android TIF启动流程

TIF是Tv Input Framework的简称，是Android在5.0后加入的tv框架，为了支持android tv功能。

1 TvInputManagerService启动流程

TvInputManagerService在TIF框架结构中扮演Java service层的角色，向java api提供接口实现。

在SystemServer的Main  Thread里面，执行run函数时，回去启动各种services :

startBootstrapServices();
startCoreServices();
startOtherServices();

在startOtherServices()函数里会去启动TvInputManagerService服务：

 if (mPackageManager.hasSystemFeature(PackageManager.FEATURE_LIVE_TV)) {
        mSystemServiceManager.startService(TvInputManagerService.class);
}

支持TIF，平台需要配置feature PackageManager.FEATURE_LIVE_TV，否则无法启动TvInputManagerService.

startService函数会做下面几件事情：

1)TvInputManagerService注册到SystemService

 // Register it.
mServices.add(service);

2)通过反射获取TvInputManagerService实例

 public TvInputManagerService(Context context) {
        super(context);

        mContext = context;
        mWatchLogHandler = new WatchLogHandler(mContext.getContentResolver(),
                IoThread.get().getLooper());
        mTvInputHardwareManager = new TvInputHardwareManager(context, new HardwareListener());

        synchronized (mLock) {
            getOrCreateUserStateLocked(mCurrentUserId);
        }
    }

主要实例化TvInputHardwareManager，TvInputHardwareManager辅助TvInputManagerService管理Tv Input device，包含Tv Input Device Status变化等。
WatchLogHandler是一个Handler，用于处理watch事件，对于这个handler的解释如下：

 // There are only two kinds of watch events that can happen on the system:
        // 1. The current TV input session is tuned to a new channel.
        // 2. The session is released for some reason.

看实现是有一个db去保存watch 状态，可以控制start watch或end watch.

Handler使用的Looper不是System Server Main thread Looper,所以不会卡System Server Main Thread.

3)调用TvInputManagerService  onStart函数

 @Override
    public void onStart() {
        publishBinderService(Context.TV_INPUT_SERVICE, new BinderService());
    }

将ITvInputManager service注册到ServiceManager，在BinderService类中实现ITvInputManager的aidl接口，这个实现代码很长，也是TvInputManagerService主要业务，java api层的接口实现就是在BinderService。

4)调用TvInputManagerService onBootPhase函数

在TvInputManagerService启动时，会call到如下函数：

  @Override
    public void onBootPhase(int phase) {
        if (phase == SystemService.PHASE_SYSTEM_SERVICES_READY) {
            registerBroadcastReceivers();
        } else if (phase == SystemService.PHASE_THIRD_PARTY_APPS_CAN_START) {
            synchronized (mLock) {
                buildTvInputListLocked(mCurrentUserId, null);
                buildTvContentRatingSystemListLocked(mCurrentUserId);
            }
        }
        mTvInputHardwareManager.onBootPhase(phase);
    }

对于phase的两种事件解释如下：

  /**
     * After receiving this boot phase, services can safely call into core system services
     * such as the PowerManager or PackageManager.
     */
    public static final int PHASE_SYSTEM_SERVICES_READY = 500;
  /**
     * After receiving this boot phase, services can start/bind to third party apps.
     * Apps will be able to make Binder calls into services at this point.
     */
    public static final int PHASE_THIRD_PARTY_APPS_CAN_START = 600;

看起来是TvInputManagerService在启动时，有两个启动完毕时间点，一个是可以被core service call，另外一种是被third party apps start/bind

在收到PHASE_SYSTEM_SERVICES_READY  event后，会去注册广播接收器：

 private void registerBroadcastReceivers() {
PackageMonitor monitor = new PackageMonitor() {

这里有一个内部类PackageMonitor，有很多的call back接口，以及内部接口:

 private void buildTvInputList(String[] packages) {
                synchronized (mLock) {
                    buildTvInputListLocked(getChangingUserId(), packages);
                    buildTvContentRatingSystemListLocked(getChangingUserId());
                }
            }

call back接口主要为：

public void onPackageUpdateFinished(String packageName, int uid)
public void onPackagesAvailable(String[] packages)
public void onPackagesUnavailable(String[] packages)
public void onSomePackagesChanged()
public boolean onPackageChanged(String packageName, int uid, String[] components)
public void onPackageRemoved(String packageName, int uid)

