kafka.javaapi.FetchResponse Java Examples

private int readNext() {
   FetchRequestBuilder requestBuilder =
         new FetchRequestBuilder()
            .clientId(clientId);
   for(Map.Entry<TopicAndPartition, Long> offset: offsets.entrySet()) {
      if(offset.getValue() == null) {
         logger.warn("Invalid offset for topic: [{}] partition: [{}]", offset.getKey().topic(), offset.getKey().partition());
      }
      else {
         requestBuilder.addFetch(offset.getKey().topic(), offset.getKey().partition(), offset.getValue(), fetchSize);
      }
   }
   FetchRequest request = requestBuilder.build();
   FetchResponse response = getKafkaConsumer().fetch(request);
   // FIXME handle errors / leader rebalances hear
   return dispatch(response);
}
 

void nextMessageSet() throws Exception {
  FetchRequest req = 
      new FetchRequestBuilder().
      clientId(name).
      addFetch(topic, partitionMetadata.partitionId(), currentOffset, fetchSize).
      minBytes(1).
      maxWait(1000).
      build();
  
  FetchResponse fetchResponse = consumer.fetch(req);
  if(fetchResponse.hasError()) {
    throw new Exception("TODO: handle the error, reset the consumer....");
  }
  
  currentMessageSet = fetchResponse.messageSet(topic, partitionMetadata.partitionId());
  currentMessageSetIterator = currentMessageSet.iterator();
}
 

public static void main(String[] args) throws Exception {
	final String topic = "topic1";
	String clientID = "DemoLowLevelConsumer1";
	SimpleConsumer simpleConsumer = new SimpleConsumer("kafka0", 9092, 100000, 64 * 1000000, clientID);
	FetchRequest req = new FetchRequestBuilder().clientId(clientID)
			.addFetch(topic, 0, 0L, 50).addFetch(topic, 1, 0L, 5000).addFetch(topic, 2, 0L, 1000000).build();
	FetchResponse fetchResponse = simpleConsumer.fetch(req);
	ByteBufferMessageSet messageSet = (ByteBufferMessageSet) fetchResponse.messageSet(topic, 0);
	for (MessageAndOffset messageAndOffset : messageSet) {
		ByteBuffer payload = messageAndOffset.message().payload();
		long offset = messageAndOffset.offset();
		byte[] bytes = new byte[payload.limit()];
		payload.get(bytes);
		System.out.println("Offset:" + offset + ", Payload:" + new String(bytes, "UTF-8"));
	}
}
 

private Iterator<KafkaConsumerRecord> getIteratorFromFetchResponse(FetchResponse fetchResponse, KafkaPartition partition) {
  try {
    ByteBufferMessageSet messageBuffer = fetchResponse.messageSet(partition.getTopicName(), partition.getId());
    return Iterators.transform(messageBuffer.iterator(),
        new Function<kafka.message.MessageAndOffset, KafkaConsumerRecord>() {
          @Override
          public KafkaConsumerRecord apply(kafka.message.MessageAndOffset input) {
            return new Kafka08ConsumerRecord(input, partition.getTopicName(), partition.getId());
          }
        });
  } catch (Exception e) {
    log.warn(String.format("Failed to retrieve next message buffer for partition %s: %s."
        + "The remainder of this partition will be skipped.", partition, e));
    return null;
  }
}
 

public List<byte[]> readMessages(String topic) {
  SimpleConsumer consumer = new SimpleConsumer("localhost", 6667, 100000, 64 * 1024, "consumer");
  FetchRequest req = new FetchRequestBuilder()
          .clientId("consumer")
          .addFetch(topic, 0, 0, 100000)
          .build();
  FetchResponse fetchResponse = consumer.fetch(req);
  Iterator<MessageAndOffset> results = fetchResponse.messageSet(topic, 0).iterator();
  List<byte[]> messages = new ArrayList<>();
  while(results.hasNext()) {
    ByteBuffer payload = results.next().message().payload();
    byte[] bytes = new byte[payload.limit()];
    payload.get(bytes);
    messages.add(bytes);
  }
  consumer.close();
  return messages;
}
 

@Override
public Iterator<KafkaConsumerRecord> consume(KafkaPartition partition, long nextOffset, long maxOffset) {
  if (nextOffset > maxOffset) {
    return null;
  }

  FetchRequest fetchRequest = createFetchRequest(partition, nextOffset);

  try {
    FetchResponse fetchResponse = getFetchResponseForFetchRequest(fetchRequest, partition);
    return getIteratorFromFetchResponse(fetchResponse, partition);
  } catch (Exception e) {
    log.warn(String.format(
        "Fetch message buffer for partition %s has failed: %s. Will refresh topic metadata and retry", partition, e));
    return refreshTopicMetadataAndRetryFetch(partition, fetchRequest);
  }
}
 

@Override
protected Iterator<MessageAndOffset> fetchNextMessageBuffer(KafkaPartition partition, long nextOffset,
    long maxOffset) {
  if (nextOffset > maxOffset) {
    return null;
  }

