pl.allegro.tech.hermes.common.admin.zookeeper.ZookeeperAdminCache Maven / Gradle / Ivy

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Fast and reliable message broker built on top of Kafka.

There is a newer version: 2.7.0

package pl.allegro.tech.hermes.common.admin.zookeeper;

import com.fasterxml.jackson.databind.ObjectMapper;
import org.apache.curator.framework.CuratorFramework;
import org.apache.curator.framework.recipes.cache.PathChildrenCache;
import org.apache.curator.framework.recipes.cache.PathChildrenCacheEvent;
import org.apache.curator.framework.recipes.cache.PathChildrenCacheListener;
import pl.allegro.tech.hermes.api.SubscriptionName;
import pl.allegro.tech.hermes.common.admin.AdminOperationsCallback;
import pl.allegro.tech.hermes.infrastructure.zookeeper.ZookeeperPaths;

import java.time.Clock;
import java.util.ArrayList;
import java.util.List;

import static pl.allegro.tech.hermes.common.admin.AdminTool.Operations.RETRANSMIT;

public class ZookeeperAdminCache extends PathChildrenCache implements PathChildrenCacheListener {

    private final ObjectMapper objectMapper;
    private final List adminCallbacks = new ArrayList<>();

    private final long initializationTime;

    public ZookeeperAdminCache(ZookeeperPaths zookeeperPaths,
                               CuratorFramework client,
                               ObjectMapper objectMapper,
                               Clock clock) {
        super(client, zookeeperPaths.adminPath(), true);
        this.objectMapper = objectMapper;
        this.initializationTime = clock.millis();
        getListenable().addListener(this);
    }

    @Override
    public void childEvent(CuratorFramework client, PathChildrenCacheEvent event) throws Exception {
        switch (event.getType()) {
            case CHILD_UPDATED:
            case CHILD_ADDED:
                if (event.getData().getPath().contains(RETRANSMIT.name()) && isYoungerThanThisNode(event)) {
                    retransmit(event);
                }
                break;
            default:
                break;
        }
    }

    private boolean isYoungerThanThisNode(PathChildrenCacheEvent event) {
        return event.getData().getStat().getMtime() > initializationTime;
    }

    private void retransmit(PathChildrenCacheEvent event) throws Exception {
        SubscriptionName subscriptionName = objectMapper.readValue(event.getData().getData(), SubscriptionName.class);

        for (AdminOperationsCallback adminCallback : adminCallbacks) {
            adminCallback.onRetransmissionStarts(subscriptionName);
        }
    }

    public void addCallback(AdminOperationsCallback callback) {
        adminCallbacks.add(callback);
    }
}