CHRE: contexthub service代码实现

contexthub代码总结构

contexhub的代码包括AP和SLPI上的两部分：

contexthub有两个相关的接口层分别是contexthub对应的IContextHubService.hal 和[email protected]对应的IContexthub，两者分别生成client/server代码; IContextHubService的server端调用IContexthub的client端向下通信；IContexthub调用IContextHubService注册的回调函数向上通信。

contexthub service的实现

frameworks/base/core/java/android/hardware/location/ 

contexthub service的接口定义 xxx.aidl生成对用的client/server 其中主要是IContextHubService.aidl，其中java代码是怎样使用 contexthub service.
IContextHubCallback.aidl
IContextHubClient.aidl
IContextHubClientCallback.aidl
IContextHubService.aidl
IContextHubTransactionCallback.aidl
ContextHubClient.java
ContextHubClientCallback.java
ContextHubInfo.aidl
ContextHubInfo.java
ContextHubManager.java
ContextHubMessage.aidl
ContextHubMessage.java
ContextHubTransaction.java

frameworks/base/services/core/java/com/android/server/location/

该路径的文件实现具体的ContextHubService，实现接口功能，为实现接口功能就有和hidl生成的client通信
ContextHubClientBroker.java
ContextHubClientManager.java
ContextHubService.java
ContextHubServiceTransaction.java
ContextHubServiceUtil.java
ContextHubTransactionManager.java

 

该aidl文件生成的对应的ava文件位于
out/soong/.intermediates/frameworks/base/framework/android_common/gen/aidl

生成的接口类和Stub是个abstract不能被创建对象
public static abstract class Stub extends android.os.Binder implements android.hardware.location.IContextHubService

具体的接口都是在这里实现的
frameworks/base/services/core/java/com/android/server/location/ContextHubService.java
public class ContextHubService extends IContextHubService.Stub{
}

1] IContexthub.getService(true )调用静态函数获得IContexthub的client，用于和IContexthub的通信

2] ContextHubService.java实现 class ContextHubServiceCallback extends IContexthubCallback.Stub并向hidl层注册，这里注册的函数调用了clientManager和transManager等等，这样回调函数最终到client端。

3] contexthub系统service的注册和启动

4] ContextHubService的创建：看下图中的创建

 

 ContextHubClient 

能看出 ContextHubService的实现中有ContextHubClientManager但它管理的是ContextHubClientBroker 而不是从名字上看更贴切的ContextHubClient，这里只关注ContextHubService的实现中使用的IContextHubClient

IContextHubClient

interface IContextHubClient {

    // Sends a message to a nanoapp
    int sendMessageToNanoApp(in NanoAppMessage message);

    // Closes the connection with the Context Hub
    void close();
}

IContextHubClientCallback

oneway interface IContextHubClientCallback {

    // Callback invoked when receiving a message from a nanoapp.
    void onMessageFromNanoApp(in NanoAppMessage message);

    // Callback invoked when the attached Context Hub has reset.
    void onHubReset();

    // Callback invoked when a nanoapp aborts at the attached Context Hub.
    void onNanoAppAborted(long nanoAppId, int abortCode);

    // Callback invoked when a nanoapp is loaded at the attached Context Hub.
    void onNanoAppLoaded(long nanoAppId);

    // Callback invoked when a nanoapp is unloaded from the attached Context Hub.
    void onNanoAppUnloaded(long nanoAppId);

    // Callback invoked when a nanoapp is enabled at the attached Context Hub.
    void onNanoAppEnabled(long nanoAppId);

    // Callback invoked when a nanoapp is disabled at the attached Context Hub.
    void onNanoAppDisabled(long nanoAppId);
}

 ContextHubClient是通过ContextHubClientManger来管理的，当调用mClientManager.registerClient()时注册client回调函数。

class ContextHubClientManager

/**
 * A class that manages registration/unregistration of clients and manages messages to/from clients.
 *
 * @hide
 */
class ContextHubClientManager {
    ContextHubClientManager(
            Context context, IContexthub contextHubProxy) {
        mContext = context;
        mContextHubProxy = contextHubProxy;
    }

1] registerClient: 引入host endpoint ID
    IContextHubClient registerClient(//由clientCallback, contextHubId创建Client
            IContextHubClientCallback clientCallback, int contextHubId) {
        ContextHubClientBroker broker = createNewClientBroker(clientCallback, contextHubId);

        try {
            broker.attachDeathRecipient();
        }

        Log.d(TAG, "Registered client with host endpoint ID " + broker.getHostEndPointId());
        return IContextHubClient.Stub.asInterface(broker);
    }

    private synchronized ContextHubClientBroker createNewClientBroker(
            IContextHubClientCallback clientCallback, int contextHubId) {
        ContextHubClientBroker broker = null;

