Chapter 29. The Infinispan CDI Module

An Infinispan cache is one of the multiple components that can be injected into the project’s CDI beans.

The following code snippet illustrates how to inject a cache instance into the CDI bean:

public class MyCDIBean {
    @Inject
    Cache<String, String> cache;
}

The code snippet to inject a normal cache is slightly modified to inject a remote Infinispan cache, as follows:

public class MyCDIBean {
    @Inject
    RemoteCache<String, String> remoteCache;
}

A Red Hat JBoss Data Grid Cache Manager (both embedded and remote) can be configured using CDI. Whether configuring an embedded or remote cache manager, the first step is to specify a default configuration that is annotated to act as a producer.

Specify a method annotated as a producer for the Red Hat JBoss Data Grid configuration object to replace the default Infinispan Configuration. The following sample configuration illustrates this step:

public class Config {
    @Produces
    public Configuration defaultEmbeddedConfiguration () {
        return new ConfigurationBuilder()
                         .eviction()
                                 .strategy(EvictionStrategy.LRU)
                                 .maxEntries(100)
                         .build();
    }
}

If a @Produces annotation is placed in a method that returns a Configuration instance, the method is invoked when a Configuration object is required.

In the provided example configuration, the method creates a new Configuration object which is subsequently configured and returned.

public class Config {

    @Produces
    @ApplicationScoped
    public EmbeddedCacheManager defaultEmbeddedCacheManager() {
        Configuration cfg = new ConfigurationBuilder()
                                    .eviction()
                                            .strategy(EvictionStrategy.LRU)
                                            .maxEntries(150)
                                    .build();
        return new DefaultCacheManager(cfg);
    }
}

The @ApplicationScoped annotation specifies that the method is only called once.

public class Config {

	@Produces
	@ApplicationScoped
	public EmbeddedCacheManager defaultClusteredCacheManager() {
		GlobalConfiguration g = new GlobalConfigurationBuilder()
				.clusteredDefault()
				.transport()
				.clusterName("InfinispanCluster")
				.build();
		Configuration cfg = new ConfigurationBuilder()
				.eviction()
				.strategy(EvictionStrategy.LRU)
				.maxEntries(150)
				.build();
		return new DefaultCacheManager(g, cfg);
	}
}

Add an injection as follows in your CDI Bean to invoke the appropriate annotated method. This generates EmbeddedCacheManager and injects it into the code at runtime.

...
@Inject
EmbeddedCacheManager cacheManager;
...

The RemoteCacheManager is configured in a manner similar to EmbeddedCacheManagers, as follows:

public class Config {
	@Produces
	@ApplicationScoped
	public RemoteCacheManager defaultRemoteCacheManager() {
           Configuration conf = new ConfigurationBuilder().addServer().host(ADDRESS).port(PORT).build();
            return new RemoteCacheManager(conf);
	}
}}

A single class can be used to configure multiple cache managers and remote cache managers based on the created qualifiers. An example of this is as follows:

public class Config {
    @Produces
    @ApplicationScoped
    public org.infinispan.manager.EmbeddedCacheManager
    defaultEmbeddedCacheManager() {
        Configuration cfg = new ConfigurationBuilder()
                .eviction()
                .strategy(EvictionStrategy.LRU)
                .maxEntries(150)
                .build();
        return new DefaultCacheManager(cfg);
    }

    @Produces
    @ApplicationScoped
    @DefaultClustered
    public org.infinispan.manager.EmbeddedCacheManager
    defaultClusteredCacheManager() {
        GlobalConfiguration g = new GlobalConfigurationBuilder()
                .clusteredDefault()
                .transport()
                .clusterName("InfinispanCluster")
                .build();
        Configuration cfg = new ConfigurationBuilder()
                .eviction()
                .strategy(EvictionStrategy.LRU)
                .maxEntries(150)
                .build();
        return new DefaultCacheManager(g, cfg);
    }

    @Produces
    @ApplicationScoped
    @DefaultRemote
    public RemoteCacheManager
    defaultRemoteCacheManager() {
        org.infinispan.client.hotrod.configuration.Configuration conf = new org.infinispan.client.hotrod.configuration.ConfigurationBuilder().addServer().host(ADDRESS).port(PORT).build();
        return new RemoteCacheManager(conf);
    }

    @Produces
    @ApplicationScoped
    @RemoteCacheInDifferentDataCentre
    public RemoteCacheManager newRemoteCacheManager() {
        org.infinispan.client.hotrod.configuration.Configuration confid = new org.infinispan.client.hotrod.configuration.ConfigurationBuilder().addServer().host(ADDRESS_FAR_AWAY).port(PORT).build();
        return new RemoteCacheManager(confid);
    }
}

