Examples with ConsumerIterator kafka.consumer.ConsumerIterator used on opensource projects

Example 1 with ConsumerIterator

use of kafka.consumer.ConsumerIterator in project graylog2-server by Graylog2.

the class KafkaTransport method doLaunch.

@Override
public void doLaunch(final MessageInput input) throws MisfireException {
    serverStatus.awaitRunning(new Runnable() {

        @Override
        public void run() {
            lifecycleStateChange(Lifecycle.RUNNING);
        }
    });
    // listen for lifecycle changes
    serverEventBus.register(this);
    final Properties props = new Properties();
    props.put("group.id", GROUP_ID);
    props.put("client.id", "gl2-" + nodeId + "-" + input.getId());
    props.put("fetch.min.bytes", String.valueOf(configuration.getInt(CK_FETCH_MIN_BYTES)));
    props.put("fetch.wait.max.ms", String.valueOf(configuration.getInt(CK_FETCH_WAIT_MAX)));
    props.put("zookeeper.connect", configuration.getString(CK_ZOOKEEPER));
    // Default auto commit interval is 60 seconds. Reduce to 1 second to minimize message duplication
    // if something breaks.
    props.put("auto.commit.interval.ms", "1000");
    // Set a consumer timeout to avoid blocking on the consumer iterator.
    props.put("consumer.timeout.ms", "1000");
    final int numThreads = configuration.getInt(CK_THREADS);
    final ConsumerConfig consumerConfig = new ConsumerConfig(props);
    cc = Consumer.createJavaConsumerConnector(consumerConfig);
    final TopicFilter filter = new Whitelist(configuration.getString(CK_TOPIC_FILTER));
    final List<KafkaStream<byte[], byte[]>> streams = cc.createMessageStreamsByFilter(filter, numThreads);
    final ExecutorService executor = executorService(numThreads);
    // this is being used during shutdown to first stop all submitted jobs before committing the offsets back to zookeeper
    // and then shutting down the connection.
    // this is to avoid yanking away the connection from the consumer runnables
    stopLatch = new CountDownLatch(streams.size());
    for (final KafkaStream<byte[], byte[]> stream : streams) {
        executor.submit(new Runnable() {

            @Override
            public void run() {
                final ConsumerIterator<byte[], byte[]> consumerIterator = stream.iterator();
                boolean retry;
                do {
                    retry = false;
                    try {
                        // noinspection WhileLoopReplaceableByForEach
                        while (consumerIterator.hasNext()) {
                            if (paused) {
                                // we try not to spin here, so we wait until the lifecycle goes back to running.
                                LOG.debug("Message processing is paused, blocking until message processing is turned back on.");
                                Uninterruptibles.awaitUninterruptibly(pausedLatch);
                            }
                            // check for being stopped before actually getting the message, otherwise we could end up losing that message
                            if (stopped) {
                                break;
                            }
                            if (isThrottled()) {
                                blockUntilUnthrottled();
                            }
                            // process the message, this will immediately mark the message as having been processed. this gets tricky
                            // if we get an exception about processing it down below.
                            final MessageAndMetadata<byte[], byte[]> message = consumerIterator.next();
                            final byte[] bytes = message.message();
                            // it is possible that the message is null
                            if (bytes == null) {
                                continue;
                            }
                            totalBytesRead.addAndGet(bytes.length);
                            lastSecBytesReadTmp.addAndGet(bytes.length);
                            final RawMessage rawMessage = new RawMessage(bytes);
                            // TODO implement throttling
                            input.processRawMessage(rawMessage);
                        }
                    } catch (ConsumerTimeoutException e) {
                        // Happens when there is nothing to consume, retry to check again.
                        retry = true;
                    } catch (Exception e) {
                        LOG.error("Kafka consumer error, stopping consumer thread.", e);
                    }
                } while (retry && !stopped);
                // explicitly commit our offsets when stopping.
                // this might trigger a couple of times, but it won't hurt
                cc.commitOffsets();
                stopLatch.countDown();
            }
        });
    }
    scheduler.scheduleAtFixedRate(new Runnable() {

        @Override
        public void run() {
            lastSecBytesRead.set(lastSecBytesReadTmp.getAndSet(0));
        }
    }, 1, 1, TimeUnit.SECONDS);
}