Examples with Function1 scala.Function1 used on opensource projects

Example 1 with Function1

use of scala.Function1 in project samza by apache.

the class KafkaSystemAdmin method getSSPMetadata.

/**
 * Given a set of SystemStreamPartition, fetch metadata from Kafka for each
 * of them, and return a map from ssp to SystemStreamPartitionMetadata for
 * each of them. This method will return null for oldest and newest offsets
 * if a given SystemStreamPartition is empty. This method will block and
 * retry indefinitely until it gets a successful response from Kafka.
 * @param ssps a set of strings of SSP
 * @param retryBackoff retry backoff strategy
 * @return a map from ssp to sspMetadata which has offsets
 */
Map<SystemStreamPartition, SystemStreamMetadata.SystemStreamPartitionMetadata> getSSPMetadata(Set<SystemStreamPartition> ssps, ExponentialSleepStrategy retryBackoff) {
    LOG.info("Fetching SSP metadata for: {}", ssps);
    List<TopicPartition> topicPartitions = ssps.stream().map(ssp -> new TopicPartition(ssp.getStream(), ssp.getPartition().getPartitionId())).collect(Collectors.toList());
    Function1<ExponentialSleepStrategy.RetryLoop, Map<SystemStreamPartition, SystemStreamMetadata.SystemStreamPartitionMetadata>> fetchTopicPartitionMetadataOperation = new AbstractFunction1<ExponentialSleepStrategy.RetryLoop, Map<SystemStreamPartition, SystemStreamMetadata.SystemStreamPartitionMetadata>>() {

        @Override
        public Map<SystemStreamPartition, SystemStreamMetadata.SystemStreamPartitionMetadata> apply(ExponentialSleepStrategy.RetryLoop loop) {
            OffsetsMaps topicPartitionsMetadata = fetchTopicPartitionsMetadata(topicPartitions);
            Map<SystemStreamPartition, SystemStreamMetadata.SystemStreamPartitionMetadata> sspToSSPMetadata = new HashMap<>();
            for (SystemStreamPartition ssp : ssps) {
                String oldestOffset = topicPartitionsMetadata.getOldestOffsets().get(ssp);
                String newestOffset = topicPartitionsMetadata.getNewestOffsets().get(ssp);
                String upcomingOffset = topicPartitionsMetadata.getUpcomingOffsets().get(ssp);
                sspToSSPMetadata.put(ssp, new SystemStreamMetadata.SystemStreamPartitionMetadata(oldestOffset, newestOffset, upcomingOffset));
            }
            loop.done();
            return sspToSSPMetadata;
        }
    };
    Function2<Exception, ExponentialSleepStrategy.RetryLoop, BoxedUnit> onExceptionRetryOperation = new AbstractFunction2<Exception, ExponentialSleepStrategy.RetryLoop, BoxedUnit>() {

        @Override
        public BoxedUnit apply(Exception exception, ExponentialSleepStrategy.RetryLoop loop) {
            if (loop.sleepCount() < MAX_RETRIES_ON_EXCEPTION) {
                LOG.warn(String.format("Fetching SSP metadata for: %s threw an exception. Retrying.", ssps), exception);
            } else {
                LOG.error(String.format("Fetching SSP metadata for: %s threw an exception.", ssps), exception);
                loop.done();
                throw new SamzaException(exception);
            }
            return null;
        }
    };
    Function0<Map<SystemStreamPartition, SystemStreamMetadata.SystemStreamPartitionMetadata>> fallbackOperation = new AbstractFunction0<Map<SystemStreamPartition, SystemStreamMetadata.SystemStreamPartitionMetadata>>() {

        @Override
        public Map<SystemStreamPartition, SystemStreamMetadata.SystemStreamPartitionMetadata> apply() {
            throw new SamzaException("Failed to get SSP metadata");
        }
    };
    return retryBackoff.run(fetchTopicPartitionMetadataOperation, onExceptionRetryOperation).getOrElse(fallbackOperation);
}