nl.topicus.jdbc.shaded.com.google.api.gax.rpc.ServerStreamingCallable Maven / Gradle / Ivy

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package nl.topicus.jdbc.shaded.com.google.api.gax.rpc;

import nl.topicus.jdbc.shaded.com.google.api.core.BetaApi;
import java.util.Iterator;

/**
 * A ServerStreamingCallable is an immutable object which is capable of making RPC calls to server
 * streaming API methods. Not all transports support streaming.
 *
 * It is considered advanced usage for a user to create a ServerStreamingCallable themselves.
 * This class is intended to be created by a generated client class, and configured by instances of
 * StreamingCallSettings.Builder which are exposed through the client settings class.
 */
@BetaApi("The surface for streaming is not stable yet and may change in the future.")
public abstract class ServerStreamingCallable {

  protected ServerStreamingCallable() {}

  /**
   * Conduct a server streaming call with the given {@link ApiCallContext}.
   *
   * @param request request
   * @param responseObserver {@link ResponseObserver} to observe the streaming responses
   * @param context {@link ApiCallContext} to provide context information for the RPC call.
   */
  public abstract void call(
      RequestT request, ResponseObserver responseObserver, ApiCallContext context);

  /**
   * Conduct a server streaming call
   *
   * @param request request
   * @param responseObserver {@link ResponseObserver} to observe the streaming responses
   */
  public void call(RequestT request, ResponseObserver responseObserver) {
    call(request, responseObserver, null);
  }

  /**
   * Conduct a server streaming call with the given {@link ApiCallContext}.
   *
   * @param request request
   * @param responseObserver {@link ApiStreamObserver} to observe the streaming responses
   * @param context {@link ApiCallContext} to provide context information for the RPC call.
   * @deprecated Please use the {@link ResponseObserver} variant instead.
   */
  @Deprecated
  public void serverStreamingCall(
      RequestT request,
      final ApiStreamObserver responseObserver,
      ApiCallContext context) {

    call(request, new ApiStreamObserverAdapter<>(responseObserver), context);
  }

  /**
   * Conduct a server streaming call
   *
   * @param request request
   * @param responseObserver {@link ApiStreamObserver} to observe the streaming responses
   * @deprecated Please use the {@link ResponseObserver} variant instead.
   */
  @Deprecated
  public void serverStreamingCall(RequestT request, ApiStreamObserver responseObserver) {
    serverStreamingCall(request, responseObserver, null);
  }

  /**
   * Conduct a iteration server streaming call
   *
   * @param request request
   * @return {@link Iterator} which is used for iterating the responses.
   */
  public abstract Iterator blockingServerStreamingCall(
      RequestT request, ApiCallContext context);

  public Iterator blockingServerStreamingCall(RequestT request) {
    return blockingServerStreamingCall(request, null);
  }

  /**
   * Returns a new {@code ServerStreamingCallable} with an {@link ApiCallContext} that is used as a
   * default when none is supplied in individual calls.
   *
   * @param defaultCallContext the default {@link ApiCallContext}.
   */
  public ServerStreamingCallable withDefaultCallContext(
      final ApiCallContext defaultCallContext) {
    return new ServerStreamingCallable() {
      @Override
      public void call(
          RequestT request,
          ResponseObserver responseObserver,
          ApiCallContext thisCallContext) {
        ServerStreamingCallable.this.call(
            request, responseObserver, defaultCallContext.merge(thisCallContext));
      }

      @Override
      public Iterator blockingServerStreamingCall(
          RequestT request, ApiCallContext thisCallContext) {
        return ServerStreamingCallable.this.blockingServerStreamingCall(
            request, defaultCallContext.merge(thisCallContext));
      }
    };
  }

  /**
   * Backwards compatibility bridge from the new {@link ResponseObserver} api to the old {@link
   * ApiStreamObserver} api.
   *
   * @param  The type of the response.
   * @deprecated Use ResponseObserver directly
   */
  @Deprecated
  private static class ApiStreamObserverAdapter implements ResponseObserver {
    private final ApiStreamObserver delegate;

    ApiStreamObserverAdapter(ApiStreamObserver delegate) {
      this.delegate = delegate;
    }

    @Override
    public void onStart(StreamController controller) {
      // Noop: the old style assumes automatic flow control and doesn't support cancellation.
    }

    @Override
    public void onResponse(T response) {
      delegate.onNext(response);
    }

    @Override
    public void onError(Throwable t) {
      delegate.onError(t);
    }

    @Override
    public void onComplete() {
      delegate.onCompleted();
    }
  }
}