Android:StateMachine 之 WifiStateMachine
一、状态图:
二、代码分析: \frameworks\opt\net\wifi\service\java\com\android\server\wifi\WifiStateMachine.java
1.创建WifiStateMachine的构造函数中添加各个状态:
/*调用stateMachine类的构造方法完成状态机的构造,名字为WifiStateMachine*/
super("WifiStateMachine"); /*添加状态*/
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); /*设置初始状态*/
setInitialState(mInitialState); /*设置状态日志记录*/
setLogRecSize(2000);
setLogOnlyTransitions(false); /*开始状态机*/
start();
2.状态切换-开启AP (access point:热点)
(1)TetheredState监听中收到CMD_TETHER_STATE_CHANGE消息后调用setHostApRunning() 开启AP功能,此方法发送CMD_START_AP消息:
public void setHostApRunning(WifiConfiguration wifiConfig, boolean enable) {
if (enable) {
sendMessage(CMD_START_AP, wifiConfig);
} else {
sendMessage(CMD_STOP_AP);
}
}
(2)状态机启动后处于InitialState状态,processMessage()中处理CMD_START_AP消息:
case CMD_START_AP: if (enableSoftAp() == true) {
/*设置AP状态*/
setWifiApState(WIFI_AP_STATE_ENABLING, 0);
/*状态切换mSoftApStartingState*/
transitionTo(mSoftApStartingState);
} else {
setWifiApState(WIFI_AP_STATE_FAILED,
WifiManager.SAP_START_FAILURE_GENERAL);
transitionTo(mInitialState);
}
break;
(3)CMD_START_AP消息处理完后,跳转到mSoftApStartingState进入mSoftApStartingState的enter方法:
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);
/*开启AP*/
startSoftApWithConfig(config);
}
} else {
throw new RuntimeException("Illegal transition to SoftApStartingState: " + message);
}
}
......
}
(4)startSoftApWithConfig开启AP成功后,会发送CMD_START_AP_SUCCESS:
// 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 {
// 重置热点
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");
// 发送消息
sendMessage(CMD_START_AP_SUCCESS);
}
}).start();
}
SoftApStartingState中处理CMD_START_AP_SUCCESS消息:
public boolean processMessage(Message message) {
switch(message.what) { case CMD_START_AP_SUCCESS:
/*设置AP状态*/
setWifiApState(WIFI_AP_STATE_ENABLED);
/*跳转到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消息处理完后,跳转到mSoftApStartedState状态,执行该状态的enter方法。
此状态下收到CMD_TETHER_STATE_CHANGE消息后做进一步处理:
public boolean processMessage(Message message) {
switch(message.what) {
//
case CMD_TETHER_STATE_CHANGE:
TetherStateChange stateChange = (TetherStateChange) message.obj;
/*开启tethering*/
if (startTethering(stateChange.available)) {
transitionTo(mTetheringState);
}
break;
}
}
(6)开启startTethering成功后,跳转到mTetheringState状态,执行其enter方法:
public void enter() {
/*发送延时消息,超时时间5s*/
sendMessageDelayed(obtainMessage(CMD_TETHER_NOTIFICATION_TIMED_OUT,
++mTetherToken, 0), TETHER_NOTIFICATION_TIME_OUT_MSECS);
}
mTetheringState状态下,收到CMD_TETHER_NOTIFICATION_TIMED_OUT超时消息,则启动tether失败,一步步切回到init状态。
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;
......
}
如果在超时消息之前收到CMD_TETHER_STATE_CHANGE消息,则跳转到 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");
// 开启热点
setHostApRunning(null, false);
setHostApRunning(null, true);
}
return HANDLED;
......
}
}
其中setHostApRunning方法中发送CMD_START_AP消息:
public void setHostApRunning(WifiConfiguration wifiConfig, boolean enable) {
if (enable) {
sendMessage(CMD_START_AP, wifiConfig);
} else {
sendMessage(CMD_STOP_AP);
}
}
上面发送的CMD_START_AP消息会传到DefaultState中处理。
至此整个状态机的状态历经如下切换,稳定在mThertheredState:
mInitialState->mSoftApStartingState->mSoftApStartedState->mThetheringState->mThertheredState
若在mThertheredState状态下关闭AP,则按照如下流程切换:
mThertheredState->mUntetheringState->mSoftApStartedState->mInitialState
这个流程中用到了deferMessage来实现相同消息的反复发送。
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