Poll UID stats during iface changes, enforce idx.

When ifaces change, poll UID stats without persisting, since they
depend on knowing active iface to store correctly.  Log dropped UID
stats when iface is unknown.  Switch to using flags when calling
performPoll().

Enforce that "idx" values are consistent from xt_qtaguid.  Transition
to using Log.wtf() for important checks, mostly around file I/O,
kernel stats parsing, and kernel module control.  Increase stats
persist threshold to 2MB to reduce churn.

Bug: 5269476, 5270106
Change-Id: I721215bfb65127f95775c71cf135e907cd567e92

3 files changed, 127 insertions, 141 deletions

diff --git a/services/java/com/android/server/NetworkManagementService.java b/services/java/com/android/server/NetworkManagementService.java
index 1497511..f774dea 100644
--- a/services/java/com/android/server/NetworkManagementService.java
+++ b/services/java/com/android/server/NetworkManagementService.java
@@ -98,6 +98,7 @@ public class NetworkManagementService extends INetworkManagementService.Stub
     public static final String LIMIT_GLOBAL_ALERT = "globalAlert";
 
     /** {@link #mStatsXtUid} headers. */
+    private static final String KEY_IDX = "idx";
     private static final String KEY_IFACE = "iface";
     private static final String KEY_UID = "uid_tag_int";
     private static final String KEY_COUNTER_SET = "cnt_set";
@@ -1323,17 +1324,20 @@ public class NetworkManagementService extends INetworkManagementService.Stub
 
         // TODO: remove knownLines check once 5087722 verified
         final HashSet<String> knownLines = Sets.newHashSet();
+        // TODO: remove lastIdx check once 5270106 verified
+        int lastIdx = 0;
 
         final ArrayList<String> keys = Lists.newArrayList();
         final ArrayList<String> values = Lists.newArrayList();
         final HashMap<String, String> parsed = Maps.newHashMap();
 
         BufferedReader reader = null;
+        String line = null;
         try {
             reader = new BufferedReader(new FileReader(mStatsXtUid));
 
             // parse first line as header
-            String line = reader.readLine();
+            line = reader.readLine();
             splitLine(line, keys);
 
             // parse remaining lines
@@ -1342,32 +1346,35 @@ public class NetworkManagementService extends INetworkManagementService.Stub
                 parseLine(keys, values, parsed);
 
                 if (!knownLines.add(line)) {
-                    throw new IllegalStateException("encountered duplicate proc entry");
+                    throw new IllegalStateException("duplicate proc entry: " + line);
                 }
 
