co.cask.cdap.data2.transaction.stream

Interface StreamConsumer

All Superinterfaces:

AutoCloseable, Closeable, co.cask.tephra.TransactionAware

All Known Implementing Classes:

AbstractStreamFileConsumer, ForwardingStreamConsumer, HBaseStreamFileConsumer, LevelDBStreamFileConsumer, QueueToStreamConsumer

public interface StreamConsumer
extends Closeable, co.cask.tephra.TransactionAware

Represents a transaction stream consumer. On each call to poll(int, long, java.util.concurrent.TimeUnit), it will try ro read from stream starting from where it get initialized with or from what last poll left off. On transaction rollback, all events that are read by poll calls will be reverted so that when poll is issued on a new transaction afterwards, it will start giving stream events from the where last committed poll ended.

Method Summary

Methods

Modifier and Type	Method and Description
ConsumerConfig	getConsumerConfig()
Id.Stream	getStreamId()
DequeueResult<co.cask.cdap.api.flow.flowlet.StreamEvent>	poll(int maxEvents, long timeout, TimeUnit timeoutUnit) Retrieves up to maxEvents of StreamEvent from the stream.

Methods inherited from interface java.io.Closeable

close

Methods inherited from interface co.cask.tephra.TransactionAware

commitTx, getTransactionAwareName, getTxChanges, postTxCommit, rollbackTx, startTx, updateTx

Method Detail

getStreamId

Id.Stream getStreamId()

Returns:

Id of the stream this consumer is consuming.

getConsumerConfig

ConsumerConfig getConsumerConfig()

Returns:

Configuration of this consumer.

poll

DequeueResult<co.cask.cdap.api.flow.flowlet.StreamEvent> poll(int maxEvents,
                                                            long timeout,
                                                            TimeUnit timeoutUnit)
                                                              throws IOException,
                                                                     InterruptedException

Retrieves up to maxEvents of StreamEvent from the stream.

Parameters:

maxEvents - Maximum number of events to retrieve

timeout - Maximum of time to spend on trying to read up to maxEvents

timeoutUnit - Unit for the timeout

Returns:

An instance of DequeueResult which carries StreamEvents inside.

Throws:

IOException - If there is error while reading events

InterruptedException - If interrupted while waiting