[GitHub] [flink] stevenzwu commented on a change in pull request #13574: [FLINK-18323] Add a Kafka source implementation based on FLIP-27.

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stevenzwu commented on a change in pull request #13574:
URL: https://github.com/apache/flink/pull/13574#discussion_r502608464



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File path: flink-connectors/flink-connector-kafka/src/main/java/org/apache/flink/connector/kafka/source/enumerator/subscriber/TopicListSubscriber.java
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@@ -0,0 +1,67 @@
+/*
+ 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.flink.connector.kafka.source.enumerator.subscriber;
+
+import org.apache.kafka.clients.consumer.KafkaConsumer;
+import org.apache.kafka.common.PartitionInfo;
+import org.apache.kafka.common.TopicPartition;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+
+import static org.apache.flink.connector.kafka.source.enumerator.subscriber.KafkaSubscriberUtils.maybeLog;
+import static org.apache.flink.connector.kafka.source.enumerator.subscriber.KafkaSubscriberUtils.updatePartitionChanges;
+
+/**
+ * A subscriber to a fixed list of topics.
+ */
+class TopicListSubscriber implements KafkaSubscriber {
+	private static final long serialVersionUID = -6917603843104947866L;
+	private static final Logger LOG = LoggerFactory.getLogger(TopicListSubscriber.class);
+	private final List<String> topics;
+
+	TopicListSubscriber(List<String> topics) {
+		this.topics = topics;
+	}
+
+	@Override
+	public PartitionChange getPartitionChanges(
+			KafkaConsumer<?, ?> consumer,
+			Set<TopicPartition> currentAssignment) {
+		Set<TopicPartition> newPartitions = new HashSet<>();
+		Set<TopicPartition> removedPartitions = new HashSet<>(currentAssignment);
+
+		// We cannot call partitionsFor() directly on each topic because this may accidentally create the topic
+		// if the topic does not exist. In Kafka 2.3+ we can use the "allow.auto.create.topics" configuration on

Review comment:
       Since this module already depends on `2.4.1`, can we avoid listing all topics by using the new config that you mentioned? It is probably better to avoid fetching all topics/partitions for large clusters?




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