-                try {
-                    entry.iface = parsed.get(KEY_IFACE);
-                    entry.uid = getParsedInt(parsed, KEY_UID);
-                    entry.set = getParsedInt(parsed, KEY_COUNTER_SET);
-                    entry.tag = kernelToTag(parsed.get(KEY_TAG_HEX));
-                    entry.rxBytes = getParsedLong(parsed, KEY_RX_BYTES);
-                    entry.rxPackets = getParsedLong(parsed, KEY_RX_PACKETS);
-                    entry.txBytes = getParsedLong(parsed, KEY_TX_BYTES);
-                    entry.txPackets = getParsedLong(parsed, KEY_TX_PACKETS);
-
-                    if (limitUid == UID_ALL || limitUid == entry.uid) {
-                        stats.addValues(entry);
-                    }
-                } catch (NumberFormatException e) {
-                    Slog.w(TAG, "problem parsing stats row '" + line + "': " + e);
+                final int idx = getParsedInt(parsed, KEY_IDX);
+                if (idx > lastIdx + 1) {
+                    throw new IllegalStateException(
+                            "inconsistent idx=" + idx + " after lastIdx=" + lastIdx);
+                }
+                lastIdx = idx;
+
+                entry.iface = parsed.get(KEY_IFACE);
+                entry.uid = getParsedInt(parsed, KEY_UID);
+                entry.set = getParsedInt(parsed, KEY_COUNTER_SET);
+                entry.tag = kernelToTag(parsed.get(KEY_TAG_HEX));
+                entry.rxBytes = getParsedLong(parsed, KEY_RX_BYTES);
+                entry.rxPackets = getParsedLong(parsed, KEY_RX_PACKETS);
+                entry.txBytes = getParsedLong(parsed, KEY_TX_BYTES);
+                entry.txPackets = getParsedLong(parsed, KEY_TX_PACKETS);
+
+                if (limitUid == UID_ALL || limitUid == entry.uid) {
+                    stats.addValues(entry);
                 }
             }
         } catch (NullPointerException e) {
-            throw new IllegalStateException("problem parsing stats: " + e);
+            throw new IllegalStateException("problem parsing line: " + line, e);
         } catch (NumberFormatException e) {
-            throw new IllegalStateException("problem parsing stats: " + e);
+            throw new IllegalStateException("problem parsing line: " + line, e);
         } catch (IOException e) {
-            throw new IllegalStateException("problem parsing stats: " + e);
+            throw new IllegalStateException("problem parsing line: " + line, e);
         } finally {
             IoUtils.closeQuietly(reader);
         }
diff --git a/services/java/com/android/server/net/NetworkPolicyManagerService.java b/services/java/com/android/server/net/NetworkPolicyManagerService.java
index 8af90ff..9067fae 100644
--- a/services/java/com/android/server/net/NetworkPolicyManagerService.java
+++ b/services/java/com/android/server/net/NetworkPolicyManagerService.java
@@ -100,6 +100,7 @@ import android.provider.Settings;
 import android.telephony.TelephonyManager;
 import android.text.format.Formatter;
 import android.text.format.Time;
+import android.util.Log;
 import android.util.NtpTrustedTime;
 import android.util.Slog;
 import android.util.SparseArray;
@@ -298,18 +299,9 @@ public class NetworkPolicyManagerService extends INetworkPolicyManager.Stub {
 
         try {
             mActivityManager.registerProcessObserver(mProcessObserver);
-        } catch (RemoteException e) {
-            // ouch, no foregroundActivities updates means some processes may
-            // never get network access.
-            Slog.e(TAG, "unable to register IProcessObserver", e);
-        }
-
-        try {
             mNetworkManager.registerObserver(mAlertObserver);
         } catch (RemoteException e) {
-            // ouch, no alert updates means we fall back to
-            // ACTION_NETWORK_STATS_UPDATED broadcasts.
-            Slog.e(TAG, "unable to register INetworkManagementEventObserver", e);
+            // ignored; both services live in system_server
         }
 
         // TODO: traverse existing processes to know foreground state, or have
@@ -462,7 +454,7 @@ public class NetworkPolicyManagerService extends INetworkPolicyManager.Stub {
                         // caused alert to trigger.
                         mNetworkStats.forceUpdate();
                     } catch (RemoteException e) {
-                        Slog.w(TAG, "problem updating network stats");
+                        // ignored; service lives in system_server
                     }
 
                     updateNetworkEnabledLocked();
@@ -495,9 +487,7 @@ public class NetworkPolicyManagerService extends INetworkPolicyManager.Stub {
 
             final long start = computeLastCycleBoundary(currentTime, policy);
             final long end = currentTime;
-
             final long totalBytes = getTotalBytes(policy.template, start, end);
-            if (totalBytes == UNKNOWN_BYTES) continue;
 
             if (policy.limitBytes != LIMIT_DISABLED && totalBytes >= policy.limitBytes) {
                 if (policy.lastSnooze >= start) {
@@ -671,7 +661,7 @@ public class NetworkPolicyManagerService extends INetworkPolicyManager.Stub {
                     packageName, tag, 0x0, builder.getNotification(), idReceived);
             mActiveNotifs.add(tag);
         } catch (RemoteException e) {
-            Slog.w(TAG, "problem during enqueueNotification: " + e);
+            // ignored; service lives in system_server
         }
     }
 
@@ -705,7 +695,7 @@ public class NetworkPolicyManagerService extends INetworkPolicyManager.Stub {
                     0x0, builder.getNotification(), idReceived);
             mActiveNotifs.add(tag);
         } catch (RemoteException e) {
-            Slog.w(TAG, "problem during enqueueNotification: " + e);
+            // ignored; service lives in system_server
         }
     }
 
