[SP28] Add API for set data warning

To have better control and race-free of set data warning
to tether offload hardware, an interface of set warning and
limit at the same time in the NetworkStatsProvider is needed.

This is a no-op change which expose such interface with minimum
changes in service side to get build pass. The implementation
would be included in follow-up patches.

Test: atest NetworkStatsServiceTest
Test: atest NetworkPolicyManagerServiceTest
Test: atest GtsNetworkStackHostTestCases
Test: m doc-comment-check-docs
Bug: 149467454
Bug: 170699770
Bug: 170179169
Ignore-AOSP-First: avoid long automerger delay
Change-Id: I6ee661497f7dedb871c85786d1950cab951d8aa2

core/java/android/net/netstats/provider/INetworkStatsProvider.aidl

@@ -23,6 +23,6 @@ package android.net.netstats.provider;
  */
 oneway interface INetworkStatsProvider {
     void onRequestStatsUpdate(int token);
-    void onSetLimit(String iface, long quotaBytes);
     void onSetAlert(long quotaBytes);
+    void onSetWarningAndLimit(String iface, long warningBytes, long limitBytes);
 }

core/java/android/net/netstats/provider/INetworkStatsProviderCallback.aidl

@@ -26,6 +26,6 @@ import android.net.NetworkStats;
 oneway interface INetworkStatsProviderCallback {
     void notifyStatsUpdated(int token, in NetworkStats ifaceStats, in NetworkStats uidStats);
     void notifyAlertReached();
-    void notifyLimitReached();
+    void notifyWarningOrLimitReached();
     void unregister();
 }

core/java/android/net/netstats/provider/NetworkStatsProvider.java

@@ -29,7 +29,8 @@ import android.os.RemoteException;
 @SystemApi
 public abstract class NetworkStatsProvider {
     /**
-     * A value used by {@link #onSetLimit} and {@link #onSetAlert} indicates there is no limit.
+     * A value used by {@link #onSetLimit}, {@link #onSetAlert} and {@link #onSetWarningAndLimit}
+     * indicates there is no limit.
      */
     public static final int QUOTA_UNLIMITED = -1;
 
@@ -42,13 +43,13 @@ public abstract class NetworkStatsProvider {
         }
 
         @Override
-        public void onSetLimit(String iface, long quotaBytes) {
-            NetworkStatsProvider.this.onSetLimit(iface, quotaBytes);
+        public void onSetAlert(long quotaBytes) {
+            NetworkStatsProvider.this.onSetAlert(quotaBytes);
         }
 
         @Override
-        public void onSetAlert(long quotaBytes) {
-            NetworkStatsProvider.this.onSetAlert(quotaBytes);
+        public void onSetWarningAndLimit(String iface, long warningBytes, long limitBytes) {
+            NetworkStatsProvider.this.onSetWarningAndLimit(iface, warningBytes, limitBytes);
         }
     };
 
@@ -145,11 +146,28 @@ public abstract class NetworkStatsProvider {
     }
 
     /**
-     * Notify system that the quota set by {@code onSetLimit} has been reached.
+     * Notify system that the warning set by {@link #onSetWarningAndLimit} has been reached.
+     *
+     * @hide
+     */
+    // TODO: Expose as system API.
+    public void notifyWarningReached() {
+        try {
+            // Reuse the code path to notify warning reached with limit reached
+            // since framework handles them in the same way.
+            getProviderCallbackBinderOrThrow().notifyWarningOrLimitReached();
+        } catch (RemoteException e) {
+            e.rethrowAsRuntimeException();
+        }
+    }
+
+    /**
+     * Notify system that the quota set by {@link #onSetLimit} or limit set by
+     * {@link #onSetWarningAndLimit} has been reached.
      */
     public void notifyLimitReached() {
         try {
-            getProviderCallbackBinderOrThrow().notifyLimitReached();
+            getProviderCallbackBinderOrThrow().notifyWarningOrLimitReached();
         } catch (RemoteException e) {
             e.rethrowAsRuntimeException();
         }
@@ -180,8 +198,34 @@ public abstract class NetworkStatsProvider {
      * @param quotaBytes the quota defined as the number of bytes, starting from zero and counting
      *                   from now. A value of {@link #QUOTA_UNLIMITED} indicates there is no limit.
      */
+    // TODO: deprecate this once onSetWarningAndLimit is ready.
     public abstract void onSetLimit(@NonNull String iface, long quotaBytes);
 
+    /**
+     * Called by {@code NetworkStatsService} when setting the interface quotas for the specified
+     * upstream interface. If a provider implements {@link #onSetWarningAndLimit}, the system
+     * will not call {@link #onSetLimit}. When this method is called, the implementation
+     * should behave as follows:
+     *   1. If {@code warningBytes} is reached on {@code iface}, block all further traffic on
+     *      {@code iface} and call {@link NetworkStatsProvider@notifyWarningReached()}.
+     *   2. If {@code limitBytes} is reached on {@code iface}, block all further traffic on
+     *   {@code iface} and call {@link NetworkStatsProvider#notifyLimitReached()}.
+     *
+     * @param iface the interface requiring the operation.
+     * @param warningBytes the warning defined as the number of bytes, starting from zero and
+     *                     counting from now. A value of {@link #QUOTA_UNLIMITED} indicates
+     *                     there is no warning.
+     * @param limitBytes the limit defined as the number of bytes, starting from zero and counting
+     *                   from now. A value of {@link #QUOTA_UNLIMITED} indicates there is no limit.
+     *
+     * @hide
+     */
+    // TODO: Expose as system API.
+    public void onSetWarningAndLimit(@NonNull String iface, long warningBytes, long limitBytes) {
+        // Backward compatibility for those who didn't override this function.
+        onSetLimit(iface, limitBytes);
+    }
+
     /**
      * Called by {@code NetworkStatsService} when setting the alert bytes. Custom implementations
      * MUST call {@link NetworkStatsProvider#notifyAlertReached()} when {@code quotaBytes} bytes

services/core/java/com/android/server/net/NetworkStatsService.java

@@ -1676,7 +1676,9 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
         @Override
         public void setStatsProviderLimitAsync(@NonNull String iface, long quota) {
             if (LOGV) Slog.v(TAG, "setStatsProviderLimitAsync(" + iface + "," + quota + ")");
-            invokeForAllStatsProviderCallbacks((cb) -> cb.mProvider.onSetLimit(iface, quota));
+            // TODO: Set warning accordingly.
+            invokeForAllStatsProviderCallbacks((cb) -> cb.mProvider.onSetWarningAndLimit(iface,
+                    NetworkStatsProvider.QUOTA_UNLIMITED, quota));
         }
     }
 
@@ -2071,10 +2073,10 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
         }
 
         @Override
-        public void notifyLimitReached() {
-            Log.d(TAG, mTag + ": onLimitReached");
+        public void notifyWarningOrLimitReached() {
+            Log.d(TAG, mTag + ": notifyWarningOrLimitReached");
             LocalServices.getService(NetworkPolicyManagerInternal.class)
-                    .onStatsProviderLimitReached(mTag);
+                    .onStatsProviderWarningOrLimitReached(mTag);
         }
 
         @Override