Expose ContextHubClient ID

Bug: 194287786
Test: Manual check ID is correct
Change-Id: Ia240a88e5687564fd339da3fab61437e3015da83

core/api/system-current.txt

@@ -3893,6 +3893,7 @@ package android.hardware.location {
   public class ContextHubClient implements java.io.Closeable {
     method public void close();
     method @NonNull public android.hardware.location.ContextHubInfo getAttachedHub();
+    method public int getId();
     method @RequiresPermission(android.Manifest.permission.ACCESS_CONTEXT_HUB) public int sendMessageToNanoApp(@NonNull android.hardware.location.NanoAppMessage);
   }
 

core/java/android/hardware/location/ContextHubClient.java

@@ -60,6 +60,8 @@ public class ContextHubClient implements Closeable {
      */
     private final boolean mPersistent;
 
+    private Integer mId = null;
+
     /* package */ ContextHubClient(ContextHubInfo hubInfo, boolean persistent) {
         mAttachedHub = hubInfo;
         mPersistent = persistent;
@@ -85,6 +87,11 @@ public class ContextHubClient implements Closeable {
         }
 
         mClientProxy = clientProxy;
+        try {
+            mId = Integer.valueOf(mClientProxy.getId());
+        } catch (RemoteException e) {
+            throw e.rethrowFromSystemServer();
+        }
     }
 
     /**
@@ -97,6 +104,31 @@ public class ContextHubClient implements Closeable {
         return mAttachedHub;
     }
 
+    /**
+     * Returns the system-wide unique identifier for this ContextHubClient.
+     *
+     * This value can be used as an identifier for the messaging channel between a
+     * ContextHubClient and the Context Hub. This may be used as a routing mechanism
+     * between various ContextHubClient objects within an application.
+     *
+     * The value returned by this method will remain the same if it is associated with
+     * the same client reference at the ContextHubService (for instance, the ID of a
+     * PendingIntent ContextHubClient will remain the same even if the local object
+     * has been regenerated with the equivalent PendingIntent). If the ContextHubClient
+     * is newly generated (e.g. any regeneration of a callback client, or generation
+     * of a non-equal PendingIntent client), the ID will not be the same.
+     *
+     * @return The ID of this ContextHubClient.
+     *
+     * @throws IllegalStateException if the ID was not set internally.
+     */
+    public int getId() {
+        if (mId == null) {
+            throw new IllegalStateException("ID was not set");
+        }
+        return mId;
+    }
+
     /**
      * Closes the connection for this client and the Context Hub Service.
      *

core/java/android/hardware/location/IContextHubClient.aidl

@@ -29,4 +29,7 @@ interface IContextHubClient {
 
     // Closes the connection with the Context Hub
     void close();
+
+    // Returns the unique ID for this client.
+    int getId();
 }

services/core/java/com/android/server/location/contexthub/ContextHubClientBroker.java

@@ -427,6 +427,11 @@ public class ContextHubClientBroker extends IContextHubClient.Stub
         onClientExit();
     }
 
+    @Override
+    public int getId() {
+        return mHostEndPointId;
+    }
+
     /**
      * Invoked when the underlying binder of this broker has died at the client process.
      */