Cherry-pick: Remove WifiWatchdogStateMachineandroid-wear-n-preview-2android-wear-7.1.1_r1android-n-preview-5android-n-iot-preview-2nougat-mr1-wear-releasen-iot-preview-2

Wifi watchdog is not being used anymore, the associated setting
("Settings -> Wi-Fi -> Advanced -> Avoid poor internet connection")
had already been deleted from UI.  So remove it.

While there, remove the unused state VerifyingLinkState in WifiStateMachine,
which is only triggered by WifiWatchdogStateMachine.

BUG=29533054
BUG=26254553

TEST=compile

Change-Id: I77dd1bc2b90cc0f3f94619e7b7df8293b068fcce

3 files changed, 0 insertions, 1268 deletions

diff --git a/service/java/com/android/server/wifi/WifiServiceImpl.java b/service/java/com/android/server/wifi/WifiServiceImpl.java
index 55c604070..d7f7277af 100644
--- a/service/java/com/android/server/wifi/WifiServiceImpl.java
+++ b/service/java/com/android/server/wifi/WifiServiceImpl.java
@@ -313,8 +313,6 @@ public final class WifiServiceImpl extends IWifiManager.Stub {
 
     WifiStateMachineHandler mWifiStateMachineHandler;
 
-    private WifiWatchdogStateMachine mWifiWatchdogStateMachine;
-
     private WifiController mWifiController;
 
     public WifiServiceImpl(Context context) {
@@ -396,9 +394,6 @@ public final class WifiServiceImpl extends IWifiManager.Stub {
         // If we are already disabled (could be due to airplane mode), avoid changing persist
         // state here
         if (wifiEnabled) setWifiEnabled(wifiEnabled);
-
-        mWifiWatchdogStateMachine = WifiWatchdogStateMachine.
-               makeWifiWatchdogStateMachine(mContext, mWifiStateMachine.getMessenger());
     }
 
     /**
@@ -1537,7 +1532,6 @@ public final class WifiServiceImpl extends IWifiManager.Stub {
             pw.println(l);
         }
 
-        mWifiWatchdogStateMachine.dump(fd, pw, args);
         pw.println();
         mWifiStateMachine.dump(fd, pw, args);
         pw.println();
diff --git a/service/java/com/android/server/wifi/WifiStateMachine.java b/service/java/com/android/server/wifi/WifiStateMachine.java
index adfc049ea..2fb3d6404 100644
--- a/service/java/com/android/server/wifi/WifiStateMachine.java
+++ b/service/java/com/android/server/wifi/WifiStateMachine.java
@@ -969,8 +969,6 @@ public class WifiStateMachine extends StateMachine implements WifiNative.WifiPno
     private State mL2ConnectedState = new L2ConnectedState();
     /* fetching IP after connection to access point (assoc+auth complete) */
     private State mObtainingIpState = new ObtainingIpState();
-    /* Waiting for link quality verification to be complete */
-    private State mVerifyingLinkState = new VerifyingLinkState();
     /* Connected with IP addr */
     private State mConnectedState = new ConnectedState();
     /* Roaming */
@@ -1323,7 +1321,6 @@ public class WifiStateMachine extends StateMachine implements WifiNative.WifiPno
                     addState(mConnectModeState, mDriverStartedState);
                         addState(mL2ConnectedState, mConnectModeState);
                             addState(mObtainingIpState, mL2ConnectedState);
-                            addState(mVerifyingLinkState, mL2ConnectedState);
                             addState(mConnectedState, mL2ConnectedState);
                             addState(mRoamingState, mL2ConnectedState);
                         addState(mDisconnectingState, mConnectModeState);
@@ -5626,8 +5623,6 @@ public class WifiStateMachine extends StateMachine implements WifiNative.WifiPno
                 case CMD_SET_AP_CONFIG_COMPLETED:
                 case CMD_REQUEST_AP_CONFIG:
                 case CMD_RESPONSE_AP_CONFIG:
-                case WifiWatchdogStateMachine.POOR_LINK_DETECTED:
-                case WifiWatchdogStateMachine.GOOD_LINK_DETECTED:
                 case CMD_NO_NETWORKS_PERIODIC_SCAN:
                 case CMD_DISABLE_P2P_RSP:
                 case WifiMonitor.SUP_REQUEST_IDENTITY:
@@ -6953,12 +6948,6 @@ public class WifiStateMachine extends StateMachine implements WifiNative.WifiPno
             case CMD_DISABLE_P2P_REQ:
                 s = "CMD_DISABLE_P2P_REQ";
                 break;
-            case WifiWatchdogStateMachine.GOOD_LINK_DETECTED:
-                s = "GOOD_LINK_DETECTED";
-                break;
-            case WifiWatchdogStateMachine.POOR_LINK_DETECTED:
-                s = "POOR_LINK_DETECTED";
-                break;
             case WifiP2pServiceImpl.GROUP_CREATING_TIMED_OUT:
                 s = "GROUP_CREATING_TIMED_OUT";
                 break;
@@ -8730,40 +8719,6 @@ public class WifiStateMachine extends StateMachine implements WifiNative.WifiPno
       }
     }
 
-    // Note: currently, this state is never used, because WifiWatchdogStateMachine unconditionally
-    // sets mPoorNetworkDetectionEnabled to false.
-    class VerifyingLinkState extends State {
-        @Override
-        public void enter() {
-            log(getName() + " enter");
-            setNetworkDetailedState(DetailedState.VERIFYING_POOR_LINK);
-            mWifiConfigStore.updateStatus(mLastNetworkId, DetailedState.VERIFYING_POOR_LINK);
-            sendNetworkStateChangeBroadcast(mLastBssid);
-            // End roaming
-            mAutoRoaming = WifiAutoJoinController.AUTO_JOIN_IDLE;
-        }
-        @Override
-        public boolean processMessage(Message message) {
-            logStateAndMessage(message, this);
-
-            switch (message.what) {
-                case WifiWatchdogStateMachine.POOR_LINK_DETECTED:
-                    // Stay here
-                    log(getName() + " POOR_LINK_DETECTED: no transition");
-                    break;
-                case WifiWatchdogStateMachine.GOOD_LINK_DETECTED:
-                    log(getName() + " GOOD_LINK_DETECTED: transition to CONNECTED");
-                    sendConnectedState();
-                    transitionTo(mConnectedState);
-                    break;
-                default:
-                    if (DBG) log(getName() + " what=" + message.what + " NOT_HANDLED");
-                    return NOT_HANDLED;
-            }
-            return HANDLED;
-        }
-    }
-
     private void sendConnectedState() {
         // If this network was explicitly selected by the user, evaluate whether to call
         // explicitlySelected() so the system can treat it appropriately.
