Android R Framework wifi扫描场景总结

文章目录

Android Framework wifi扫描
Android R wifi扫描场景(包含客制化项)
- 亮屏情况下，在 WifiSetting 界面
- 亮屏情况下,在非 WifiSettings 界面
- 灭屏情况下
- 无保存网络情况下，固定扫描

Android Framework wifi扫描

当打开wifi时、进入wifi settings时、亮屏时、灭屏时、连接状态变化时，都会触发扫描

以下场景1/2/4中的扫描是全信道扫描，扫描控制逻辑在Android framework，涉及模块依次是WifiTracker、WifiConnectivityManager、WifiStateMachine

场景3中的扫描是PNO扫描，即只扫描已保存的网络，PNO扫描的控制逻辑涉及较广，从上到下：WifiConnectivityManager、WifiScanner、WifiScanningServiceImpl、WifiNative、wificond、wifi driver、firmware

Android R wifi扫描场景(包含客制化项)

代码只展示关键部分

亮屏情况下，在 WifiSetting 界面

固定扫描，时间间隔为 10s
注意，进入 WifiSettings 界面是一定会扫描的!
验证手段可见 adb logcat -s WifiService startScan uid = 1000

/* WifiSettings2.java */
// Interval between initiating WifiPickerTracker scans
private static final long SCAN_INTERVAL_MILLIS = 10_000;mWifiPickerTracker = new WifiPickerTracker(getSettingsLifecycle(), mAppContext == null?context:mAppContext,mAppContext.getSystemService(WifiManager.class),mAppContext.getSystemService(ConnectivityManager.class),mAppContext.getSystemService(NetworkScoreManager.class),new Handler(Looper.getMainLooper()),mWorkerThread.getThreadHandler(),elapsedRealtimeClock,MAX_SCAN_AGE_MILLIS,SCAN_INTERVAL_MILLIS,this);/* WifiPickerTracker.java */
public class WifiPickerTracker extends BaseWifiTracker
WifiPickerTracker Constructor/* BaseWifiTracker.java */
BaseWifiTracker Constructor
mScanIntervalMillis = scanIntervalMillis;private final BroadcastReceiver mBroadcastReceiver = new BroadcastReceiver() {public void onReceive(Context context, Intent intent) {String action = intent.getAction();// 监听wifi打开事件if (WifiManager.WIFI_STATE_CHANGED_ACTION.equals(action)) {if (mWifiManager.getWifiState() == WifiManager.WIFI_STATE_ENABLED) {mScanner.start();} else {mScanner.stop();}}}
}private class Scanner extends Handler {private static final int SCAN_RETRY_TIMES = 3;private void start() {postScan();}private void postScan() {if (mWifiManager.startScan()) {mRetry = 0;} else if (++mRetry >= SCAN_RETRY_TIMES) {mRetry = 0;return;}postDelayed(this::postScan, mScanIntervalMillis);}
}

亮屏情况下,在非 WifiSettings 界面

分以下几种情形：

已连接，且满足以下条件之一，就不进行扫描
- 通过 sufficiency check，主要是信号值的检查，2.4G -73dBm, 5G -70dBm
- 网络状态好
- 有活跃的数据流
已连接，但不满足上述条件的任意一个，进行配置的全频段扫描
- 前3min，5s扫描一次
- 3 ~ 10min，10s扫描一次
- 10min后，20s，而后二进制指数退避，即 20-40-80-160

