Fix the memory leak in nsd tests

The NsdManager constructor creates a new thread, which is not
intended to be closed. However, the test in NsdMangerTest and
NsdServiceTest create a new NsdManager instance, resulting in a
large number of threads running during the tests. This can lead
to an out-of-memory error for the tests. To resolve this issue,
use the common singleton thread ConnectivityThread to handle
tasks from the various instances.

Fix: 308544734
Test: atest ConnectivityCoverageTests --test-filter Nsd*
Change-Id: I1908a2bb1bd20da8e0498353bca26f7e89e16626

framework-t/src/android/net/nsd/NsdManager.java

@@ -34,10 +34,10 @@ import android.app.compat.CompatChanges;
 import android.content.Context;
 import android.net.ConnectivityManager;
 import android.net.ConnectivityManager.NetworkCallback;
+import android.net.ConnectivityThread;
 import android.net.Network;
 import android.net.NetworkRequest;
 import android.os.Handler;
-import android.os.HandlerThread;
 import android.os.Looper;
 import android.os.Message;
 import android.os.RemoteException;
@@ -632,10 +632,9 @@ public final class NsdManager {
      */
     public NsdManager(Context context, INsdManager service) {
         mContext = context;
-
-        HandlerThread t = new HandlerThread("NsdManager");
-        t.start();
-        mHandler = new ServiceHandler(t.getLooper());
+        // Use a common singleton thread ConnectivityThread to be shared among all nsd tasks.
+        // Instead of launching separate threads to handle tasks from the various instances.
+        mHandler = new ServiceHandler(ConnectivityThread.getInstanceLooper());
 
         try {
             mService = service.connect(new NsdCallbackImpl(mHandler), CompatChanges.isChangeEnabled(

tests/unit/java/android/net/nsd/NsdManagerTest.java

@@ -51,6 +51,7 @@ import org.mockito.ArgumentCaptor;
 import org.mockito.Mock;
 import org.mockito.MockitoAnnotations;
 
+@DevSdkIgnoreRunner.MonitorThreadLeak
 @RunWith(DevSdkIgnoreRunner.class)
 @SmallTest
 @DevSdkIgnoreRule.IgnoreUpTo(Build.VERSION_CODES.S_V2)

tests/unit/java/com/android/server/NsdServiceTest.java

@@ -145,6 +145,7 @@ import java.util.Queue;
 // TODOs:
 //  - test client can send requests and receive replies
 //  - test NSD_ON ENABLE/DISABLED listening
+@DevSdkIgnoreRunner.MonitorThreadLeak
 @RunWith(DevSdkIgnoreRunner.class)
 @SmallTest
 @DevSdkIgnoreRule.IgnoreUpTo(Build.VERSION_CODES.S_V2)