**
+     * Used to do a delayed data write to a given {@link OutputStream}.
+     */
     public interface Writer {
-        public void onWriteCalled(DataOutputStream out) throws IOException;
+        /**
+         * write data to a given {@link OutputStream}.
+         */
+        void onWriteCalled(DataOutputStream out) throws IOException;
     }
 
+    /**
+     * Do a delayed data write to a given output stream opened from filePath.
+     */
     public void write(final String filePath, final Writer w) {
         write(filePath, w, true);
     }
 
+    /**
+     * Do a delayed data write to a given output stream opened from filePath.
+     */
     public void write(final String filePath, final Writer w, final boolean open) {
         if (TextUtils.isEmpty(filePath)) {
             throw new IllegalArgumentException("empty file path");
@@ -77,7 +93,7 @@
             if (out != null) {
                 try {
                     out.close();
-                } catch (Exception e) {}
+                } catch (Exception e) { }
             }
 
             // Quit if no more writes sent
diff --git a/service-t/src/com/android/server/net/InterfaceMapValue.java b/service-t/src/com/android/server/net/InterfaceMapValue.java
new file mode 100644
index 0000000..061f323
--- /dev/null
+++ b/service-t/src/com/android/server/net/InterfaceMapValue.java
@@ -0,0 +1,35 @@
+/*
+ * Copyright (C) 2020 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.android.server.net;
+
+import com.android.net.module.util.Struct;
+import com.android.net.module.util.Struct.Field;
+import com.android.net.module.util.Struct.Type;
+
+/**
+ * The value of bpf interface index map which is used for NetworkStatsService.
+ */
+public class InterfaceMapValue extends Struct {
+    @Field(order = 0, type = Type.ByteArray, arraysize = 16)
+    public final byte[] interfaceName;
+
+    public InterfaceMapValue(String iface) {
+        final byte[] ifaceArray = iface.getBytes();
+        interfaceName = new byte[16];
+        // All array bytes after the interface name, if any, must be 0.
+        System.arraycopy(ifaceArray, 0, interfaceName, 0, ifaceArray.length);
+    }
+}
diff --git a/service-t/src/com/android/server/net/NetworkStatsFactory.java b/service-t/src/com/android/server/net/NetworkStatsFactory.java
index bb123a3..17f3455 100644
--- a/service-t/src/com/android/server/net/NetworkStatsFactory.java
+++ b/service-t/src/com/android/server/net/NetworkStatsFactory.java
@@ -26,10 +26,10 @@
 
 import android.annotation.NonNull;
 import android.annotation.Nullable;
-import android.net.INetd;
+import android.content.Context;
+import android.net.ConnectivityManager;
 import android.net.NetworkStats;
 import android.net.UnderlyingNetworkInfo;
-import android.os.RemoteException;
 import android.os.StrictMode;
 import android.os.SystemClock;
 
@@ -70,7 +70,7 @@
 
     private final boolean mUseBpfStats;
 
-    private final INetd mNetd;
+    private final Context mContext;
 
     /**
      * Guards persistent data access in this class
@@ -158,12 +158,12 @@
         NetworkStats.apply464xlatAdjustments(baseTraffic, stackedTraffic, mStackedIfaces);
     }
 
-    public NetworkStatsFactory(@NonNull INetd netd) {
-        this(new File("/proc/"), true, netd);
+    public NetworkStatsFactory(@NonNull Context ctx) {
+        this(ctx, new File("/proc/"), true);
     }
 
