core/src/main/java/io/grpc/internal/AbstractManagedChannelImplBuilder.java

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package io.grpc.internal;

import io.grpc.ClientInterceptor;
import io.grpc.Internal;
import io.grpc.ManagedChannelBuilder;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.concurrent.ExecutorService;

import javax.annotation.Nullable;

/**
 * The base class for channel builders.
 *
 * @param <T> The concrete type of this builder.
 */
public abstract class AbstractManagedChannelImplBuilder
        <T extends AbstractManagedChannelImplBuilder<T>> extends ManagedChannelBuilder<T> {

  @Nullable
  private ExecutorService executor;
  private final List<ClientInterceptor> interceptors = new ArrayList<ClientInterceptor>();

  @Nullable
  private String userAgent;

  @Override
  public final T executor(ExecutorService executor) {
    this.executor = executor;
    return thisT();
  }

  @Override
  public final T intercept(List<ClientInterceptor> interceptors) {
    this.interceptors.addAll(interceptors);
    return thisT();
  }

  @Override
  public final T intercept(ClientInterceptor... interceptors) {
    return intercept(Arrays.asList(interceptors));
  }

  private T thisT() {
    @SuppressWarnings("unchecked")
    T thisT = (T) this;
    return thisT;
  }

  @Override
  public final T userAgent(String userAgent) {
    this.userAgent = userAgent;
    return thisT();
  }

  @Override
  public ManagedChannelImpl build() {
    ClientTransportFactory transportFactory = buildTransportFactory();
    return new ManagedChannelImpl(transportFactory, executor, userAgent, interceptors);
  }

  /**
   * Children of AbstractChannelBuilder should override this method to provide the
   * {@link ClientTransportFactory} appropriate for this channel.  This method is meant for
   * Transport implementors and should not be used by normal users.
   */
  @Internal
  protected abstract ClientTransportFactory buildTransportFactory();
}