pl.allegro.tech.hermes.common.message.undelivered.ZookeeperLastUndeliveredMessageReader Maven / Gradle / Ivy

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Fast and reliable message broker built on top of Kafka.

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package pl.allegro.tech.hermes.common.message.undelivered;

import com.fasterxml.jackson.databind.ObjectMapper;
import org.apache.curator.framework.CuratorFramework;
import pl.allegro.tech.hermes.api.SentMessageTrace;
import pl.allegro.tech.hermes.api.TopicName;
import pl.allegro.tech.hermes.common.exception.InternalProcessingException;
import pl.allegro.tech.hermes.infrastructure.zookeeper.ZookeeperPaths;

import java.util.Optional;

import static java.lang.String.format;

public class ZookeeperLastUndeliveredMessageReader implements LastUndeliveredMessageReader {

    private final CuratorFramework curator;
    private final UndeliveredMessagePaths paths;
    private final ObjectMapper mapper;

    public ZookeeperLastUndeliveredMessageReader(CuratorFramework curator,
                                                 ZookeeperPaths zookeeperPaths,
                                                 ObjectMapper mapper) {
        this.curator = curator;
        this.paths = new UndeliveredMessagePaths(zookeeperPaths);
        this.mapper = mapper;
    }

    @Override
    public Optional last(TopicName topicName, String subscriptionName) {
        try {
            String path = paths.buildPath(topicName, subscriptionName);
            if (exists(path)) {
                return Optional.of(mapper.readValue(curator.getData().forPath(path), SentMessageTrace.class));
            } else {
                return Optional.empty();
            }
        } catch (Exception e) {
            throw new InternalProcessingException(
                    format("Could not read latest undelivered message for topic: %s and subscription: %s .",
                            topicName.qualifiedName(), subscriptionName),
                    e);
        }
    }

    private boolean exists(String path) throws Exception {
        return curator.checkExists().forPath(path) != null;
    }
}