1.3. The AdvancedCache Interface

Red Hat JBoss Data Grid offers an AdvancedCache interface, geared towards extending JBoss Data Grid, in addition to its simple Cache Interface. The AdvancedCache Interface can:
  • Inject custom interceptors
  • Access certain internal components
  • Apply flags to alter the behavior of certain cache methods
The following code snippet presents an example of how to obtain an AdvancedCache: 
AdvancedCache advancedCache = cache.getAdvancedCache();
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1.3.1. Flag Usage with the AdvancedCache Interface

Flags, when applied to certain cache methods in Red Hat JBoss Data Grid, alter the behavior of the target method. Use AdvancedCache.withFlags() to apply any number of flags to a cache invocation.

Example 1.3. Applying Flags to a Cache Invocation

advancedCache.withFlags(Flag.CACHE_MODE_LOCAL, Flag.SKIP_LOCKING)
   .withFlags(Flag.FORCE_SYNCHRONOUS)
   .put("hello", "world");
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1.3.2. Custom Interceptors and the AdvancedCache Interface

The AdvancedCache Interface provides a mechanism that allows advanced developers to attach custom interceptors. Custom interceptors can alter the behavior of the Cache API methods and the AdvacedCache Interface can be used to attach such interceptors programmatically at run time.
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1.3.3. Limitations of Map Methods

Specific Map methods, such as size(), values(), keySet() and entrySet(), can be used with certain limitations with Red Hat JBoss Data Grid as they are unreliable. These methods do not acquire locks (global or local) and concurrent modification, additions and removals are excluded from consideration in these calls.
The listed methods have a significant impact on performance. As a result, it is recommended that these methods are used for informational and debugging purposes only.
Performance Concerns

In JBoss Data Grid 7.0 the map methods size(), values(), keySet(), and entrySet() include entries in the cache loader by default. The cache loader in use will determine the performance of these commands; for instance, when using a database these methods will run a complete scan of the table where data is stored, which may result in slower processing. To not load entries from the cache loader, and avoid any potential performance hit, use Cache.getAdvancedCache().withFlags(Flag.SKIP_CACHE_LOAD) before executing the desired method.

Understanding the size() Method (Embedded Caches)

In JBoss Data Grid 7.0 the Cache.size() method provides a count of all elements in both this cache and cache loader across the entire cluster. When using a loader or remote entries, only a subset of entries is held in memory at any given time to prevent possible memory issues, and the loading of all entries may be slow.

In this mode of operation, the result returned by the size() method is affected by the flags org.infinispan.context.Flag#CACHE_MODE_LOCAL, to force it to return the number of entries present on the local node, and org.infinispan.context.Flag#SKIP_CACHE_LOAD, to ignore any passivated entries. Either of these flags may be used to increase performance of this method, at the cost of not returning a count of all elements across the entire cluster.
Understanding the size() Method (Remote Caches)

In JBoss Data Grid 7.0 the Hot Rod protocol contain a dedicated SIZE operation, and the clients use this operation to calculate the size of all entries.

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1.3.4. Custom Interceptors

Custom interceptors can be added to Red Hat JBoss Data Grid declaratively or programmatically. Custom interceptors extend JBoss Data Grid by allowing it to influence or respond to cache modifications. Examples of such cache modifications are the addition, removal or updating of elements or transactions.

Warning

Support for custom interceptors is being deprecated in JBoss Data Grid 7.0. A new method of executing custom interceptors is expected to be introduced in JBoss Data Grid 7.1. In addition, the interceptor stack is part of JBoss Data Grid's internal API, and is subject to change from release to release. Due to this it is not recommended to use custom interceptors directly from your application.
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1.3.4.1. Custom Interceptor Design

To design a custom interceptor in Red Hat JBoss Data Grid, adhere to the following guidelines:
  • A custom interceptor must extend the CommandInterceptor.
  • A custom interceptor must declare a public, empty constructor to allow for instantiation.
  • A custom interceptor must have JavaBean style setters defined for any property that is defined through the property element.
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1.3.4.2. Adding Custom Interceptors Programmatically

To add a custom interceptor programmatically in Red Hat JBoss Data Grid, first obtain a reference to the AdvancedCache.

Example 1.4. Obtain a Reference to the AdvancedCache

CacheManager cm = getCacheManager();
Cache aCache = cm.getCache("aName");
AdvancedCache advCache = aCache.getAdvancedCache();
Then use an addInterceptor() method to add the interceptor.

Example 1.5. Add the Interceptor

advCache.addInterceptor(new MyInterceptor(), 0);
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