Package org.apache.storm.topology

Class BaseStatefulBoltExecutor

java.lang.Object

org.apache.storm.topology.BaseStatefulBoltExecutor

All Implemented Interfaces:

Serializable, IBolt, IComponent, IRichBolt

Direct Known Subclasses:

CheckpointTupleForwarder, StatefulBoltExecutor

public abstract class BaseStatefulBoltExecutor
extends Object
implements IRichBolt

Base class that abstracts the common logic for executing bolts in a stateful topology.

See Also:

• Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
protected static class	BaseStatefulBoltExecutor.AnchoringOutputCollector

Field Summary

Fields

Modifier and Type	Field	Description
protected OutputCollector	collector

Constructor Summary

Constructors

Constructor	Description
BaseStatefulBoltExecutor()

Method Summary

Modifier and Type	Method	Description
protected void	declareCheckpointStream(OutputFieldsDeclarer declarer)
void	execute(Tuple input)	Process a single tuple of input.
protected abstract void	handleCheckpoint(Tuple checkpointTuple, CheckPointState.Action action, long txid)	Sub-classes can implement the logic for handling checkpoint tuple.
protected abstract void	handleTuple(Tuple input)	Sub-classes can implement the logic for handling the tuple.
protected void	init(TopologyContext context, OutputCollector collector)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface org.apache.storm.task.IBolt

cleanup, prepare

Methods inherited from interface org.apache.storm.topology.IComponent

declareOutputFields, getComponentConfiguration

Field Details

collector

protected OutputCollector collector

Constructor Details

BaseStatefulBoltExecutor

public BaseStatefulBoltExecutor()

Method Details

init

protected void init(TopologyContext context,
 OutputCollector collector)

execute

public void execute(Tuple input)

Description copied from interface: IBolt

Process a single tuple of input. The Tuple object contains metadata on it about which component/stream/task it came from. The values of the Tuple can be accessed using Tuple#getValue. The IBolt does not have to process the Tuple immediately. It is perfectly fine to hang onto a tuple and process it later (for instance, to do an aggregation or join).

Tuples should be emitted using the OutputCollector provided through the prepare method. It is required that all input tuples are acked or failed at some point using the OutputCollector. Otherwise, Storm will be unable to determine when tuples coming off the spouts have been completed.

For the common case of acking an input tuple at the end of the execute method, see IBasicBolt which automates this.

Specified by:

execute in interface IBolt

Parameters:

input - The input tuple to be processed.

declareCheckpointStream

protected void declareCheckpointStream(OutputFieldsDeclarer declarer)

handleTuple

protected abstract void handleTuple(Tuple input)

Sub-classes can implement the logic for handling the tuple.

Parameters:

input - the input tuple

handleCheckpoint

protected abstract void handleCheckpoint(Tuple checkpointTuple,
 CheckPointState.Action action,
 long txid)

Sub-classes can implement the logic for handling checkpoint tuple.

Parameters:

checkpointTuple - the checkpoint tuple

action - the action (prepare, commit, rollback or initstate)

txid - the transaction id.