看起来都是对package事件的处理，那么看下PackageMonitor注册广播类型：

static {
        sPackageFilt.addAction(Intent.ACTION_PACKAGE_ADDED);
        sPackageFilt.addAction(Intent.ACTION_PACKAGE_REMOVED);
        sPackageFilt.addAction(Intent.ACTION_PACKAGE_CHANGED);
        sPackageFilt.addAction(Intent.ACTION_QUERY_PACKAGE_RESTART);
        sPackageFilt.addAction(Intent.ACTION_PACKAGE_RESTARTED);
        sPackageFilt.addDataScheme("package");
        sNonDataFilt.addAction(Intent.ACTION_UID_REMOVED);
        sNonDataFilt.addAction(Intent.ACTION_USER_STOPPED);
        sExternalFilt.addAction(Intent.ACTION_EXTERNAL_APPLICATIONS_AVAILABLE);
        sExternalFilt.addAction(Intent.ACTION_EXTERNAL_APPLICATIONS_UNAVAILABLE);
    }

看起来都是和apps相关的，这里的apps应该是指TvInputService的实现。

在TIF中，每一种通道可以理解为一个Tv Input Device,有一个Tv Input Service去实现相关的业务逻辑。

比如对于Tunel device，有切台，修改音量，创建会话等行为，都需要Tv Input Service去实现。

当Tv Input Service的apps卸载或安装时，会触发这里的广播reciver.

在收到PHASE_THIRD_PARTY_APPS_CAN_START事件时,会去call buildTvInputListLocked函数，

buildTvInputListLocked函数实现如下：

private void buildTvInputListLocked(int userId, String[] updatedPackages) {
       // 获取系统所有的TvInputService，在AndroidManifest.xml中注册TvInputService时需要带关键字TvInputService.SERVICE_INTERFACE
        PackageManager pm = mContext.getPackageManager();
        List services = pm.queryIntentServicesAsUser(
                new Intent(TvInputService.SERVICE_INTERFACE),
                PackageManager.GET_SERVICES | PackageManager.GET_META_DATA,
                userId);
       ...
      //每一个TvInputService对应一个TvInputInfo，保存TvInput device信息
      List inputList = new ArrayList<>();
      for (ResolveInfo ri : services) {
            ServiceInfo si = ri.serviceInfo;
            //每个TvInputService需要注册BIND_TV_INPUT权限，否则无法启动
            if (!android.Manifest.permission.BIND_TV_INPUT.equals(si.permission)) {
                Slog.w(TAG, "Skipping TV input " + si.name + ": it does not require the permission "
                        + android.Manifest.permission.BIND_TV_INPUT);
                continue;
            }
             ComponentName component = new ComponentName(si.packageName, si.name);
           // 注册TvInputService的app要注册TV_INPUT_HARDWARE权限，否则也无法启动
            if (hasHardwarePermission(pm, component)) {
           ...
           serviceState = new ServiceState(component, userId);
            userState.serviceStateMap.put(component, serviceState);
             //绑定TvInputService
             updateServiceConnectionLocked(component, userId);
             ...
            //保存TvInputService对应的TvInputInfo到TvInput List
            inputList.addAll(serviceState.inputList);
            ....
             for (String inputId : inputMap.keySet()) {
            if (!userState.inputMap.containsKey(inputId)) {
               // Tv Input device status变化，通知上层
                notifyInputAddedLocked(userState, inputId);
            } else if (updatedPackages != null) {
                // Notify the package updates
                ComponentName component = inputMap.get(inputId).info.getComponent();
                for (String updatedPackage : updatedPackages) {
                    if (component.getPackageName().equals(updatedPackage)) {
                       // TvInputService所在的apk有更新，更新service的连接状态
                        updateServiceConnectionLocked(component, userId);
                        notifyInputUpdatedLocked(userState, inputId);
                        break;
                    }
                }
            }
        }
      ....
       for (String inputId : userState.inputMap.keySet()) {
            if (!inputMap.containsKey(inputId)) {
                TvInputInfo info = userState.inputMap.get(inputId).info;
                ServiceState serviceState = userState.serviceStateMap.get(info.getComponent());
                if (serviceState != null) {
                    abortPendingCreateSessionRequestsLocked(serviceState, inputId, userId);
                }
                //tv input device有移除，通知上层
                notifyInputRemovedLocked(userState, inputId);
            }
        }

在TIF设计中考虑了Android多用户的情况，不同的用户，可能会安装不同TvInputService组件。因此TvInputService的状态，Tv input device的状态等需要分别去管理。UserState内部类的添加实现了对多用户的支持。

 private static final class UserState {
        // A mapping from the TV input id to its TvInputState.
        private Map inputMap = new HashMap<>();

