| package backtype.storm.transactional; |
| |
| import backtype.storm.coordination.BatchOutputCollector; |
| import backtype.storm.task.TopologyContext; |
| import backtype.storm.topology.IComponent; |
| import java.math.BigInteger; |
| import java.util.Map; |
| |
| public interface ITransactionalSpout<T> extends IComponent { |
| public interface Coordinator<X> { |
| /** |
| * Create metadata for this particular transaction id which has never |
| * been emitted before. The metadata should contain whatever is necessary |
| * to be able to replay the exact batch for the transaction at a later point. |
| * |
| * The metadata is stored in Zookeeper. |
| * |
| * Storm uses the Kryo serializations configured in the component configuration |
| * for this spout to serialize and deserialize the metadata. |
| * |
| * @param txid The id of the transaction. |
| * @param prevMetadata The metadata of the previous transaction |
| * @return the metadata for this new transaction |
| */ |
| X initializeTransaction(BigInteger txid, X prevMetadata); |
| |
| /** |
| * 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(); |
| |
| /** |
| * Release any resources from this coordinator. |
| */ |
| void close(); |
| } |
| |
| public interface Emitter<X> { |
| /** |
| * Emit a batch for the specified transaction attempt and metadata for the transaction. The metadata |
| * was created by the Coordinator in the initializeTranaction method. This method must always emit |
| * the same batch of tuples across all tasks for the same transaction id. |
| * |
| * The first field of all emitted tuples must contain the provided TransactionAttempt. |
| * |
| */ |
| void emitBatch(TransactionAttempt tx, X coordinatorMeta, BatchOutputCollector collector); |
| |
| /** |
| * Any state for transactions prior to the provided transaction id can be safely cleaned up, so this |
| * method should clean up that state. |
| */ |
| void cleanupBefore(BigInteger txid); |
| |
| /** |
| * Release any resources held by this emitter. |
| */ |
| void close(); |
| } |
| |
| /** |
| * The coordinator for a TransactionalSpout runs in a single thread and indicates when batches |
| * of tuples should be emitted and when transactions should commit. The Coordinator that you provide |
| * in a TransactionalSpout provides metadata for each transaction so that the transactions can be replayed. |
| */ |
| Coordinator<T> getCoordinator(Map conf, TopologyContext context); |
| |
| /** |
| * The emitter for a TransactionalSpout runs as many tasks across the cluster. Emitters are responsible for |
| * emitting batches of tuples for a transaction and must ensure that the same batch of tuples is always |
| * emitted for the same transaction id. |
| */ |
| Emitter<T> getEmitter(Map conf, TopologyContext context); |
| } |