@@ -8819,9 +8774,6 @@ public class WifiStateMachine extends StateMachine implements WifiNative.WifiPno
                                 WifiConfiguration.ROAMING_FAILURE_IP_CONFIG);
                     }
                     return NOT_HANDLED;
-                case WifiWatchdogStateMachine.POOR_LINK_DETECTED:
-                    if (DBG) log("Roaming and Watchdog reports poor link -> ignore");
-                    return HANDLED;
                 case CMD_UNWANTED_NETWORK:
                     if (DBG) log("Roaming and CS doesnt want the network -> ignore");
                     return HANDLED;
@@ -9016,10 +8968,6 @@ public class WifiStateMachine extends StateMachine implements WifiNative.WifiPno
                 case CMD_UPDATE_ASSOCIATED_SCAN_PERMISSION:
                     updateAssociatedScanPermission();
                     break;
-                case WifiWatchdogStateMachine.POOR_LINK_DETECTED:
-                    if (DBG) log("Watchdog reports poor link");
-                    transitionTo(mVerifyingLinkState);
-                    break;
                 case CMD_UNWANTED_NETWORK:
                     if (message.arg1 == NETWORK_STATUS_UNWANTED_DISCONNECT) {
                         mWifiConfigStore.handleBadNetworkDisconnectReport(mLastNetworkId, mWifiInfo);
diff --git a/service/java/com/android/server/wifi/WifiWatchdogStateMachine.java b/service/java/com/android/server/wifi/WifiWatchdogStateMachine.java
deleted file mode 100644
index 0ef18e6ae..000000000
--- a/service/java/com/android/server/wifi/WifiWatchdogStateMachine.java
+++ /dev/null
@@ -1,1210 +0,0 @@
-/*
- * Copyright (C) 2011 The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package com.android.server.wifi;
-
-import android.content.BroadcastReceiver;
-import android.content.ContentResolver;
-import android.content.Context;
-import android.content.Intent;
-import android.content.IntentFilter;
-import android.database.ContentObserver;
-import android.net.ConnectivityManager;
-import android.net.LinkProperties;
-import android.net.NetworkInfo;
-import android.net.wifi.RssiPacketCountInfo;
-import android.net.wifi.SupplicantState;
-import android.net.wifi.WifiInfo;
-import android.net.wifi.WifiManager;
-import android.os.Message;
-import android.os.Messenger;
-import android.os.SystemClock;
-import android.provider.Settings;
-import android.util.LruCache;
-
-import com.android.internal.util.AsyncChannel;
-import com.android.internal.util.Protocol;
-import com.android.internal.util.State;
-import com.android.internal.util.StateMachine;
-
-import java.io.FileDescriptor;
-import java.io.PrintWriter;
-import java.text.DecimalFormat;
-
-/**
- * WifiWatchdogStateMachine monitors the connection to a WiFi network. When WiFi
- * connects at L2 layer, the beacons from access point reach the device and it
- * can maintain a connection, but the application connectivity can be flaky (due
- * to bigger packet size exchange).
- * <p>
- * We now monitor the quality of the last hop on WiFi using packet loss ratio as
- * an indicator to decide if the link is good enough to switch to Wi-Fi as the
- * uplink.
- * <p>
- * When WiFi is connected, the WiFi watchdog keeps sampling the RSSI and the
- * instant packet loss, and record it as per-AP loss-to-rssi statistics. When
- * the instant packet loss is higher than a threshold, the WiFi watchdog sends a
- * poor link notification to avoid WiFi connection temporarily.
- * <p>
- * While WiFi is being avoided, the WiFi watchdog keep watching the RSSI to
- * bring the WiFi connection back. Once the RSSI is high enough to achieve a
- * lower packet loss, a good link detection is sent such that the WiFi
- * connection become available again.
- * <p>
- * BSSID roaming has been taken into account. When user is moving across
- * multiple APs, the WiFi watchdog will detect that and keep watching the
- * currently connected AP.
- * <p>
- * Power impact should be minimal since much of the measurement relies on
- * passive statistics already being tracked at the driver and the polling is
- * done when screen is turned on and the RSSI is in a certain range.
- *
- * @hide
- */
-public class WifiWatchdogStateMachine extends StateMachine {
-
-    private static final boolean DBG = false;
-
-    private static final int BASE = Protocol.BASE_WIFI_WATCHDOG;
-
-    /* Internal events */
-    private static final int EVENT_WATCHDOG_TOGGLED                 = BASE + 1;
-    private static final int EVENT_NETWORK_STATE_CHANGE             = BASE + 2;
-    private static final int EVENT_RSSI_CHANGE                      = BASE + 3;
-    private static final int EVENT_SUPPLICANT_STATE_CHANGE          = BASE + 4;
-    private static final int EVENT_WIFI_RADIO_STATE_CHANGE          = BASE + 5;
-    private static final int EVENT_WATCHDOG_SETTINGS_CHANGE         = BASE + 6;
-    private static final int EVENT_BSSID_CHANGE                     = BASE + 7;
-    private static final int EVENT_SCREEN_ON                        = BASE + 8;
-    private static final int EVENT_SCREEN_OFF                       = BASE + 9;
-
-    /* Internal messages */
-    private static final int CMD_RSSI_FETCH                         = BASE + 11;
-
-    /* Notifications from/to WifiStateMachine */
-    static final int POOR_LINK_DETECTED                             = BASE + 21;
-    static final int GOOD_LINK_DETECTED                             = BASE + 22;
-
-    /*
-     * RSSI levels as used by notification icon
-     * Level 4  -55 <= RSSI
-     * Level 3  -66 <= RSSI < -55
-     * Level 2  -77 <= RSSI < -67
-     * Level 1  -88 <= RSSI < -78
-     * Level 0         RSSI < -88
-     */
-
-    /**
-     * WiFi link statistics is monitored and recorded actively below this threshold.
-     * <p>
-     * Larger threshold is more adaptive but increases sampling cost.
-     */
-    private static final int LINK_MONITOR_LEVEL_THRESHOLD = WifiManager.RSSI_LEVELS - 1;
-
-    /**
-     * Remember packet loss statistics of how many BSSIDs.
-     * <p>
-     * Larger size is usually better but requires more space.
-     */
-    private static final int BSSID_STAT_CACHE_SIZE = 20;
-
-    /**
-     * RSSI range of a BSSID statistics.
-     * Within the range, (RSSI -> packet loss %) mappings are stored.
-     * <p>
-     * Larger range is usually better but requires more space.
-     */
-    private static final int BSSID_STAT_RANGE_LOW_DBM  = -105;
-
-    /**
-     * See {@link #BSSID_STAT_RANGE_LOW_DBM}.
-     */
-    private static final int BSSID_STAT_RANGE_HIGH_DBM = -45;
-
-    /**
-     * How many consecutive empty data point to trigger a empty-cache detection.
-     * In this case, a preset/default loss value (function on RSSI) is used.
-     * <p>
-     * In normal uses, some RSSI values may never be seen due to channel randomness.
-     * However, the size of such empty RSSI chunk in normal use is generally 1~2.
-     */
-    private static final int BSSID_STAT_EMPTY_COUNT = 3;
-
-    /**
-     * Sample interval for packet loss statistics, in msec.
-     * <p>
-     * Smaller interval is more accurate but increases sampling cost (battery consumption).
-     */
-    private static final long LINK_SAMPLING_INTERVAL_MS = 1 * 1000;
-
-    /**
-     * Coefficients (alpha) for moving average for packet loss tracking.
-     * Must be within (0.0, 1.0).