@@ -716,7 +706,7 @@ public class NetworkPolicyManagerService extends INetworkPolicyManager.Stub {
             mNotifManager.cancelNotificationWithTag(
                     packageName, tag, 0x0);
         } catch (RemoteException e) {
-            Slog.w(TAG, "problem during enqueueNotification: " + e);
+            // ignored; service lives in system_server
         }
     }
 
@@ -758,9 +748,7 @@ public class NetworkPolicyManagerService extends INetworkPolicyManager.Stub {
 
             final long start = computeLastCycleBoundary(currentTime, policy);
             final long end = currentTime;
-
             final long totalBytes = getTotalBytes(policy.template, start, end);
-            if (totalBytes == UNKNOWN_BYTES) continue;
 
             // disable data connection when over limit and not snoozed
             final boolean overLimit = policy.limitBytes != LIMIT_DISABLED
@@ -810,7 +798,7 @@ public class NetworkPolicyManagerService extends INetworkPolicyManager.Stub {
         try {
             states = mConnManager.getAllNetworkState();
         } catch (RemoteException e) {
-            Slog.w(TAG, "problem reading network state");
+            // ignored; service lives in system_server
             return;
         }
 
@@ -857,9 +845,7 @@ public class NetworkPolicyManagerService extends INetworkPolicyManager.Stub {
 
             final long start = computeLastCycleBoundary(currentTime, policy);
             final long end = currentTime;
-
             final long totalBytes = getTotalBytes(policy.template, start, end);
-            if (totalBytes == UNKNOWN_BYTES) continue;
 
             if (LOGD) {
                 Slog.d(TAG, "applying policy " + policy.toString() + " to ifaces "
@@ -1006,9 +992,9 @@ public class NetworkPolicyManagerService extends INetworkPolicyManager.Stub {
             // missing policy is okay, probably first boot
             upgradeLegacyBackgroundData();
         } catch (IOException e) {
-            Slog.e(TAG, "problem reading network stats", e);
+            Log.wtf(TAG, "problem reading network policy", e);
         } catch (XmlPullParserException e) {
-            Slog.e(TAG, "problem reading network stats", e);
+            Log.wtf(TAG, "problem reading network policy", e);
         } finally {
             IoUtils.closeQuietly(fis);
         }
@@ -1246,12 +1232,10 @@ public class NetworkPolicyManagerService extends INetworkPolicyManager.Stub {
 
         final long currentTime = currentTimeMillis(false);
 
+        // find total bytes used under policy
         final long start = computeLastCycleBoundary(currentTime, policy);
         final long end = currentTime;
-
-        // find total bytes used under policy
         final long totalBytes = getTotalBytes(policy.template, start, end);
-        if (totalBytes == UNKNOWN_BYTES) return null;
 
         // report soft and hard limits under policy
         final long softLimitBytes = policy.warningBytes != WARNING_DISABLED ? policy.warningBytes
@@ -1369,6 +1353,7 @@ public class NetworkPolicyManagerService extends INetworkPolicyManager.Stub {
             try {
                 mScreenOn = mPowerManager.isScreenOn();
             } catch (RemoteException e) {
+                // ignored; service lives in system_server
             }
             updateRulesForScreenLocked();
         }
@@ -1448,7 +1433,7 @@ public class NetworkPolicyManagerService extends INetworkPolicyManager.Stub {
             // adjust stats accounting based on foreground status
             mNetworkStats.setUidForeground(uid, uidForeground);
         } catch (RemoteException e) {
-            Slog.w(TAG, "problem dispatching foreground change");
+            // ignored; service lives in system_server
         }
     }
 
@@ -1498,9 +1483,9 @@ public class NetworkPolicyManagerService extends INetworkPolicyManager.Stub {
         try {
             mNetworkManager.setInterfaceQuota(iface, quotaBytes);
         } catch (IllegalStateException e) {
-            Slog.e(TAG, "problem setting interface quota", e);
+            Log.wtf(TAG, "problem setting interface quota", e);
         } catch (RemoteException e) {
-            Slog.e(TAG, "problem setting interface quota", e);
+            // ignored; service lives in system_server
         }
     }
 
