org.apache.beam.sdk.state

Interface GroupingState<InputT,OutputT>

Type Parameters:

InputT - the type of values added to the state

OutputT - the type of value extracted from the state

All Superinterfaces:

ReadableState<OutputT>, State

All Known Subinterfaces:

BagState<T>, CombiningState<InputT,AccumT,OutputT>, SetState<T>, WatermarkHoldState

@Experimental(value=STATE)
public interface GroupingState<InputT,OutputT>
extends ReadableState<OutputT>, State

A ReadableState cell that combines multiple input values and outputs a single value of a different type.

This generalizes GroupByKey and Combine styles of grouping.

Method Summary

Modifier and Type	Method and Description
void	add(InputT value) Add a value to the buffer.
ReadableState<java.lang.Boolean>	isEmpty() Returns a ReadableState whose ReadableState.read() method will return true if this state is empty at the point when that ReadableState.read() call returns.
GroupingState<InputT,OutputT>	readLater() Indicate that the value will be read later.

Methods inherited from interface org.apache.beam.sdk.state.ReadableState

read

Methods inherited from interface org.apache.beam.sdk.state.State

clear

Method Detail

add

void add(InputT value)

Add a value to the buffer.

Elements added will not be reflected in OutputT objects returned by previous calls to ReadableState.read().

isEmpty

ReadableState<java.lang.Boolean> isEmpty()

Returns a ReadableState whose ReadableState.read() method will return true if this state is empty at the point when that ReadableState.read() call returns.

readLater

GroupingState<InputT,OutputT> readLater()

Description copied from interface: ReadableState

Indicate that the value will be read later.

This allows an implementation to start an asynchronous prefetch or to include this state in the next batch of reads.

Specified by:

readLater in interface ReadableState<OutputT>

Returns:

this for convenient chaining