        // A set of all TV input packages.
        private final Set packageSet = new HashSet<>();

        // A list of all TV content rating systems defined.
        private final List
                contentRatingSystemList = new ArrayList<>();

        // A mapping from the token of a client to its state.
        private final Map clientStateMap = new HashMap<>();

        // A mapping from the name of a TV input service to its state.
        private final Map serviceStateMap = new HashMap<>();

        // A mapping from the token of a TV input session to its state.
        private final Map sessionStateMap = new HashMap<>();

        // A set of callbacks.
        private final Set callbackSet = new HashSet<>();

        // The token of a "main" TV input session.
        private IBinder mainSessionToken = null;

        // Persistent data store for all internal settings maintained by the TV input manager
        // service.
        private final PersistentDataStore persistentDataStore;

        private UserState(Context context, int userId) {
            persistentDataStore = new PersistentDataStore(context, userId);
        }
    }

ServiceState是对TvInputService状态的记录，TvInputState是对TvInputDevice状态的记录，packageset是对所有TvInputService组件的记录。

   private final class ServiceState {
        private final List sessionTokens = new ArrayList<>();
        private final ServiceConnection connection;
        private final ComponentName component;
        private final boolean isHardware;
        private final List inputList = new ArrayList<>();

        private ITvInputService service;
        private ServiceCallback callback;
        private boolean bound;
        private boolean reconnecting;

        private ServiceState(ComponentName component, int userId) {
            this.component = component;
            this.connection = new InputServiceConnection(component, userId);
            this.isHardware = hasHardwarePermission(mContext.getPackageManager(), component);
        }
    }

    private static final class TvInputState {
        // A TvInputInfo object which represents the TV input.
        private TvInputInfo info;

        // The state of TV input. Connected by default.
        private int state = INPUT_STATE_CONNECTED;

        @Override
        public String toString() {
            return "info: " + info + "; state: " + state;
        }
    }

2 TvInputService启动

启动TvInputService的方法是通过bind方式：

private void updateServiceConnectionLocked(ComponentName component, int userId) {
...
 Intent i = new Intent(TvInputService.SERVICE_INTERFACE).setComponent(component);
            serviceState.bound = mContext.bindServiceAsUser(
                    i, serviceState.connection,
                    Context.BIND_AUTO_CREATE | Context.BIND_FOREGROUND_SERVICE_WHILE_AWAKE,
                    new UserHandle(userId));

bind后，可以拿到TvInputService实例。

private final class InputServiceConnection implements ServiceConnection {
...
 @Override
        public void onServiceConnected(ComponentName component, IBinder service) {
            if (DEBUG) {
                Slog.d(TAG, "onServiceConnected(component=" + component + ")");
            }
            synchronized (mLock) {
                UserState userState = getOrCreateUserStateLocked(mUserId);
                ServiceState serviceState = userState.serviceStateMap.get(mComponent);
                serviceState.service = ITvInputService.Stub.asInterface(service);

在TvInputManagerService中会监控设备插拔事件，并将插拔事件给到TvInputService，TvInputService可以进行对应的逻辑处理。

    private final class HardwareListener implements TvInputHardwareManager.Listener {
        @Override
        public void onStateChanged(String inputId, int state) {
            synchronized (mLock) {
                setStateLocked(inputId, state, mCurrentUserId);
            }
        }

        @Override
        public void onHardwareDeviceAdded(TvInputHardwareInfo info) {
            synchronized (mLock) {
                UserState userState = getOrCreateUserStateLocked(mCurrentUserId);
                // Broadcast the event to all hardware inputs.
                for (ServiceState serviceState : userState.serviceStateMap.values()) {
                    if (!serviceState.isHardware || serviceState.service == null) continue;
                    try {
                        serviceState.service.notifyHardwareAdded(info);
                    } catch (RemoteException e) {
                        Slog.e(TAG, "error in notifyHardwareAdded", e);
                    }
                }
            }
        }

        @Override
        public void onHardwareDeviceRemoved(TvInputHardwareInfo info) {
            synchronized (mLock) {
                UserState userState = getOrCreateUserStateLocked(mCurrentUserId);
                // Broadcast the event to all hardware inputs.
                for (ServiceState serviceState : userState.serviceStateMap.values()) {
                    if (!serviceState.isHardware || serviceState.service == null) continue;
                    try {
                        serviceState.service.notifyHardwareRemoved(info);
                    } catch (RemoteException e) {
                        Slog.e(TAG, "error in notifyHardwareRemoved", e);
                    }
                }
            }
        }

