org.apache.nifi.distributed.cache.client

Interface AtomicDistributedMapCacheClient

All Superinterfaces:

ConfigurableComponent, ControllerService, DistributedMapCacheClient

@Tags(value={"distributed","client","cluster","map","cache"})
 @CapabilityDescription(value="Provides the ability to communicate with a DistributedMapCacheServer. This allows multiple nodes to coordinate state with a single remote entity.")
public interface AtomicDistributedMapCacheClient
extends DistributedMapCacheClient

This interface defines an API that can be used for interacting with a Distributed Cache that functions similarly to a Map.

In addition to the API defined in DistributedMapCacheClient super class, this class provides methods for concurrent atomic updates those are added since Map Cache protocol version 2.

If a remote cache server doesn't support Map Cache protocol version 2, these methods throw UnsupportedOperationException.

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static interface	AtomicDistributedMapCacheClient.CacheEntry<K,V>

Method Summary

Modifier and Type	Method and Description
<K,V> AtomicDistributedMapCacheClient.CacheEntry<K,V>	fetch(K key, Serializer<K> keySerializer, Deserializer<V> valueDeserializer) Fetch a CacheEntry with a key.
<K,V> boolean	replace(K key, V value, Serializer<K> keySerializer, Serializer<V> valueSerializer, long revision) Replace an existing key with new value.

Methods inherited from interface org.apache.nifi.distributed.cache.client.DistributedMapCacheClient

close, containsKey, get, getAndPutIfAbsent, put, putIfAbsent, remove, removeByPattern

Methods inherited from interface org.apache.nifi.controller.ControllerService

initialize

Methods inherited from interface org.apache.nifi.components.ConfigurableComponent

getIdentifier, getPropertyDescriptor, getPropertyDescriptors, onPropertyModified, validate

Method Detail

fetch

<K,V> AtomicDistributedMapCacheClient.CacheEntry<K,V> fetch(K key,
                                                            Serializer<K> keySerializer,
                                                            Deserializer<V> valueDeserializer)
                                                     throws IOException

Fetch a CacheEntry with a key.

Type Parameters:

K - the key type

V - the value type

Parameters:

key - the key to lookup in the map

keySerializer - key serializer

valueDeserializer - value deserializer

Returns:

A CacheEntry instance if one exists, otherwise null.

Throws:

IOException - if unable to communicate with the remote instance

replace

<K,V> boolean replace(K key,
                      V value,
                      Serializer<K> keySerializer,
                      Serializer<V> valueSerializer,
                      long revision)
               throws IOException

Replace an existing key with new value.

Type Parameters:

K - the key type

V - the value type

Parameters:

key - the key to replace

value - the new value for the key

keySerializer - key serializer

valueSerializer - value serializer

revision - a revision that was retrieved by a preceding fetch operation, if the key is already updated by other client, this doesn't match with the one on server, therefore the replace operation will not be performed. If there's no existing entry for the key, any revision can replace the key.

Returns:

true only if the key is replaced.

Throws:

IOException - if unable to communicate with the remote instance