@@ -1508,29 +1493,9 @@ public class NetworkPolicyManagerService extends INetworkPolicyManager.Stub {
         try {
             mNetworkManager.removeInterfaceQuota(iface);
         } catch (IllegalStateException e) {
-            Slog.e(TAG, "problem removing interface quota", e);
+            Log.wtf(TAG, "problem removing interface quota", e);
         } catch (RemoteException e) {
-            Slog.e(TAG, "problem removing interface quota", e);
-        }
-    }
-
-    private void setInterfaceAlert(String iface, long alertBytes) {
-        try {
-            mNetworkManager.setInterfaceAlert(iface, alertBytes);
-        } catch (IllegalStateException e) {
-            Slog.e(TAG, "problem setting interface alert", e);
-        } catch (RemoteException e) {
-            Slog.e(TAG, "problem setting interface alert", e);
-        }
-    }
-
-    private void removeInterfaceAlert(String iface) {
-        try {
-            mNetworkManager.removeInterfaceAlert(iface);
-        } catch (IllegalStateException e) {
-            Slog.e(TAG, "problem removing interface alert", e);
-        } catch (RemoteException e) {
-            Slog.e(TAG, "problem removing interface alert", e);
+            // ignored; service lives in system_server
         }
     }
 
@@ -1538,9 +1503,9 @@ public class NetworkPolicyManagerService extends INetworkPolicyManager.Stub {
         try {
             mNetworkManager.setUidNetworkRules(uid, rejectOnQuotaInterfaces);
         } catch (IllegalStateException e) {
-            Slog.e(TAG, "problem setting uid rules", e);
+            Log.wtf(TAG, "problem setting uid rules", e);
         } catch (RemoteException e) {
-            Slog.e(TAG, "problem setting uid rules", e);
+            // ignored; service lives in system_server
         }
     }
 
@@ -1556,7 +1521,7 @@ public class NetworkPolicyManagerService extends INetworkPolicyManager.Stub {
             try {
                 mConnManager.setPolicyDataEnable(networkType, enabled);
             } catch (RemoteException e) {
-                Slog.e(TAG, "problem setting network enabled", e);
+                // ignored; service lives in system_server
             }
 
             mActiveNetworkEnabled.put(networkType, enabled);
@@ -1569,8 +1534,6 @@ public class NetworkPolicyManagerService extends INetworkPolicyManager.Stub {
         return telephony.getSubscriberId();
     }
 
-    private static final long UNKNOWN_BYTES = -1;
-
     private long getTotalBytes(NetworkTemplate template, long start, long end) {
         try {
             final NetworkStats stats = mNetworkStats.getSummaryForNetwork(
@@ -1578,8 +1541,8 @@ public class NetworkPolicyManagerService extends INetworkPolicyManager.Stub {
             final NetworkStats.Entry entry = stats.getValues(0, null);
             return entry.rxBytes + entry.txBytes;
         } catch (RemoteException e) {
-            Slog.w(TAG, "problem reading summary for template " + template);
-            return UNKNOWN_BYTES;
+            // ignored; service lives in system_server
+            return 0;
         }
     }
 
diff --git a/services/java/com/android/server/net/NetworkStatsService.java b/services/java/com/android/server/net/NetworkStatsService.java
index 4d54fd4..af29d85 100644
--- a/services/java/com/android/server/net/NetworkStatsService.java
+++ b/services/java/com/android/server/net/NetworkStatsService.java
@@ -79,6 +79,7 @@ import android.os.SystemClock;
 import android.provider.Settings;
 import android.telephony.TelephonyManager;
 import android.util.EventLog;
+import android.util.Log;
 import android.util.NtpTrustedTime;
 import android.util.Slog;
 import android.util.SparseIntArray;
@@ -128,7 +129,16 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
     private static final int VERSION_UID_WITH_SET = 4;
 