  FetchRequest fetchRequest = createFetchRequest(partition, nextOffset);

  try {
    FetchResponse fetchResponse = getFetchResponseForFetchRequest(fetchRequest, partition);
    return getIteratorFromFetchResponse(fetchResponse, partition);
  } catch (Exception e) {
    LOG.warn(
        String.format("Fetch message buffer for partition %s has failed: %s. Will refresh topic metadata and retry",
            partition, e));
    return refreshTopicMetadataAndRetryFetch(partition, fetchRequest);
  }
}
 

private Iterator<MessageAndOffset> refreshTopicMetadataAndRetryFetch(KafkaPartition partition,
    FetchRequest fetchRequest) {
  try {
    refreshTopicMetadata(partition);
    FetchResponse fetchResponse = getFetchResponseForFetchRequest(fetchRequest, partition);
    return getIteratorFromFetchResponse(fetchResponse, partition);
  } catch (Exception e) {
    LOG.warn(String.format("Fetch message buffer for partition %s has failed: %s. This partition will be skipped.",
        partition, e));
    return null;
  }
}
 

public static ByteBufferMessageSet fetchMessages(KafkaConfig config, SimpleConsumer consumer, Partition partition, long offset) {
    ByteBufferMessageSet msgs = null;
    String topic = config.topic;
    int partitionId = partition.partition;
    for (int errors = 0; errors < 2 && msgs == null; errors++) {
        FetchRequestBuilder builder = new FetchRequestBuilder();
        FetchRequest fetchRequest = builder.addFetch(topic, partitionId, offset, config.fetchSizeBytes).
                clientId(config.clientId).build();
        FetchResponse fetchResponse;
        try {
            fetchResponse = consumer.fetch(fetchRequest);
        } catch (Exception e) {
            if (e instanceof ConnectException) {
                throw new FailedFetchException(e);
            } else {
                throw new RuntimeException(e);
            }
        }
        if (fetchResponse.hasError()) {
            KafkaError error = KafkaError.getError(fetchResponse.errorCode(topic, partitionId));
            if (error.equals(KafkaError.OFFSET_OUT_OF_RANGE) && config.useStartOffsetTimeIfOffsetOutOfRange && errors == 0) {
                long startOffset = getOffset(consumer, topic, partitionId, config.startOffsetTime);
                LOG.warn("Got fetch request with offset out of range: [" + offset + "]; " +
                        "retrying with default start offset time from configuration. " +
                        "configured start offset time: [" + config.startOffsetTime + "] offset: [" + startOffset + "]");
                offset = startOffset;
            } else {
                String message = "Error fetching data from [" + partition + "] for topic [" + topic + "]: [" + error + "]";
                LOG.error(message);
                throw new FailedFetchException(message);
            }
        } else {
            msgs = fetchResponse.messageSet(topic, partitionId);
        }
    }
    return msgs;
}
 

public List<byte[]> execute() throws Exception {
  FetchRequest req = 
      new FetchRequestBuilder().
      clientId(name).
      addFetch(topic, partitionMetadata.partitionId(), currentOffset, fetchSize).
      minBytes(1).
      maxWait(maxWait).
      build();
  
  FetchResponse fetchResponse = consumer.fetch(req);
  if(fetchResponse.hasError()) {
    short errorCode = fetchResponse.errorCode(topic, partitionMetadata.partitionId());
    String msg = "Kafka error code = " + errorCode + ", Partition  " + partitionMetadata.partitionId() ;
    throw new Exception(msg);
  }
  List<byte[]> holder = new ArrayList<byte[]>();
  ByteBufferMessageSet messageSet = fetchResponse.messageSet(topic, partitionMetadata.partitionId());
  int count = 0;
  for(MessageAndOffset messageAndOffset : messageSet) {
    if (messageAndOffset.offset() < currentOffset) continue; //old offset, ignore
    ByteBuffer payload = messageAndOffset.message().payload();
    byte[] bytes = new byte[payload.limit()];
    payload.get(bytes);
    holder.add(bytes);
    currentOffset = messageAndOffset.nextOffset();
    count++;
    if(count == maxRead) break;
  }
  return holder ;
}
 

@Override
public FetchResponse fetch(FetchRequest request) {
  scala.collection.Traversable<Tuple2<TopicAndPartition, PartitionFetchInfo>> requestInfo = request.requestInfo();
  java.util.Map<TopicAndPartition, Short> errorMap = new HashMap<>();

  while (requestInfo.headOption().isDefined()) {
    // jfim: IntelliJ erroneously thinks the following line is an incompatible type error, but it's only because
    // it doesn't understand scala covariance when called from Java (ie. it thinks head() is of type A even though
    // it's really of type Tuple2[TopicAndPartition, PartitionFetchInfo])
    Tuple2<TopicAndPartition, PartitionFetchInfo> t2 = requestInfo.head();
    TopicAndPartition topicAndPartition = t2._1();
    PartitionFetchInfo partitionFetchInfo = t2._2();

    if (!topicAndPartition.topic().equals(topicName)) {
      errorMap.put(topicAndPartition, Errors.UNKNOWN_TOPIC_OR_PARTITION.code());
    } else if (partitionLeaderIndices.length < topicAndPartition.partition()) {
      errorMap.put(topicAndPartition, Errors.UNKNOWN_TOPIC_OR_PARTITION.code());
    } else if (partitionLeaderIndices[topicAndPartition.partition()] != index) {
      errorMap.put(topicAndPartition, Errors.NOT_LEADER_FOR_PARTITION.code());
    } else {
      // Do nothing, we'll generate a fake message
    }

