TBKafkaConsumerTemplate.java

/**
 * Copyright © 2016-2018 The Thingsboard Authors
 *
 * Licensed 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.thingsboard.server.kafka;

import lombok.Builder;
import lombok.Getter;
import org.apache.kafka.clients.consumer.ConsumerConfig;
import org.apache.kafka.clients.consumer.ConsumerRecord;
import org.apache.kafka.clients.consumer.ConsumerRecords;
import org.apache.kafka.clients.consumer.KafkaConsumer;

import java.io.IOException;
import java.time.Duration;
import java.util.Collections;
import java.util.Properties;
import java.util.UUID;

/**
 * Created by ashvayka on 24.09.18.
 */
public class TBKafkaConsumerTemplate<T> {

    private final KafkaConsumer<String, byte[]> consumer;
    private final TbKafkaDecoder<T> decoder;

    @Builder.Default
    private TbKafkaRequestIdExtractor<T> requestIdExtractor = ((response) -> null);

    @Getter
    private final String topic;

    @Builder
    private TBKafkaConsumerTemplate(TbKafkaSettings settings, TbKafkaDecoder<T> decoder,
                                    TbKafkaRequestIdExtractor<T> requestIdExtractor,
                                    String clientId, String groupId, String topic,
                                    boolean autoCommit, int autoCommitIntervalMs,
                                    int maxPollRecords) {
        Properties props = settings.toProps();
        props.put(ConsumerConfig.CLIENT_ID_CONFIG, clientId);
        if (groupId != null) {
            props.put(ConsumerConfig.GROUP_ID_CONFIG, groupId);
        }
        props.put(ConsumerConfig.ENABLE_AUTO_COMMIT_CONFIG, autoCommit);
        props.put(ConsumerConfig.AUTO_COMMIT_INTERVAL_MS_CONFIG, autoCommitIntervalMs);
        props.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, "org.apache.kafka.common.serialization.StringDeserializer");
        props.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, "org.apache.kafka.common.serialization.ByteArrayDeserializer");
        if (maxPollRecords > 0) {
            props.put(ConsumerConfig.MAX_POLL_RECORDS_CONFIG, maxPollRecords);
        }
        this.consumer = new KafkaConsumer<>(props);
        this.decoder = decoder;
        this.requestIdExtractor = requestIdExtractor;
        this.topic = topic;
    }

    public void subscribe() {
        consumer.subscribe(Collections.singletonList(topic));
    }

    public void unsubscribe() {
        consumer.unsubscribe();
    }

    public ConsumerRecords<String, byte[]> poll(Duration duration) {
        return consumer.poll(duration);
    }

    public T decode(ConsumerRecord<String, byte[]> record) throws IOException {
        return decoder.decode(record.value());
    }

    public UUID extractRequestId(T value) {
        return requestIdExtractor.extractRequestId(value);
    }
}