opendaylight/md-sal/sal-dom-spi/src/main/java/org/opendaylight/controller/md/sal/dom/spi/RegistrationTreeNode.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.md.sal.dom.spi;
   9
  10 import com.google.common.base.MoreObjects;
  11 import com.google.common.base.Preconditions;
  12 import java.lang.ref.Reference;
  13 import java.lang.ref.WeakReference;
  14 import java.util.ArrayList;
  15 import java.util.Collection;
  16 import java.util.Collections;
  17 import java.util.HashMap;
  18 import java.util.Map;
  19 import javax.annotation.Nonnull;
  20 import org.opendaylight.yangtools.concepts.Identifiable;
  21 import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier.NodeIdentifier;
  22 import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier.NodeIdentifierWithPredicates;
  23 import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier.NodeWithValue;
  24 import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier.PathArgument;
  25 import org.slf4j.Logger;
  26 import org.slf4j.LoggerFactory;
  27
  28 /**
  29  * This is a single node within the registration tree. Note that the data returned from
  30  * and instance of this class is guaranteed to have any relevance or consistency
  31  * only as long as the {@link RegistrationTreeSnapshot} instance through which it is reached
  32  * remains unclosed.
  33  *
  34  * @param <T> registration type
  35  * @author Robert Varga
  36  */
  37 public final class RegistrationTreeNode<T> implements Identifiable<PathArgument> {
  38     private static final Logger LOG = LoggerFactory.getLogger(RegistrationTreeNode.class);
  39
  40     private final Map<PathArgument, RegistrationTreeNode<T>> children = new HashMap<>();
  41     private final Collection<T> registrations = new ArrayList<>(2);
  42     private final Collection<T> publicRegistrations = Collections.unmodifiableCollection(registrations);
  43     private final Reference<RegistrationTreeNode<T>> parent;
  44     private final PathArgument identifier;
  45
  46     RegistrationTreeNode(final RegistrationTreeNode<T> parent, final PathArgument identifier) {
  47         this.parent = new WeakReference<>(parent);
  48         this.identifier = identifier;
  49     }
  50
  51     @Override
  52     public PathArgument getIdentifier() {
  53         return identifier;
  54     }
  55
  56     /**
  57      * Return the child matching a {@link PathArgument} specification.
  58      *
  59      * @param arg Child identifier
  60      * @return Child matching exactly, or null.
  61      */
  62     public RegistrationTreeNode<T> getExactChild(@Nonnull final PathArgument arg) {
  63         return children.get(Preconditions.checkNotNull(arg));
  64     }
  65
  66     /**
  67      * Return a collection children which match a {@link PathArgument} specification inexactly.
  68      * This explicitly excludes the child returned by {@link #getExactChild(PathArgument)}.
  69      *
  70      * @param arg Child identifier
  71      * @return Collection of children, guaranteed to be non-null.
  72      */
  73     public @Nonnull Collection<RegistrationTreeNode<T>> getInexactChildren(@Nonnull final PathArgument arg) {
  74         Preconditions.checkNotNull(arg);
  75         if (arg instanceof NodeWithValue || arg instanceof NodeIdentifierWithPredicates) {
  76             /*
  77              * TODO: This just all-or-nothing wildcards, which we have historically supported. Given
  78              *       that the argument is supposed to have all the elements filled out, we could support
  79              *       partial wildcards by iterating over the registrations and matching the maps for
  80              *       partial matches.
  81              */
  82             final RegistrationTreeNode<T> child = children.get(new NodeIdentifier(arg.getNodeType()));
  83             if (child == null) {
  84                 return Collections.emptyList();
  85             } else {
  86                 return Collections.singletonList(child);
  87             }
  88         } else {
  89             return Collections.emptyList();
  90         }
  91     }
  92
  93     public Collection<T> getRegistrations() {
  94         return publicRegistrations;
  95     }
  96
  97     RegistrationTreeNode<T> ensureChild(@Nonnull final PathArgument child) {
  98         RegistrationTreeNode<T> potential = children.get(Preconditions.checkNotNull(child));
  99         if (potential == null) {
 100             potential = new RegistrationTreeNode<>(this, child);
 101             children.put(child, potential);
 102         }
 103         return potential;
 104     }
 105
 106     void addRegistration(@Nonnull final T registration) {
 107         registrations.add(Preconditions.checkNotNull(registration));
 108         LOG.debug("Registration {} added", registration);
 109     }
 110
 111     void removeRegistration(@Nonnull final T registration) {
 112         registrations.remove(Preconditions.checkNotNull(registration));
 113         LOG.debug("Registration {} removed", registration);
 114
 115         // We have been called with the write-lock held, so we can perform some cleanup.
 116         removeThisIfUnused();
 117     }
 118
 119     private void removeThisIfUnused() {
 120         final RegistrationTreeNode<T> p = parent.get();
 121         if (p != null && registrations.isEmpty() && children.isEmpty()) {
 122             p.removeChild(identifier);
 123         }
 124     }
 125
 126     private void removeChild(final PathArgument arg) {
 127         children.remove(arg);
 128         removeThisIfUnused();
 129     }
 130
 131     @Override
 132     public String toString() {
 133         return MoreObjects.toStringHelper(this)
 134                 .add("identifier", identifier)
 135                 .add("registrations", registrations.size())
 136                 .add("children", children.size()).toString();
 137     }
 138 }