-     * <p>
-     * Equivalent number of samples: N = 2 / alpha - 1 .
-     * We want the historic loss to base on more data points to be statistically reliable.
-     * We want the current instant loss to base on less data points to be responsive.
-     */
-    private static final double EXP_COEFFICIENT_RECORD  = 0.1;
-
-    /**
-     * See {@link #EXP_COEFFICIENT_RECORD}.
-     */
-    private static final double EXP_COEFFICIENT_MONITOR = 0.5;
-
-    /**
-     * Thresholds for sending good/poor link notifications, in packet loss %.
-     * Good threshold must be smaller than poor threshold.
-     * Use smaller poor threshold to avoid WiFi more aggressively.
-     * Use smaller good threshold to bring back WiFi more conservatively.
-     * <p>
-     * When approaching the boundary, loss ratio jumps significantly within a few dBs.
-     * 50% loss threshold is a good balance between accuracy and reponsiveness.
-     * <=10% good threshold is a safe value to avoid jumping back to WiFi too easily.
-     */
-    private static final double POOR_LINK_LOSS_THRESHOLD = 0.5;
-
-    /**
-     * See {@link #POOR_LINK_LOSS_THRESHOLD}.
-     */
-    private static final double GOOD_LINK_LOSS_THRESHOLD = 0.1;
-
-    /**
-     * Number of samples to confirm before sending a poor link notification.
-     * Response time = confirm_count * sample_interval .
-     * <p>
-     * A smaller threshold improves response speed but may suffer from randomness.
-     * According to experiments, 3~5 are good values to achieve a balance.
-     * These parameters should be tuned along with {@link #LINK_SAMPLING_INTERVAL_MS}.
-     */
-    private static final int POOR_LINK_SAMPLE_COUNT = 3;
-
-    /**
-     * Minimum volume (converted from pkt/sec) to detect a poor link, to avoid randomness.
-     * <p>
-     * According to experiments, 1pkt/sec is too sensitive but 3pkt/sec is slightly unresponsive.
-     */
-    private static final double POOR_LINK_MIN_VOLUME = 2.0 * LINK_SAMPLING_INTERVAL_MS / 1000.0;
-
-    /**
-     * When a poor link is detected, we scan over this range (based on current
-     * poor link RSSI) for a target RSSI that satisfies a target packet loss.
-     * Refer to {@link #GOOD_LINK_TARGET}.
-     * <p>
-     * We want range_min not too small to avoid jumping back to WiFi too easily.
-     */
-    private static final int GOOD_LINK_RSSI_RANGE_MIN = 3;
-
-    /**
-     * See {@link #GOOD_LINK_RSSI_RANGE_MIN}.
-     */
-    private static final int GOOD_LINK_RSSI_RANGE_MAX = 20;
-
-    /**
-     * Adaptive good link target to avoid flapping.
-     * When a poor link is detected, a good link target is calculated as follows:
-     * <p>
-     *      targetRSSI = min { rssi | loss(rssi) < GOOD_LINK_LOSS_THRESHOLD } + rssi_adj[i],
-     *                   where rssi is within the above GOOD_LINK_RSSI_RANGE.
-     *      targetCount = sample_count[i] .
-     * <p>
-     * While WiFi is being avoided, we keep monitoring its signal strength.
-     * Good link notification is sent when we see current RSSI >= targetRSSI
-     * for targetCount consecutive times.
-     * <p>
-     * Index i is incremented each time after a poor link detection.
-     * Index i is decreased to at most k if the last poor link was at lease reduce_time[k] ago.
-     * <p>
-     * Intuitively, larger index i makes it more difficult to get back to WiFi, avoiding flapping.
-     * In experiments, (+9 dB / 30 counts) makes it quite difficult to achieve.
-     * Avoid using it unless flapping is really bad (say, last poor link is < 1 min ago).
-     */
-    private static final GoodLinkTarget[] GOOD_LINK_TARGET = {
-        /*                  rssi_adj,       sample_count,   reduce_time */
-        new GoodLinkTarget( 0,              3,              30 * 60000   ),
-        new GoodLinkTarget( 3,              5,              5  * 60000   ),
-        new GoodLinkTarget( 6,              10,             1  * 60000   ),
-        new GoodLinkTarget( 9,              30,             0  * 60000   ),
-    };
-
-    /**
-     * The max time to avoid a BSSID, to prevent avoiding forever.
-     * If current RSSI is at least min_rssi[i], the max avoidance time is at most max_time[i]
-     * <p>
-     * It is unusual to experience high packet loss at high RSSI. Something unusual must be
-     * happening (e.g. strong interference). For higher signal strengths, we set the avoidance
-     * time to be low to allow for quick turn around from temporary interference.
-     * <p>
-     * See {@link BssidStatistics#poorLinkDetected}.
-     */
-    private static final MaxAvoidTime[] MAX_AVOID_TIME = {
-        /*                  max_time,           min_rssi */
-        new MaxAvoidTime(   30 * 60000,         -200      ),
-        new MaxAvoidTime(   5  * 60000,         -70       ),
-        new MaxAvoidTime(   0  * 60000,         -55       ),
-    };
-
-    /* Framework related */
-    private Context mContext;
-    private ContentResolver mContentResolver;
-    private WifiManager mWifiManager;
-    private IntentFilter mIntentFilter;
-    private BroadcastReceiver mBroadcastReceiver;
-    private AsyncChannel mWsmChannel = new AsyncChannel();
-    private WifiInfo mWifiInfo;
-    private LinkProperties mLinkProperties;
-
-    /* System settingss related */
-    private static boolean sWifiOnly = false;
-    private boolean mPoorNetworkDetectionEnabled;
-
-    /* Poor link detection related */
-    private LruCache<String, BssidStatistics> mBssidCache =
-            new LruCache<String, BssidStatistics>(BSSID_STAT_CACHE_SIZE);
-    private int mRssiFetchToken = 0;
-    private int mCurrentSignalLevel;
-    private BssidStatistics mCurrentBssid;
-    private VolumeWeightedEMA mCurrentLoss;
-    private boolean mIsScreenOn = true;
-    private static double sPresetLoss[];
-
-    /* WiFi watchdog state machine related */
-    private DefaultState mDefaultState = new DefaultState();
-    private WatchdogDisabledState mWatchdogDisabledState = new WatchdogDisabledState();
-    private WatchdogEnabledState mWatchdogEnabledState = new WatchdogEnabledState();
-    private NotConnectedState mNotConnectedState = new NotConnectedState();
-    private VerifyingLinkState mVerifyingLinkState = new VerifyingLinkState();
-    private ConnectedState mConnectedState = new ConnectedState();
-    private OnlineWatchState mOnlineWatchState = new OnlineWatchState();
-    private LinkMonitoringState mLinkMonitoringState = new LinkMonitoringState();
-    private OnlineState mOnlineState = new OnlineState();
-
