Package org.apache.nifi.distributed.cache.client

Interface AtomicDistributedMapCacheClient<R>

Type Parameters:

R - The revision type. If the underlying cache storage supports the concept of revision to implement optimistic locking, then a client implementation should use that. Otherwise set the cached value and check if the key is not updated at replace(AtomicCacheEntry, Serializer, Serializer)

All Superinterfaces:

org.apache.nifi.components.ConfigurableComponent, org.apache.nifi.controller.ControllerService, DistributedMapCacheClient

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

Method Summary

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

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

getIdentifier, getPropertyDescriptor, getPropertyDescriptors, onPropertyModified, validate

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

initialize, isStateful, migrateProperties

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

close, containsKey, get, getAndPutIfAbsent, keySet, put, putAll, putIfAbsent, remove, removeAndGet, subMap

Method Details

fetch

<K,
V> AtomicCacheEntry<K,V,R> 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(AtomicCacheEntry<K,V,R> entry,
 Serializer<K> keySerializer,
 Serializer<V> valueSerializer)
                throws IOException

Replace an existing key with new value.

Type Parameters:

K - the key type

V - the value type

Parameters:

entry - should provide the new value for AtomicCacheEntry.getValue(), and the same revision in the cache storage for AtomicCacheEntry.getRevision(), if the revision does not match with the one in the cache storage, value will not be replaced.

keySerializer - key serializer

valueSerializer - value serializer

Returns:

true only if the key is replaced.

Throws:

IOException - if unable to communicate with the remote instance