        @Override
        public void onHdmiDeviceAdded(HdmiDeviceInfo deviceInfo) {
            synchronized (mLock) {
                UserState userState = getOrCreateUserStateLocked(mCurrentUserId);
                // Broadcast the event to all hardware inputs.
                for (ServiceState serviceState : userState.serviceStateMap.values()) {
                    if (!serviceState.isHardware || serviceState.service == null) continue;
                    try {
                        serviceState.service.notifyHdmiDeviceAdded(deviceInfo);
                    } catch (RemoteException e) {
                        Slog.e(TAG, "error in notifyHdmiDeviceAdded", e);
                    }
                }
            }
        }

        @Override
        public void onHdmiDeviceRemoved(HdmiDeviceInfo deviceInfo) {
            synchronized (mLock) {
                UserState userState = getOrCreateUserStateLocked(mCurrentUserId);
                // Broadcast the event to all hardware inputs.
                for (ServiceState serviceState : userState.serviceStateMap.values()) {
                    if (!serviceState.isHardware || serviceState.service == null) continue;
                    try {
                        serviceState.service.notifyHdmiDeviceRemoved(deviceInfo);
                    } catch (RemoteException e) {
                        Slog.e(TAG, "error in notifyHdmiDeviceRemoved", e);
                    }
                }
            }
        }

        @Override
        public void onHdmiDeviceUpdated(String inputId, HdmiDeviceInfo deviceInfo) {
            synchronized (mLock) {
                Integer state;
                switch (deviceInfo.getDevicePowerStatus()) {
                    case HdmiControlManager.POWER_STATUS_ON:
                        state = INPUT_STATE_CONNECTED;
                        break;
                    case HdmiControlManager.POWER_STATUS_STANDBY:
                    case HdmiControlManager.POWER_STATUS_TRANSIENT_TO_ON:
                    case HdmiControlManager.POWER_STATUS_TRANSIENT_TO_STANDBY:
                        state = INPUT_STATE_CONNECTED_STANDBY;
                        break;
                    case HdmiControlManager.POWER_STATUS_UNKNOWN:
                    default:
                        state = null;
                        break;
                }
                if (state != null) {
                    setStateLocked(inputId, state, mCurrentUserId);
                }
            }
        }
    }

TvInputHardwareManager是辅助TvInputManagerService管理的类。

3 TvInputHardwareManager介绍

在TvInputManagerSerivce的构造函数中会实例化TvInputHardwareManager:
mTvInputHardwareManager = new TvInputHardwareManager(context, new HardwareListener());
参数HardwareListener即是TvInputManagerService监控Hardware的监听器。

 public TvInputHardwareManager(Context context, Listener listener) {
        mContext = context;
        mListener = listener;
        mAudioManager = (AudioManager) context.getSystemService(Context.AUDIO_SERVICE);
        mHal.init();
    }

TvInputHardwareManager的构造函数很简单，实例化AudioManager以及HAL init，变量mHal是TvInputHal。
TvInputHal的类继承关系：
final class TvInputHal implements Handler.Callback {
主要功能是处理队列消息。

  public void init() {
        synchronized (mLock) {
            mPtr = nativeOpen(mHandler.getLooper().getQueue());
        }
    }

初始化函数是打开一个Message Queue。
在TvInputManagerService中启动时会call到onBootPhase函数：

public void onBootPhase(int phase) {
        if (phase == SystemService.PHASE_SYSTEM_SERVICES_READY) {
            IHdmiControlService hdmiControlService = IHdmiControlService.Stub.asInterface(
                    ServiceManager.getService(Context.HDMI_CONTROL_SERVICE));
            if (hdmiControlService != null) {
                try {
                    hdmiControlService.addHotplugEventListener(mHdmiHotplugEventListener);
                    hdmiControlService.addDeviceEventListener(mHdmiDeviceEventListener);
                    hdmiControlService.addSystemAudioModeChangeListener(
                            mHdmiSystemAudioModeChangeListener);
                    mHdmiDeviceList.addAll(hdmiControlService.getInputDevices());
                } catch (RemoteException e) {
                    Slog.w(TAG, "Error registering listeners to HdmiControlService:", e);
                }
            } else {
                Slog.w(TAG, "HdmiControlService is not available");
            }
            final IntentFilter filter = new IntentFilter();
            filter.addAction(AudioManager.VOLUME_CHANGED_ACTION);
            filter.addAction(AudioManager.STREAM_MUTE_CHANGED_ACTION);
            mContext.registerReceiver(mVolumeReceiver, filter);
            updateVolume();
        }
    }