-    /**
-     * STATE MAP
-     *          Default
-     *         /       \
-     * Disabled      Enabled
-     *             /     \     \
-     * NotConnected  Verifying  Connected
-     *                         /---------\
-     *                       (all other states)
-     */
-    private WifiWatchdogStateMachine(Context context, Messenger dstMessenger) {
-        super("WifiWatchdogStateMachine");
-        mContext = context;
-        mContentResolver = context.getContentResolver();
-        mWifiManager = (WifiManager) context.getSystemService(Context.WIFI_SERVICE);
-
-        mWsmChannel.connectSync(mContext, getHandler(), dstMessenger);
-
-        setupNetworkReceiver();
-
-        // the content observer to listen needs a handler
-        registerForSettingsChanges();
-        registerForWatchdogToggle();
-        addState(mDefaultState);
-            addState(mWatchdogDisabledState, mDefaultState);
-            addState(mWatchdogEnabledState, mDefaultState);
-                addState(mNotConnectedState, mWatchdogEnabledState);
-                addState(mVerifyingLinkState, mWatchdogEnabledState);
-                addState(mConnectedState, mWatchdogEnabledState);
-                    addState(mOnlineWatchState, mConnectedState);
-                    addState(mLinkMonitoringState, mConnectedState);
-                    addState(mOnlineState, mConnectedState);
-
-        if (isWatchdogEnabled()) {
-            setInitialState(mNotConnectedState);
-        } else {
-            setInitialState(mWatchdogDisabledState);
-        }
-        setLogRecSize(25);
-        setLogOnlyTransitions(true);
-        updateSettings();
-    }
-
-    public static WifiWatchdogStateMachine makeWifiWatchdogStateMachine(Context context, Messenger dstMessenger) {
-        ContentResolver contentResolver = context.getContentResolver();
-
-        ConnectivityManager cm = (ConnectivityManager) context.getSystemService(
-                Context.CONNECTIVITY_SERVICE);
-        sWifiOnly = (cm.isNetworkSupported(ConnectivityManager.TYPE_MOBILE) == false);
-
-        // Watchdog is always enabled. Poor network detection can be seperately turned on/off
-        // TODO: Remove this setting & clean up state machine since we always have
-        // watchdog in an enabled state
-        putSettingsGlobalBoolean(contentResolver, Settings.Global.WIFI_WATCHDOG_ON, true);
-
-        WifiWatchdogStateMachine wwsm = new WifiWatchdogStateMachine(context, dstMessenger);
-        wwsm.start();
-        return wwsm;
-    }
-
-    private void setupNetworkReceiver() {
-        mBroadcastReceiver = new BroadcastReceiver() {
-            @Override
-            public void onReceive(Context context, Intent intent) {
-                String action = intent.getAction();
-                if (action.equals(WifiManager.RSSI_CHANGED_ACTION)) {
-                    obtainMessage(EVENT_RSSI_CHANGE,
-                            intent.getIntExtra(WifiManager.EXTRA_NEW_RSSI, -200), 0).sendToTarget();
-                } else if (action.equals(WifiManager.SUPPLICANT_STATE_CHANGED_ACTION)) {
-                    sendMessage(EVENT_SUPPLICANT_STATE_CHANGE, intent);
-                } else if (action.equals(WifiManager.NETWORK_STATE_CHANGED_ACTION)) {
-                    sendMessage(EVENT_NETWORK_STATE_CHANGE, intent);
-                } else if (action.equals(Intent.ACTION_SCREEN_ON)) {
-                    sendMessage(EVENT_SCREEN_ON);
-                } else if (action.equals(Intent.ACTION_SCREEN_OFF)) {
-                    sendMessage(EVENT_SCREEN_OFF);
-                } else if (action.equals(WifiManager.WIFI_STATE_CHANGED_ACTION)) {
-                    sendMessage(EVENT_WIFI_RADIO_STATE_CHANGE,intent.getIntExtra(
-                            WifiManager.EXTRA_WIFI_STATE, WifiManager.WIFI_STATE_UNKNOWN));
-                }
-            }
-        };
-
-        mIntentFilter = new IntentFilter();
-        mIntentFilter.addAction(WifiManager.NETWORK_STATE_CHANGED_ACTION);
-        mIntentFilter.addAction(WifiManager.WIFI_STATE_CHANGED_ACTION);
-        mIntentFilter.addAction(WifiManager.RSSI_CHANGED_ACTION);
-        mIntentFilter.addAction(WifiManager.SUPPLICANT_STATE_CHANGED_ACTION);
-        mIntentFilter.addAction(Intent.ACTION_SCREEN_ON);
-        mIntentFilter.addAction(Intent.ACTION_SCREEN_OFF);
-        mContext.registerReceiver(mBroadcastReceiver, mIntentFilter);
-    }
-
-    /**
-     * Observes the watchdog on/off setting, and takes action when changed.
-     */
-    private void registerForWatchdogToggle() {
-        ContentObserver contentObserver = new ContentObserver(this.getHandler()) {
-            @Override
-            public void onChange(boolean selfChange) {
-                sendMessage(EVENT_WATCHDOG_TOGGLED);
-            }
-        };
-
-        mContext.getContentResolver().registerContentObserver(
-                Settings.Global.getUriFor(Settings.Global.WIFI_WATCHDOG_ON),
-                false, contentObserver);
-    }
-
-    /**
-     * Observes watchdogs secure setting changes.
-     */
-    private void registerForSettingsChanges() {
-        ContentObserver contentObserver = new ContentObserver(this.getHandler()) {
-            @Override
-            public void onChange(boolean selfChange) {
-                sendMessage(EVENT_WATCHDOG_SETTINGS_CHANGE);
-            }
-        };
-
-        mContext.getContentResolver().registerContentObserver(
-                Settings.Global.getUriFor(Settings.Global.WIFI_WATCHDOG_POOR_NETWORK_TEST_ENABLED),
-                false, contentObserver);
-    }
-
-    public void dump(FileDescriptor fd, PrintWriter pw, String[] args) {
-        super.dump(fd, pw, args);
-        pw.println("mWifiInfo: [" + mWifiInfo + "]");
-        pw.println("mLinkProperties: [" + mLinkProperties + "]");
-        pw.println("mCurrentSignalLevel: [" + mCurrentSignalLevel + "]");
-        pw.println("mPoorNetworkDetectionEnabled: [" + mPoorNetworkDetectionEnabled + "]");
-    }
-
-    private boolean isWatchdogEnabled() {
-        boolean ret = getSettingsGlobalBoolean(
-                mContentResolver, Settings.Global.WIFI_WATCHDOG_ON, true);
-        if (DBG) logd("Watchdog enabled " + ret);
-        return ret;
-    }
-
-    private void updateSettings() {
-        if (DBG) logd("Updating secure settings");
-
-        // Unconditionally disable poor network avoidance, since this mechanism is obsolete
-        mPoorNetworkDetectionEnabled = false;
-    }
-
-    /**
-     * Default state, guard for unhandled messages.
