multimapcache.adoc

Multimap Cache

Infinispan Multimap Cache is a new distributed and clustered collection type introduced in Infinispan 9. MutimapCache is a type of Infinispan Cache that maps keys to values in which each key can contain multiple values.

Installation and configuration

pom.xml

<dependency>
   <groupId>org.infinispan</groupId>
   <artifactId>infinispan-multimap</artifactId>
   <version>...</version> <!-- 9.2.0.Final or higher -->
</dependency>

MultimapCache API

MultimapCache API exposes several methods to interact with the Multimap Cache. All these methods are non-blocking in most of the cases. See [limitations]

public interface MultimapCache<K, V> {

   CompletableFuture<Void> put(K key, V value);

   CompletableFuture<Collection<V>> get(K key);

   CompletableFuture<Boolean> remove(K key);

   CompletableFuture<Boolean> remove(K key, V value);

   CompletableFuture<Void> remove(Predicate<? super V> p);

   CompletableFuture<Boolean> containsKey(K key);

   CompletableFuture<Boolean> containsValue(V value);

   CompletableFuture<Boolean> containsEntry(K key, V value);

   CompletableFuture<Long> size();

   boolean supportsDuplicates();

}

CompletableFuture<Void> put(K key, V value)

Puts a key-value pair in the multimap cache.

MultimapCache<String, String> multimapCache = ...;

multimapCache.put("girlNames", "marie")
             .thenCompose(r1 -> multimapCache.put("girlNames", "oihana"))
             .thenCompose(r3 -> multimapCache.get("girlNames"))
             .thenAccept(names -> {
                          if(names.contains("marie"))
                              System.out.println("Marie is a girl name");

                           if(names.contains("oihana"))
                               System.out.println("Oihana is a girl name");
                        });

The output of this code is :

Marie is a girl name
Oihana is a girl name

CompletableFuture<Collection<V>> get(K key)

Returns a view collection of the values associated with key in this multimap cache, if any. Any changes to the retrieved collection won’t change the values in this multimap cache. When this method returns an empty collection, it means the key was not found.

CompletableFuture<Boolean> remove(K key)

Removes the entry associated with the key from the multimap cache, if such exists.

CompletableFuture<Boolean> remove(K key, V value)

Removes a key-value pair from the multimap cache, if such exists.

CompletableFuture<Void> remove(Predicate<? super V> p)

CompletableFuture<Boolean> containsKey(K key)

CompletableFuture<Boolean> containsValue(V value)

CompletableFuture<Boolean> containsEntry(K key, V value)

CompletableFuture<Long> size()

Returns the number of key-value pairs in the multimap cache. It doesn’t return the distinct number of keys.

boolean supportsDuplicates()

Creating a Multimap Cache

In version 9.2, the MultimapCache is configured as a regular cache. This can be done either by code or XML configuration. See how to configure a regular Cache in the section link to [configure a cache].

Embedded mode

// create or obtain your EmbeddedCacheManager
EmbeddedCacheManager cm = ... ;

// create or obtain a MultimapCache passing the name, the cache manager and the configuration
MultimapCache multimapCache = EmbeddedMultimapCacheManagerFactory.get("test", cm, c.build());

Server mode

TODO

Limitations

In almost every case the Multimap Cache will behave as a regular Cache, but some limitations exist in the first 9.2 version.

Support for duplicates

Duplicates are not supported yet. This means that the multimap won’t contain any duplicate key-value pair. Whenever put method is called, if the key-value pair already exist, this key-value par won’t be added. Methods used to check if a key-value pair is already present in the Multimap are the equals and hashcode.

Eviction

For now, the eviction works per key, and not per key-value pair. This means that whenever a key is evicted, all the values associated with the key will be evicted too. Eviction per key-value could be supported in the future.

Transactions

Implicit transactions are supported through the auto-commit and all the methods are non blocking. Explicit transactions work without blocking in most of the cases. Methods that will block are size, containsEntry and remove(Predicate<? super V> p)