OptimisticPermitAcquisition.java

final static String KEY_PREFIX = "gatekeeper";

ConcurrentMap definitionMap = hazelcast.getMap(KEY_PREFIX + ".semaphoreDefinitions");
ConcurrentMap permitMap = hazelcast.getMap(KEY_PREFIX + ".semaphorePermits");

    // Logic:
    //  - Lookup the definition
    //  - Check the group and acquirer pattern
    //  - Check for an available permit
    //  - Issue the permit

if (!permitMap.replace(semaphoreName, origPermits, updatedPermits)) {
  throw new OptimisticLockingFailureException("Conflict "
    + "while updating semaphore permits.");
}