     private static final int MSG_PERFORM_POLL = 0x1;
-    private static final int MSG_PERFORM_POLL_DETAILED = 0x2;
+
+    /** Flags to control detail level of poll event. */
+    private static final int FLAG_POLL_NETWORK = 0x1;
+    private static final int FLAG_POLL_UID = 0x2;
+    private static final int FLAG_PERSIST_NETWORK = 0x10;
+    private static final int FLAG_PERSIST_UID = 0x20;
+    private static final int FLAG_FORCE_PERSIST = 0x100;
+
+    private static final int FLAG_POLL_ALL = FLAG_POLL_NETWORK | FLAG_POLL_UID;
+    private static final int FLAG_PERSIST_ALL = FLAG_PERSIST_NETWORK | FLAG_PERSIST_UID;
 
     private final Context mContext;
     private final INetworkManagementService mNetworkManager;
@@ -261,9 +271,7 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
         try {
             mNetworkManager.registerObserver(mAlertObserver);
         } catch (RemoteException e) {
-            // ouch, no push updates means we fall back to
-            // ACTION_NETWORK_STATS_POLL intervals.
-            Slog.e(TAG, "unable to register INetworkManagementEventObserver", e);
+            // ignored; service lives in system_server
         }
 
         registerPollAlarmLocked();
@@ -305,7 +313,7 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
             mAlarmManager.setInexactRepeating(AlarmManager.ELAPSED_REALTIME, currentRealtime,
                     mSettings.getPollInterval(), mPollIntent);
         } catch (RemoteException e) {
-            Slog.w(TAG, "problem registering for poll alarm: " + e);
+            // ignored; service lives in system_server
         }
     }
 
@@ -321,7 +329,7 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
         } catch (IllegalStateException e) {
             Slog.w(TAG, "problem registering for global alert: " + e);
         } catch (RemoteException e) {
-            Slog.w(TAG, "problem registering for global alert: " + e);
+            // ignored; service lives in system_server
         }
     }
 
@@ -509,7 +517,7 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
     @Override
     public void forceUpdate() {
         mContext.enforceCallingOrSelfPermission(READ_NETWORK_USAGE_HISTORY, TAG);
-        performPoll(true, false);
+        performPoll(FLAG_POLL_ALL | FLAG_PERSIST_ALL);
     }
 
     /**
@@ -538,7 +546,7 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
         public void onReceive(Context context, Intent intent) {
             // on background handler thread, and verified UPDATE_DEVICE_STATS
             // permission above.
-            performPoll(true, false);
+            performPoll(FLAG_POLL_ALL | FLAG_PERSIST_ALL);
 
             // verify that we're watching global alert
             registerGlobalAlert();
@@ -585,7 +593,8 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
             if (LIMIT_GLOBAL_ALERT.equals(limitName)) {
                 // kick off background poll to collect network stats; UID stats
                 // are handled during normal polling interval.
-                mHandler.obtainMessage(MSG_PERFORM_POLL).sendToTarget();
+                final int flags = FLAG_POLL_NETWORK | FLAG_PERSIST_NETWORK;
+                mHandler.obtainMessage(MSG_PERFORM_POLL, flags, 0).sendToTarget();
 
                 // re-arm global alert for next update
                 registerGlobalAlert();
@@ -605,13 +614,17 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
         // take one last stats snapshot before updating iface mapping. this
         // isn't perfect, since the kernel may already be counting traffic from
         // the updated network.
-        performPollLocked(false, false);
+
+        // poll both network and UID stats, but only persist network stats,
+        // since this codepath should stay fast. UID stats will be persisted
+        // during next alarm poll event.
+        performPollLocked(FLAG_POLL_ALL | FLAG_PERSIST_NETWORK);
 
         final NetworkState[] states;
         try {
             states = mConnManager.getAllNetworkState();
         } catch (RemoteException e) {
-            Slog.w(TAG, "problem reading network state");
+            // ignored; service lives in system_server
             return;
         }
 
@@ -646,15 +659,15 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
         } catch (IllegalStateException e) {
             Slog.w(TAG, "problem reading network stats: " + e);
         } catch (RemoteException e) {
-            Slog.w(TAG, "problem reading network stats: " + e);
+            // ignored; service lives in system_server
         }
     }
 
