Repository: apache/kafka
File: metadata/src/main/java/org/apache/kafka/metadata/publisher/DynamicTopicClusterQuotaPublisher.java (Java)

Code before:
import org.apache.kafka.common.internals.Plugin;
import org.apache.kafka.image.MetadataDelta;
import org.apache.kafka.image.MetadataImage;
import org.apache.kafka.image.loader.LoaderManifest;
import org.apache.kafka.image.publisher.MetadataPublisher;
import org.apache.kafka.metadata.MetadataCache;
import org.apache.kafka.server.fault.FaultHandler;
import org.apache.kafka.server.quota.ClientQuotaCallback;

import java.util.Optional;

public class DynamicTopicClusterQuotaPublisher implements MetadataPublisher {
    private final String clusterId;
    private final int nodeId;
    private final FaultHandler faultHandler;
    private final String nodeType;
    private final Optional<Plugin<ClientQuotaCallback>> clientQuotaCallbackPlugin;
    private final Runnable updateQuotaMetricConfigs;

    public DynamicTopicClusterQuotaPublisher(
        String clusterId,
        int nodeId,
        FaultHandler faultHandler,
        String nodeType,
        Optional<Plugin<ClientQuotaCallback>> clientQuotaCallbackPlugin,
        Runnable updateQuotaMetricConfigs
    ) {
        this.clusterId = clusterId;
        this.nodeId = nodeId;
        this.faultHandler = faultHandler;
        this.nodeType = nodeType;
        this.clientQuotaCallbackPlugin = clientQuotaCallbackPlugin;
        this.updateQuotaMetricConfigs = updateQuotaMetricConfigs;
    }

    @Override
    public String name() {
        return "DynamicTopicClusterQuotaPublisher " + nodeType + " id=" + nodeId;
    }

    @Override
    public void onMetadataUpdate(MetadataDelta delta, MetadataImage newImage, LoaderManifest manifest) {
        try {
            clientQuotaCallbackPlugin.ifPresent(plugin -> {
                if (delta.topicsDelta() != null || delta.clusterDelta() != null) {
                    Cluster cluster = MetadataCache.toCluster(clusterId, newImage);
                    if (plugin.get().updateClusterMetadata(cluster)) {
                        updateQuotaMetricConfigs.run();
                    }
                }
            });

Review comment (suggestion):
Could you add comments explaining why we use `Runnable` here

Code after:
import org.apache.kafka.common.internals.Plugin;
import org.apache.kafka.image.MetadataDelta;
import org.apache.kafka.image.MetadataImage;
import org.apache.kafka.image.loader.LoaderManifest;
import org.apache.kafka.image.publisher.MetadataPublisher;
import org.apache.kafka.metadata.MetadataCache;
import org.apache.kafka.server.fault.FaultHandler;
import org.apache.kafka.server.quota.ClientQuotaCallback;

import java.util.Optional;

public class DynamicTopicClusterQuotaPublisher implements MetadataPublisher {
    private final String clusterId;
    private final int nodeId;
    private final FaultHandler faultHandler;
    private final String nodeType;
    private final Optional<Plugin<ClientQuotaCallback>> clientQuotaCallbackPlugin;
    private final QuotaConfigChangeListener quotaConfigChangeListener;

    public DynamicTopicClusterQuotaPublisher(
        String clusterId,
        int nodeId,
        FaultHandler faultHandler,
        String nodeType,
        Optional<Plugin<ClientQuotaCallback>> clientQuotaCallbackPlugin,
        QuotaConfigChangeListener quotaConfigChangeListener
    ) {
        this.clusterId = clusterId;
        this.nodeId = nodeId;
        this.faultHandler = faultHandler;
        this.nodeType = nodeType;
        this.clientQuotaCallbackPlugin = clientQuotaCallbackPlugin;
        this.quotaConfigChangeListener = quotaConfigChangeListener;
    }

    @Override
    public String name() {
        return "DynamicTopicClusterQuotaPublisher " + nodeType + " id=" + nodeId;
    }

    @Override
    public void onMetadataUpdate(MetadataDelta delta, MetadataImage newImage, LoaderManifest manifest) {
        try {
            clientQuotaCallbackPlugin.ifPresent(plugin -> {
                if (delta.topicsDelta() != null || delta.clusterDelta() != null) {
                    Cluster cluster = MetadataCache.toCluster(clusterId, newImage);
                    if (plugin.get().updateClusterMetadata(cluster)) {
                        quotaConfigChangeListener.onChange();
                    }
                }
            });