1. Bluetooth Enable Overview
1.1 Bluetooth Enable Entrance
packages/apps/Bluetooth/src/com/android/bluetooth/btservice/AdapterService.java
public static class AdapterServiceBinder extends IBluetooth.Stub {
@Override
public boolean enable(boolean quietMode) {
AdapterService service = getService();
......
return service.enable(quietMode);
}
}
public synchronized boolean enable(boolean quietMode) {
......
mQuietmode = quietMode; // 由上層傳遞诅迷，測(cè)試設(shè)備的值 false
mAdapterStateMachine.sendMessage(AdapterState.BLE_TURN_ON);
return true;
}
1.2 Bluetooth StateMachine Overview
packages/apps/Bluetooth/src/com/android/bluetooth/btservice/AdapterState.java
根據(jù)源碼注釋可知，藍(lán)牙開啟的狀態(tài)轉(zhuǎn)換關(guān)系如下圖：
由上圖可知，經(jīng)歷 Off、TurningBleOn贺归、BleOn蕾殴、TurningOn、On 共五個(gè)狀態(tài)脑沿，藍(lán)牙處于完全的開啟狀態(tài)捉兴。
五個(gè)狀態(tài)中蝎困，僅僅 TurningBleOn 和 TurningOn 是不穩(wěn)定狀態(tài)，無論操作成功與否都需要恢復(fù)到穩(wěn)定狀態(tài) Off倍啥、BleOn禾乘、On 三種狀態(tài)中的一種。
下面開始分析藍(lán)牙 enable 整體流程虽缕，分為 TurningBleOn 和 TurningOn 兩個(gè)流程分析盖袭。
首先整體介紹 enable 流程中狀態(tài)機(jī)的轉(zhuǎn)化，再分析 TurningBleOn彼宠，最后分析 TurningOn。
packages/apps/Bluetooth/src/com/android/bluetooth/btservice/AdapterState.java
final class AdapterState extends StateMachine {
// 所有狀態(tài)的基類
private abstract class BaseAdapterState extends State {
abstract int getStateValue();
// 進(jìn)入所有的具體狀態(tài)時(shí)弟塞，需要更新狀態(tài)信息凭峡。（若子類未重寫）
@Override
public void enter() {
int currState = getStateValue();
mAdapterService.updateAdapterState(mPrevState, currState); // 0
mPrevState = currState;
}
......
}
private class OffState extends BaseAdapterState {
@Override
public boolean processMessage(Message msg) {
switch (msg.what) {
case BLE_TURN_ON:
transitionTo(mTurningBleOnState); // 1
break;
}
return true;
}
}
private class TurningBleOnState extends BaseAdapterState {
@Override
public void enter() {
super.enter();
sendMessageDelayed(BLE_START_TIMEOUT, BLE_START_TIMEOUT_DELAY);
mAdapterService.bringUpBle(); // 2
}
@Override
public boolean processMessage(Message msg) {
switch (msg.what) {
case BLE_STARTED:
transitionTo(mBleOnState); // 3
break;
......
}
return true;
}
}
private class BleOnState extends BaseAdapterState {
@Override
public boolean processMessage(Message msg) {
switch (msg.what) {
case USER_TURN_ON:
transitionTo(mTurningOnState); // 4
break;
......
}
return true;
}
}
private class TurningOnState extends BaseAdapterState {
@Override
public void enter() {
super.enter();
sendMessageDelayed(BREDR_START_TIMEOUT, BREDR_START_TIMEOUT_DELAY);
mAdapterService.startProfileServices(); // 5
}
@Override
public boolean processMessage(Message msg) {
switch (msg.what) {
case BREDR_STARTED:
transitionTo(mOnState); // 6
break;
......
}
return true;
}
}
private class OnState extends BaseAdapterState {
@Override
public boolean processMessage(Message msg) {
switch (msg.what) {
case USER_TURN_OFF:
transitionTo(mTurningOffState);
break;
}
return true;
}
}
}
從以上 0~6 共計(jì) 7 個(gè)數(shù)字注釋可知，除了狀態(tài)轉(zhuǎn)移决记，狀態(tài)機(jī)主要執(zhí)行三個(gè)方法：
- mAdapterService.updateAdapterState(mPrevState, currState); 【//0摧冀，通用方法】
- mAdapterService.bringUpBle(); 【//2， TurningBleOn】
- mAdapterService.startProfileServices(); 【// 5系宫，TurningOn】
狀態(tài)機(jī)的狀態(tài)流轉(zhuǎn)過程中會(huì)先后執(zhí)行 bringUpBle() 和 startProfileServices()索昂，但此處還沒有涉及到這些方法是如何被觸發(fā)的，后續(xù)需要將這些內(nèi)容連貫起來扩借。
updateAdapterState() 方法是狀態(tài)機(jī)的通用方法椒惨。先分析其處理流程，再分析狀態(tài)機(jī)的狀態(tài)變化流程潮罪。
2. Bluetooth StateMachine State Update - updateAdapterState()
packages/apps/Bluetooth/src/com/android/bluetooth/btservice/AdapterService.java
void updateAdapterState(int prevState, int newState) {
mAdapterProperties.setState(newState);
invalidateBluetoothGetStateCache();
if (mCallbacks != null) {
int n = mCallbacks.beginBroadcast();
for (int i = 0; i < n; i++) {
try {
mCallbacks.getBroadcastItem(i).onBluetoothStateChange(prevState, newState);
} catch (RemoteException e) {
......