    requestInfo = requestInfo.tail();
  }

  return new MockFetchResponse(errorMap);
}
 

/**
 * Fetch messages and the per-partition high watermark from Kafka between the specified offsets.
 *
 * @param startOffset The offset of the first message desired, inclusive
 * @param endOffset The offset of the last message desired, exclusive, or {@link Long#MAX_VALUE} for no end offset.
 * @param timeoutMillis Timeout in milliseconds
 * @throws java.util.concurrent.TimeoutException If the operation could not be completed within {@code timeoutMillis}
 * milliseconds
 * @return An iterable containing messages fetched from Kafka and their offsets, as well as the high watermark for
 * this partition.
 */
public synchronized MessageBatch fetchMessages(long startOffset, long endOffset, int timeoutMillis)
    throws java.util.concurrent.TimeoutException {
  // TODO Improve error handling

  final long connectEndTime = System.currentTimeMillis() + _connectTimeoutMillis;
  while (_currentState.getStateValue() != KafkaConnectionHandler.ConsumerState.CONNECTED_TO_PARTITION_LEADER
      && System.currentTimeMillis() < connectEndTime) {
    _currentState.process();
  }
  if (_currentState.getStateValue() != KafkaConnectionHandler.ConsumerState.CONNECTED_TO_PARTITION_LEADER
      && connectEndTime <= System.currentTimeMillis()) {
    throw new java.util.concurrent.TimeoutException();
  }

  FetchResponse fetchResponse = _simpleConsumer.fetch(
      new FetchRequestBuilder().minBytes(_fetchRequestMinBytes).maxWait(timeoutMillis)
          .addFetch(_topic, _partition, startOffset, _fetchRequestSizeBytes).build());

  if (!fetchResponse.hasError()) {
    final Iterable<MessageAndOffset> messageAndOffsetIterable =
        buildOffsetFilteringIterable(fetchResponse.messageSet(_topic, _partition), startOffset, endOffset);

    // TODO: Instantiate with factory
    return new SimpleConsumerMessageBatch(messageAndOffsetIterable);
  } else {
    throw exceptionForKafkaErrorCode(fetchResponse.errorCode(_topic, _partition));
  }
}
 

private Iterator<KafkaConsumerRecord> refreshTopicMetadataAndRetryFetch(KafkaPartition partition,
    FetchRequest fetchRequest) {
  try {
    refreshTopicMetadata(partition);
    FetchResponse fetchResponse = getFetchResponseForFetchRequest(fetchRequest, partition);
    return getIteratorFromFetchResponse(fetchResponse, partition);
  } catch (Exception e) {
    log.warn(String.format("Fetch message buffer for partition %s has failed: %s. This partition will be skipped.",
        partition, e));
    return null;
  }
}
 

private synchronized FetchResponse getFetchResponseForFetchRequest(FetchRequest fetchRequest, KafkaPartition partition) {
  SimpleConsumer consumer = getSimpleConsumer(partition.getLeader().getHostAndPort());

  FetchResponse fetchResponse = consumer.fetch(fetchRequest);
  if (fetchResponse.hasError()) {
    throw new RuntimeException(String.format("error code %d",
        fetchResponse.errorCode(partition.getTopicName(), partition.getId())));
  }
  return fetchResponse;
}
 

private Iterator<MessageAndOffset> getIteratorFromFetchResponse(FetchResponse fetchResponse,
    KafkaPartition partition) {
  try {
    ByteBufferMessageSet messageBuffer = fetchResponse.messageSet(partition.getTopicName(), partition.getId());
    return messageBuffer.iterator();
  } catch (Exception e) {
    LOG.warn(String.format("Failed to retrieve next message buffer for partition %s: %s."
        + "The remainder of this partition will be skipped.", partition, e));
    return null;
  }
}
 

private synchronized FetchResponse getFetchResponseForFetchRequest(FetchRequest fetchRequest,
    KafkaPartition partition) {
  SimpleConsumer consumer = getSimpleConsumer(partition.getLeader().getHostAndPort());

  FetchResponse fetchResponse = consumer.fetch(fetchRequest);
  if (fetchResponse.hasError()) {
    throw new RuntimeException(
        String.format("error code %d", fetchResponse.errorCode(partition.getTopicName(), partition.getId())));
  }
  return fetchResponse;
}
 

private void initializeLastProcessingOffset()
{
  // read last received kafka message
  TopicMetadata tm = KafkaMetadataUtil.getTopicMetadata(Sets.newHashSet((String)getConfigProperties().get(KafkaMetadataUtil.PRODUCER_PROP_BROKERLIST)), this.getTopic());

  if (tm == null) {
    throw new RuntimeException("Failed to retrieve topic metadata");
  }

  partitionNum = tm.partitionsMetadata().size();

  lastMsgs = new HashMap<Integer, Pair<byte[],byte[]>>(partitionNum);

  for (PartitionMetadata pm : tm.partitionsMetadata()) {

    String leadBroker = pm.leader().host();
    int port = pm.leader().port();
    String clientName = this.getClass().getName().replace('$', '.') + "_Client_" + tm.topic() + "_" + pm.partitionId();
    SimpleConsumer consumer = new SimpleConsumer(leadBroker, port, 100000, 64 * 1024, clientName);

    long readOffset = KafkaMetadataUtil.getLastOffset(consumer, tm.topic(), pm.partitionId(), kafka.api.OffsetRequest.LatestTime(), clientName);