     @VisibleForTesting
-    public NetworkStatsFactory(File procRoot, boolean useBpfStats, @NonNull INetd netd) {
+    public NetworkStatsFactory(@NonNull Context ctx, File procRoot, boolean useBpfStats) {
         mStatsXtIfaceAll = new File(procRoot, "net/xt_qtaguid/iface_stat_all");
         mStatsXtIfaceFmt = new File(procRoot, "net/xt_qtaguid/iface_stat_fmt");
         mStatsXtUid = new File(procRoot, "net/xt_qtaguid/stats");
@@ -172,7 +172,7 @@
             mPersistSnapshot = new NetworkStats(SystemClock.elapsedRealtime(), -1);
             mTunAnd464xlatAdjustedStats = new NetworkStats(SystemClock.elapsedRealtime(), -1);
         }
-        mNetd = netd;
+        mContext = ctx;
     }
 
     public NetworkStats readBpfNetworkStatsDev() throws IOException {
@@ -295,11 +295,12 @@
     }
 
     @GuardedBy("mPersistentDataLock")
-    private void requestSwapActiveStatsMapLocked() throws RemoteException {
-        // Ask netd to do a active map stats swap. When the binder call successfully returns,
+    private void requestSwapActiveStatsMapLocked() {
+        // Do a active map stats swap. When the binder call successfully returns,
         // the system server should be able to safely read and clean the inactive map
         // without race problem.
-        mNetd.trafficSwapActiveStatsMap();
+        final ConnectivityManager cm = mContext.getSystemService(ConnectivityManager.class);
+        cm.swapActiveStatsMap();
     }
 
     /**
@@ -327,7 +328,7 @@
                 if (mUseBpfStats) {
                     try {
                         requestSwapActiveStatsMapLocked();
-                    } catch (RemoteException e) {
+                    } catch (RuntimeException e) {
                         throw new IOException(e);
                     }
                     // Stats are always read from the inactive map, so they must be read after the
diff --git a/service-t/src/com/android/server/net/NetworkStatsObservers.java b/service-t/src/com/android/server/net/NetworkStatsObservers.java
index b57a4f9..1953624 100644
--- a/service-t/src/com/android/server/net/NetworkStatsObservers.java
+++ b/service-t/src/com/android/server/net/NetworkStatsObservers.java
@@ -26,13 +26,12 @@
 import android.net.NetworkStatsCollection;
 import android.net.NetworkStatsHistory;
 import android.net.NetworkTemplate;
-import android.os.Bundle;
+import android.net.netstats.IUsageCallback;
 import android.os.Handler;
 import android.os.HandlerThread;
 import android.os.IBinder;
 import android.os.Looper;
 import android.os.Message;
-import android.os.Messenger;
 import android.os.Process;
 import android.os.RemoteException;
 import android.util.ArrayMap;
@@ -75,10 +74,10 @@
      *
      * @return the normalized request wrapped within {@link RequestInfo}.
      */
-    public DataUsageRequest register(DataUsageRequest inputRequest, Messenger messenger,
-                IBinder binder, int callingUid, @NetworkStatsAccess.Level int accessLevel) {
-        DataUsageRequest request = buildRequest(inputRequest);
-        RequestInfo requestInfo = buildRequestInfo(request, messenger, binder, callingUid,
+    public DataUsageRequest register(DataUsageRequest inputRequest, IUsageCallback callback,
+            int callingUid, @NetworkStatsAccess.Level int accessLevel) {
+        DataUsageRequest request = buildRequest(inputRequest, callingUid);
+        RequestInfo requestInfo = buildRequestInfo(request, callback, callingUid,
                 accessLevel);
 
         if (LOGV) Log.v(TAG, "Registering observer for " + request);
@@ -195,10 +194,12 @@
         }
     }
 
-    private DataUsageRequest buildRequest(DataUsageRequest request) {
-        // Cap the minimum threshold to a safe default to avoid too many callbacks
-        long thresholdInBytes = Math.max(MIN_THRESHOLD_BYTES, request.thresholdInBytes);
-        if (thresholdInBytes < request.thresholdInBytes) {
+    private DataUsageRequest buildRequest(DataUsageRequest request, int callingUid) {
+        // For non-system uid, cap the minimum threshold to a safe default to avoid too
+        // many callbacks.
+        long thresholdInBytes = (callingUid == Process.SYSTEM_UID ? request.thresholdInBytes
+                : Math.max(MIN_THRESHOLD_BYTES, request.thresholdInBytes));
+        if (thresholdInBytes > request.thresholdInBytes) {
             Log.w(TAG, "Threshold was too low for " + request
                     + ". Overriding to a safer default of " + thresholdInBytes + " bytes");
         }
@@ -206,11 +207,10 @@
                 request.template, thresholdInBytes);
     }
 