/* WifiConnectivityManager.java */
private static final boolean SCAN_ON_SCHEDULE = false;
private static final int QUICK_SCAN_TIME =  3 * 60 * 1000;
public static final int QUICK_PERIODIC_SCAN_INTERVAL_MS = 5 * 1000;
private static final int QUICK_SCAN_TIME_LONG =  10 * 60 * 1000;
private static final int QUICK_PERIODIC_SCAN_INTERVAL_MS_LONG = 10 * 1000;public void handleScreenStateChanged(boolean screenOn){mScreenOn = screenOn;if(mScreenOn){mScreenOnTimeStamp = mClock.getElapsedSinceBootMillis();}startConnectivityScan(SCAN_ON_SCHEDULE);
}private void startConnectivityScan(boolean scanImmediately) {stopConnectivityScan();// Don't start a connectivity scan while Wifi is in the transition// between connected and disconnected states.if ((mWifiState != WIFI_STATE_CONNECTED && mWifiState != WIFI_STATE_DISCONNECTED)|| (getSingleScanningSchedule() == null)) {return;}if (mScreenOn) {//此处 scanImmediately 为 false，表明不是立即扫描startPeriodicScan(scanImmediately);} else {if (mWifiState == WIFI_STATE_DISCONNECTED && !mPnoScanStarted) {startDisconnectedPnoScan();}}
}// Start a periodic scan when screen is on
private void startPeriodicScan(boolean scanImmediately) {if (scanImmediately) {resetLastPeriodicSingleScanTimeStamp();}mCurrentSingleScanScheduleIndex = 0;startPeriodicSingleScan();
}// Start a single scan and set up the interval for next single scan.
private void startPeriodicSingleScan() {long currentTimeStamp = mClock.getElapsedSinceBootMillis();if (mLastPeriodicSingleScanTimeStamp != RESET_TIME_STAMP) {long msSinceLastScan = currentTimeStamp - mLastPeriodicSingleScanTimeStamp;if (msSinceLastScan < getScheduledSingleScanIntervalMs(0)) {localLog("Last periodic single scan started " + msSinceLastScan+ "ms ago, defer this new scan request.");schedulePeriodicScanTimer(getScheduledSingleScanIntervalMs(0) - (int) msSinceLastScan);return;}}boolean isScanNeeded = true;boolean isFullBandScan = true;// Check it is one of following conditions to skip scan (with firmware roaming)// or do partial scan only (without firmware roaming).// 1) Network is sufficient// 2) link is good, internet status is acceptable//    and it is a short time since last network selection// 3) There is active stream such that scan will be likely disruptiveif (mWifiState == WIFI_STATE_CONNECTED&& (mNetworkSelector.isNetworkSufficient(mWifiInfo)|| isGoodLinkAndAcceptableInternetAndShortTimeSinceLastNetworkSelection|| mNetworkSelector.hasActiveStream(mWifiInfo))) {// If only partial scan is proposed and firmware roaming control is supported,// we will not issue any scan because firmware roaming will take care of// intra-SSID roam.// 此处返回 true，将 isScanNeeded 置为 falseif (mConnectivityHelper.isFirmwareRoamingSupported()) {localLog("No partial scan because firmware roaming is supported.");isScanNeeded = false;} else {localLog("No full band scan because current network is sufficient");isFullBandScan = false;}}if (isScanNeeded) {mLastPeriodicSingleScanTimeStamp = currentTimeStamp;if (mWifiState == WIFI_STATE_DISCONNECTED&& mInitialScanState == INITIAL_SCAN_STATE_START) {startSingleScan(false, WIFI_WORK_SOURCE);return;}startSingleScan(isFullBandScan, WIFI_WORK_SOURCE);schedulePeriodicScanTimer(getScheduledSingleScanIntervalMs(mCurrentSingleScanScheduleIndex));// Set up the next scan interval in an exponential backoff fashion.mCurrentSingleScanScheduleIndex++;} else {// Since we already skipped this scan, keep the same scan interval for next scan.schedulePeriodicScanTimer(getScheduledSingleScanIntervalMs(mCurrentSingleScanScheduleIndex));}
}// Retrieve a value from single scanning schedule in ms
private int getScheduledSingleScanIntervalMs(int index) {synchronized (mLock) {long currentTimeStamp = mClock.getElapsedSinceBootMillis();boolean qucikScanProcess = (currentTimeStamp - mScreenOnTimeStamp) < QUICK_SCAN_TIME|| (currentTimeStamp - mDisconnectTimeStamp) < QUICK_SCAN_TIME;boolean qucikScanProcessSecond = (currentTimeStamp - mScreenOnTimeStamp) < QUICK_SCAN_TIME_LONG|| (currentTimeStamp - mDisconnectTimeStamp) < QUICK_SCAN_TIME_LONG;if(qucikScanProcess){mCurrentSingleScanScheduleIndex = 0;return QUICK_PERIODIC_SCAN_INTERVAL_MS;}else if(qucikScanProcessSecond){mCurrentSingleScanScheduleIndex = 0;return QUICK_PERIODIC_SCAN_INTERVAL_MS_LONG;}if (mCurrentSingleScanScheduleSec == null) {Log.e(TAG, "Invalid attempt to get schedule interval, Schedule array is null ");// Use a default valuereturn DEFAULT_SCANNING_SCHEDULE_SEC[0] * 1000;}if (index >= mCurrentSingleScanScheduleSec.length) {index = mCurrentSingleScanScheduleSec.length - 1;}return mCurrentSingleScanScheduleSec[index] * 1000;}
}

灭屏情况下

有连接，不扫描
无连接，又分以下情形
- 没有保存网络，不扫描
- 有保存网络，根据设备移动状态来决定扫描间隔，20s或者60s

// Start a DisconnectedPNO scan when screen is off and Wifi is disconnected
private void startDisconnectedPnoScan() {PnoSettings pnoSettings = new PnoSettings();List<PnoSettings.PnoNetwork> pnoNetworkList = retrievePnoNetworkList();int listSize = pnoNetworkList.size();if (listSize == 0) {return;}pnoSettings.networkList = new PnoSettings.PnoNetwork[listSize];pnoSettings.networkList = pnoNetworkList.toArray(pnoSettings.networkList);pnoSettings.min6GHzRssi = mScoringParams.getEntryRssi(ScanResult.BAND_6_GHZ_START_FREQ_MHZ);pnoSettings.min5GHzRssi = mScoringParams.getEntryRssi(ScanResult.BAND_5_GHZ_START_FREQ_MHZ);pnoSettings.min24GHzRssi = mScoringParams.getEntryRssi(ScanResult.BAND_24_GHZ_START_FREQ_MHZ);// Initialize scan settingsScanSettings scanSettings = new ScanSettings();scanSettings.band = getScanBand();scanSettings.reportEvents = WifiScanner.REPORT_EVENT_NO_BATCH;scanSettings.numBssidsPerScan = 0;scanSettings.periodInMs = deviceMobilityStateToPnoScanIntervalMs(mDeviceMobilityState);mPnoScanListener.clearScanDetails();mScanner.startDisconnectedPnoScan(scanSettings, pnoSettings, new HandlerExecutor(mEventHandler), mPnoScanListener);mPnoScanStarted = true;
}private int deviceMobilityStateToPnoScanIntervalMs(@DeviceMobilityState int state) {switch (state) {case WifiManager.DEVICE_MOBILITY_STATE_UNKNOWN:case WifiManager.DEVICE_MOBILITY_STATE_LOW_MVMT:case WifiManager.DEVICE_MOBILITY_STATE_HIGH_MVMT:return mContext.getResources().getInteger(R.integer.config_wifiMovingPnoScanIntervalMillis);case WifiManager.DEVICE_MOBILITY_STATE_STATIONARY:return mContext.getResources().getInteger(R.integer.config_wifiStationaryPnoScanIntervalMillis);default:return -1;}
}

无保存网络情况下，固定扫描

间隔为5分钟，用于通知用户周围存在可用开放网络
这部分代码没看过，不确定是不是这样

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