org.apache.flink.streaming.api.scala.function

Interface StatefulFunction<I,O,S>

All Superinterfaces:

Function, RichFunction, Serializable

public interface StatefulFunction<I,O,S>
extends RichFunction

Trait implementing the functionality necessary to apply stateful functions in RichFunctions without exposing the OperatorStates to the user. The user should call the applyWithState method in his own RichFunction implementation.

Method Summary

Modifier and Type	Method and Description
O	applyWithState(I in, scala.Function2<I,scala.Option<S>,scala.Tuple2<O,scala.Option<S>>> fun)
void	open(Configuration c) Initialization method for the function.
TypeSerializer<S>	stateSerializer()

Methods inherited from interface org.apache.flink.api.common.functions.RichFunction

close, getIterationRuntimeContext, getRuntimeContext, setRuntimeContext

Method Detail

stateSerializer

TypeSerializer<S> stateSerializer()

applyWithState

O applyWithState(I in,
                 scala.Function2<I,scala.Option<S>,scala.Tuple2<O,scala.Option<S>>> fun)

open

void open(Configuration c)

Description copied from interface: RichFunction

Initialization method for the function. It is called before the actual working methods (like map or join) and thus suitable for one time setup work. For functions that are part of an iteration, this method will be invoked at the beginning of each iteration superstep.

The configuration object passed to the function can be used for configuration and initialization. The configuration contains all parameters that were configured on the function in the program composition.

 public class MyMapper extends FilterFunction<String> {
 
     private String searchString;
     
     public void open(Configuration parameters) {
         this.searchString = parameters.getString("foo");
     }
     
     public boolean filter(String value) {
         return value.equals(searchString);
     }
 }
 

By default, this method does nothing.

Specified by:

open in interface RichFunction

Parameters:

c - The configuration containing the parameters attached to the contract.

See Also:

Configuration