Dump top distinct tag counts per uid

Sample Output:
NetworkStatsFactory logs:
  Top distinct tag counts in UidTagSets:
    1000=3
    10115=2
    1073=2
    1051=1
    10037=1
    10113=1
    0=1

Test: manual
Bug: 364353020
Change-Id: I1707d28efc991b083d360ff479216e1480ab0e7a

service-t/src/com/android/server/net/NetworkStatsFactory.java

@@ -28,7 +28,9 @@ import android.net.UnderlyingNetworkInfo;
 import android.os.ServiceSpecificException;
 import android.os.SystemClock;
 import android.util.ArraySet;
+import android.util.IndentingPrintWriter;
 import android.util.Log;
+import android.util.Pair;
 import android.util.SparseArray;
 import android.util.SparseBooleanArray;
 
@@ -40,6 +42,9 @@ import com.android.server.connectivity.InterfaceTracker;
 
 import java.io.IOException;
 import java.net.ProtocolException;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
 import java.util.Map;
 import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
@@ -76,6 +81,7 @@ public class NetworkStatsFactory {
     static final String CONFIG_PER_UID_TAG_THROTTLING_THRESHOLD =
             "per_uid_tag_throttling_threshold";
     private static final int DEFAULT_TAGS_PER_UID_THRESHOLD = 1000;
+    private static final int DUMP_TAGS_PER_UID_COUNT = 20;
     private final boolean mSupportPerUidTagThrottling;
     private final int mPerUidTagThrottlingThreshold;
 
@@ -387,4 +393,34 @@ public class NetworkStatsFactory {
         pe.initCause(cause);
         return pe;
     }
+
+    /**
+     * Dump the contents of NetworkStatsFactory.
+     */
+    public void dump(IndentingPrintWriter pw) {
+        dumpUidTagSets(pw);
+    }
+
+    private void dumpUidTagSets(IndentingPrintWriter pw) {
+        pw.println("Top distinct tag counts in UidTagSets:");
+        pw.increaseIndent();
+        final List<Pair<Integer, Integer>> countForUidList = new ArrayList<>();
+        synchronized (mPersistentDataLock) {
+            for (int i = 0; i < mUidTagSets.size(); i++) {
+                final Pair<Integer, Integer> countForUid =
+                        new Pair<>(mUidTagSets.keyAt(i), mUidTagSets.valueAt(i).size());
+                countForUidList.add(countForUid);
+            }
+        }
+        Collections.sort(countForUidList,
+                (entry1, entry2) -> Integer.compare(entry2.second, entry1.second));
+        final int dumpSize = Math.min(countForUidList.size(), DUMP_TAGS_PER_UID_COUNT);
+        for (int j = 0; j < dumpSize; j++) {
+            final Pair<Integer, Integer> entry = countForUidList.get(j);
+            pw.print(entry.first);
+            pw.print("=");
+            pw.println(entry.second);
+        }
+        pw.decreaseIndent();
+    }
 }

service-t/src/com/android/server/net/NetworkStatsService.java

@@ -3228,6 +3228,12 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
             pw.increaseIndent();
             mSkDestroyListener.dump(pw);
             pw.decreaseIndent();
+
+            pw.println();
+            pw.println("NetworkStatsFactory logs:");
+            pw.increaseIndent();
+            mStatsFactory.dump(pw);
+            pw.decreaseIndent();
         }
     }