/*
* 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.twill.internal.kafka.client;
import com.google.common.base.Objects;
import com.google.common.collect.Lists;
import com.google.common.util.concurrent.Futures;
import com.google.common.util.concurrent.ListenableFuture;
import kafka.javaapi.producer.Producer;
import kafka.producer.KeyedMessage;
import kafka.producer.ProducerConfig;
import org.apache.twill.common.Cancellable;
import org.apache.twill.common.Threads;
import org.apache.twill.kafka.client.BrokerService;
import org.apache.twill.kafka.client.Compression;
import org.apache.twill.kafka.client.KafkaPublisher;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.nio.ByteBuffer;
import java.util.List;
import java.util.Properties;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicReference;
/**
* Implementation of {@link KafkaPublisher} using the kafka scala-java api.
*/
final class SimpleKafkaPublisher implements KafkaPublisher {
private static final Logger LOG = LoggerFactory.getLogger(SimpleKafkaPublisher.class);
private final BrokerService brokerService;
private final Ack ack;
private final Compression compression;
private final AtomicReference<Producer<Integer, ByteBuffer>> producer;
private final AtomicBoolean listenerCancelled;
public SimpleKafkaPublisher(BrokerService brokerService, Ack ack, Compression compression) {
this.brokerService = brokerService;
this.ack = ack;
this.compression = compression;
this.producer = new AtomicReference<Producer<Integer, ByteBuffer>>();
this.listenerCancelled = new AtomicBoolean(false);
}
/**
* Start the publisher. This method must be called before other methods. This method is only to be called
* by KafkaClientService who own this object.
* @return A Cancellable for closing this publish.
*/
Cancellable start() {
ExecutorService listenerExecutor
= Executors.newSingleThreadExecutor(Threads.createDaemonThreadFactory("kafka-publisher"));
// Listen to changes in broker list
final BrokerListChangeListener listener = new BrokerListChangeListener(listenerCancelled, producer,
ack, compression);
Cancellable cancelChangeListener = brokerService.addChangeListener(listener, listenerExecutor);
// Invoke the change listener at least once. Since every call to the listener is through the single thread
// executor, there is no race and for sure the listener always see the latest change, either through this call
// or from the BrokerService callback.
Future<?> completion = listenerExecutor.submit(new Runnable() {
@Override
public void run() {
listener.changed(brokerService);
}
});
Futures.getUnchecked(completion);
return new ProducerCancellable(listenerExecutor, listenerCancelled, cancelChangeListener, producer);
}
@Override
public Preparer prepare(String topic) {
return new SimplePreparer(topic);
}
private final class SimplePreparer implements Preparer {
private final String topic;
private final List<KeyedMessage<Integer, ByteBuffer>> messages;
private SimplePreparer(String topic) {
this.topic = topic;
this.messages = Lists.newLinkedList();
}
@Override
public Preparer add(ByteBuffer message, Object partitionKey) {
messages.add(new KeyedMessage<Integer, ByteBuffer>(topic, Math.abs(partitionKey.hashCode()), message));
return this;
}
@Override
public ListenableFuture<Integer> send() {
try {
int size = messages.size();
Producer<Integer, ByteBuffer> kafkaProducer = producer.get();
if (kafkaProducer == null) {
return Futures.immediateFailedFuture(new IllegalStateException("No kafka producer available."));
}
kafkaProducer.send(messages);
return Futures.immediateFuture(size);
} catch (Exception e) {
return Futures.immediateFailedFuture(e);
} finally {
messages.clear();
}
}
}
/**
* Listener for watching for changes in broker list.
* This needs to be a static class so that no reference to the publisher instance is held in order for
* weak reference inside ZKBrokerService to publish works and be able to GC the Publisher instance and hence
* closing the underlying kafka producer.
*/
private static final class BrokerListChangeListener extends BrokerService.BrokerChangeListener {
private final AtomicBoolean listenerCancelled;
private final AtomicReference<Producer<Integer, ByteBuffer>> producer;
private final Ack ack;
private final Compression compression;
private String brokerList;
private BrokerListChangeListener(AtomicBoolean listenerCancelled,
AtomicReference<Producer<Integer, ByteBuffer>> producer,
Ack ack, Compression compression) {
this.listenerCancelled = listenerCancelled;
this.producer = producer;
this.ack = ack;
this.compression = compression;
}
@Override
public void changed(BrokerService brokerService) {
if (listenerCancelled.get()) {
return;
}
String newBrokerList = brokerService.getBrokerList();
if (newBrokerList.isEmpty()) {
LOG.warn("Broker list is empty. No Kafka producer is created.");
return;
}
if (Objects.equal(brokerList, newBrokerList)) {
return;
}
Properties props = new Properties();
props.put("metadata.broker.list", newBrokerList);
props.put("serializer.class", ByteBufferEncoder.class.getName());
props.put("key.serializer.class", IntegerEncoder.class.getName());
props.put("partitioner.class", IntegerPartitioner.class.getName());
props.put("request.required.acks", Integer.toString(ack.getAck()));
props.put("compression.codec", compression.getCodec());
ProducerConfig config = new ProducerConfig(props);
Producer<Integer, ByteBuffer> oldProducer = producer.getAndSet(new Producer<Integer, ByteBuffer>(config));
if (oldProducer != null) {
oldProducer.close();
}
LOG.info("Update Kafka producer broker list: {}", newBrokerList);
brokerList = newBrokerList;
}
}
/**
* For stopping and releasing resource for the publisher. This class shouldn't hold any references to the
* Publisher class.
*/
private static final class ProducerCancellable implements Cancellable, Runnable {
private final ExecutorService executor;
private final AtomicBoolean listenerCancelled;
private final Cancellable cancelChangeListener;
private final AtomicReference<Producer<Integer, ByteBuffer>> producer;
private ProducerCancellable(ExecutorService executor, AtomicBoolean listenerCancelled,
Cancellable cancelChangeListener,
AtomicReference<Producer<Integer, ByteBuffer>> producer) {
this.executor = executor;
this.listenerCancelled = listenerCancelled;
this.cancelChangeListener = cancelChangeListener;
this.producer = producer;
}
@Override
public void cancel() {
if (listenerCancelled.compareAndSet(false, true)) {
executor.execute(this);
}
}
@Override
public void run() {
// Call from cancel() through executor only.
cancelChangeListener.cancel();
Producer<Integer, ByteBuffer> kafkaProducer = producer.get();
kafkaProducer.close();
executor.shutdownNow();
}
}
}