-     */
-    class DefaultState extends State {
-        @Override
-        public void enter() {
-            if (DBG) logd(getName());
-        }
-
-        @Override
-        public boolean processMessage(Message msg) {
-            switch (msg.what) {
-                case EVENT_WATCHDOG_SETTINGS_CHANGE:
-                    updateSettings();
-                    if (DBG) logd("Updating wifi-watchdog secure settings");
-                    break;
-                case EVENT_RSSI_CHANGE:
-                    mCurrentSignalLevel = calculateSignalLevel(msg.arg1);
-                    break;
-                case EVENT_WIFI_RADIO_STATE_CHANGE:
-                case EVENT_NETWORK_STATE_CHANGE:
-                case EVENT_SUPPLICANT_STATE_CHANGE:
-                case EVENT_BSSID_CHANGE:
-                case CMD_RSSI_FETCH:
-                case WifiManager.RSSI_PKTCNT_FETCH_SUCCEEDED:
-                case WifiManager.RSSI_PKTCNT_FETCH_FAILED:
-                    // ignore
-                    break;
-                case EVENT_SCREEN_ON:
-                    mIsScreenOn = true;
-                    break;
-                case EVENT_SCREEN_OFF:
-                    mIsScreenOn = false;
-                    break;
-                default:
-                    loge("Unhandled message " + msg + " in state " + getCurrentState().getName());
-                    break;
-            }
-            return HANDLED;
-        }
-    }
-
-    /**
-     * WiFi watchdog is disabled by the setting.
-     */
-    class WatchdogDisabledState extends State {
-        @Override
-        public void enter() {
-            if (DBG) logd(getName());
-        }
-
-        @Override
-        public boolean processMessage(Message msg) {
-            switch (msg.what) {
-                case EVENT_WATCHDOG_TOGGLED:
-                    if (isWatchdogEnabled())
-                        transitionTo(mNotConnectedState);
-                    return HANDLED;
-                case EVENT_NETWORK_STATE_CHANGE:
-                    Intent intent = (Intent) msg.obj;
-                    NetworkInfo networkInfo = (NetworkInfo)
-                            intent.getParcelableExtra(WifiManager.EXTRA_NETWORK_INFO);
-
-                    switch (networkInfo.getDetailedState()) {
-                        case VERIFYING_POOR_LINK:
-                            if (DBG) logd("Watchdog disabled, verify link");
-                            sendLinkStatusNotification(true);
-                            break;
-                        default:
-                            break;
-                    }
-                    break;
-            }
-            return NOT_HANDLED;
-        }
-    }
-
-    /**
-     * WiFi watchdog is enabled by the setting.
-     */
-    class WatchdogEnabledState extends State {
-        @Override
-        public void enter() {
-            if (DBG) logd(getName());
-        }
-
-        @Override
-        public boolean processMessage(Message msg) {
-            Intent intent;
-            switch (msg.what) {
-                case EVENT_WATCHDOG_TOGGLED:
-                    if (!isWatchdogEnabled())
-                        transitionTo(mWatchdogDisabledState);
-                    break;
-
-                case EVENT_NETWORK_STATE_CHANGE:
-                    intent = (Intent) msg.obj;
-                    NetworkInfo networkInfo =
-                            (NetworkInfo) intent.getParcelableExtra(WifiManager.EXTRA_NETWORK_INFO);
-                    if (DBG) logd("Network state change " + networkInfo.getDetailedState());
-
-                    mWifiInfo = (WifiInfo) intent.getParcelableExtra(WifiManager.EXTRA_WIFI_INFO);
-                    updateCurrentBssid(mWifiInfo != null ? mWifiInfo.getBSSID() : null);
-
-                    switch (networkInfo.getDetailedState()) {
-                        case VERIFYING_POOR_LINK:
-                            mLinkProperties = (LinkProperties) intent.getParcelableExtra(
-                                    WifiManager.EXTRA_LINK_PROPERTIES);
-                            if (mPoorNetworkDetectionEnabled) {
-                                if (mWifiInfo == null || mCurrentBssid == null) {
-                                    loge("Ignore, wifiinfo " + mWifiInfo +" bssid " + mCurrentBssid);
-                                    sendLinkStatusNotification(true);
-                                } else {
-                                    transitionTo(mVerifyingLinkState);
-                                }
-                            } else {
-                                sendLinkStatusNotification(true);
-                            }
-                            break;
-                        case CONNECTED:
-                            transitionTo(mOnlineWatchState);
-                            break;
-                        default:
-                            transitionTo(mNotConnectedState);
-                            break;
-                    }
-                    break;
-
-                case EVENT_SUPPLICANT_STATE_CHANGE:
-                    intent = (Intent) msg.obj;
-                    SupplicantState supplicantState = (SupplicantState) intent.getParcelableExtra(
-                            WifiManager.EXTRA_NEW_STATE);
-                    if (supplicantState == SupplicantState.COMPLETED) {
-                        mWifiInfo = mWifiManager.getConnectionInfo();
-                        updateCurrentBssid(mWifiInfo.getBSSID());
-                    }
-                    break;
-
-                case EVENT_WIFI_RADIO_STATE_CHANGE:
-                    if (msg.arg1 == WifiManager.WIFI_STATE_DISABLING) {
-                        transitionTo(mNotConnectedState);
-                    }
-                    break;
-
-                default:
-                    return NOT_HANDLED;
-            }
-
-            return HANDLED;
-        }
-    }
-
-    /**
-     * WiFi is disconnected.
-     */
-    class NotConnectedState extends State {
-        @Override
-        public void enter() {
-            if (DBG) logd(getName());
-        }
-    }
-
-    /**
-     * WiFi is connected, but waiting for good link detection message.
-     */
-    class VerifyingLinkState extends State {
-
-        private int mSampleCount;
-
-        @Override
-        public void enter() {
-            if (DBG) logd(getName());
-            mSampleCount = 0;
-            if (mCurrentBssid != null) mCurrentBssid.newLinkDetected();
-            sendMessage(obtainMessage(CMD_RSSI_FETCH, ++mRssiFetchToken, 0));
-        }
-
-        @Override
-        public boolean processMessage(Message msg) {
-            switch (msg.what) {
-                case EVENT_WATCHDOG_SETTINGS_CHANGE:
-                    updateSettings();
-                    if (!mPoorNetworkDetectionEnabled) {
-                        sendLinkStatusNotification(true);
-                    }
-                    break;
-
-                case EVENT_BSSID_CHANGE:
-                    transitionTo(mVerifyingLinkState);
-                    break;
-
-                case CMD_RSSI_FETCH:
-                    if (msg.arg1 == mRssiFetchToken) {
-                        mWsmChannel.sendMessage(WifiManager.RSSI_PKTCNT_FETCH);
-                        sendMessageDelayed(obtainMessage(CMD_RSSI_FETCH, ++mRssiFetchToken, 0),
-                                LINK_SAMPLING_INTERVAL_MS);
-                    }
-                    break;
-
-                case WifiManager.RSSI_PKTCNT_FETCH_SUCCEEDED:
-                    if (mCurrentBssid == null || msg.obj == null) {
-                        break;
-                    }
-                    RssiPacketCountInfo info = (RssiPacketCountInfo) msg.obj;
-                    int rssi = info.rssi;
-                    if (DBG) logd("Fetch RSSI succeed, rssi=" + rssi);
-
-                    long time = mCurrentBssid.mBssidAvoidTimeMax - SystemClock.elapsedRealtime();
-                    if (time <= 0) {
-                        // max avoidance time is met
-                        if (DBG) logd("Max avoid time elapsed");
-                        sendLinkStatusNotification(true);
-                    } else {
-                        if (rssi >= mCurrentBssid.mGoodLinkTargetRssi) {
-                            if (++mSampleCount >= mCurrentBssid.mGoodLinkTargetCount) {
-                                // link is good again
-                                if (DBG) logd("Good link detected, rssi=" + rssi);
-                                mCurrentBssid.mBssidAvoidTimeMax = 0;
-                                sendLinkStatusNotification(true);
-                            }
-                        } else {
-                            mSampleCount = 0;
-                            if (DBG) logd("Link is still poor, time left=" + time);
-                        }
-                    }
-                    break;
-
-                case WifiManager.RSSI_PKTCNT_FETCH_FAILED:
-                    if (DBG) logd("RSSI_FETCH_FAILED");
-                    break;
-
-                default:
-                    return NOT_HANDLED;
-            }
-            return HANDLED;
-        }
-    }
-
-    /**
-     * WiFi is connected and link is verified.
