package backtype.storm.transactional.partitioned;
import backtype.storm.task.TopologyContext;
import backtype.storm.topology.IComponent;
import backtype.storm.transactional.TransactionAttempt;
import backtype.storm.coordination.BatchOutputCollector;
import java.util.Map;
/**
* This interface defines a transactional spout that reads its tuples from a
* partitioned set of brokers. It automates the storing of metadata for each
* partition to ensure that the same batch is always emitted for the same
* transaction id. The partition metadata is stored in Zookeeper.
*/
public interface IPartitionedTransactionalSpout<T> extends IComponent {
public interface Coordinator {
/**
* Return the number of partitions currently in the source of data. The
* idea is is that if a new partition is added and a prior transaction
* is replayed, it doesn't emit tuples for the new partition because it
* knows how many partitions were in that transaction.
*/
int numPartitions();
/**
* Returns true if its ok to emit start a new transaction, false
* otherwise (will skip this transaction).
*
* You should sleep here if you want a delay between asking for the next
* transaction (this will be called repeatedly in a loop).
*/
boolean isReady();
void close();
}
public interface Emitter<X> {
/**
* Emit a batch of tuples for a partition/transaction that's never been
* emitted before. Return the metadata that can be used to reconstruct
* this partition/batch in the future.
*/
X emitPartitionBatchNew(TransactionAttempt tx,
BatchOutputCollector collector, int partition,
X lastPartitionMeta);
/**
* Emit a batch of tuples for a partition/transaction that has been
* emitted before, using the metadata created when it was first emitted.
*/
void emitPartitionBatch(TransactionAttempt tx,
BatchOutputCollector collector, int partition, X partitionMeta);
void close();
}
Coordinator getCoordinator(Map conf, TopologyContext context);
Emitter<T> getEmitter(Map conf, TopologyContext context);
}