s2a: Cleanups to IntegrationTest

Move unused and unimportant fields to local variables. pickUnusedPort()
is inherently racy, so avoid using it when unnecessary. The channel's
default executor is fine to use, but if you don't like it
directExecutor() would be an option too. But blocking stub doesn't even
use the executor for unary RPCs. Thread.join() does not propagate
exceptions from the Thread; it just waits for the thread to exit.

s2a/src/test/java/io/grpc/s2a/handshaker/IntegrationTest.java

@@ -44,9 +44,7 @@
 import io.netty.handler.ssl.SslProvider;
 import java.io.ByteArrayInputStream;
 import java.io.File;
-import java.util.concurrent.ExecutorService;
-import java.util.concurrent.Executors;
-import java.util.logging.Level;
+import java.util.concurrent.FutureTask;
 import java.util.logging.Logger;
 import javax.net.ssl.SSLException;
 import javax.net.ssl.SSLSessionContext;
@@ -127,28 +125,21 @@ public final class IntegrationTest {
         + "-----END PRIVATE KEY-----";
 
   private String s2aAddress;
-  private int s2aPort;
   private Server s2aServer;
   private String s2aDelayAddress;
-  private int s2aDelayPort;
   private Server s2aDelayServer;
   private String mtlsS2AAddress;
-  private int mtlsS2APort;
   private Server mtlsS2AServer;
-  private int serverPort;
   private String serverAddress;
   private Server server;
 
   @Before
   public void setUp() throws Exception {
-    s2aPort = Utils.pickUnusedPort();
+    s2aServer = ServerBuilder.forPort(0).addService(new FakeS2AServer()).build().start();
+    int s2aPort = s2aServer.getPort();
     s2aAddress = "localhost:" + s2aPort;
-    s2aServer = ServerBuilder.forPort(s2aPort).addService(new FakeS2AServer()).build();
     logger.info("S2A service listening on localhost:" + s2aPort);
-    s2aServer.start();
 
-    mtlsS2APort = Utils.pickUnusedPort();
-    mtlsS2AAddress = "localhost:" + mtlsS2APort;
     File s2aCert = new File("src/test/resources/server_cert.pem");
     File s2aKey = new File("src/test/resources/server_key.pem");
     File rootCert = new File("src/test/resources/root_cert.pem");
@@ -158,24 +149,25 @@ public void setUp() throws Exception {
             .trustManager(rootCert)
             .clientAuth(TlsServerCredentials.ClientAuth.REQUIRE)
             .build();
-    mtlsS2AServer =
-        NettyServerBuilder.forPort(mtlsS2APort, s2aCreds).addService(new FakeS2AServer()).build();
-    logger.info("mTLS S2A service listening on localhost:" + mtlsS2APort);
+    mtlsS2AServer = NettyServerBuilder.forPort(0, s2aCreds).addService(new FakeS2AServer()).build();
     mtlsS2AServer.start();
+    int mtlsS2APort = mtlsS2AServer.getPort();
+    mtlsS2AAddress = "localhost:" + mtlsS2APort;
+    logger.info("mTLS S2A service listening on localhost:" + mtlsS2APort);
 
-    s2aDelayPort = Utils.pickUnusedPort();
+    int s2aDelayPort = Utils.pickUnusedPort();
     s2aDelayAddress = "localhost:" + s2aDelayPort;
     s2aDelayServer = ServerBuilder.forPort(s2aDelayPort).addService(new FakeS2AServer()).build();
 
-    serverPort = Utils.pickUnusedPort();
-    serverAddress = "localhost:" + serverPort;
     server =
-        NettyServerBuilder.forPort(serverPort)
+        NettyServerBuilder.forPort(0)
             .addService(new SimpleServiceImpl())
             .sslContext(buildSslContext())
-            .build();
+            .build()
+            .start();
+    int serverPort = server.getPort();
+    serverAddress = "localhost:" + serverPort;
     logger.info("Simple Service listening on localhost:" + serverPort);
-    server.start();
   }
 
   @After
@@ -193,28 +185,23 @@ public void tearDown() throws Exception {
 
   @Test
   public void clientCommunicateUsingS2ACredentials_succeeds() throws Exception {
-    ExecutorService executor = Executors.newSingleThreadExecutor();
     ChannelCredentials credentials =
         S2AChannelCredentials.createBuilder(s2aAddress).setLocalSpiffeId("test-spiffe-id").build();
-    ManagedChannel channel =
-        Grpc.newChannelBuilder(serverAddress, credentials).executor(executor).build();
+    ManagedChannel channel = Grpc.newChannelBuilder(serverAddress, credentials).build();
 
