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

   1 /*
   2  * Copyright (c) 2015 Cisco 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.Preconditions;
  11 import java.util.Collections;
  12 import java.util.Map.Entry;
  13 import javax.annotation.concurrent.GuardedBy;
  14 import org.opendaylight.controller.cluster.datastore.messages.RegisterDataTreeChangeListener;
  15 import org.opendaylight.controller.md.sal.dom.api.DOMDataTreeChangeListener;
  16 import org.opendaylight.yangtools.concepts.ListenerRegistration;
  17 import org.opendaylight.yangtools.yang.data.api.schema.tree.DataTreeCandidate;
  18
  19 /**
  20  * Intermediate proxy registration returned to the user when we cannot
  21  * instantiate the registration immediately. It provides a bridge to
  22  * a real registration which may materialize at some point in the future.
  23  */
  24 final class DelayedDataTreeListenerRegistration implements ListenerRegistration<DOMDataTreeChangeListener> {
  25     private final RegisterDataTreeChangeListener registerTreeChangeListener;
  26     private volatile ListenerRegistration<DOMDataTreeChangeListener> delegate;
  27     @GuardedBy("this")
  28     private boolean closed;
  29
  30     DelayedDataTreeListenerRegistration(final RegisterDataTreeChangeListener registerTreeChangeListener) {
  31         this.registerTreeChangeListener = Preconditions.checkNotNull(registerTreeChangeListener);
  32     }
  33
  34     synchronized void createDelegate(final DelegateFactory<RegisterDataTreeChangeListener, ListenerRegistration<DOMDataTreeChangeListener>, DataTreeCandidate> factory) {
  35         if (!closed) {
  36             final Entry<ListenerRegistration<DOMDataTreeChangeListener>, DataTreeCandidate> res = factory.createDelegate(registerTreeChangeListener);
  37             this.delegate = res.getKey();
  38             if (res.getValue() != null) {
  39                 delegate.getInstance().onDataTreeChanged(Collections.singletonList(res.getValue()));
  40             }
  41         }
  42     }
  43
  44     @Override
  45     public DOMDataTreeChangeListener getInstance() {
  46         final ListenerRegistration<DOMDataTreeChangeListener> d = delegate;
  47         return d == null ? null : 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 }
  60