Use mutation methods for stub reconfiguration.

This makes the reconfiguration code more concise.

- Remove configureNewStub().
- Add mutation methods withDeadlineNanoTime(), withChannel() etc that
  returns the reconfigured stub.

interop-testing/src/main/java/io/grpc/testing/integration/AbstractTransportTest.java

@@ -588,9 +588,7 @@ public abstract class AbstractTransportTest {
   public void sendsTimeoutHeader() {
     long configuredTimeoutMinutes = 100;
     TestServiceGrpc.TestServiceBlockingStub stub = TestServiceGrpc.newBlockingStub(channel)
-        .configureNewStub()
-        .setDeadlineAfter(configuredTimeoutMinutes, TimeUnit.MINUTES)
-        .build();
+        .withDeadlineAfter(configuredTimeoutMinutes, TimeUnit.MINUTES);
     stub.emptyCall(Empty.getDefaultInstance());
     long transferredTimeoutMinutes = TimeUnit.MICROSECONDS.toMinutes(
         requestHeadersCapture.get().get(ChannelImpl.TIMEOUT_KEY));
@@ -607,9 +605,8 @@ public abstract class AbstractTransportTest {
     // warm up the channel and JVM
     blockingStub.emptyCall(Empty.getDefaultInstance());
     TestServiceGrpc.newBlockingStub(channel)
-        .configureNewStub()
-        .setDeadlineAfter(50, TimeUnit.MILLISECONDS)
-        .build().emptyCall(Empty.getDefaultInstance());
+        .withDeadlineAfter(50, TimeUnit.MILLISECONDS)
+        .emptyCall(Empty.getDefaultInstance());
   }
 
   @Test(timeout = 10000)
@@ -618,9 +615,7 @@ public abstract class AbstractTransportTest {
     // warm up the channel and JVM
     blockingStub.emptyCall(Empty.getDefaultInstance());
     TestServiceGrpc.TestServiceBlockingStub stub = TestServiceGrpc.newBlockingStub(channel)
-        .configureNewStub()
-        .setDeadlineAfter(10, TimeUnit.MILLISECONDS)
-        .build();
+        .withDeadlineAfter(10, TimeUnit.MILLISECONDS);
     try {
       stub.emptyCall(Empty.getDefaultInstance());
       fail("Expected deadline to be exceeded");
@@ -647,9 +642,8 @@ public abstract class AbstractTransportTest {
         .build();
     StreamRecorder<StreamingOutputCallResponse> recorder = StreamRecorder.create();
     TestServiceGrpc.newStub(channel)
-        .configureNewStub()
-        .setDeadlineAfter(30, TimeUnit.MILLISECONDS)
-        .build().streamingOutputCall(request, recorder);
+        .withDeadlineAfter(30, TimeUnit.MILLISECONDS)
+        .streamingOutputCall(request, recorder);
     recorder.awaitCompletion();
     assertEquals(Status.DEADLINE_EXCEEDED, Status.fromThrowable(recorder.getError()));
     assertNotEquals(0, recorder.getValues().size());
@@ -723,9 +717,8 @@ public abstract class AbstractTransportTest {
     GoogleCredentials credentials =
         (ServiceAccountCredentials) GoogleCredentials.fromStream(credentialsStream);
     credentials = credentials.createScoped(Arrays.<String>asList(authScope));
-    TestServiceGrpc.TestServiceBlockingStub stub = blockingStub.configureNewStub()
-        .addInterceptor(new ClientAuthInterceptor(credentials, testServiceExecutor))
-        .build();
+    TestServiceGrpc.TestServiceBlockingStub stub = blockingStub
+        .withInterceptors(new ClientAuthInterceptor(credentials, testServiceExecutor));
     final SimpleRequest request = SimpleRequest.newBuilder()
         .setFillUsername(true)
         .setFillOauthScope(true)
@@ -756,9 +749,8 @@ public abstract class AbstractTransportTest {
   /** Sends a large unary rpc with compute engine credentials. */
   public void computeEngineCreds(String serviceAccount, String oauthScope) throws Exception {
     ComputeEngineCredentials credentials = new ComputeEngineCredentials();
-    TestServiceGrpc.TestServiceBlockingStub stub = blockingStub.configureNewStub()
-        .addInterceptor(new ClientAuthInterceptor(credentials, testServiceExecutor))
-        .build();
+    TestServiceGrpc.TestServiceBlockingStub stub = blockingStub
+        .withInterceptors(new ClientAuthInterceptor(credentials, testServiceExecutor));
     final SimpleRequest request = SimpleRequest.newBuilder()
         .setFillUsername(true)
         .setFillOauthScope(true)

interop-testing/src/test/java/io/grpc/stub/StubConfigTest.java

@@ -87,8 +87,7 @@ public class StubConfigTest {
     TestServiceGrpc.TestServiceBlockingStub stub = TestServiceGrpc.newBlockingStub(channel);
     assertNull(stub.getCallOptions().getDeadlineNanoTime());
     // Reconfigure it
-    TestServiceGrpc.TestServiceBlockingStub reconfiguredStub =
-        stub.configureNewStub().setDeadlineNanoTime(2L).build();
+    TestServiceGrpc.TestServiceBlockingStub reconfiguredStub = stub.withDeadlineNanoTime(2L);
     // New altered config
     assertEquals(2L, (long) reconfiguredStub.getCallOptions().getDeadlineNanoTime());
     // Default config unchanged
@@ -102,7 +101,7 @@ public class StubConfigTest {
     SimpleRequest request = SimpleRequest.getDefaultInstance();
     stub.unaryCall(request, responseObserver);
     verify(channel).newCall(same(TestServiceGrpc.METHOD_UNARY_CALL), same(options1));
-    stub = stub.configureNewStub().setDeadlineNanoTime(2L).build();
+    stub = stub.withDeadlineNanoTime(2L);
     CallOptions options2 = stub.getCallOptions();
     assertNotSame(options1, options2);
     stub.unaryCall(request, responseObserver);

stub/src/main/java/io/grpc/stub/AbstractStub.java

@@ -36,8 +36,6 @@ import io.grpc.Channel;
 import io.grpc.ClientInterceptor;
 import io.grpc.ClientInterceptors;
 