    FetchRequest req = new FetchRequestBuilder().clientId(clientName).addFetch(tm.topic(), pm.partitionId(), readOffset - 1, 100000).build();

    FetchResponse fetchResponse = consumer.fetch(req);
    for (MessageAndOffset messageAndOffset : fetchResponse.messageSet(tm.topic(), pm.partitionId())) {

      Message m = messageAndOffset.message();

      ByteBuffer payload = m.payload();
      ByteBuffer key = m.key();
      byte[] valueBytes = new byte[payload.limit()];
      byte[] keyBytes = new byte[key.limit()];
      payload.get(valueBytes);
      key.get(keyBytes);
      lastMsgs.put(pm.partitionId(), new Pair<byte[], byte[]>(keyBytes, valueBytes));
    }
  }
}
 

/**
 * Makes a call to kafka to fetch messages.
 */
private FetchResponse fetchMessages(SimpleConsumer consumer, long offset) {
  FetchRequest request = new FetchRequestBuilder()
    .clientId(consumer.clientId())
    .addFetch(topicPart.getTopic(), topicPart.getPartition(), offset, FETCH_SIZE)
    .maxWait(MAX_WAIT)
    .build();
  return consumer.fetch(request);
}
 

public static void main(String[] args) throws Exception {
    generateData();

    SimpleConsumer simpleConsumer = new SimpleConsumer(KafkaProperties.KAFKA_SERVER_URL,
        KafkaProperties.KAFKA_SERVER_PORT,
        KafkaProperties.CONNECTION_TIMEOUT,
        KafkaProperties.KAFKA_PRODUCER_BUFFER_SIZE,
        KafkaProperties.CLIENT_ID);

    System.out.println("Testing single fetch");
    FetchRequest req = new FetchRequestBuilder()
        .clientId(KafkaProperties.CLIENT_ID)
        .addFetch(KafkaProperties.TOPIC2, 0, 0L, 100)
        .build();
    FetchResponse fetchResponse = simpleConsumer.fetch(req);
    printMessages(fetchResponse.messageSet(KafkaProperties.TOPIC2, 0));

    System.out.println("Testing single multi-fetch");
    Map<String, List<Integer>> topicMap = new HashMap<String, List<Integer>>();
    topicMap.put(KafkaProperties.TOPIC2, Collections.singletonList(0));
    topicMap.put(KafkaProperties.TOPIC3, Collections.singletonList(0));
    req = new FetchRequestBuilder()
        .clientId(KafkaProperties.CLIENT_ID)
        .addFetch(KafkaProperties.TOPIC2, 0, 0L, 100)
        .addFetch(KafkaProperties.TOPIC3, 0, 0L, 100)
        .build();
    fetchResponse = simpleConsumer.fetch(req);
    int fetchReq = 0;
    for (Map.Entry<String, List<Integer>> entry : topicMap.entrySet()) {
        String topic = entry.getKey();
        for (Integer offset : entry.getValue()) {
            System.out.println("Response from fetch request no: " + ++fetchReq);
            printMessages(fetchResponse.messageSet(topic, offset));
        }
    }
}
 

private int dispatch(FetchResponse response) {
   int numDispatched = 0;
   for(TopicAndPartition tap: new ArrayList<>(offsets.keySet())) {
      short errorCode = response.errorCode(tap.topic(), tap.partition());
      if(errorCode != 0) {
         logger.warn("Error reading from topic: [{}] partition: [{}]", tap.topic(), tap.partition(), ErrorMapping.exceptionFor(errorCode));
         continue;
      }

      ByteBufferMessageSet message = response.messageSet(tap.topic(), tap.partition());
      for(MessageAndOffset mao: message) {
         Long offset = offsets.get(tap);
         if(offset != null && offset > mao.offset()) {
            // skip older offsets
            continue;
         }
         KafkaConsumer handler = handlers.computeIfAbsent(tap, handlerFactory);
         if(handler == null) {
            logger.debug("No handler for topic: [{}] partition: [{}], this partition won't be processed", tap.topic(), tap.partition());
            offsets.remove(tap);
            handlers.remove(tap);
            break;
         }
         if(handler.apply(tap, mao.message())) {
            numDispatched++;
            offsets.put(tap, mao.nextOffset());
         }
         else {
            logger.debug("Done processing topic: [{}] partition: [{}]", tap.topic(), tap.partition());
            offsets.remove(tap);
            handlers.remove(tap);
            break;
         }
      }
   }

   return numDispatched;
}
 

public Iterable<BytesMessageWithOffset> fetch(long offset, int timeoutMs) throws InterruptedException {
    List<BytesMessageWithOffset> newOffsetMsg = new ArrayList<BytesMessageWithOffset>();
    FetchResponse response = null;
    Broker previousLeader = leaderBroker;
    while (true) {
        ensureConsumer(previousLeader);

        if (offset == Long.MAX_VALUE) {
            offset = getOffset(false);
            logger.info("offset max long, fetch from latest in kafka {}", offset);
        }

        FetchRequest request = new FetchRequestBuilder()
                .clientId(clientId)
                .addFetch(topic, partitionId, offset, 100000000)
                .maxWait(timeoutMs)
                .minBytes(1)
                .build();

