Revert "NetworkStatsService: Fix getDetailedUidStats to take VPNs into account."

This reverts commit 8481d9d55d.

Reason for revert: This change has been implicated in 4-way deadlocks as seen in b/134244752.

Bug: 134244752
Change-Id: I0c00e8f0e30cee987b71b561079a97bf09d4dae4

core/java/android/net/NetworkStats.java

@@ -34,7 +34,6 @@ import libcore.util.EmptyArray;
 import java.io.CharArrayWriter;
 import java.io.PrintWriter;
 import java.util.Arrays;
-import java.util.function.Predicate;
 import java.util.HashSet;
 import java.util.Map;
 import java.util.Objects;
@@ -995,33 +994,23 @@ public class NetworkStats implements Parcelable {
         if (limitUid == UID_ALL && limitTag == TAG_ALL && limitIfaces == INTERFACES_ALL) {
             return;
         }
-        filter(e -> (limitUid == UID_ALL || limitUid == e.uid)
-            && (limitTag == TAG_ALL || limitTag == e.tag)
-            && (limitIfaces == INTERFACES_ALL
-                    || ArrayUtils.contains(limitIfaces, e.iface)));
-    }
 
-    /**
-     * Only keep entries with {@link #set} value less than {@link #SET_DEBUG_START}.
-     *
-     * <p>This mutates the original structure in place.
-     */
-    public void filterDebugEntries() {
-        filter(e -> e.set < SET_DEBUG_START);
-    }
-
-    private void filter(Predicate<Entry> predicate) {
         Entry entry = new Entry();
         int nextOutputEntry = 0;
         for (int i = 0; i < size; i++) {
             entry = getValues(i, entry);
-            if (predicate.test(entry)) {
+            final boolean matches =
-                if (nextOutputEntry != i) {
+                    (limitUid == UID_ALL || limitUid == entry.uid)
-                    setValues(nextOutputEntry, entry);
+                    && (limitTag == TAG_ALL || limitTag == entry.tag)
-                }
+                    && (limitIfaces == INTERFACES_ALL
+                            || ArrayUtils.contains(limitIfaces, entry.iface));
+
+            if (matches) {
+                setValues(nextOutputEntry, entry);
                 nextOutputEntry++;
             }
         }
+
         size = nextOutputEntry;
     }
 

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

@@ -263,10 +263,6 @@ public class NetworkStatsFactory {
         return stats;
     }
 
-    /**
-     * @deprecated Use NetworkStatsService#getDetailedUidStats which also accounts for
-     * VPN traffic
-     */
     public NetworkStats readNetworkStatsDetail() throws IOException {
         return readNetworkStatsDetail(UID_ALL, null, TAG_ALL, null);
     }

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

@@ -293,22 +293,6 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
     /** Data layer operation counters for splicing into other structures. */
     private NetworkStats mUidOperations = new NetworkStats(0L, 10);
 
-    /**
-     * Snapshot containing most recent network stats for all UIDs across all interfaces and tags
-     * since boot.
-     *
-     * <p>Maintains migrated VPN stats which are result of performing TUN migration on {@link
-     * #mLastUidDetailSnapshot}.
-     */
-    @GuardedBy("mStatsLock")
-    private NetworkStats mTunAdjustedStats;
-    /**
-     * Used by {@link #mTunAdjustedStats} to migrate VPN traffic over delta between this snapshot
-     * and latest snapshot.
-     */
-    @GuardedBy("mStatsLock")
-    private NetworkStats mLastUidDetailSnapshot;
-
     /** Must be set in factory by calling #setHandler. */
     private Handler mHandler;
     private Handler.Callback mHandlerCallback;
@@ -828,39 +812,15 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
     @Override
     public NetworkStats getDetailedUidStats(String[] requiredIfaces) {
         try {
-            // Get the latest snapshot from NetworkStatsFactory.
-            // TODO: Querying for INTERFACES_ALL may incur performance penalty. Consider restricting
-            // this to limited set of ifaces.
-            NetworkStats uidDetailStats = getNetworkStatsUidDetail(INTERFACES_ALL);
-
-            // Migrate traffic from VPN UID over delta and update mTunAdjustedStats.
-            NetworkStats result;
-            synchronized (mStatsLock) {
-                migrateTunTraffic(uidDetailStats, mVpnInfos);
-                result = mTunAdjustedStats.clone();
-            }
-
-            // Apply filter based on ifacesToQuery.
             final String[] ifacesToQuery =
                     NetworkStatsFactory.augmentWithStackedInterfaces(requiredIfaces);
-            result.filter(UID_ALL, ifacesToQuery, TAG_ALL);
+            return getNetworkStatsUidDetail(ifacesToQuery);
-            return result;
         } catch (RemoteException e) {
             Log.wtf(TAG, "Error compiling UID stats", e);
             return new NetworkStats(0L, 0);
         }
     }
 
-    @VisibleForTesting
-    NetworkStats getTunAdjustedStats() {
-        synchronized (mStatsLock) {
-            if (mTunAdjustedStats == null) {
-                return null;
-            }
-            return mTunAdjustedStats.clone();
-        }
-    }
-
     @Override
     public String[] getMobileIfaces() {
         return mMobileIfaces;
@@ -1335,34 +1295,6 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
         // a race condition between the service handler thread and the observer's
         mStatsObservers.updateStats(xtSnapshot, uidSnapshot, new ArrayMap<>(mActiveIfaces),
                 new ArrayMap<>(mActiveUidIfaces), vpnArray, currentTime);
-
-        migrateTunTraffic(uidSnapshot, vpnArray);
-    }
-
-    /**
-     * Updates {@link #mTunAdjustedStats} with the delta containing traffic migrated off of VPNs.
-     */
-    @GuardedBy("mStatsLock")
-    private void migrateTunTraffic(NetworkStats uidDetailStats, VpnInfo[] vpnInfoArray) {
-        if (mTunAdjustedStats == null) {
-            // Either device booted or system server restarted, hence traffic cannot be migrated
-            // correctly without knowing the past state of VPN's underlying networks.
-            mTunAdjustedStats = uidDetailStats;
-            mLastUidDetailSnapshot = uidDetailStats;
-            return;
-        }
-        // Migrate delta traffic from VPN to other apps.
-        NetworkStats delta = uidDetailStats.subtract(mLastUidDetailSnapshot);
-        for (VpnInfo info : vpnInfoArray) {
-            delta.migrateTun(info.ownerUid, info.vpnIface, info.underlyingIfaces);
-        }
-        // Filter out debug entries as that may lead to over counting.
-        delta.filterDebugEntries();
-        // Update #mTunAdjustedStats with migrated delta.
-        mTunAdjustedStats.combineAllValues(delta);
-        mTunAdjustedStats.setElapsedRealtime(uidDetailStats.getElapsedRealtime());
-        // Update last snapshot.
-        mLastUidDetailSnapshot = uidDetailStats;
     }
 
     /**