        int id = mNextHostEndpointId;//同一个HubId上可能有多个NanoApp
        for (int i = 0; i <= MAX_CLIENT_ID; i++) {
            if (!mHostEndPointIdToClientMap.containsKey((short)id)) {
                broker = new ContextHubClientBroker(
                        mContext, mContextHubProxy, this, contextHubId, (short)id, clientCallback);
                mHostEndPointIdToClientMap.put((short)id, broker);
                mNextHostEndpointId = (id == MAX_CLIENT_ID) ? 0 : id + 1;
                break;
            }

            id = (id == MAX_CLIENT_ID) ? 0 : id + 1;
        }

        return broker;
    }

2] callback: 广播的形式发出还是发给某个具体的nanoApp
    void onMessageFromNanoApp(int contextHubId, ContextHubMsg message) {
        NanoAppMessage clientMessage = ContextHubServiceUtil.createNanoAppMessage(message);
    //广播消息:同一个HubId
        if (clientMessage.isBroadcastMessage()) {
            broadcastMessage(contextHubId, clientMessage);
        } else {//某个具体的NanoApp
            ContextHubClientBroker proxy = mHostEndPointIdToClientMap.get(message.hostEndPoint);
            if (proxy != null) {
                proxy.sendMessageToClient(clientMessage);
            } else {
                Log.e(TAG, "Cannot send message to unregistered client (host endpoint ID = "
                        + message.hostEndPoint + ")");
            }
        }
    }
}

class ContextHubClientBroker extends IContextHubClient.Stub

/**
 * A class that acts as a broker for the ContextHubClient, which handles messaging and life-cycle
 * notification callbacks. This class implements the IContextHubClient object, and the implemented
 * APIs must be thread-safe.??
 *
 * @hide
 */
public class ContextHubClientBroker extends IContextHubClient.Stub
        implements IBinder.DeathRecipient {
    /*
     * The ID of the hub that this client is attached to.
     */
    private final int mAttachedContextHubId;

    /*
     * The host end point ID of this client. ??
     */
    private final short mHostEndPointId;

1] 构造函数
    /* package */ 
    ContextHubClientBroker(
            Context context, IContexthub contextHubProxy, ContextHubClientManager clientManager,
            int contextHubId, short hostEndPointId, IContextHubClientCallback callback) {
        mContext = context;
        mContextHubProxy = contextHubProxy;
        mClientManager = clientManager;
        mAttachedContextHubId = contextHubId;
        mHostEndPointId = hostEndPointId;
        mCallbackInterface = callback;
    }

2] IContextHubClient
    public int sendMessageToNanoApp(NanoAppMessage message) {
        ContextHubServiceUtil.checkPermissions(mContext);

        int result;
        if (mConnectionOpen.get()) {//这里不是hubID而是HostEndPointId
            ContextHubMsg messageToNanoApp = ContextHubServiceUtil.createHidlContextHubMessage(
                    mHostEndPointId, message);
            try {
                result = mContextHubProxy.sendMessageToHub(mAttachedContextHubId, messageToNanoApp);
            }
        }

        return ContextHubServiceUtil.toTransactionResult(result);
    }

    public void close() {
        if (mConnectionOpen.getAndSet(false)) {
            mClientManager.unregisterClient(mHostEndPointId);
        }
    }

3] 封装一层对IContextHubClientCallback的调用(判断是否连接状态)
    void onNanoAppLoaded(long nanoAppId) {
        if (mConnectionOpen.get()) {
            try {
                mCallbackInterface.onNanoAppLoaded(nanoAppId);
            }
        }
    }
}

IContexthubCallback

ContextHubService.java实现了 IContexthubCallback

dump contexthub

 

    protected void dump(FileDescriptor fd, PrintWriter pw, String[] args) {
        if (!DumpUtils.checkDumpPermission(mContext, TAG, pw)) return;

        pw.println("Dumping ContextHub Service");

        pw.println("");
        // dump ContextHubInfo
        pw.println("=================== CONTEXT HUBS ====================");
        for (ContextHubInfo hubInfo : mContextHubIdToInfoMap.values()) {
            pw.println(hubInfo);
        }
        pw.println("");
        pw.println("=================== NANOAPPS ====================");
        // Dump nanoAppHash
        for (NanoAppInstanceInfo info : mNanoAppStateManager.getNanoAppInstanceInfoCollection()) {
            pw.println(info);
        }

        // dump eventLog
    }

Dumping ContextHub Service

=================== CONTEXT HUBS ====================
ID/handle : 0, Name : CHRE on SLPI
    Vendor : Google, Toolchain : Hexagon Tools 8.x (clang 5.0.0), Toolchain version: 0x5000000
    PlatformVersion : 0x0, SwVersion : 1.2.1, CHRE platform ID: 0x476f6f676c000002
    PeakMips : 350.0, StoppedPowerDraw : 0.0 mW, PeakPowerDraw : 15.0 mW, MaxPacketLength : 4000 Bytes

=================== NANOAPPS ====================