-import java.util.ArrayList;
-import java.util.List;
 import java.util.concurrent.TimeUnit;
 
 import javax.annotation.Nullable;
@@ -74,13 +72,6 @@ public abstract class AbstractStub<S extends AbstractStub<?>> {
     this.callOptions = callOptions;
   }
 
-  /**
-   * Creates a builder for reconfiguring the stub.
-   */
-  public StubConfigBuilder configureNewStub() {
-    return new StubConfigBuilder();
-  }
-
   /**
    * The underlying channel of the stub.
    */
@@ -104,63 +95,38 @@ public abstract class AbstractStub<S extends AbstractStub<?>> {
   protected abstract S build(Channel channel, CallOptions callOptions);
 
   /**
-   * Utility class for (re) configuring the operations in a stub.
+   * Returns a new stub with an absolute deadline in nanoseconds in the clock as per {@link
+   * System#nanoTime()}.
+   *
+   * <p>This is mostly used for propagating an existing deadline. {@link #withDeadlineAfter} is the
+   * recommended way of setting a new deadline,
+   *
+   * @param deadlineNanoTime nanoseconds in the clock as per {@link System#nanoTime()}
    */
-  public class StubConfigBuilder {
+  public final S withDeadlineNanoTime(@Nullable Long deadlineNanoTime) {
+    return build(channel, callOptions.withDeadlineNanoTime(deadlineNanoTime));
+  }
 
-    private final List<ClientInterceptor> interceptors = new ArrayList<ClientInterceptor>();
-    private CallOptions callOptions = AbstractStub.this.callOptions;
-    private Channel stubChannel;
+  /**
+   * Returns a new stub with a deadline that is after the given {@code duration} from now.
+   *
+   * @see CallOptions#withDeadlineAfter
+   */
+  public final S withDeadlineAfter(long duration, TimeUnit unit) {
+    return build(channel, callOptions.withDeadlineAfter(duration, unit));
+  }
 
-    private StubConfigBuilder() {
-      this.stubChannel = AbstractStub.this.channel;
-    }
+  /**
+   * Returns a new stub that uses the given channel.
+   */
+  public final S withChannel(Channel newChannel) {
+    return build(newChannel, callOptions);
+  }
 
-    /**
-     * Sets an absolute deadline in nanoseconds in the clock as per {@link System#nanoTime()}.
-     *
-     * <p>This is mostly used for propagating an existing deadline. {@link #setDeadlineAfter} is the
-     * recommended way of setting a new deadline,
-     *
-     * @param deadlineNanoTime nanoseconds in the clock as per {@link System#nanoTime()}
-     */
-    public StubConfigBuilder setDeadlineNanoTime(@Nullable Long deadlineNanoTime) {
-      callOptions = callOptions.withDeadlineNanoTime(deadlineNanoTime);
-      return this;
-    }
-
-    /**
-     * Sets a deadline that is after the given {@code duration} from now.
-     *
-     * @see CallOptions#withDeadlineAfter
-     */
-    public StubConfigBuilder setDeadlineAfter(long duration, TimeUnit unit) {
-      callOptions = callOptions.withDeadlineAfter(duration, unit);
-      return this;
-    }
-
-    /**
-     * Set the channel to be used by the stub.
-     */
-    public StubConfigBuilder setChannel(Channel channel) {
-      this.stubChannel = channel;
-      return this;
-    }
-
-    /**
-     * Adds a client interceptor to be attached to the channel of the reconfigured stub.
-     */
-    public StubConfigBuilder addInterceptor(ClientInterceptor interceptor) {
-      interceptors.add(interceptor);
-      return this;
-    }
-
-    /**
-     * Create a new stub with the configurations made on this builder.
-     */
-    public S build() {
-      return AbstractStub.this.build(
-          ClientInterceptors.intercept(stubChannel, interceptors), callOptions);
-    }
+  /**
+   * Returns a new stub that has the given interceptors attached to the underlying channel.
+   */
+  public final S withInterceptors(ClientInterceptor... interceptors) {
+    return build(ClientInterceptors.intercept(channel, interceptors), callOptions);
   }
 }

stub/src/main/java/io/grpc/stub/MetadataUtils.java

@@ -59,8 +59,7 @@ public class MetadataUtils {
   public static <T extends AbstractStub> T attachHeaders(
       T stub,
       final Metadata.Headers extraHeaders) {
-    return (T) stub.configureNewStub().addInterceptor(
-        newAttachHeadersInterceptor(extraHeaders)).build();
+    return (T) stub.withInterceptors(newAttachHeadersInterceptor(extraHeaders));
   }
 
   /**
@@ -100,8 +99,8 @@ public class MetadataUtils {
       T stub,
       AtomicReference<Metadata.Headers> headersCapture,
       AtomicReference<Metadata.Trailers> trailersCapture) {
-    return (T) stub.configureNewStub().addInterceptor(
-        newCaptureMetadataInterceptor(headersCapture, trailersCapture)).build();
+    return (T) stub.withInterceptors(
+        newCaptureMetadataInterceptor(headersCapture, trailersCapture));
   }
 
   /**