Add UMA to measure NPEs coming from Android Wifi/Connectivity services

net/android/java/src/org/chromium/net/NetworkChangeNotifierAutoDetect.java

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package org.chromium.net;
 
 import static android.net.ConnectivityManager.TYPE_VPN;
 import static android.net.NetworkCapabilities.NET_CAPABILITY_INTERNET;
 import static android.net.NetworkCapabilities.NET_CAPABILITY_NOT_VPN;
 import static android.net.NetworkCapabilities.TRANSPORT_VPN;
@@ skipping 12 matching lines @@
 import android.net.NetworkInfo;
 import android.net.NetworkRequest;
 import android.net.wifi.WifiInfo;
 import android.net.wifi.WifiManager;
 import android.os.Build;
 import android.telephony.TelephonyManager;
 import android.util.Log;
 
 import org.chromium.base.ThreadUtils;
 import org.chromium.base.VisibleForTesting;
+import org.chromium.base.metrics.RecordHistogram;
 
 import java.io.IOException;
 import java.util.Arrays;
 
 /**
  * Used by the NetworkChangeNotifier to listens to platform changes in connectivity.
  * Note that use of this class requires that the app have the platform
  * ACCESS_NETWORK_STATE permission.
  */
 public class NetworkChangeNotifierAutoDetect extends BroadcastReceiver {
@@ skipping 37 matching lines @@
         }
 
         /**
          * Returns connection type and status information about the current
          * default network.
          */
         NetworkState getNetworkState() {
             return getNetworkState(mConnectivityManager.getActiveNetworkInfo());
         }
 
+        // Fetch NetworkInfo and record UMA for NPEs.

[xunjieli, 2016/06/14 13:55:06]

nit: s/Fetch/Fetches. Maybe also spell out NPE. 

[pauljensen, 2016/06/14 13:59:03]

Done.

+        private NetworkInfo getNetworkInfo(Network network) {
+            try {
+                NetworkInfo networkInfo = mConnectivityManager.getNetworkInfo(network);
+                RecordHistogram.recordBooleanHistogram("NCN.getNetInfo1stSuccess", true);
+                return networkInfo;
+            } catch (NullPointerException firstException) {
+                RecordHistogram.recordBooleanHistogram("NCN.getNetInfo1stSuccess", false);
+                try {
+                    NetworkInfo networkInfo = mConnectivityManager.getNetworkInfo(network);

[xunjieli, 2016/06/14 13:55:06]

Why do we do getNetworkInfo twice?

[pauljensen, 2016/06/14 13:59:03]

To see if trying again might be a viable solution.  The idea is to test if the
NPE is a random/transient/ephemeral failure.

[xunjieli, 2016/06/14 14:10:50]

I see. Could you make a quick comment here and below in getWifiInfo?

[pauljensen, 2016/06/14 14:59:41]

Done.

+                    RecordHistogram.recordBooleanHistogram("NCN.getNetInfo2ndSuccess", true);
+                    return networkInfo;
+                } catch (NullPointerException secondException) {
+                    RecordHistogram.recordBooleanHistogram("NCN.getNetInfo2ndSuccess", false);
+                    throw secondException;
+                }
+            }
+        }
+
         /**
          * Returns connection type and status information about |network|.
          * Only callable on Lollipop and newer releases.
          */
         @TargetApi(Build.VERSION_CODES.LOLLIPOP)
         NetworkState getNetworkState(Network network) {
-            final NetworkInfo networkInfo = mConnectivityManager.getNetworkInfo(network);
+            final NetworkInfo networkInfo = getNetworkInfo(network);
             if (networkInfo != null && networkInfo.getType() == TYPE_VPN) {
                 // When a VPN is in place the underlying network type can be queried via
                 // getActiveNeworkInfo() thanks to
                 // https://android.googlesource.com/platform/frameworks/base/+/d6a7980d
                 return getNetworkState();
             }
             return getNetworkState(networkInfo);
         }
 
         /**
@@ skipping 77 matching lines @@
             // API to return the NetworkInfo for the default network. To
             // determine the default network one can find the network with
             // type matching that of the default network.
             final NetworkInfo defaultNetworkInfo = mConnectivityManager.getActiveNetworkInfo();
             if (defaultNetworkInfo == null) {
                 return NetId.INVALID;
             }
             final Network[] networks = getAllNetworksFiltered(this, null);
             int defaultNetId = NetId.INVALID;
             for (Network network : networks) {
-                final NetworkInfo networkInfo = mConnectivityManager.getNetworkInfo(network);
+                final NetworkInfo networkInfo = getNetworkInfo(network);
                 if (networkInfo != null
                         && (networkInfo.getType() == defaultNetworkInfo.getType()
                                    // getActiveNetworkInfo() will not return TYPE_VPN types due to
                                    // https://android.googlesource.com/platform/frameworks/base/+/d6a7980d
                                    // so networkInfo.getType() can't be matched against
                                    // defaultNetworkInfo.getType() but networkInfo.getType() should
                                    // be TYPE_VPN. In the case of a VPN, getAllNetworks() will have
                                    // returned just this VPN if it applies.
                                    || networkInfo.getType() == TYPE_VPN)) {
                     // There should not be multiple connected networks of the
@@ skipping 43 matching lines @@
                 if (wifiInfo != null) {
                     final String ssid = wifiInfo.getSSID();
                     if (ssid != null) {
                         return ssid;
                     }
                 }
             }
             return "";
         }
 
+        // Fetch WifiInfo and record UMA for NPEs.
+        private WifiInfo getWifiInfo() {
+            try {
+                WifiInfo wifiInfo = mWifiManager.getConnectionInfo();
+                RecordHistogram.recordBooleanHistogram("NCN.getWifiInfo1stSuccess", true);
+                return wifiInfo;
+            } catch (NullPointerException firstException) {
+                RecordHistogram.recordBooleanHistogram("NCN.getWifiInfo1stSuccess", false);
+                try {
+                    WifiInfo wifiInfo = mWifiManager.getConnectionInfo();
+                    RecordHistogram.recordBooleanHistogram("NCN.getWifiInfo2ndSuccess", true);
+                    return wifiInfo;
+                } catch (NullPointerException secondException) {
+                    RecordHistogram.recordBooleanHistogram("NCN.getWifiInfo2ndSuccess", false);
+                    throw secondException;
+                }
+            }
+        }
+
         /*
          * Requires ACCESS_WIFI_STATE permission to get the real link speed, else returns
          * UNKNOWN_LINK_SPEED.
          */
         int getLinkSpeedInMbps() {
             if (!mHasWifiPermission || mWifiManager == null) return UNKNOWN_LINK_SPEED;
-            final WifiInfo wifiInfo = mWifiManager.getConnectionInfo();
+            final WifiInfo wifiInfo = getWifiInfo();
             if (wifiInfo == null) return UNKNOWN_LINK_SPEED;
 
             // wifiInfo.getLinkSpeed returns the current wifi linkspeed, which can change even
             // though the connection type hasn't changed.
             return wifiInfo.getLinkSpeed();
         }
 
         boolean getHasWifiPermission() {
             return mHasWifiPermission;
         }
@@ skipping 612 matching lines @@
      */
     @TargetApi(Build.VERSION_CODES.LOLLIPOP)
     @VisibleForTesting
     static int networkToNetId(Network network) {
         // NOTE(pauljensen): This depends on Android framework implementation details.
         // Fortunately this functionality is unlikely to ever change.
         // TODO(pauljensen): When we update to Android M SDK, use Network.getNetworkHandle().
         return Integer.parseInt(network.toString());
     }
 }