        //logger.debug("fetch offset {}", offset);

        try {
            response = consumer.fetch(request);
        } catch (Exception e) {
            // e could be an instance of ClosedByInterruptException as SimpleConsumer.fetch uses nio
            if (Thread.interrupted()) {
                logger.info("catch exception of {} with interrupted in fetch for {} - {} with offset {}",
                        e.getClass().getName(), topic, partitionId, offset);

                throw new InterruptedException();
            }
            logger.warn("caughte exception in fetch {} - {}", topic, partitionId, e);
            response = null;
        }

        if (response == null || response.hasError()) {
            short errorCode = response != null ? response.errorCode(topic, partitionId) : ErrorMapping.UnknownCode();
            logger.warn("fetch {} - {} with offset {} encounters error: {}", topic, partitionId, offset, errorCode);

            boolean needNewLeader = false;
            if (errorCode == ErrorMapping.RequestTimedOutCode()) {
                //TODO: leave it here
            } else if (errorCode == ErrorMapping.OffsetOutOfRangeCode()) {
                //TODO: fetch the earliest offset or latest offset ?
                // seems no obvious correct way to handle it
                long earliestOffset = getOffset(true);
                logger.debug("get earilset offset {} for {} - {}", earliestOffset, topic, partitionId);
                if (earliestOffset < 0) {
                    needNewLeader = true;
                } else {
                    newOffsetMsg.add(new BytesMessageWithOffset(null, earliestOffset));
                    offset = earliestOffset;
                    continue;
                }
            } else {
                needNewLeader = true;
            }

            if (needNewLeader) {
                stopConsumer();
                previousLeader = leaderBroker;
                leaderBroker = null;
                continue;
            }
        } else {
            break;
        }
    }

    return response != null ? filterAndDecode(response.messageSet(topic, partitionId), offset) :
        (newOffsetMsg.size() > 0 ? newOffsetMsg : EMPTY_MSGS);
}
 

/**
 * Creates a fetch request.
 *
 * @return false if there's no more fetches
 * @throws IOException
 */

public boolean fetch() throws IOException {
  if (currentOffset >= lastOffset) {
    return false;
  }
  long tempTime = System.currentTimeMillis();
  TopicAndPartition topicAndPartition = new TopicAndPartition(
      kafkaRequest.getTopic(), kafkaRequest.getPartition());
  log.debug("\nAsking for offset : " + (currentOffset));
  PartitionFetchInfo partitionFetchInfo = new PartitionFetchInfo(
      currentOffset, fetchBufferSize);

  HashMap<TopicAndPartition, PartitionFetchInfo> fetchInfo = new HashMap<TopicAndPartition, PartitionFetchInfo>();
  fetchInfo.put(topicAndPartition, partitionFetchInfo);

  FetchRequest fetchRequest = new FetchRequest(
      1, // fetch request correlation id
      "hive_kafka_client", // client name
      1000, // fetch request max wait
      1024, // fetch request min bytes
      fetchInfo);

  FetchResponse fetchResponse = null;
  try {
    fetchResponse = simpleConsumer.fetch(fetchRequest);
    if (fetchResponse.hasError()) {
      log.info("Error encountered during a fetch request from Kafka");
      log.info("Error Code generated : "
          + fetchResponse.errorCode(kafkaRequest.getTopic(),
          kafkaRequest.getPartition()));
      return false;
    } else {
      ByteBufferMessageSet messageBuffer = fetchResponse.messageSet(
          kafkaRequest.getTopic(), kafkaRequest.getPartition());
      lastFetchTime = (System.currentTimeMillis() - tempTime);
      log.debug("Time taken to fetch : "
          + (lastFetchTime / 1000) + " seconds");
      log.debug("The size of the ByteBufferMessageSet returned is : " + messageBuffer.sizeInBytes());
      int skipped = 0;
      totalFetchTime += lastFetchTime;
      messageIter = messageBuffer.iterator();
      //boolean flag = false;
      Iterator<MessageAndOffset> messageIter2 = messageBuffer
          .iterator();
      MessageAndOffset message = null;
      while (messageIter2.hasNext()) {
        message = messageIter2.next();
        if (message.offset() < currentOffset) {
          //flag = true;
          skipped++;
        } else {
          log.debug("Skipped offsets till : "
              + message.offset());
          break;
        }
      }
      log.debug("Number of offsets to be skipped: " + skipped);
      while(skipped !=0 )
      {
        MessageAndOffset skippedMessage = messageIter.next();
        log.debug("Skipping offset : " + skippedMessage.offset());
        skipped --;
      }

      if (!messageIter.hasNext()) {
        System.out
            .println("No more data left to process. Returning false");
        messageIter = null;
        return false;
      }

      return true;
    }
  } catch (Exception e) {
    log.info("Exception generated during fetch");
    e.printStackTrace();
    return false;
  }

}
 

@Override
public List<MessageAndOffset> read(long offset) throws StageException {