}
}
mCallbacks.finishBroadcast();
}
// Turn the Adapter all the way off if we are disabling and the snoop log setting changed.
if (newState == BluetoothAdapter.STATE_BLE_TURNING_ON) {
mSnoopLogSettingAtEnable =
SystemProperties.get(BLUETOOTH_BTSNOOP_LOG_MODE_PROPERTY, "empty");
mDefaultSnoopLogSettingAtEnable =
Settings.Global.getString(getContentResolver(),
Settings.Global.BLUETOOTH_BTSNOOP_DEFAULT_MODE);
SystemProperties.set(BLUETOOTH_BTSNOOP_DEFAULT_MODE_PROPERTY,
mDefaultSnoopLogSettingAtEnable);
} else if (newState == BluetoothAdapter.STATE_BLE_ON
&& prevState != BluetoothAdapter.STATE_OFF) {
String snoopLogSetting =
SystemProperties.get(BLUETOOTH_BTSNOOP_LOG_MODE_PROPERTY, "empty");
String snoopDefaultModeSetting =
Settings.Global.getString(getContentResolver(),
Settings.Global.BLUETOOTH_BTSNOOP_DEFAULT_MODE);
if (!TextUtils.equals(mSnoopLogSettingAtEnable, snoopLogSetting)
|| !TextUtils.equals(mDefaultSnoopLogSettingAtEnable,
snoopDefaultModeSetting)) {
mAdapterStateMachine.sendMessage(AdapterState.BLE_TURN_OFF);
}
}
}
3. bringUpBle
packages/apps/Bluetooth/src/com/android/bluetooth/btservice/AdapterService.java
void bringUpBle() {
if (getResources().getBoolean(
R.bool.config_bluetooth_reload_supported_profiles_when_enabled)) {
Config.init(getApplicationContext());
}
mRemoteDevices.reset();
mAdapterProperties.init(mRemoteDevices);
mBondStateMachine = BondStateMachine.make(this, mAdapterProperties, mRemoteDevices);
mJniCallbacks.init(mBondStateMachine, mRemoteDevices);
try {
mBatteryStats.noteResetBleScan();
} catch (RemoteException e) {
Log.w(TAG, "RemoteException trying to send a reset to BatteryStats");
}
// 5 Start Gatt service
setProfileServiceState(GattService.class, BluetoothAdapter.STATE_ON);
}
3.1 RemoteDevices
3.2 AdapterProperties
3.3 BondStateMachine
3.4 JniCallbacks
3.5 GattService Initialization
GattService 初始化詳情：GattService Initialization
根據(jù) GattService 的基類初始化 ProfileService Initialization 的內(nèi)容可知康谆，Profile 啟動(dòng)之后领斥，在AdapterService 中會(huì)記錄狀態(tài)以及可能會(huì)觸發(fā)后續(xù)的 藍(lán)牙enable 流程。
packages/apps/Bluetooth/src/com/android/bluetooth/btservice/AdapterService.java
public class AdapterService extends Service {
private void processProfileServiceStateChanged(ProfileService profile, int state) {
switch (state) {
case BluetoothAdapter.STATE_ON:
......
if (GattService.class.getSimpleName().equals(profile.getName())) {
// 啟動(dòng) GATT service 時(shí)沃暗，走該分支月洛，繼續(xù)執(zhí)行 enable
enableNative();
} else if (mRegisteredProfiles.size() == Config.getSupportedProfiles().length
&& mRegisteredProfiles.size() == mRunningProfiles.size()) {
// 所有支持的 profile service 啟動(dòng)后，走該分支
......
}
break;
......