-     */
-    class ConnectedState extends State {
-        @Override
-        public void enter() {
-            if (DBG) logd(getName());
-        }
-
-        @Override
-        public boolean processMessage(Message msg) {
-            switch (msg.what) {
-                case EVENT_WATCHDOG_SETTINGS_CHANGE:
-                    updateSettings();
-                    if (mPoorNetworkDetectionEnabled) {
-                        transitionTo(mOnlineWatchState);
-                    } else {
-                        transitionTo(mOnlineState);
-                    }
-                    return HANDLED;
-            }
-            return NOT_HANDLED;
-        }
-    }
-
-    /**
-     * RSSI is high enough and don't need link monitoring.
-     */
-    class OnlineWatchState extends State {
-        @Override
-        public void enter() {
-            if (DBG) logd(getName());
-            if (mPoorNetworkDetectionEnabled) {
-                // treat entry as an rssi change
-                handleRssiChange();
-            } else {
-                transitionTo(mOnlineState);
-            }
-        }
-
-        private void handleRssiChange() {
-            if (mCurrentSignalLevel <= LINK_MONITOR_LEVEL_THRESHOLD && mCurrentBssid != null) {
-                transitionTo(mLinkMonitoringState);
-            } else {
-                // stay here
-            }
-        }
-
-        @Override
-        public boolean processMessage(Message msg) {
-            switch (msg.what) {
-                case EVENT_RSSI_CHANGE:
-                    mCurrentSignalLevel = calculateSignalLevel(msg.arg1);
-                    handleRssiChange();
-                    break;
-                default:
-                    return NOT_HANDLED;
-            }
-            return HANDLED;
-        }
-    }
-
-    /**
-     * Keep sampling the link and monitor any poor link situation.
-     */
-    class LinkMonitoringState extends State {
-
-        private int mSampleCount;
-
-        private int mLastRssi;
-        private int mLastTxGood;
-        private int mLastTxBad;
-
-        @Override
-        public void enter() {
-            if (DBG) logd(getName());
-            mSampleCount = 0;
-            mCurrentLoss = new VolumeWeightedEMA(EXP_COEFFICIENT_MONITOR);
-            sendMessage(obtainMessage(CMD_RSSI_FETCH, ++mRssiFetchToken, 0));
-        }
-
-        @Override
-        public boolean processMessage(Message msg) {
-            switch (msg.what) {
-                case EVENT_RSSI_CHANGE:
-                    mCurrentSignalLevel = calculateSignalLevel(msg.arg1);
-                    if (mCurrentSignalLevel <= LINK_MONITOR_LEVEL_THRESHOLD) {
-                        // stay here;
-                    } else {
-                        // we don't need frequent RSSI monitoring any more
-                        transitionTo(mOnlineWatchState);
-                    }
-                    break;
-
-                case EVENT_BSSID_CHANGE:
-                    transitionTo(mLinkMonitoringState);
-                    break;
-
-                case CMD_RSSI_FETCH:
-                    if (!mIsScreenOn) {
-                        transitionTo(mOnlineState);
-                    } else if (msg.arg1 == mRssiFetchToken) {
-                        mWsmChannel.sendMessage(WifiManager.RSSI_PKTCNT_FETCH);
-                        sendMessageDelayed(obtainMessage(CMD_RSSI_FETCH, ++mRssiFetchToken, 0),
-                                LINK_SAMPLING_INTERVAL_MS);
-                    }
-                    break;
-
-                case WifiManager.RSSI_PKTCNT_FETCH_SUCCEEDED:
-                    if (mCurrentBssid == null) {
-                        break;
-                    }
-                    RssiPacketCountInfo info = (RssiPacketCountInfo) msg.obj;
-                    int rssi = info.rssi;
-                    int mrssi = (mLastRssi + rssi) / 2;
-                    int txbad = info.txbad;
-                    int txgood = info.txgood;
-                    if (DBG) logd("Fetch RSSI succeed, rssi=" + rssi + " mrssi=" + mrssi + " txbad="
-                            + txbad + " txgood=" + txgood);
-
-                    // skip the first data point as we want incremental values
-                    long now = SystemClock.elapsedRealtime();
-                    if (now - mCurrentBssid.mLastTimeSample < LINK_SAMPLING_INTERVAL_MS * 2) {
-
-                        // update packet loss statistics
-                        int dbad = txbad - mLastTxBad;
-                        int dgood = txgood - mLastTxGood;
-                        int dtotal = dbad + dgood;
-
-                        if (dtotal > 0) {
-                            // calculate packet loss in the last sampling interval
-                            double loss = ((double) dbad) / ((double) dtotal);
-
-                            mCurrentLoss.update(loss, dtotal);
-
-                            if (DBG) {
-                                DecimalFormat df = new DecimalFormat("#.##");
-                                logd("Incremental loss=" + dbad + "/" + dtotal + " Current loss="
-                                        + df.format(mCurrentLoss.mValue * 100) + "% volume="
-                                        + df.format(mCurrentLoss.mVolume));
-                            }
-
-                            mCurrentBssid.updateLoss(mrssi, loss, dtotal);
-
-                            // check for high packet loss and send poor link notification
-                            if (mCurrentLoss.mValue > POOR_LINK_LOSS_THRESHOLD
-                                    && mCurrentLoss.mVolume > POOR_LINK_MIN_VOLUME) {
-                                if (++mSampleCount >= POOR_LINK_SAMPLE_COUNT)
-                                    if (mCurrentBssid.poorLinkDetected(rssi)) {
-                                        sendLinkStatusNotification(false);
-                                        ++mRssiFetchToken;
-                                    }
-                            } else {
-                                mSampleCount = 0;
-                            }
-                        }
-                    }
-
-                    mCurrentBssid.mLastTimeSample = now;
-                    mLastTxBad = txbad;
-                    mLastTxGood = txgood;
-                    mLastRssi = rssi;
-                    break;
-
-                case WifiManager.RSSI_PKTCNT_FETCH_FAILED:
-                    // can happen if we are waiting to get a disconnect notification
-                    if (DBG) logd("RSSI_FETCH_FAILED");
-                    break;
-
-                default:
-                    return NOT_HANDLED;
-            }
-            return HANDLED;
-        }
-   }
-
-    /**
-     * Child state of ConnectedState indicating that we are online and there is nothing to do.
