com.google.cloud.dataflow.sdk.util.state

Class MergingStateInternals

java.lang.Object

com.google.cloud.dataflow.sdk.util.state.MergingStateInternals

All Implemented Interfaces:

StateInternals

Direct Known Subclasses:

InMemoryStateInternals, WindmillStateInternals

public abstract class MergingStateInternals
extends Object
implements StateInternals

Abstract implementation of StateInternals that provides mergedState(java.lang.Iterable<com.google.cloud.dataflow.sdk.util.state.StateNamespace>, com.google.cloud.dataflow.sdk.util.state.StateNamespace, com.google.cloud.dataflow.sdk.util.state.StateTag<T>) in terms of StateInternals.state(com.google.cloud.dataflow.sdk.util.state.StateNamespace, com.google.cloud.dataflow.sdk.util.state.StateTag<T>).

Constructor Summary

Constructors

Constructor and Description
MergingStateInternals()

Method Summary

Modifier and Type	Method and Description
<T extends MergeableState<?,?>> T	mergedState(Iterable<StateNamespace> sourceNamespaces, StateNamespace resultNamespace, StateTag<T> address) Return state that reads from all the source namespaces.

Methods inherited from class java.lang.Object

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

Methods inherited from interface com.google.cloud.dataflow.sdk.util.state.StateInternals

state

Constructor Detail

MergingStateInternals

public MergingStateInternals()

Method Detail

mergedState

public <T extends MergeableState<?,?>> T mergedState(Iterable<StateNamespace> sourceNamespaces,
                                                     StateNamespace resultNamespace,
                                                     StateTag<T> address)

Description copied from interface: StateInternals

Return state that reads from all the source namespaces. Only required to ensure that resultNamespace contains all the data that is added.

Merging state is potentially destructive, in that it may move information from the sourceNamespaces to resultNamespace. As a result, after calling this all future calls should include as their namespaces a superset of sourceNamespaces and resultNamespace.

Specified by:

mergedState in interface StateInternals