Android：StateMachine 之 WifiStateMachine

時間 2019-11-07

標籤 android statemachine wifistatemachine 欄目 Android 简体版

原文原文鏈接

1、狀態圖：java

2、代碼分析： \frameworks\opt\net\wifi\service\java\com\android\server\wifi\WifiStateMachine.javaandroid

　　1.建立WifiStateMachine的構造函數中添加各個狀態：ide

/*調用stateMachine類的構造方法完成狀態機的構造，名字爲WifiStateMachine*/ 
 super("WifiStateMachine"); 

/*添加狀態*/     
   addState(mDefaultState);
            addState(mInitialState, mDefaultState);
            addState(mSupplicantStartingState, mDefaultState);
            addState(mSupplicantStartedState, mDefaultState);
                addState(mDriverStartingState, mSupplicantStartedState);
                addState(mDriverStartedState, mSupplicantStartedState);
                    addState(mScanModeState, mDriverStartedState);
                    addState(mConnectModeState, mDriverStartedState);
                        addState(mL2ConnectedState, mConnectModeState);
                            addState(mObtainingIpState, mL2ConnectedState);
                            addState(mVerifyingLinkState, mL2ConnectedState);
                            addState(mConnectedState, mL2ConnectedState);
                            addState(mRoamingState, mL2ConnectedState);
                        addState(mDisconnectingState, mConnectModeState);
                        addState(mDisconnectedState, mConnectModeState);
                        addState(mWpsRunningState, mConnectModeState);
                addState(mWaitForP2pDisableState, mSupplicantStartedState);
                addState(mDriverStoppingState, mSupplicantStartedState);
                addState(mDriverStoppedState, mSupplicantStartedState);
            addState(mSupplicantStoppingState, mDefaultState);
            addState(mSoftApStartingState, mDefaultState);
            addState(mSoftApStartedState, mDefaultState);
                addState(mTetheringState, mSoftApStartedState);
                addState(mTetheredState, mSoftApStartedState);
                addState(mUntetheringState, mSoftApStartedState);


/*設置初始狀態*/
setInitialState(mInitialState);

/*設置狀態日誌記錄*/
setLogRecSize(2000);
setLogOnlyTransitions(false);

/*開始狀態機*/
start();

　　2.狀態切換-開啓AP (access point：熱點)函數

　　　　（1）TetheredState監聽中收到CMD_TETHER_STATE_CHANGE消息後調用setHostApRunning() 開啓AP功能，此方法發送CMD_START_AP消息：spa

    public void setHostApRunning(WifiConfiguration wifiConfig, boolean enable) {
        if (enable) {
            sendMessage(CMD_START_AP, wifiConfig);
        } else {
            sendMessage(CMD_STOP_AP);
        }
    }

　　　　（2）狀態機啓動後處於InitialState狀態，processMessage()中處理CMD_START_AP消息：日誌

case CMD_START_AP:　　if (enableSoftAp() == true) {
　　　　/*設置AP狀態*/
　　　　setWifiApState(WIFI_AP_STATE_ENABLING, 0);
　　　　/*狀態切換mSoftApStartingState*/
　　　　transitionTo(mSoftApStartingState);
　　} else {
　　　　setWifiApState(WIFI_AP_STATE_FAILED,
　　　　WifiManager.SAP_START_FAILURE_GENERAL);
　　　　transitionTo(mInitialState);
　　}
break;

　　　　（3）CMD_START_AP消息處理完後，跳轉到mSoftApStartingState進入mSoftApStartingState的enter方法：code

    class SoftApStartingState extends State {
        @Override
        public void enter() {
            final Message message = getCurrentMessage();
            if (message.what == CMD_START_AP) {
                final WifiConfiguration config = (WifiConfiguration) message.obj;

                if (config == null) {
                    mWifiApConfigChannel.sendMessage(CMD_REQUEST_AP_CONFIG);
                } else {
                    mWifiApConfigChannel.sendMessage(CMD_SET_AP_CONFIG, config);
　　　　　　　　　　　　/*開啓AP*/
                    startSoftApWithConfig(config);
                }
            } else {
                throw new RuntimeException("Illegal transition to SoftApStartingState: " + message);
            }
        }
     ......      
}

