dielhennr commented on a change in pull request #9101: URL: https://github.com/apache/kafka/pull/9101#discussion_r465907401
########## File path: clients/src/main/java/org/apache/kafka/clients/consumer/internals/DynamicConsumerConfig.java ########## @@ -0,0 +1,168 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed with + * this work for additional information regarding copyright ownership. + * The ASF licenses this file to You under the Apache License, Version 2.0 + * (the "License"); you may not use this file except in compliance with + * the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ +package org.apache.kafka.clients.consumer.internals; + +import java.util.HashMap; +import java.util.Map; + +import org.apache.kafka.clients.ClientResponse; +import org.apache.kafka.clients.DynamicClientConfigUpdater; +import org.apache.kafka.clients.GroupRebalanceConfig; +import org.apache.kafka.common.Node; +import org.apache.kafka.common.requests.DescribeConfigsRequest; +import org.apache.kafka.common.requests.DescribeConfigsResponse; +import org.apache.kafka.common.utils.LogContext; +import org.apache.kafka.common.utils.Time; +import org.slf4j.Logger; + +/** + * Handles the request and response of a dynamic client configuration update for the consumer + */ +public class DynamicConsumerConfig extends DynamicClientConfigUpdater { + /* Client to use */ + private ConsumerNetworkClient client; + + /* Configs to update */ + private GroupRebalanceConfig rebalanceConfig; + + /* Object to synchronize on when response is recieved */ + Object lock; + + /* Logger to use */ + private Logger log; + + /* The resource name to use when constructing a DescribeConfigsRequest */ + private final String clientId; + + /* Dynamic Configs recieved from the previous DescribeConfigsResponse */ + private Map<String, String> previousDynamicConfigs; + + /* Indicates if we have recieved the initial dynamic configurations */ + private boolean initialConfigsFetched; + + public DynamicConsumerConfig(ConsumerNetworkClient client, Object lock, GroupRebalanceConfig config, Time time, LogContext logContext) { + super(time); + this.rebalanceConfig = config; + this.log = logContext.logger(DynamicConsumerConfig.class); + this.client = client; + this.lock = lock; + this.clientId = rebalanceConfig.clientId; + this.previousDynamicConfigs = new HashMap<>(); + this.initialConfigsFetched = false; + } + + /** + * Send a {@link DescribeConfigsRequest} to a node specifically for dynamic client configurations + * + * @return {@link RequestFuture} + */ + public RequestFuture<ClientResponse> maybeFetchInitialConfigs() { + if (!initialConfigsFetched) { + Node node = null; + while (node == null) { + node = client.leastLoadedNode(); Review comment: The main thread is calling the method and the main thread is polling. This was a hack to try to force the initial describe configs before the join group request. This returns non-null when there is a connected node, connecting node, or node with no connection. It may be best to just fetch the configs and poll for them if the node is non-null and ready to send a request to. If it is null or not ready then maybe skip the first synchronous DescribeConfigs RPC and fetch the configs asynchronously on the next try. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org
