GemFire Distributed Types

This is a collection of various Java data types that are backed by GemFire, thus making them naturally distributed and highly available.

The following types are provided

• DList
• DSet
• DBlockingQueue
• DCircularQueue
• DAtomicLong
• DSemaphore
• DAtomicReference
• DCountDownLatch
• DSnowflakeId

Distributed Type instances are created with a DTypeFactory. For example:

 ClientCache client = new ClientCacheFactory()
     .addPoolLocator("localhost", locatorPort)
     .create();

 DTypeFactory factory = new DTypeFactory(client);

 DList<String> list = factory.createDList("myList");
 DSet<Account> accounts = factory.createDSet("accounts");
 DSemaphore semaphore = factory.createDSemaphore("semaphore", 1);
 DBlockingQueue<String> queue = factory.createDQueue("queue", 5);
 DCircularQueue<Requests> queue = factory.createDCircularQueue("requests", 1000);
 

The various types are intended for use from GemFire clients and allow for concurrent and distributed access from clients running in different JVMs. Client structures hold almost no state and most all operations are performed on backend structures that are stored and managed by GemFire.

Note that iteration operations will serialize and retrieve the full structure to the client. Iteration is not performed remotely on the server. Only DList supports removal of elements when iterating.

Operations that take lambdas as arguments need to ensure that the lambda is also declared as Serializable. For example, the method removeIf(Predicate) could be used as:

   // DSet<Integer> set = ....
   set.removeIf((Predicate<Integer> & Serializable) x -> x % 2 == 0);