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 com.google.common.base.Optional;
  11 import java.util.EventListener;
  12 import java.util.Map.Entry;
  13 import javax.annotation.concurrent.GuardedBy;
  14 import org.opendaylight.yangtools.concepts.ListenerRegistration;
  15 import org.opendaylight.yangtools.yang.data.api.schema.tree.DataTreeCandidate;
  16
  17 abstract class DelayedListenerRegistration<L extends EventListener, R> implements ListenerRegistration<L> {
  18     private final R registrationMessage;
  19     private volatile ListenerRegistration<L> delegate;
  20
  21     @GuardedBy("this")
  22     private boolean closed;
  23
  24     protected DelayedListenerRegistration(R registrationMessage) {
  25         this.registrationMessage = registrationMessage;
  26     }
  27
  28     R getRegistrationMessage() {
  29         return registrationMessage;
  30     }
  31
  32     ListenerRegistration<L> getDelegate() {
  33         return delegate;
  34     }
  35
  36     synchronized <LR extends ListenerRegistration<L>> void createDelegate(
  37             final LeaderLocalDelegateFactory<R, LR, Optional<DataTreeCandidate>> factory) {
  38         if (!closed) {
  39             final Entry<LR, Optional<DataTreeCandidate>> res = factory.createDelegate(registrationMessage);
  40             this.delegate = res.getKey();
  41         }
  42     }
  43
  44     @Override
  45     public L getInstance() {
  46         final ListenerRegistration<L> d = delegate;
  47         return d == null ? null : (L)d.getInstance();
  48     }
  49
  50     @Override
  51     public synchronized void close() {
  52         if (!closed) {
  53             closed = true;
  54             if (delegate != null) {
  55                 delegate.close();
  56             }
  57         }
  58     }
  59 }