}
}
}
}
以上代碼內(nèi)容孽锥，不僅是 ProfileService 的通用流程嚼黔，還是藍(lán)牙enable的整體流程的內(nèi)容。
- 若 GattService 啟動(dòng)完成惜辑，則執(zhí)行 enableNative()唬涧，詳情：Bluetooth initialization - enable in Bluetooth process - Native(Cpp) ；
- 若所有支持的 profile 啟動(dòng)完成韵丑，則執(zhí)行另外一個(gè)分支爵卒，具體內(nèi)容在下文介紹。
4. startProfileServices
void startProfileServices() {
Class[] supportedProfileServices = Config.getSupportedProfiles();
if (supportedProfileServices.length == 1 && GattService.class.getSimpleName()
.equals(supportedProfileServices[0].getSimpleName())) {
...... // 設(shè)備只支持 BLE 時(shí)走這里撵彻，不分析此路徑
} else {
setAllProfileServiceStates(supportedProfileServices, BluetoothAdapter.STATE_ON);
}
}
private void setAllProfileServiceStates(Class[] services, int state) {
for (Class service : services) {
if (GattService.class.getSimpleName().equals(service.getSimpleName())) {
continue; // GattService 已經(jīng)初始化過了钓株，排除之
}
setProfileServiceState(service, state);
}
}
01-15 21:33:43.404 31081 31081 V AdapterServiceConfig: Adding HeadsetService
01-15 21:33:43.404 31081 31081 V AdapterServiceConfig: Adding A2dpService
01-15 21:33:43.404 31081 31081 V AdapterServiceConfig: Adding HidHostService
01-15 21:33:43.404 31081 31081 V AdapterServiceConfig: Adding PanService
01-15 21:33:43.404 31081 31081 V AdapterServiceConfig: Adding GattService
01-15 21:33:43.404 31081 31081 V AdapterServiceConfig: Adding BluetoothMapService
01-15 21:33:43.404 31081 31081 V AdapterServiceConfig: Adding AvrcpTargetService
01-15 21:33:43.404 31081 31081 V AdapterServiceConfig: Adding SapService
01-15 21:33:43.404 31081 31081 V AdapterServiceConfig: Adding HidDeviceService
01-15 21:33:43.404 31081 31081 V AdapterServiceConfig: Adding BluetoothOppService
01-15 21:33:43.404 31081 31081 V AdapterServiceConfig: Adding BluetoothPbapService
01-15 21:33:43.404 31081 31081 V AdapterServiceConfig: Adding HearingAidService
Android 11 Pixel5 在藍(lán)牙進(jìn)程初始化時(shí)會(huì)添加以上這些Service，此處會(huì)分別初始化它們（除 GattService之外陌僵，GattService 在 bingUpBle 階段初始化）轴合。
Profiles 的初始化過程如下：
Profile Initialization - HeadsetService
Profile Initialization - A2dpService
Profile Initialization - HidHostService
Profile Initialization - HidDeviceService
Profile Initialization - PanService
Profile Initialization - SapService
Profile Initialization - AvrcpTargetService
Profile Initialization - BluetoothMapService
Profile Initialization - BluetoothPbapService
Profile Initialization - BluetoothOppService
Profile Initialization - HearingAidService
當(dāng)所有支持的 Profile 全部注冊(cè)并啟動(dòng)之后，執(zhí)行
packages/apps/Bluetooth/src/com/android/bluetooth/btservice/AdapterService.java
public class AdapterService extends Service {
private void processProfileServiceStateChanged(ProfileService profile, int state) {
switch (state) {
case BluetoothAdapter.STATE_ON:
......
if (GattService.class.getSimpleName().equals(profile.getName())) {
// 啟動(dòng) GATT service 時(shí)碗短，走該分支受葛，繼續(xù)執(zhí)行 enable
......
} else if (mRegisteredProfiles.size() == Config.getSupportedProfiles().length
&& mRegisteredProfiles.size() == mRunningProfiles.size()) {
// 所有支持的 profile service 啟動(dòng)后，走該分支
mAdapterProperties.onBluetoothReady();
updateUuids();
setBluetoothClassFromConfig();
initProfileServices();
getAdapterPropertyNative(AbstractionLayer.BT_PROPERTY_LOCAL_IO_CAPS);
getAdapterPropertyNative(AbstractionLayer.BT_PROPERTY_LOCAL_IO_CAPS_BLE);
mAdapterStateMachine.sendMessage(AdapterState.BREDR_STARTED);
}
break;
......
}
}
}
}
若所有支持的 profile 啟動(dòng)完成偎谁，則執(zhí)行一些其他的初始化操作总滩。
隨后向狀態(tài)機(jī)發(fā)送 BREDR_STARTED 消息，狀態(tài)機(jī)進(jìn)入 OnState巡雨。
5. Summary
經(jīng)過以上分析闰渔，藍(lán)牙初始化整體架構(gòu)如下圖：