  FetchRequest req = buildFetchRequest(offset);
  FetchResponse fetchResponse;
  try {
    fetchResponse = consumer.fetch(req);
  } catch (Exception e) {
    if(e instanceof SocketTimeoutException) {
      //If the value of consumer.timeout.ms is set to a positive integer, a timeout exception is thrown to the
      //consumer if no message is available for consumption after the specified timeout value.
      //If this happens exit gracefully
      LOG.warn(KafkaErrors.KAFKA_28.getMessage());
      return Collections.emptyList();
    } else {
      throw new StageException(KafkaErrors.KAFKA_29, e.toString(), e);
    }
  }

  if(fetchResponse.hasError()) {
    short code = fetchResponse.errorCode(topic, partition);
    if(code == ErrorMapping.OffsetOutOfRangeCode()) {
      //invalid offset
      offset = getLastOffset(consumer, topic, partition, kafka.api.OffsetRequest.LatestTime(), clientName);
    } else {
      //try re-initializing connection with kafka
      consumer.close();
      consumer = null;
      leader = findNewLeader(leader, topic, partition);
    }

    //re-fetch
    req = buildFetchRequest(offset);
    fetchResponse = consumer.fetch(req);

    if(fetchResponse.hasError()) {
      //could not fetch the second time, give kafka some time
      LOG.error(KafkaErrors.KAFKA_26.getMessage(), topic, partition, offset);
    }
  }

  List<MessageAndOffset> partitionToPayloadMapArrayList = new ArrayList<>();
  for (kafka.message.MessageAndOffset messageAndOffset : fetchResponse.messageSet(topic, partition)) {
    long currentOffset = messageAndOffset.offset();
    if (currentOffset < offset) {
      LOG.warn(KafkaErrors.KAFKA_27.getMessage(), currentOffset, offset);
      continue;
    }
    ByteBuffer payload = messageAndOffset.message().payload();
    final Object key = messageAndOffset.message().key();
    byte[] bytes = new byte[payload.limit()];
    payload.get(bytes);
    MessageAndOffset partitionToPayloadMap = new MessageAndOffset(
        key,
        bytes,
        messageAndOffset.nextOffset(),
        partition
    );
    partitionToPayloadMapArrayList.add(partitionToPayloadMap);
  }
  return partitionToPayloadMapArrayList;
}
 

@Override
public List<MessageAndOffset> read(long offset) throws StageException {

  FetchRequest req = buildFetchRequest(offset);
  FetchResponse fetchResponse;
  try {
    fetchResponse = consumer.fetch(req);
  } catch (Exception e) {
    if(e instanceof SocketTimeoutException) {
      //If the value of consumer.timeout.ms is set to a positive integer, a timeout exception is thrown to the
      //consumer if no message is available for consumption after the specified timeout value.
      //If this happens exit gracefully
      LOG.warn(KafkaErrors.KAFKA_28.getMessage());
      return Collections.emptyList();
    } else {
      throw new StageException(KafkaErrors.KAFKA_29, e.toString(), e);
    }
  }

  if(fetchResponse.hasError()) {
    short code = fetchResponse.errorCode(topic, partition);
    if(code == ErrorMapping.OffsetOutOfRangeCode()) {
      //invalid offset
      offset = getLastOffset(consumer, topic, partition, kafka.api.OffsetRequest.LatestTime(), clientName);
    } else {
      //try re-initializing connection with kafka
      consumer.close();
      consumer = null;
      leader = findNewLeader(leader, topic, partition);
    }

    //re-fetch
    req = buildFetchRequest(offset);
    fetchResponse = consumer.fetch(req);

    if(fetchResponse.hasError()) {
      //could not fetch the second time, give kafka some time
      LOG.error(KafkaErrors.KAFKA_26.getMessage(), topic, partition, offset);
    }
  }

  List<MessageAndOffset> partitionToPayloadMapArrayList = new ArrayList<>();
  for (kafka.message.MessageAndOffset messageAndOffset : fetchResponse.messageSet(topic, partition)) {
    long currentOffset = messageAndOffset.offset();
    if (currentOffset < offset) {
      LOG.warn(KafkaErrors.KAFKA_27.getMessage(), currentOffset, offset);
      continue;
    }
    ByteBuffer payload = messageAndOffset.message().payload();
    final Object key = messageAndOffset.message().key();
    byte[] bytes = new byte[payload.limit()];
    payload.get(bytes);
    MessageAndOffset partitionToPayloadMap = new MessageAndOffset(
        key,
        bytes,
        messageAndOffset.nextOffset(),
        partition
    );
    partitionToPayloadMapArrayList.add(partitionToPayloadMap);
  }
  return partitionToPayloadMapArrayList;
}
 

private Message getMessage(TopicPartition topicPartition, long offset,
                           SimpleConsumer consumer) {
    LOG.debug("fetching message topic {} partition {} offset {}",
            topicPartition.getTopic(), topicPartition.getPartition(), offset);
    final int MAX_MESSAGE_SIZE_BYTES = mConfig.getMaxMessageSizeBytes();
    final String clientName = getClientName(topicPartition);
    kafka.api.FetchRequest request = new FetchRequestBuilder().clientId(clientName)
            .addFetch(topicPartition.getTopic(), topicPartition.getPartition(), offset,
                      MAX_MESSAGE_SIZE_BYTES)
            .build();
    FetchResponse response = consumer.fetch(request);
    if (response.hasError()) {
        consumer.close();
        int errorCode = response.errorCode(topicPartition.getTopic(), topicPartition.getPartition());

