org.entur.pubsub.base.AbstractEnturGooglePubSubConsumer Maven / Gradle / Ivy

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Base configuration for Google PubSub clients, to be used for non-Camel clients. Camel-based clients should use camel-entur-google-pubsub instead.
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package org.entur.pubsub.base;

import com.google.cloud.pubsub.v1.Subscriber;
import com.google.cloud.spring.pubsub.core.PubSubTemplate;
import com.google.cloud.spring.pubsub.support.BasicAcknowledgeablePubsubMessage;
import com.google.pubsub.v1.PubsubMessage;
import java.util.ArrayList;
import java.util.List;
import java.util.function.Consumer;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.event.ContextClosedEvent;
import org.springframework.context.event.ContextRefreshedEvent;
import org.springframework.context.event.EventListener;
import org.springframework.core.Ordered;
import org.springframework.core.annotation.Order;
import org.springframework.stereotype.Component;

/**
 * Base class for PubSub message consumers.
 * Consumers are started as late as possible after the Spring context initialization is complete,
 * and stopped as early as possible on context shutdown.
 */
@Component
public abstract class AbstractEnturGooglePubSubConsumer
  implements EnturGooglePubSubConsumer {

  @Autowired
  private EnturGooglePubSubAdmin enturGooglePubSubAdmin;

  @Autowired
  private PubSubTemplate pubSubTemplate;

  @Value("${entur.pubsub.consumer.retry.delay:15000}")
  private long retryDelay;

  private final List subscribers = new ArrayList<>();
  private static final Logger LOGGER = LoggerFactory.getLogger(
    AbstractEnturGooglePubSubConsumer.class
  );

  protected abstract String getDestinationName();

  protected int getConcurrentConsumers() {
    return 1;
  }

  @EventListener
  public void handleContextRefreshed(
    ContextRefreshedEvent contextRefreshedEvent
  ) {
    LOGGER.info(
      "Initializing PubSub consumers for destination {}",
      getDestinationName()
    );

    enturGooglePubSubAdmin.createSubscriptionIfMissing(getDestinationName());

    Consumer messageConsumer =
      basicAcknowledgeablePubsubMessage -> {
        PubsubMessage pubsubMessage =
          basicAcknowledgeablePubsubMessage.getPubsubMessage();
        if (LOGGER.isTraceEnabled()) {
          LOGGER.trace(
            "Received message ID : {}",
            pubsubMessage.getMessageId()
          );
        }
        try {
          onMessage(
            pubsubMessage.getData().toByteArray(),
            pubsubMessage.getAttributesMap()
          );
          basicAcknowledgeablePubsubMessage.ack();
        } catch (Exception e) {
          basicAcknowledgeablePubsubMessage.nack();
          LOGGER.error(
            "Message processing failed, retrying in {} milliseconds",
            retryDelay,
            e
          );
          delay(retryDelay);
        }
      };
    for (int i = 0; i < getConcurrentConsumers(); i++) {
      Subscriber subscriber = pubSubTemplate.subscribe(
        getDestinationName(),
        messageConsumer
      );
      subscribers.add(subscriber);
    }

    LOGGER.info(
      "Initialized PubSub consumers for destination {}",
      getDestinationName()
    );
  }

  /**
   * Wait for the number of specified milliseconds.
   * @param delay delay in milliseconds
   */
  private static void delay(long delay) {
    try {
      Thread.sleep(delay);
    } catch (InterruptedException e) {
      Thread.currentThread().interrupt();
      throw new EnturGooglePubSubException(e);
    }
  }

  @EventListener
  @Order(Ordered.HIGHEST_PRECEDENCE)
  public void handleContextClosedEvent(ContextClosedEvent contextClosedEvent) {
    LOGGER.info(
      "Stopping Google PubSub consumer for subscription {}",
      getDestinationName()
    );
    for (Subscriber subscriber : subscribers) {
      EnturGooglePubSubUtils.closeSubscriber(subscriber);
    }
    LOGGER.info(
      "Stopped Google PubSub consumer for subscription {}",
      getDestinationName()
    );
  }
}