主要是对HDMI Control service实例化以及初始化，并注册音量变化广播。
TvInputHardwareManager类的实现：
class TvInputHardwareManager implements TvInputHal.Callback
TvInputHal主要是对Message队列消息的处理，Callback函数定义如下：

    public interface Callback {
        void onDeviceAvailable(TvInputHardwareInfo info, TvStreamConfig[] configs);
        void onDeviceUnavailable(int deviceId);
        void onStreamConfigurationChanged(int deviceId, TvStreamConfig[] configs);
        void onFirstFrameCaptured(int deviceId, int streamId);
    }

即TvInputHardwareManager对device状态的监听，是由TvInputHal通知出来。
TvInputHal.java

    // Called from native
    private void deviceAvailableFromNative(TvInputHardwareInfo info) {
        if (DEBUG) {
            Slog.d(TAG, "deviceAvailableFromNative: info = " + info);
        }
        mHandler.obtainMessage(EVENT_DEVICE_AVAILABLE, info).sendToTarget();
    }

    private void deviceUnavailableFromNative(int deviceId) {
        mHandler.obtainMessage(EVENT_DEVICE_UNAVAILABLE, deviceId, 0).sendToTarget();
    }

    private void streamConfigsChangedFromNative(int deviceId) {
        mHandler.obtainMessage(EVENT_STREAM_CONFIGURATION_CHANGED, deviceId, 0).sendToTarget();
    }

    private void firstFrameCapturedFromNative(int deviceId, int streamId) {
        mHandler.sendMessage(
                mHandler.obtainMessage(EVENT_STREAM_CONFIGURATION_CHANGED, deviceId, streamId));
    }

JNI层call到TvInputHal java层接口，将Event给到TvInputHal层，TvInputHal发送Handler消息，在HandlerMessage函数处理handler消息：

    @Override
    public boolean handleMessage(Message msg) {
        switch (msg.what) {
            case EVENT_DEVICE_AVAILABLE: {
                TvStreamConfig[] configs;
                TvInputHardwareInfo info = (TvInputHardwareInfo)msg.obj;
                synchronized (mLock) {
                    retrieveStreamConfigsLocked(info.getDeviceId());
                    if (DEBUG) {
                        Slog.d(TAG, "EVENT_DEVICE_AVAILABLE: info = " + info);
                    }
                    configs = mStreamConfigs.get(info.getDeviceId());
                }
                mCallback.onDeviceAvailable(info, configs);
                break;
            }

            case EVENT_DEVICE_UNAVAILABLE: {
                int deviceId = msg.arg1;
                if (DEBUG) {
                    Slog.d(TAG, "EVENT_DEVICE_UNAVAILABLE: deviceId = " + deviceId);
                }
                mCallback.onDeviceUnavailable(deviceId);
                break;
            }

            case EVENT_STREAM_CONFIGURATION_CHANGED: {
                TvStreamConfig[] configs;
                int deviceId = msg.arg1;
                synchronized (mLock) {
                    if (DEBUG) {
                        Slog.d(TAG, "EVENT_STREAM_CONFIGURATION_CHANGED: deviceId = " + deviceId);
                    }
                    retrieveStreamConfigsLocked(deviceId);
                    configs = mStreamConfigs.get(deviceId);
                }
                mCallback.onStreamConfigurationChanged(deviceId, configs);
                break;
            }

            case EVENT_FIRST_FRAME_CAPTURED: {
                int deviceId = msg.arg1;
                int streamId = msg.arg2;
                mCallback.onFirstFrameCaptured(deviceId, streamId);
                break;
            }

            default:
                Slog.e(TAG, "Unknown event: " + msg);
                return false;
        }

        return true;
    }

处理Handler消息即通过callback将Message给到TvInputHardwareManager。

Tv Input Device state变化的流程可以汇总如下：
HAL->JNI->TvInputHal->TvInputHardwareManager->TvInputManagerService->TvInputService

通过这篇文章，学习了TvInputManagerService启动TvInputService的过程，以及TvInputManagerService,TvInputHardwareManager以及TvinputHal传递TvInputDevice的流程。