-    private RequestInfo buildRequestInfo(DataUsageRequest request,
-                Messenger messenger, IBinder binder, int callingUid,
-                @NetworkStatsAccess.Level int accessLevel) {
+    private RequestInfo buildRequestInfo(DataUsageRequest request, IUsageCallback callback,
+            int callingUid, @NetworkStatsAccess.Level int accessLevel) {
         if (accessLevel <= NetworkStatsAccess.Level.USER) {
-            return new UserUsageRequestInfo(this, request, messenger, binder, callingUid,
+            return new UserUsageRequestInfo(this, request, callback, callingUid,
                     accessLevel);
         } else {
             // Safety check in case a new access level is added and we forgot to update this
@@ -218,7 +218,7 @@
                 throw new IllegalArgumentException(
                         "accessLevel " + accessLevel + " is less than DEVICESUMMARY.");
             }
-            return new NetworkUsageRequestInfo(this, request, messenger, binder, callingUid,
+            return new NetworkUsageRequestInfo(this, request, callback, callingUid,
                     accessLevel);
         }
     }
@@ -230,25 +230,23 @@
     private abstract static class RequestInfo implements IBinder.DeathRecipient {
         private final NetworkStatsObservers mStatsObserver;
         protected final DataUsageRequest mRequest;
-        private final Messenger mMessenger;
-        private final IBinder mBinder;
+        private final IUsageCallback mCallback;
         protected final int mCallingUid;
         protected final @NetworkStatsAccess.Level int mAccessLevel;
         protected NetworkStatsRecorder mRecorder;
         protected NetworkStatsCollection mCollection;
 
         RequestInfo(NetworkStatsObservers statsObserver, DataUsageRequest request,
-                    Messenger messenger, IBinder binder, int callingUid,
+                IUsageCallback callback, int callingUid,
                     @NetworkStatsAccess.Level int accessLevel) {
             mStatsObserver = statsObserver;
             mRequest = request;
-            mMessenger = messenger;
-            mBinder = binder;
+            mCallback = callback;
             mCallingUid = callingUid;
             mAccessLevel = accessLevel;
 
             try {
-                mBinder.linkToDeath(this, 0);
+                mCallback.asBinder().linkToDeath(this, 0);
             } catch (RemoteException e) {
                 binderDied();
             }
@@ -257,7 +255,7 @@
         @Override
         public void binderDied() {
             if (LOGV) {
-                Log.v(TAG, "RequestInfo binderDied(" + mRequest + ", " + mBinder + ")");
+                Log.v(TAG, "RequestInfo binderDied(" + mRequest + ", " + mCallback + ")");
             }
             mStatsObserver.unregister(mRequest, Process.SYSTEM_UID);
             callCallback(NetworkStatsManager.CALLBACK_RELEASED);
@@ -270,9 +268,7 @@
         }
 
         private void unlinkDeathRecipient() {
-            if (mBinder != null) {
-                mBinder.unlinkToDeath(this, 0);
-            }
+            mCallback.asBinder().unlinkToDeath(this, 0);
         }
 