-    private void performPoll(boolean detailedPoll, boolean forcePersist) {
+    private void performPoll(int flags) {
         synchronized (mStatsLock) {
             mWakeLock.acquire();
             try {
-                performPollLocked(detailedPoll, forcePersist);
+                performPollLocked(flags);
             } finally {
                 mWakeLock.release();
             }
@@ -664,14 +677,17 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
     /**
      * Periodic poll operation, reading current statistics and recording into
      * {@link NetworkStatsHistory}.
-     *
-     * @param detailedPoll Indicate if detailed UID stats should be collected
-     *            during this poll operation.
      */
-    private void performPollLocked(boolean detailedPoll, boolean forcePersist) {
-        if (LOGV) Slog.v(TAG, "performPollLocked()");
+    private void performPollLocked(int flags) {
+        if (LOGV) Slog.v(TAG, "performPollLocked(flags=0x" + Integer.toHexString(flags) + ")");
         final long startRealtime = SystemClock.elapsedRealtime();
 
+        final boolean pollNetwork = (flags & FLAG_POLL_NETWORK) != 0;
+        final boolean pollUid = (flags & FLAG_POLL_UID) != 0;
+        final boolean persistNetwork = (flags & FLAG_PERSIST_NETWORK) != 0;
+        final boolean persistUid = (flags & FLAG_PERSIST_UID) != 0;
+        final boolean forcePersist = (flags & FLAG_FORCE_PERSIST) != 0;
+
         // try refreshing time source when stale
         if (mTime.getCacheAge() > mSettings.getTimeCacheMaxAge()) {
             mTime.forceRefresh();
@@ -680,41 +696,40 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
         // TODO: consider marking "untrusted" times in historical stats
         final long currentTime = mTime.hasCache() ? mTime.currentTimeMillis()
                 : System.currentTimeMillis();
-        final long persistThreshold = mSettings.getPersistThreshold();
+        final long threshold = mSettings.getPersistThreshold();
 
-        final NetworkStats networkSnapshot;
-        final NetworkStats uidSnapshot;
         try {
-            networkSnapshot = mNetworkManager.getNetworkStatsSummary();
-            uidSnapshot = detailedPoll ? mNetworkManager.getNetworkStatsUidDetail(UID_ALL) : null;
-        } catch (IllegalStateException e) {
-            Slog.w(TAG, "problem reading network stats: " + e);
-            return;
-        } catch (RemoteException e) {
-            Slog.w(TAG, "problem reading network stats: " + e);
-            return;
-        }
-
-        performNetworkPollLocked(networkSnapshot, currentTime);
-
-        // persist when enough network data has occurred
-        final NetworkStats persistNetworkDelta = computeStatsDelta(
-                mLastPersistNetworkSnapshot, networkSnapshot, true);
-        if (forcePersist || persistNetworkDelta.getTotalBytes() > persistThreshold) {
-            writeNetworkStatsLocked();
-            mLastPersistNetworkSnapshot = networkSnapshot;
-        }
-
-        if (detailedPoll) {
-            performUidPollLocked(uidSnapshot, currentTime);
+            if (pollNetwork) {
+                final NetworkStats networkSnapshot = mNetworkManager.getNetworkStatsSummary();
+                performNetworkPollLocked(networkSnapshot, currentTime);
+
+                // persist when enough network data has occurred
+                final NetworkStats persistNetworkDelta = computeStatsDelta(
+                        mLastPersistNetworkSnapshot, networkSnapshot, true);
+                final boolean pastThreshold = persistNetworkDelta.getTotalBytes() > threshold;
+                if (forcePersist || (persistNetwork && pastThreshold)) {
+                    writeNetworkStatsLocked();
+                    mLastPersistNetworkSnapshot = networkSnapshot;
+                }
+            }
 
