Package org.apache.heron.api.topology
Interface IStatefulComponent<K extends Serializable,V extends Serializable>
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- All Superinterfaces:
IComponent
,Serializable
- All Known Subinterfaces:
IStatefulWindowedBolt<K,V>
,ITwoPhaseStatefulComponent<K,V>
- All Known Implementing Classes:
BaseStatefulWindowedBolt
,ComplexSink
,ComplexSource
,StatefulWindowedBoltExecutor
,StreamletSource
,SupplierSource
,TransformOperator
,WindowedBoltExecutor
public interface IStatefulComponent<K extends Serializable,V extends Serializable> extends IComponent
Defines a component that saves its internal state in the State interface
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Method Summary
All Methods Instance Methods Abstract Methods Modifier and Type Method Description void
initState(State<K,V> state)
Initializes the state of the function or operator to that of a previous checkpoint.void
preSave(String checkpointId)
This is a hook for the component to perform some actions just before the framework saves its state.-
Methods inherited from interface org.apache.heron.api.topology.IComponent
declareOutputFields, getComponentConfiguration
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Method Detail
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initState
void initState(State<K,V> state)
Initializes the state of the function or operator to that of a previous checkpoint. This method is invoked when a component is executed as part of a recovery run. In case there was prior state associated with the component, the state will be empty. Stateful Spouts/Bolts are expected to hold on to the state variable to save their internal stateNote that initialState() is called before open() or prepare().
- Parameters:
state
- the previously saved state of the component.
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preSave
void preSave(String checkpointId)
This is a hook for the component to perform some actions just before the framework saves its state.- Parameters:
checkpointId
- the ID of the checkpoint
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