-     */
-    class OnlineState extends State {
-        @Override
-        public void enter() {
-            if (DBG) logd(getName());
-        }
-
-        @Override
-        public boolean processMessage(Message msg) {
-            switch (msg.what) {
-                case EVENT_SCREEN_ON:
-                    mIsScreenOn = true;
-                    if (mPoorNetworkDetectionEnabled)
-                        transitionTo(mOnlineWatchState);
-                    break;
-                default:
-                    return NOT_HANDLED;
-            }
-            return HANDLED;
-        }
-    }
-
-    private void updateCurrentBssid(String bssid) {
-        if (DBG) logd("Update current BSSID to " + (bssid != null ? bssid : "null"));
-
-        // if currently not connected, then set current BSSID to null
-        if (bssid == null) {
-            if (mCurrentBssid == null) return;
-            mCurrentBssid = null;
-            if (DBG) logd("BSSID changed");
-            sendMessage(EVENT_BSSID_CHANGE);
-            return;
-        }
-
-        // if it is already the current BSSID, then done
-        if (mCurrentBssid != null && bssid.equals(mCurrentBssid.mBssid)) return;
-
-        // search for the new BSSID in the cache, add to cache if not found
-        mCurrentBssid = mBssidCache.get(bssid);
-        if (mCurrentBssid == null) {
-            mCurrentBssid = new BssidStatistics(bssid);
-            mBssidCache.put(bssid, mCurrentBssid);
-        }
-
-        // send BSSID change notification
-        if (DBG) logd("BSSID changed");
-        sendMessage(EVENT_BSSID_CHANGE);
-    }
-
-    private int calculateSignalLevel(int rssi) {
-        int signalLevel = WifiManager.calculateSignalLevel(rssi, WifiManager.RSSI_LEVELS);
-        if (DBG)
-            logd("RSSI current: " + mCurrentSignalLevel + " new: " + rssi + ", " + signalLevel);
-        return signalLevel;
-    }
-
-    private void sendLinkStatusNotification(boolean isGood) {
-        if (DBG) logd("########################################");
-        if (isGood) {
-            mWsmChannel.sendMessage(GOOD_LINK_DETECTED);
-            if (mCurrentBssid != null) {
-                mCurrentBssid.mLastTimeGood = SystemClock.elapsedRealtime();
-            }
-            if (DBG) logd("Good link notification is sent");
-        } else {
-            mWsmChannel.sendMessage(POOR_LINK_DETECTED);
-            if (mCurrentBssid != null) {
-                mCurrentBssid.mLastTimePoor = SystemClock.elapsedRealtime();
-            }
-            logd("Poor link notification is sent");
-        }
-    }
-
-    /**
-     * Convenience function for retrieving a single secure settings value as a
-     * boolean. Note that internally setting values are always stored as
-     * strings; this function converts the string to a boolean for you. The
-     * default value will be returned if the setting is not defined or not a
-     * valid boolean.
-     *
-     * @param cr The ContentResolver to access.
-     * @param name The name of the setting to retrieve.
-     * @param def Value to return if the setting is not defined.
-     * @return The setting's current value, or 'def' if it is not defined or not
-     *         a valid boolean.
-     */
-    private static boolean getSettingsGlobalBoolean(ContentResolver cr, String name, boolean def) {
-        return Settings.Global.getInt(cr, name, def ? 1 : 0) == 1;
-    }
-
-    /**
-     * Convenience function for updating a single settings value as an integer.
-     * This will either create a new entry in the table if the given name does
-     * not exist, or modify the value of the existing row with that name. Note
-     * that internally setting values are always stored as strings, so this
-     * function converts the given value to a string before storing it.
-     *
-     * @param cr The ContentResolver to access.
-     * @param name The name of the setting to modify.
-     * @param value The new value for the setting.
-     * @return true if the value was set, false on database errors
-     */
-    private static boolean putSettingsGlobalBoolean(ContentResolver cr, String name, boolean value) {
-        return Settings.Global.putInt(cr, name, value ? 1 : 0);
-    }
-
-    /**
-     * Bundle of good link count parameters
-     */
-    private static class GoodLinkTarget {
-        public final int RSSI_ADJ_DBM;
-        public final int SAMPLE_COUNT;
-        public final int REDUCE_TIME_MS;
-        public GoodLinkTarget(int adj, int count, int time) {
-            RSSI_ADJ_DBM = adj;
-            SAMPLE_COUNT = count;
-            REDUCE_TIME_MS = time;
-        }
-    }
-
-    /**
-     * Bundle of max avoidance time parameters
-     */
-    private static class MaxAvoidTime {
-        public final int TIME_MS;
-        public final int MIN_RSSI_DBM;
-        public MaxAvoidTime(int time, int rssi) {
-            TIME_MS = time;
-            MIN_RSSI_DBM = rssi;
-        }
-    }
-
-    /**
-     * Volume-weighted Exponential Moving Average (V-EMA)
-     *    - volume-weighted:  each update has its own weight (number of packets)
-     *    - exponential:      O(1) time and O(1) space for both update and query
-     *    - moving average:   reflect most recent results and expire old ones
-     */
-    private class VolumeWeightedEMA {
-        private double mValue;
-        private double mVolume;
-        private double mProduct;
-        private final double mAlpha;
-
-        public VolumeWeightedEMA(double coefficient) {
-            mValue   = 0.0;
-            mVolume  = 0.0;
-            mProduct = 0.0;
-            mAlpha   = coefficient;
-        }
-
-        public void update(double newValue, int newVolume) {
-            if (newVolume <= 0) return;
-            // core update formulas
-            double newProduct = newValue * newVolume;
-            mProduct = mAlpha * newProduct + (1 - mAlpha) * mProduct;
-            mVolume  = mAlpha * newVolume  + (1 - mAlpha) * mVolume;
-            mValue   = mProduct / mVolume;
-        }
-    }
-
-    /**
-     * Record (RSSI -> pakce loss %) mappings of one BSSID
-     */
-    private class BssidStatistics {
-
-        /* MAC address of this BSSID */
-        private final String mBssid;
-
-        /* RSSI -> packet loss % mappings */
-        private VolumeWeightedEMA[] mEntries;
-        private int mRssiBase;
-        private int mEntriesSize;
-
-        /* Target to send good link notification, set when poor link is detected */
-        private int mGoodLinkTargetRssi;
-        private int mGoodLinkTargetCount;
-
-        /* Index of GOOD_LINK_TARGET array */
-        private int mGoodLinkTargetIndex;
-
-        /* Timestamps of some last events */
-        private long mLastTimeSample;
-        private long mLastTimeGood;
-        private long mLastTimePoor;
-
-        /* Max time to avoid this BSSID */
-        private long mBssidAvoidTimeMax;
-
-        /**
-         * Constructor
-         *
-         * @param bssid is the address of this BSSID
-         */
-        public BssidStatistics(String bssid) {
-            this.mBssid = bssid;
-            mRssiBase = BSSID_STAT_RANGE_LOW_DBM;
-            mEntriesSize = BSSID_STAT_RANGE_HIGH_DBM - BSSID_STAT_RANGE_LOW_DBM + 1;
-            mEntries = new VolumeWeightedEMA[mEntriesSize];
-            for (int i = 0; i < mEntriesSize; i++)
-                mEntries[i] = new VolumeWeightedEMA(EXP_COEFFICIENT_RECORD);
-        }
-
-        /**
-         * Update this BSSID cache
-         *
-         * @param rssi is the RSSI
-         * @param value is the new instant loss value at this RSSI
-         * @param volume is the volume for this single update
-         */
-        public void updateLoss(int rssi, double value, int volume) {
-            if (volume <= 0) return;
-            int index = rssi - mRssiBase;
-            if (index < 0 || index >= mEntriesSize) return;
-            mEntries[index].update(value, volume);
-            if (DBG) {
-                DecimalFormat df = new DecimalFormat("#.##");
-                logd("Cache updated: loss[" + rssi + "]=" + df.format(mEntries[index].mValue * 100)
-                        + "% volume=" + df.format(mEntries[index].mVolume));
-            }
-        }
-
-        /**
-         * Get preset loss if the cache has insufficient data, observed from experiments.