         /**
@@ -294,17 +290,19 @@
         }
 
         private void callCallback(int callbackType) {
-            Bundle bundle = new Bundle();
-            bundle.putParcelable(DataUsageRequest.PARCELABLE_KEY, mRequest);
-            Message msg = Message.obtain();
-            msg.what = callbackType;
-            msg.setData(bundle);
             try {
                 if (LOGV) {
                     Log.v(TAG, "sending notification " + callbackTypeToName(callbackType)
                             + " for " + mRequest);
                 }
-                mMessenger.send(msg);
+                switch (callbackType) {
+                    case NetworkStatsManager.CALLBACK_LIMIT_REACHED:
+                        mCallback.onThresholdReached(mRequest);
+                        break;
+                    case NetworkStatsManager.CALLBACK_RELEASED:
+                        mCallback.onCallbackReleased(mRequest);
+                        break;
+                }
             } catch (RemoteException e) {
                 // May occur naturally in the race of binder death.
                 Log.w(TAG, "RemoteException caught trying to send a callback msg for " + mRequest);
@@ -334,9 +332,9 @@
 
     private static class NetworkUsageRequestInfo extends RequestInfo {
         NetworkUsageRequestInfo(NetworkStatsObservers statsObserver, DataUsageRequest request,
-                    Messenger messenger, IBinder binder, int callingUid,
+                IUsageCallback callback, int callingUid,
                     @NetworkStatsAccess.Level int accessLevel) {
-            super(statsObserver, request, messenger, binder, callingUid, accessLevel);
+            super(statsObserver, request, callback, callingUid, accessLevel);
         }
 
         @Override
@@ -376,9 +374,9 @@
 
     private static class UserUsageRequestInfo extends RequestInfo {
         UserUsageRequestInfo(NetworkStatsObservers statsObserver, DataUsageRequest request,
-                    Messenger messenger, IBinder binder, int callingUid,
+                    IUsageCallback callback, int callingUid,
                     @NetworkStatsAccess.Level int accessLevel) {
-            super(statsObserver, request, messenger, binder, callingUid, accessLevel);
+            super(statsObserver, request, callback, callingUid, accessLevel);
         }
 
         @Override
diff --git a/service-t/src/com/android/server/net/NetworkStatsService.java b/service-t/src/com/android/server/net/NetworkStatsService.java
index 9b90f3b..243d621 100644
--- a/service-t/src/com/android/server/net/NetworkStatsService.java
+++ b/service-t/src/com/android/server/net/NetworkStatsService.java
@@ -99,6 +99,7 @@
 import android.net.TrafficStats;
 import android.net.UnderlyingNetworkInfo;
 import android.net.Uri;
+import android.net.netstats.IUsageCallback;
 import android.net.netstats.provider.INetworkStatsProvider;
 import android.net.netstats.provider.INetworkStatsProviderCallback;
 import android.net.netstats.provider.NetworkStatsProvider;
@@ -106,12 +107,10 @@
 import android.os.DropBoxManager;
 import android.os.Environment;
 import android.os.Handler;
-import android.os.HandlerExecutor;
 import android.os.HandlerThread;
 import android.os.IBinder;
 import android.os.Looper;
 import android.os.Message;
-import android.os.Messenger;
 import android.os.PowerManager;
 import android.os.RemoteException;
 import android.os.ServiceSpecificException;
@@ -358,6 +357,9 @@
     @NonNull
     private final LocationPermissionChecker mLocationPermissionChecker;
 
+    @NonNull
+    private final BpfInterfaceMapUpdater mInterfaceMapUpdater;
+
     private static @NonNull File getDefaultSystemDir() {
         return new File(Environment.getDataDirectory(), "system");
     }
@@ -420,7 +422,7 @@
         final NetworkStatsService service = new NetworkStatsService(context,
                 INetd.Stub.asInterface((IBinder) context.getSystemService(Context.NETD_SERVICE)),
                 alarmManager, wakeLock, getDefaultClock(),
-                new DefaultNetworkStatsSettings(), new NetworkStatsFactory(netd),
+                new DefaultNetworkStatsSettings(), new NetworkStatsFactory(context),
                 new NetworkStatsObservers(), getDefaultSystemDir(), getDefaultBaseDir(),
                 new Dependencies());
 
