TestKafkaConsumer.java

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/* Copyright 2017 Telstra Open Source
 *
 *   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.openkilda.wfm.topology;

import static org.openkilda.messaging.Utils.MAPPER;

import org.openkilda.messaging.Destination;
import org.openkilda.messaging.Message;

import org.apache.kafka.clients.consumer.ConsumerRecord;
import org.apache.kafka.clients.consumer.ConsumerRecords;
import org.apache.kafka.clients.consumer.KafkaConsumer;
import org.apache.kafka.common.errors.WakeupException;

import java.io.IOException;
import java.util.Collections;
import java.util.Optional;
import java.util.Properties;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.TimeUnit;

public class TestKafkaConsumer extends Thread {
    private static final long CONSUMER_QUEUE_OFFER_TIMEOUT = 1000;
    private static final long KAFKA_MESSAGE_POLL_TIMEOUT = 30000;
    private static final long KAFKA_CONSUMER_POLL_TIMEOUT = 100;
    private final KafkaConsumer<String, String> consumer;
    private final String topic;
    private final Destination destination;
    private boolean checkDestination = true;
    private volatile BlockingQueue<ConsumerRecord<String, String>> records = new ArrayBlockingQueue<>(100);


    public TestKafkaConsumer(final String topic, final Destination destination, final Properties properties) {
        this.consumer = new KafkaConsumer<>(properties);
        this.topic = topic;
        this.destination = destination;
    }

    public TestKafkaConsumer(final String topic, final Properties properties) {
        this(topic, null, properties);
        checkDestination = false;
    }

    public void run() {
        System.out.println("Starting Kafka Consumer for " + topic);
        consumer.subscribe(Collections.singletonList(topic));
        try {
            while (true) {
                ConsumerRecords<String, String> records = consumer.poll(KAFKA_CONSUMER_POLL_TIMEOUT);
                for (ConsumerRecord<String, String> record : records) {
                    if (checkDestination(record.value())) {
                        this.records.offer(record, CONSUMER_QUEUE_OFFER_TIMEOUT, TimeUnit.MILLISECONDS);
                        consumer.commitSync();
                        System.out.println(String.format("Received message with destination %s: %s",
                                destination, record.value()));
                    }
                }
            }
        } catch (WakeupException e) {
            System.out.println("Stopping Kafka Consumer for " + topic);
        } catch (InterruptedException e) {
            System.out.println("Interrupting Kafka Consumer for " + topic);
        } finally {
            consumer.unsubscribe();
            consumer.close();
        }
    }

    public ConsumerRecord<String, String> pollMessage() throws InterruptedException {
        return pollMessage(KAFKA_MESSAGE_POLL_TIMEOUT);
    }

    public ConsumerRecord<String, String> pollMessage(final long timeout) throws InterruptedException {
        return records.poll(timeout, TimeUnit.MILLISECONDS);
    }

    public String pollMessageValue() throws InterruptedException {
        return Optional.ofNullable(pollMessage()).map(ConsumerRecord::value).orElse(null);
    }

    public void clear() {
        records.clear();
    }

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

    private boolean checkDestination(final String recordValue) {

        if (!checkDestination) {
            return true;
        }

        boolean result = false;
        try {
            if (destination != null) {
                Message message = MAPPER.readValue(recordValue, Message.class);
                if (destination.equals(message.getDestination())) {
                    result = true;
                }
            } else {
                Message message = MAPPER.readValue(recordValue, Message.class);
                if (message != null) {
                    result = true;
                }
            }
        } catch (IOException exception) {
            System.out.println(String.format("Can not deserialize %s with destination %s ", recordValue, destination));
            exception.printStackTrace();
        }
        return result;
    }
}