opendaylight/md-sal/sal-distributed-datastore/src/main/java/org/opendaylight/controller/cluster/datastore/DelayedListenerRegistration.java

   1 /*
   2  * Copyright (c) 2015 Brocade Communications Systems, Inc. and others.  All rights reserved.
   3  *
   4  * This program and the accompanying materials are made available under the
   5  * terms of the Eclipse Public License v1.0 which accompanies this distribution,
   6  * and is available at http://www.eclipse.org/legal/epl-v10.html
   7  */
   8 package org.opendaylight.controller.cluster.datastore;
   9
  10 import java.util.EventListener;
  11 import javax.annotation.concurrent.GuardedBy;
  12 import org.opendaylight.yangtools.concepts.ListenerRegistration;
  13
  14 abstract class DelayedListenerRegistration<L extends EventListener, M> implements ListenerRegistration<L> {
  15     private final M registrationMessage;
  16     private volatile ListenerRegistration<L> delegate;
  17
  18     @GuardedBy("this")
  19     private boolean closed;
  20
  21     protected DelayedListenerRegistration(M registrationMessage) {
  22         this.registrationMessage = registrationMessage;
  23     }
  24
  25     M getRegistrationMessage() {
  26         return registrationMessage;
  27     }
  28
  29     ListenerRegistration<L> getDelegate() {
  30         return delegate;
  31     }
  32
  33     synchronized <R extends ListenerRegistration<L>> void createDelegate(
  34             final LeaderLocalDelegateFactory<M, R> factory) {
  35         if (!closed) {
  36             this.delegate = factory.createDelegate(registrationMessage);
  37         }
  38     }
  39
  40     @Override
  41     public L getInstance() {
  42         final ListenerRegistration<L> d = delegate;
  43         return d == null ? null : (L)d.getInstance();
  44     }
  45
  46     @Override
  47     public synchronized void close() {
  48         if (!closed) {
  49             closed = true;
  50             if (delegate != null) {
  51                 delegate.close();
  52             }
  53         }
  54     }
  55 }