LoggingStatsWriter.java

package me.dinowernli.grpc.polyglot.io;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.google.protobuf.DynamicMessage;

import io.grpc.stub.StreamObserver;

/**
 * A {@link StreamObserver} which logs the progress of the rpc and some stats about the results
 * once the rpc has completed. Note that this does *not* log the contents of the response.
 */
public class LoggingStatsWriter implements StreamObserver<DynamicMessage> {
  private static final Logger logger = LoggerFactory.getLogger(LoggingStatsWriter.class);
  private int numResponses;

  public LoggingStatsWriter() {
    numResponses = 0;
  }

  @Override
  public void onCompleted() {
    logger.info("Completed rpc with " + numResponses + " response(s)");
  }

  @Override
  public void onError(Throwable t) {
    logger.error("Aborted rpc due to error", t);
  }

  @Override
  public void onNext(DynamicMessage message) {
    logger.info("Got response message");
    ++numResponses;
  }
}