flink-connector-kafka/src/main/java/org/apache/flink/connector/kafka/sink/DefaultKafkaSinkContext.java

/*
 * 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.sink;

import org.apache.kafka.clients.producer.KafkaProducer;
import org.apache.kafka.clients.producer.Producer;
import org.apache.kafka.common.PartitionInfo;

import java.util.ArrayList;
import java.util.Comparator;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Properties;

/**
 * Context providing information to assist constructing a {@link
 * org.apache.kafka.clients.producer.ProducerRecord}.
 */
public class DefaultKafkaSinkContext implements KafkaRecordSerializationSchema.KafkaSinkContext {

    private final int subtaskId;
    private final int numberOfParallelInstances;
    private final Properties kafkaProducerConfig;

    private final Map<String, int[]> cachedPartitions = new HashMap<>();

    public DefaultKafkaSinkContext(
            int subtaskId, int numberOfParallelInstances, Properties kafkaProducerConfig) {
        this.subtaskId = subtaskId;
        this.numberOfParallelInstances = numberOfParallelInstances;
        this.kafkaProducerConfig = kafkaProducerConfig;
    }

    @Override
    public int getParallelInstanceId() {
        return subtaskId;
    }

    @Override
    public int getNumberOfParallelInstances() {
        return numberOfParallelInstances;
    }

    @Override
    public int[] getPartitionsForTopic(String topic) {
        return cachedPartitions.computeIfAbsent(topic, this::fetchPartitionsForTopic);
    }

    private int[] fetchPartitionsForTopic(String topic) {
        try (final Producer<?, ?> producer = new KafkaProducer<>(kafkaProducerConfig)) {
            // the fetched list is immutable, so we're creating a mutable copy in order to sort
            // it
            final List<PartitionInfo> partitionsList =
                    new ArrayList<>(producer.partitionsFor(topic));

            return partitionsList.stream()
                    .sorted(Comparator.comparing(PartitionInfo::partition))
                    .map(PartitionInfo::partition)
                    .mapToInt(Integer::intValue)
                    .toArray();
        }
    }
}