        if (errorCode == Errors.OFFSET_OUT_OF_RANGE.code()) {
          throw new MessageDoesNotExistException();
        } else {
          throw new RuntimeException("Error fetching offset data. Reason: " + errorCode);
        }
    }
    MessageAndOffset messageAndOffset = response.messageSet(
            topicPartition.getTopic(), topicPartition.getPartition()).iterator().next();
    byte[] keyBytes = null;
    if (messageAndOffset.message().hasKey()) {
        ByteBuffer key = messageAndOffset.message().key();
        keyBytes = new byte[key.limit()];
        key.get(keyBytes);
    }
    byte[] payloadBytes = null;
    if (!messageAndOffset.message().isNull()) {
        ByteBuffer payload = messageAndOffset.message().payload();
        payloadBytes = new byte[payload.limit()];
        payload.get(payloadBytes);
    }
    long timestamp = (mConfig.useKafkaTimestamp())
            ? mKafkaMessageTimestampFactory.getKafkaMessageTimestamp().getTimestamp(messageAndOffset)
            : 0l;

    return new Message(topicPartition.getTopic(), topicPartition.getPartition(),
            messageAndOffset.offset(), keyBytes, payloadBytes, timestamp, null);
}
 

private static void consumeMessage(Arguments arguments) {

        Properties properties = new Properties();
        properties.put(SimpleConsumer.HTTP_SERVICE_URL, arguments.httpServiceUrl);
        SimpleConsumer consumer = new SimpleConsumer(arguments.serviceUrl, 0, 0, 0, "clientId", properties);

        long readOffset = kafka.api.OffsetRequest.EarliestTime();
        kafka.api.FetchRequest fReq = new FetchRequestBuilder().clientId("c1")
                .addFetch(arguments.topicName, arguments.partitionIndex, readOffset, 100000).build();
        FetchResponse fetchResponse = consumer.fetch(fReq);

        TestDecoder decoder = new TestDecoder();
        int count = 0;
        while (count < arguments.totalMessages || arguments.totalMessages == -1) {
            // 1. Read from topic without subscription/consumer-group name.
            for (MessageAndOffset messageAndOffset : fetchResponse.messageSet(arguments.topicName,
                    arguments.partitionIndex)) {
                MessageId msgIdOffset = (messageAndOffset instanceof PulsarMsgAndOffset)
                        ? ((PulsarMsgAndOffset) messageAndOffset).getFullOffset()
                        : null;
                long currentOffset = messageAndOffset.offset();
                if (currentOffset < readOffset) {
                    continue;
                }

                ByteBuffer payload = messageAndOffset.message().payload();

                byte[] bytes = new byte[payload.limit()];
                payload.get(bytes);
                Tweet tweet = decoder.fromBytes(bytes);
                log.info("Received tweet: {}-{}", tweet.userName, tweet.message);
                count++;

                TopicAndPartition topicPartition = new TopicAndPartition(arguments.topicName, arguments.partitionIndex);
                OffsetMetadataAndError offsetError = new OffsetMetadataAndError(msgIdOffset, null, (short) 0);
                Map<TopicAndPartition, OffsetMetadataAndError> requestInfo = Collections.singletonMap(topicPartition,
                        offsetError);
                // 2. Commit offset for a given topic and subscription-name/consumer-name.
                OffsetCommitRequest offsetReq = new OffsetCommitRequest(arguments.groupName, requestInfo, (short) -1, 0,
                        "c1");
                consumer.commitOffsets(offsetReq);
            }
        }

        consumer.close();
    }
 

@Override
public FetchResponse fetch(kafka.javaapi.FetchRequest request) {
  throw new RuntimeException("Unimplemented");
}
 

@Test
public void testDefaultParameters() throws IOException {
    TopicCommand.createTopic(zk.getZkClient(),
            new TopicCommand.TopicCommandOptions(new String[]{
                    "--zookeeper", "dummy", "--create", "--topic", TOPIC_NAME,
                    "--replication-factor", "2", "--partitions", "1"}));
    String description = "{\n" +
            "    \"type\": \"kafka\",\n" +
            "    \"client.id\": \"kafkasink\",\n" +
            "    \"bootstrap.servers\": \"" + kafkaServer.getBrokerListStr() + "\",\n" +
            "    \"acks\": 1\n" +
            "}";


    KafkaSink sink = jsonMapper.readValue(description, new TypeReference<Sink>(){});
    sink.open();
    Iterator<Message> msgIterator = new MessageSetReader(createMessageSet(TOPIC_NAME, 2)).iterator();
    while (msgIterator.hasNext()) {
        sink.writeTo(new StringMessage(msgIterator.next()));
    }
    assertTrue(sink.getNumOfPendingMessages() > 0);
    sink.close();
    assertEquals(sink.getNumOfPendingMessages(), 0);
    System.out.println(sink.getStat());

    // get the leader
    Option<Object> leaderOpt = ZkUtils.getLeaderForPartition(zk.getZkClient(), TOPIC_NAME, 0);
    assertTrue("Leader for topic new-topic partition 0 should exist", leaderOpt.isDefined());
    int leader = (Integer) leaderOpt.get();

    KafkaConfig config;
    if (leader == kafkaServer.getServer(0).config().brokerId()) {
        config = kafkaServer.getServer(0).config();
    } else {
        config = kafkaServer.getServer(1).config();
    }
    SimpleConsumer consumer = new SimpleConsumer(config.hostName(), config.port(), 100000, 100000, "clientId");
    FetchResponse response = consumer.fetch(new FetchRequestBuilder().addFetch(TOPIC_NAME, 0, 0, 100000).build());