-         *
-         * @param rssi is the input RSSI
-         * @return preset loss of the given RSSI
-         */
-        public double presetLoss(int rssi) {
-            if (rssi <= -90) return 1.0;
-            if (rssi > 0) return 0.0;
-
-            if (sPresetLoss == null) {
-                // pre-calculate all preset losses only once, then reuse them
-                final int size = 90;
-                sPresetLoss = new double[size];
-                for (int i = 0; i < size; i++) sPresetLoss[i] = 1.0 / Math.pow(90 - i, 1.5);
-            }
-            return sPresetLoss[-rssi];
-        }
-
-        /**
-         * A poor link is detected, calculate a target RSSI to bring WiFi back.
-         *
-         * @param rssi is the current RSSI
-         * @return true iff the current BSSID should be avoided
-         */
-        public boolean poorLinkDetected(int rssi) {
-            if (DBG) logd("Poor link detected, rssi=" + rssi);
-
-            long now = SystemClock.elapsedRealtime();
-            long lastGood = now - mLastTimeGood;
-            long lastPoor = now - mLastTimePoor;
-
-            // reduce the difficulty of good link target if last avoidance was long time ago
-            while (mGoodLinkTargetIndex > 0
-                    && lastPoor >= GOOD_LINK_TARGET[mGoodLinkTargetIndex - 1].REDUCE_TIME_MS)
-                mGoodLinkTargetIndex--;
-            mGoodLinkTargetCount = GOOD_LINK_TARGET[mGoodLinkTargetIndex].SAMPLE_COUNT;
-
-            // scan for a target RSSI at which the link is good
-            int from = rssi + GOOD_LINK_RSSI_RANGE_MIN;
-            int to = rssi + GOOD_LINK_RSSI_RANGE_MAX;
-            mGoodLinkTargetRssi = findRssiTarget(from, to, GOOD_LINK_LOSS_THRESHOLD);
-            mGoodLinkTargetRssi += GOOD_LINK_TARGET[mGoodLinkTargetIndex].RSSI_ADJ_DBM;
-            if (mGoodLinkTargetIndex < GOOD_LINK_TARGET.length - 1) mGoodLinkTargetIndex++;
-
-            // calculate max avoidance time to prevent avoiding forever
-            int p = 0, pmax = MAX_AVOID_TIME.length - 1;
-            while (p < pmax && rssi >= MAX_AVOID_TIME[p + 1].MIN_RSSI_DBM) p++;
-            long avoidMax = MAX_AVOID_TIME[p].TIME_MS;
-
-            // don't avoid if max avoidance time is 0 (RSSI is super high)
-            if (avoidMax <= 0) return false;
-
-            // set max avoidance time, send poor link notification
-            mBssidAvoidTimeMax = now + avoidMax;
-
-            if (DBG) logd("goodRssi=" + mGoodLinkTargetRssi + " goodCount=" + mGoodLinkTargetCount
-                    + " lastGood=" + lastGood + " lastPoor=" + lastPoor + " avoidMax=" + avoidMax);
-
-            return true;
-        }
-
-        /**
-         * A new BSSID is connected, recalculate target RSSI threshold
-         */
-        public void newLinkDetected() {
-            // if this BSSID is currently being avoided, the reuse those values
-            if (mBssidAvoidTimeMax > 0) {
-                if (DBG) logd("Previous avoidance still in effect, rssi=" + mGoodLinkTargetRssi
-                        + " count=" + mGoodLinkTargetCount);
-                return;
-            }
-
-            // calculate a new RSSI threshold for new link verifying
-            int from = BSSID_STAT_RANGE_LOW_DBM;
-            int to = BSSID_STAT_RANGE_HIGH_DBM;
-            mGoodLinkTargetRssi = findRssiTarget(from, to, GOOD_LINK_LOSS_THRESHOLD);
-            mGoodLinkTargetCount = 1;
-            mBssidAvoidTimeMax = SystemClock.elapsedRealtime() + MAX_AVOID_TIME[0].TIME_MS;
-            if (DBG) logd("New link verifying target set, rssi=" + mGoodLinkTargetRssi + " count="
-                    + mGoodLinkTargetCount);
-        }
-
-        /**
-         * Return the first RSSI within the range where loss[rssi] < threshold
-         *
-         * @param from start scanning from this RSSI
-         * @param to stop scanning at this RSSI
-         * @param threshold target threshold for scanning
-         * @return target RSSI
-         */
-        public int findRssiTarget(int from, int to, double threshold) {
-            from -= mRssiBase;
-            to -= mRssiBase;
-            int emptyCount = 0;
-            int d = from < to ? 1 : -1;
-            for (int i = from; i != to; i += d)
-                // don't use a data point if it volume is too small (statistically unreliable)
-                if (i >= 0 && i < mEntriesSize && mEntries[i].mVolume > 1.0) {
-                    emptyCount = 0;
-                    if (mEntries[i].mValue < threshold) {
-                        // scan target found
-                        int rssi = mRssiBase + i;
-                        if (DBG) {
-                            DecimalFormat df = new DecimalFormat("#.##");
-                            logd("Scan target found: rssi=" + rssi + " threshold="
-                                    + df.format(threshold * 100) + "% value="
-                                    + df.format(mEntries[i].mValue * 100) + "% volume="
-                                    + df.format(mEntries[i].mVolume));
-                        }
-                        return rssi;
-                    }
-                } else if (++emptyCount >= BSSID_STAT_EMPTY_COUNT) {
-                    // cache has insufficient data around this RSSI, use preset loss instead
-                    int rssi = mRssiBase + i;
-                    double lossPreset = presetLoss(rssi);
-                    if (lossPreset < threshold) {
-                        if (DBG) {
-                            DecimalFormat df = new DecimalFormat("#.##");
-                            logd("Scan target found: rssi=" + rssi + " threshold="
-                                    + df.format(threshold * 100) + "% value="
-                                    + df.format(lossPreset * 100) + "% volume=preset");
-                        }
-                        return rssi;
-                    }
-                }
-
-            return mRssiBase + to;
-        }
-    }
-}