@@ -450,11 +452,13 @@
         handlerThread.start();
         mHandler = new NetworkStatsHandler(handlerThread.getLooper());
         mNetworkStatsSubscriptionsMonitor = deps.makeSubscriptionsMonitor(mContext,
-                new HandlerExecutor(mHandler), this);
+                (command) -> mHandler.post(command) , this);
         mContentResolver = mContext.getContentResolver();
         mContentObserver = mDeps.makeContentObserver(mHandler, mSettings,
                 mNetworkStatsSubscriptionsMonitor);
         mLocationPermissionChecker = mDeps.makeLocationPermissionChecker(mContext);
+        mInterfaceMapUpdater = mDeps.makeBpfInterfaceMapUpdater(mContext, mHandler);
+        mInterfaceMapUpdater.start();
     }
 
     /**
@@ -509,6 +513,13 @@
         public LocationPermissionChecker makeLocationPermissionChecker(final Context context) {
             return new LocationPermissionChecker(context);
         }
+
+        /** Create BpfInterfaceMapUpdater to update bpf interface map. */
+        @NonNull
+        public BpfInterfaceMapUpdater makeBpfInterfaceMapUpdater(
+                @NonNull Context ctx, @NonNull Handler handler) {
+            return new BpfInterfaceMapUpdater(ctx, handler);
+        }
     }
 
     /**
@@ -557,7 +568,7 @@
         // watch for tethering changes
         final TetheringManager tetheringManager = mContext.getSystemService(TetheringManager.class);
         tetheringManager.registerTetheringEventCallback(
-                new HandlerExecutor(mHandler), mTetherListener);
+                (command) -> mHandler.post(command), mTetherListener);
 
         // listen for periodic polling events
         final IntentFilter pollFilter = new IntentFilter(ACTION_NETWORK_STATS_POLL);
@@ -989,8 +1000,17 @@
         }
 
         // TODO: switch to data layer stats once kernel exports
-        // for now, read network layer stats and flatten across all ifaces
-        final NetworkStats networkLayer = readNetworkStatsUidDetail(uid, INTERFACES_ALL, TAG_ALL);
+        // for now, read network layer stats and flatten across all ifaces.
+        // This function is used to query NeworkStats for calle's uid. The only caller method
+        // TrafficStats#getDataLayerSnapshotForUid alrady claim no special permission to query
+        // its own NetworkStats.
+        final long ident = Binder.clearCallingIdentity();
+        final NetworkStats networkLayer;
+        try {
+            networkLayer = readNetworkStatsUidDetail(uid, INTERFACES_ALL, TAG_ALL);
+        } finally {
+            Binder.restoreCallingIdentity(ident);
+        }
 
         // splice in operation counts
         networkLayer.spliceOperationsFrom(mUidOperations);
@@ -1137,21 +1157,20 @@
     }
 
     @Override
-    public DataUsageRequest registerUsageCallback(String callingPackage,
-                DataUsageRequest request, Messenger messenger, IBinder binder) {
+    public DataUsageRequest registerUsageCallback(@NonNull String callingPackage,
+                @NonNull DataUsageRequest request, @NonNull IUsageCallback callback) {
         Objects.requireNonNull(callingPackage, "calling package is null");
         Objects.requireNonNull(request, "DataUsageRequest is null");
         Objects.requireNonNull(request.template, "NetworkTemplate is null");
-        Objects.requireNonNull(messenger, "messenger is null");
-        Objects.requireNonNull(binder, "binder is null");
+        Objects.requireNonNull(callback, "callback is null");
 
         int callingUid = Binder.getCallingUid();
         @NetworkStatsAccess.Level int accessLevel = checkAccessLevel(callingPackage);
         DataUsageRequest normalizedRequest;
         final long token = Binder.clearCallingIdentity();
         try {
-            normalizedRequest = mStatsObservers.register(request, messenger, binder,
-                    callingUid, accessLevel);
+            normalizedRequest = mStatsObservers.register(
+                    request, callback, callingUid, accessLevel);
         } finally {
             Binder.restoreCallingIdentity(token);
         }