    List<MessageAndOffset> messageSet = Lists.newArrayList(response.messageSet(TOPIC_NAME, 0).iterator());
    assertEquals("Should have fetched 2 messages", 2, messageSet.size());

    assertEquals(new String(extractMessage(messageSet, 0)), "testMessage" + 0);
    assertEquals(new String(extractMessage(messageSet, 1)), "testMessage" + 1);
}
 

@Test
public void testDefaultParameters() throws IOException {
    TopicCommand.createTopic(zk.getZkClient(),
            new TopicCommand.TopicCommandOptions(new String[]{
                    "--zookeeper", "dummy", "--create", "--topic", TOPIC_NAME,
                    "--replication-factor", "2", "--partitions", "1"}));
    String description = "{\n" +
            "    \"type\": \"kafka\",\n" +
            "    \"client.id\": \"kafkasink\",\n" +
            "    \"metadata.broker.list\": \"" + kafkaServer.getBrokerListStr() + "\",\n" +
            "    \"request.required.acks\": 1\n" +
            "}";

    ObjectMapper jsonMapper = new DefaultObjectMapper();
    jsonMapper.registerSubtypes(new NamedType(KafkaSinkV2.class, "kafka"));
    KafkaSinkV2 sink = jsonMapper.readValue(description, new TypeReference<Sink>(){});
    sink.open();
    // create send test messages to Kafka
    Iterator<Message> msgIterator = new MessageSetReader(createMessageSet(TOPIC_NAME, 2)).iterator();
    HashSet<String> sentPayloads = new HashSet<String>(); // track sent messages for comparison later
    while (msgIterator.hasNext()) {
        StringMessage next = new StringMessage(msgIterator.next());
        sink.writeTo(next); // send
        sentPayloads.add( new String( next.getMessage().getPayload() ) ); // record
    }
    sink.close();
    assertEquals(sink.getNumOfPendingMessages(), 0);
    System.out.println(sink.getStat());

    // get the leader
    Option<Object> leaderOpt = ZkUtils.getLeaderForPartition(zk.getZkClient(), TOPIC_NAME, 0);
    assertTrue("Leader for topic new-topic partition 0 should exist", leaderOpt.isDefined());
    int leader = (Integer) leaderOpt.get();

    KafkaConfig config;
    if (leader == kafkaServer.getServer(0).config().brokerId()) {
        config = kafkaServer.getServer(0).config();
    } else {
        config = kafkaServer.getServer(1).config();
    }
    // get data back from Kafka
    SimpleConsumer consumer = new SimpleConsumer(config.hostName(), config.port(), 100000, 100000, "clientId");
    FetchResponse response = consumer.fetch(new FetchRequestBuilder().addFetch(TOPIC_NAME, 0, 0, 100000).build());

    List<MessageAndOffset> messageSet = Lists.newArrayList(response.messageSet(TOPIC_NAME, 0).iterator());
    assertEquals("Should have fetched 2 messages", 2, messageSet.size());

    for( int i=0; i<messageSet.size(); i++ ){
        // ensure that received message was one that was sent
        String receivedPayload = new String(extractMessage(messageSet, i));
        System.out.println( "Got message: " + new String( receivedPayload ) );
        assert( sentPayloads.remove( receivedPayload ) );
    }
    assertEquals(sentPayloads.size(), 0); // all sent messages should have been received
}
 

public ByteBufferMessageSet fetchMessages(int partition, long offset) throws IOException {

        String topic = config.topic;
        FetchRequest req = new FetchRequestBuilder().clientId(config.clientId).addFetch(topic, partition, offset, config.fetchMaxBytes)
                .maxWait(config.fetchWaitMaxMs).build();
        FetchResponse fetchResponse = null;
        SimpleConsumer simpleConsumer = null;
        try {
            simpleConsumer = findLeaderConsumer(partition);
            if (simpleConsumer == null) {
                // LOG.error(message);
                return null;
            }
            fetchResponse = simpleConsumer.fetch(req);
        } catch (Exception e) {
            if (e instanceof ConnectException || e instanceof SocketTimeoutException || e instanceof IOException
                    || e instanceof UnresolvedAddressException) {
                LOG.warn("Network error when fetching messages:", e);
                if (simpleConsumer != null) {
                    String host = simpleConsumer.host();
                    int port = simpleConsumer.port();
                    simpleConsumer = null;
                    throw new KafkaException("Network error when fetching messages: " + host + ":" + port + " , " + e.getMessage(), e);
                }

            } else {
                throw new RuntimeException(e);
            }
        }
        if (fetchResponse.hasError()) {
            short code = fetchResponse.errorCode(topic, partition);
            if (code == ErrorMapping.OffsetOutOfRangeCode() && config.resetOffsetIfOutOfRange) {
                long startOffset = getOffset(topic, partition, config.startOffsetTime);
                offset = startOffset;
            }
            if(leaderBroker != null) {
                LOG.error("fetch data from kafka topic[" + config.topic + "] host[" + leaderBroker.host() + ":" + leaderBroker.port() + "] partition["
                    + partition + "] error:" + code);
            }else {
                
            }
            return null;
        } else {
            ByteBufferMessageSet msgs = fetchResponse.messageSet(topic, partition);
            return msgs;
        }
    }