A common practice for time or resource intensive operations is to save the results in a cache for future access. The following code is an example of such an operation:

public String toCelsiusFormatted(float fahrenheit) {
	return
		NumberFormat.getInstance()
		.format((fahrenheit * 5 / 9) - 32)
		+ " degrees Celsius";
}

A common approach is to cache the results of this method call and to check the cache when the result is next required. The following is an example of a code snippet that looks up the result of such an operation in a cache. If the results are not found, the code snippet runs the toCelsiusFormatted method again and stores the result in the cache.

float f = getTemperatureInFahrenheit();
Cache<Float, String>
	fahrenheitToCelsiusCache = getCache();
String celsius =
	fahrenheitToCelsiusCache = get(f);
     if (celsius == null) {
	     celsius = toCelsiusFormatted(f);
	     fahrenheitToCelsiusCache.put(f, celsius);
     }

In such cases, the Infinispan CDI module can be used to eliminate all the extra code in the related examples. Annotate the method with the @CacheResult annotation instead, as follows:

@javax.cache.annotation.CacheResult
public String toCelsiusFormatted(float fahrenheit) {
	return NumberFormat.getInstance()
	.format((fahrenheit * 5 / 9) - 32)
	+ " degrees Celsius";
}

Due to the annotation, Infinispan checks the cache and if the results are not found, it invokes the toCelsiusFormatted() method call.

Add the following optional attribute (cacheName) to the @CacheResult annotation to specify the cache to check for results of the method call:

@CacheResult(cacheName = "mySpecialCache")
public String doSomething(String parameter) {
<!-- Additional configuration information here -->
}

As a default, the @CacheResult annotation creates a key for the results fetched from a cache. The key consists of a combination of all parameters in the relevant method.

Create a custom key using the @CacheKey annotation as follows:

@CacheResult
public String doSomething
	(@CacheKey String p1,
	@CacheKey String p2,
	String dontCare) {
<!-- Additional configuration information here -->
}

In the specified example, only the values of p1 and p2 are used to create the cache key. The value of dontCare is not used when determining the cache key.

Generate a custom key as follows:

import javax.cache.annotation.CacheKey;
import javax.cache.annotation.CacheKeyGenerator;
import javax.cache.annotation.CacheKeyInvocationContext;
import java.lang.annotation.Annotation;

public class MyCacheKeyGenerator implements CacheKeyGenerator {

   @Override
   public CacheKey generateCacheKey(CacheKeyInvocationContext<? extends Annotation> ctx) {

      return new MyCacheKey(
            ctx.getAllParameters()[0].getValue()
      );
   }
}

The listed method constructs a custom key. This key is passed as part of the value generated by the first parameter of the invocation context.

To specify the custom key generation scheme, add the optional parameter cacheKeyGenerator to the @CacheResult annotation as follows:

@CacheResult(cacheKeyGenerator = MyCacheKeyGenerator.class)
public void doSomething(String p1, String p2) {
<!-- Additional configuration information here -->
}

Using the provided method, p1 contains the custom key.

When the method that contains the @CachePut annotation is invoked, a parameter (normally passed to the method annotated with @CacheValue) is stored in the cache.

import javax.cache.annotation.CachePut;
import javax.cache.annotation.CacheKey;
import javax.cache.annotation.CacheValue;

@CachePut (cacheName = "personCache")
public void updatePerson
	(@CacheKey long personId,
	@CacheValue Person newPerson) {
<!-- Additional configuration information here -->
	}

Further customization is possible using cacheName and cacheKeyGenerator in the @CachePut method. Additionally, some parameters in the invoked method may be annotated with @CacheKey to control key generation.

See Also: Cache keys for Cached Results

The following is an example of a @CacheRemoveEntry annotated method that is used to remove an entry from the cache:

import javax.cache.annotation.CacheRemoveEntry;
import javax.cache.annotation.CacheKey;

@CacheRemoveEntry (cacheName = "cacheOfPeople")
public void changePersonName
	(@CacheKey long personId,
	string newName) {
<!-- Additional configuration information here -->
	}

The annotation accepts the optional cacheName and cacheKeyGenerator attributes.

Invoke the @CacheRemoveAll method to clear all entries from the cache.

import javax.cache.annotation.CacheRemoveAll;

@CacheRemoveAll (cacheName = "statisticsCache")
public void resetStatistics() {
<!-- Additional configuration information here -->
}

As displayed in the example, this annotation accepts an optional cacheName attribute.