PessimisticPermitAcquisition.java

final static String KEY_PREFIX = "gatekeeper";

ConcurrentMap definitionMap = hazelcast.getMap(KEY_PREFIX + ".semaphoreDefinitions");
ConcurrentMap permitMap = hazelcast.getMap(KEY_PREFIX + ".semaphorePermits");
Lock gatekeeperLock = hazelcast.getLock(KEY_PREFIX + ".lock");

if (gatekeeperLock.tryLock(LOCK_WAIT_PERIOD, TimeUnit.SECONDS)) {

 try {
  // Logic:
  //  - Lookup the definition
  //  - Check the group and acquirer pattern
  //  - Check for an available permit
  //  - Issue the permit
 }
 finally {
  if (gatekeeperLock != null) {
    gatekeeperLock.unlock();
  }
 }
}