org.apache.beam.sdk.state

Interface MapState<K,V>

Type Parameters:

K - the type of keys maintained by this map

V - the type of mapped values

All Superinterfaces:

State

@Experimental(value=STATE)
public interface MapState<K,V>
extends State

A ReadableState cell mapping keys to values.

Implementations of this form of state are expected to implement map operations efficiently as supported by some associated backing key-value store.

Method Summary

Modifier and Type	Method and Description
ReadableState<java.lang.Iterable<java.util.Map.Entry<K,V>>>	entries() Returns an Iterable over the key-value pairs contained in this map.
ReadableState<V>	get(K key) A deferred lookup.
ReadableState<java.lang.Iterable<K>>	keys() Returns an Iterable over the keys contained in this map.
void	put(K key, V value) Associates the specified value with the specified key in this state.
ReadableState<V>	putIfAbsent(K key, V value) A deferred read-followed-by-write.
void	remove(K key) Remove the mapping for a key from this map if it is present.
ReadableState<java.lang.Iterable<V>>	values() Returns an Iterable over the values contained in this map.

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

clear

Method Detail

put

void put(K key,
         V value)

Associates the specified value with the specified key in this state.

putIfAbsent

ReadableState<V> putIfAbsent(K key,
                             V value)

A deferred read-followed-by-write.

When read() is called on the result or state is committed, it forces a read of the map and reconciliation with any pending modifications.

If the specified key is not already associated with a value (or is mapped to null) associates it with the given value and returns null, else returns the current value.

remove

void remove(K key)

Remove the mapping for a key from this map if it is present.

get

ReadableState<V> get(K key)

A deferred lookup.

A user is encouraged to call get for all relevant keys and call readLater() on the results.

When read() is called, a particular state implementation is encouraged to perform all pending reads in a single batch.

keys

ReadableState<java.lang.Iterable<K>> keys()

Returns an Iterable over the keys contained in this map.

values

ReadableState<java.lang.Iterable<V>> values()

Returns an Iterable over the values contained in this map.

entries

ReadableState<java.lang.Iterable<java.util.Map.Entry<K,V>>> entries()

Returns an Iterable over the key-value pairs contained in this map.