　　　　(4)startSoftApWithConfig開啓AP成功後，會發送CMD_START_AP_SUCCESS：server

        // Start hostapd on a separate thread
        new Thread(new Runnable() {
            public void run() {
                try {
                    mNwService.startAccessPoint(config, mInterfaceName);
                } catch (Exception e) {
                    loge("Exception in softap start " + e);
                    try {
　　　　　　　　　　　 　　　// 重置熱點　　     　　　   
                        mNwService.stopAccessPoint(mInterfaceName);
                        mNwService.startAccessPoint(config, mInterfaceName);
                    } catch (Exception e1) {
                        loge("Exception in softap re-start " + e1);
                        sendMessage(CMD_START_AP_FAILURE, WifiManager.SAP_START_FAILURE_GENERAL);
                        return;
                    }
                }
                if (DBG) log("Soft AP start successful");
　　　　　　　　　　// 發送消息
                sendMessage(CMD_START_AP_SUCCESS);
            }
        }).start();
    }

　　SoftApStartingState中處理CMD_START_AP_SUCCESS消息：blog

public boolean processMessage(Message message) {
    switch(message.what) {         case CMD_START_AP_SUCCESS:
            /*設置AP狀態*/
            setWifiApState(WIFI_AP_STATE_ENABLED);
            /*跳轉到mSoftApStartedState*/
            transitionTo(mSoftApStartedState);
            break;

         case CMD_START_AP_FAILURE:
            setWifiApState(WIFI_AP_STATE_FAILED, message.arg1);
            transitionTo(mInitialState);
            break;

         default:
            return NOT_HANDLED;
    }
}

　　　　（5）CMD_START_AP_SUCCESS消息處理完後，跳轉到mSoftApStartedState狀態，執行該狀態的enter方法。get

　　　　　　此狀態下收到CMD_TETHER_STATE_CHANGE消息後作進一步處理：

public boolean processMessage(Message message) {
　　　　switch(message.what) {
        //
         　　case CMD_TETHER_STATE_CHANGE:
             　　TetherStateChange stateChange = (TetherStateChange) message.obj;
             　　/*開啓tethering*/
            　　if (startTethering(stateChange.available)) {
                　　transitionTo(mTetheringState);
            　　}
            break;
    　　}
}

　　　　（6）開啓startTethering成功後，跳轉到mTetheringState狀態，執行其enter方法：

 public void enter() {            
        /*發送延時消息，超時時間5s*/
        sendMessageDelayed(obtainMessage(CMD_TETHER_NOTIFICATION_TIMED_OUT,
                    ++mTetherToken, 0), TETHER_NOTIFICATION_TIME_OUT_MSECS);
}

　　　　　　mTetheringState狀態下，收到CMD_TETHER_NOTIFICATION_TIMED_OUT超時消息，則啓動tether失敗，一步步切回到init狀態。

           switch(message.what) {
                case CMD_TETHER_STATE_CHANGE:
                    TetherStateChange stateChange = (TetherStateChange) message.obj;
                    if (isWifiTethered(stateChange.active)) {
                        transitionTo(mTetheredState);
                    }
                    return HANDLED;
                case CMD_TETHER_NOTIFICATION_TIMED_OUT:
                    if (message.arg1 == mTetherToken) {
                        loge("Failed to get tether update, shutdown soft access point");
                        transitionTo(mSoftApStartedState);
                        // Needs to be first thing handled
                        sendMessageAtFrontOfQueue(CMD_STOP_AP);
                    }
                    break;
   ......
            }

　　　　若是在超時消息以前收到CMD_TETHER_STATE_CHANGE消息，則跳轉到 TetheredState 中：

   class TetheredState extends State {
        @Override
        public boolean processMessage(Message message) {
            logStateAndMessage(message, getClass().getSimpleName());

            switch(message.what) {
                case CMD_TETHER_STATE_CHANGE:
                    TetherStateChange stateChange = (TetherStateChange) message.obj;
                    if (!isWifiTethered(stateChange.active)) {
                        loge("Tethering reports wifi as untethered!, shut down soft Ap");
　　　　　　　　　　　　　　 // 開啓熱點
                        setHostApRunning(null, false);
                        setHostApRunning(null, true);
                    }
                    return HANDLED;
......
        }
    }

　　　　其中setHostApRunning方法中發送CMD_START_AP消息：

    public void setHostApRunning(WifiConfiguration wifiConfig, boolean enable) {
        if (enable) {
            sendMessage(CMD_START_AP, wifiConfig);
        } else {
            sendMessage(CMD_STOP_AP);
        }
    }

　　上面發送的CMD_START_AP消息會傳到DefaultState中處理。

　　至此整個狀態機的狀態歷經以下切換，穩定在mThertheredState：

　　　　mInitialState->mSoftApStartingState->mSoftApStartedState->mThetheringState->mThertheredState

　　若在mThertheredState狀態下關閉AP，則按照以下流程切換：

　　　　mThertheredState->mUntetheringState->mSoftApStartedState->mInitialState

　　這個流程中用到了deferMessage來實現相同消息的反覆發送。