-            // persist when enough network data has occurred
-            final NetworkStats persistUidDelta = computeStatsDelta(
-                    mLastPersistUidSnapshot, uidSnapshot, true);
-            if (forcePersist || persistUidDelta.getTotalBytes() > persistThreshold) {
-                writeUidStatsLocked();
-                mLastPersistUidSnapshot = networkSnapshot;
+            if (pollUid) {
+                final NetworkStats uidSnapshot = mNetworkManager.getNetworkStatsUidDetail(UID_ALL);
+                performUidPollLocked(uidSnapshot, currentTime);
+
+                // persist when enough network data has occurred
+                final NetworkStats persistUidDelta = computeStatsDelta(
+                        mLastPersistUidSnapshot, uidSnapshot, true);
+                final boolean pastThreshold = persistUidDelta.getTotalBytes() > threshold;
+                if (forcePersist || (persistUid && pastThreshold)) {
+                    writeUidStatsLocked();
+                    mLastPersistUidSnapshot = uidSnapshot;
+                }
             }
+        } catch (IllegalStateException e) {
+            Log.wtf(TAG, "problem reading network stats", e);
+        } catch (RemoteException e) {
+            // ignored; service lives in system_server
         }
 
         if (LOGV) {
@@ -722,8 +737,8 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
             Slog.v(TAG, "performPollLocked() took " + duration + "ms");
         }
 
-        // sample stats after detailed poll
-        if (detailedPoll) {
+        // sample stats after each full poll
+        if (pollNetwork && pollUid) {
             performSample();
         }
 
@@ -785,6 +800,10 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
             entry = delta.getValues(i, entry);
             final NetworkIdentitySet ident = mActiveIfaces.get(entry.iface);
             if (ident == null) {
+                if (entry.rxBytes > 0 || entry.rxPackets > 0 || entry.txBytes > 0
+                        || entry.txPackets > 0) {
+                    Log.w(TAG, "dropping UID delta from unknown iface: " + entry);
+                }
                 continue;
             }
 
@@ -959,7 +978,7 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
         } catch (FileNotFoundException e) {
             // missing stats is okay, probably first boot
         } catch (IOException e) {
-            Slog.e(TAG, "problem reading network stats", e);
+            Log.wtf(TAG, "problem reading network stats", e);
         } finally {
             IoUtils.closeQuietly(in);
         }
@@ -1032,7 +1051,7 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
         } catch (FileNotFoundException e) {
             // missing stats is okay, probably first boot
         } catch (IOException e) {
-            Slog.e(TAG, "problem reading uid stats", e);
+            Log.wtf(TAG, "problem reading uid stats", e);
         } finally {
             IoUtils.closeQuietly(in);
         }
@@ -1061,7 +1080,7 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
             out.flush();
             mNetworkFile.finishWrite(fos);
         } catch (IOException e) {
-            Slog.w(TAG, "problem writing stats: ", e);
+            Log.wtf(TAG, "problem writing stats", e);
             if (fos != null) {
                 mNetworkFile.failWrite(fos);
             }
@@ -1115,7 +1134,7 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
             out.flush();
             mUidFile.finishWrite(fos);
         } catch (IOException e) {
-            Slog.w(TAG, "problem writing stats: ", e);
+            Log.wtf(TAG, "problem writing stats", e);
             if (fos != null) {
                 mUidFile.failWrite(fos);
             }
@@ -1142,7 +1161,7 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
             }
 
             if (argSet.contains("poll")) {
-                performPollLocked(true, true);
+                performPollLocked(FLAG_POLL_ALL | FLAG_PERSIST_ALL | FLAG_FORCE_PERSIST);
                 pw.println("Forced poll");
                 return;
             }
@@ -1273,11 +1292,8 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
         public boolean handleMessage(Message msg) {
             switch (msg.what) {
                 case MSG_PERFORM_POLL: {
-                    performPoll(false, false);
-                    return true;
-                }
-                case MSG_PERFORM_POLL_DETAILED: {
-                    performPoll(true, false);
+                    final int flags = msg.arg1;
+                    performPoll(flags);
                     return true;
                 }
                 default: {
@@ -1349,7 +1365,7 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
             return getSecureLong(NETSTATS_POLL_INTERVAL, 30 * MINUTE_IN_MILLIS);
         }
         public long getPersistThreshold() {
-            return getSecureLong(NETSTATS_PERSIST_THRESHOLD, 512 * KB_IN_BYTES);
+            return getSecureLong(NETSTATS_PERSIST_THRESHOLD, 2 * MB_IN_BYTES);
         }
         public long getNetworkBucketDuration() {
             return getSecureLong(NETSTATS_NETWORK_BUCKET_DURATION, HOUR_IN_MILLIS);