-    assertThat(doUnaryRpc(executor, channel)).isTrue();
+    assertThat(doUnaryRpc(channel)).isTrue();
   }
 
   @Test
   public void clientCommunicateUsingS2ACredentialsNoLocalIdentity_succeeds() throws Exception {
-    ExecutorService executor = Executors.newSingleThreadExecutor();
     ChannelCredentials credentials = S2AChannelCredentials.createBuilder(s2aAddress).build();
-    ManagedChannel channel =
-        Grpc.newChannelBuilder(serverAddress, credentials).executor(executor).build();
+    ManagedChannel channel = Grpc.newChannelBuilder(serverAddress, credentials).build();
 
-    assertThat(doUnaryRpc(executor, channel)).isTrue();
+    assertThat(doUnaryRpc(channel)).isTrue();
   }
 
   @Test
   public void clientCommunicateUsingMtlsToS2ACredentials_succeeds() throws Exception {
-    ExecutorService executor = Executors.newSingleThreadExecutor();
     ChannelCredentials credentials =
         MtlsToS2AChannelCredentials.createBuilder(
                 /* s2aAddress= */ mtlsS2AAddress,
@@ -224,41 +211,24 @@ public void clientCommunicateUsingMtlsToS2ACredentials_succeeds() throws Excepti
             .build()
             .setLocalSpiffeId("test-spiffe-id")
             .build();
-    ManagedChannel channel =
-        Grpc.newChannelBuilder(serverAddress, credentials).executor(executor).build();
+    ManagedChannel channel = Grpc.newChannelBuilder(serverAddress, credentials).build();
 
-    assertThat(doUnaryRpc(executor, channel)).isTrue();
+    assertThat(doUnaryRpc(channel)).isTrue();
   }
 
   @Test
   public void clientCommunicateUsingS2ACredentials_s2AdelayStart_succeeds() throws Exception {
-    DoUnaryRpc doUnaryRpc = new DoUnaryRpc();
-    doUnaryRpc.start();
+    ChannelCredentials credentials = S2AChannelCredentials.createBuilder(s2aDelayAddress).build();
+    ManagedChannel channel = Grpc.newChannelBuilder(serverAddress, credentials).build();
+
+    FutureTask<Boolean> rpc = new FutureTask<>(() -> doUnaryRpc(channel));
+    new Thread(rpc).start();
     Thread.sleep(2000);
     s2aDelayServer.start();
-    doUnaryRpc.join();
-  }
-
-  private class DoUnaryRpc extends Thread {
-    @Override
-    public void run() {
-      ExecutorService executor = Executors.newSingleThreadExecutor();
-      ChannelCredentials credentials = S2AChannelCredentials.createBuilder(s2aDelayAddress).build();
-      ManagedChannel channel =
-          Grpc.newChannelBuilder(serverAddress, credentials).executor(executor).build();
-      boolean result = false;
-      try {
-        result = doUnaryRpc(executor, channel);
-      } catch (InterruptedException e) {
-        logger.log(Level.SEVERE, "Failed to do unary rpc", e);
-        result = false;
-      }
-      assertThat(result).isTrue();
-    }
+    assertThat(rpc.get()).isTrue();
   }
 
-  public static boolean doUnaryRpc(ExecutorService executor, ManagedChannel channel)
-      throws InterruptedException {
+  public static boolean doUnaryRpc(ManagedChannel channel) throws InterruptedException {
     try {
       SimpleServiceGrpc.SimpleServiceBlockingStub stub =
           SimpleServiceGrpc.newBlockingStub(channel);
@@ -277,8 +247,6 @@ public static boolean doUnaryRpc(ExecutorService executor, ManagedChannel channe
     } finally {
       channel.shutdown();
       channel.awaitTermination(1, SECONDS);
-      executor.shutdown();
-      executor.awaitTermination(1, SECONDS);
     }
   }
 
@@ -318,4 +286,4 @@ public void unaryRpc(SimpleRequest request, StreamObserver<SimpleResponse> obser
       observer.onCompleted();
     }
   }
-}
+}