Android wifi disable分析

总体流程

• 老套路基本不变： WifiSettings 通过 WifiManager 下cmd 给 WifiService
• WifiService 收到cmd后，先完成一部分列行检查（如UID的权限、是否airPlayMode等等），之后将cmd下发给到WifiController
• WifiController 收到cmd 之后，在内部状态机轮询一圈（就是将cmd送给对应的状态机进行处理，处理完后，送往下一个状态机进行加工），俨然很标准化的流水线工序，完成后再送到WifiStateMachinePrime处理
• WifiStateMachinePrime 是P 版本新增的Prime状态机，分担了原来WifiStateMachine工作，同样按照标准化流水线工序加工，完成后送到WifiNative，
• WifiNative是包工头，负责将活儿下发到工人(wpa_supplicant）身上，工人没完成一件任务，上报分销商(wifiMonitor)，各大分销商又将结果按照约定的渠道上报包工头(wifiNative)、总经销商（wifiService、wifiScanningService）等等，完成此项工作的闭环。

代码流程

1. WifiEnabler --> WifiManager

• 老规矩： WifiSettings --> WifiEnabler 调用wifiManager 来disable Wifi

packages/apps/Settings/src/com/android/settings/wifi/WifiEnabler.java
public boolean onSwitchToggled(boolean isChecked) {
  ..  
   mWifiManager.setWifiEnabled(isChecked);
}

2. WifiManager–> WifiService --> WifiServiceImpl

• setWifiEnabled 函数里 前面有一大堆列行检查
• 最后是关键，发送CMD_WIFI_TOGGLED

frameworks/opt/net/wifi/service/java/com/android/server/wifi/WifiServiceImpl.java
public synchronized boolean setWifiEnabled(String packageName, boolean enable){
	.... 
	mWifiController.sendMessage(CMD_WIFI_TOGGLED);
}

3. WifiServiceImpl --> WifiController

• 流水线上的标准加工： StaEnabledState --> StaDisabledState
• 转入到wifiStateMachinePrime 处理wifi disable 事项

frameworks/opt/net/wifi/service/java/com/android/server/wifi/WifiController.java
class StaEnabledState extends State {
  switch (msg.what) {
          case CMD_WIFI_TOGGLED:
             if (! mSettingsStore.isWifiToggleEnabled()) {
                 if (checkScanOnlyModeAvailable()) {
                     transitionTo(mStaDisabledWithScanState);
                 } else {
                     transitionTo(mStaDisabledState); // 转入StaDisableState 处理 wifi disable 事项
                 }
             }

class StaDisabledState extends State {
	public void enter() {
	   mWifiStateMachinePrime.disableWifi(); // 转入wifiStateMachinePrime 处理wifi disable 
	   // Supplicant can't restart right away, so note the time we switched off
	   mDisabledTimestamp = SystemClock.elapsedRealtime();
	   mDeferredEnableSerialNumber++;
	   mHaveDeferredEnable = false;
	   mWifiStateMachine.clearANQPCache();
  }
}

4. WifiStateMachinePrime --> WifiScaningServiceImpl

• WifiStateMachinePrime 发送CMD_DISABLE_WIFI给到内部状态机处理
• WifiDisabledState 接领任务，先广播停掉Scan（WifiManager.EXTRA_SCAN_AVALIABLE），然后 clearScanResults

frameworks/opt/net/wifi/service/java/com/android/server/wifi/WifiStateMachinePrime.java
 public void disableWifi() {
 	changeMode(ModeStateMachine.CMD_DISABLE_WIFI);
 }
class WifiDisabledState extends ModeActiveState {
	 public void enter() {
	 mDefaultModeManager.sendScanAvailableBroadcast(mContext, false);
	 mScanRequestProxy.enableScanningForHiddenNetworks(false);
	 mScanRequestProxy.clearScanResults();
	 }
}

5. WifiScaningServiceImpl 善后

• 接收到wifi disable 需求后，立即开始清掉ScanResults

frameworks/opt/net/wifi/service/java/com/android/server/wifi/scanner/WifiScanningServiceImpl.java{
public void onReceive(Context context, Intent intent){
	else if (state == WifiManager.WIFI_STATE_DISABLED) {
		  mBackgroundScanStateMachine.sendMessage(CMD_DRIVER_UNLOADED);
		  mSingleScanStateMachine.sendMessage(CMD_DRIVER_UNLOADED);
		  mPnoScanStateMachine.sendMessage(CMD_DRIVER_UNLOADED);
	}	
}

 class DefaultState extends State {
 	public void enter() {
	mActiveScans.clear();
	mPendingScans.clear()；}
 }