common/util/src/main/java/org/opendaylight/yangtools/util/ObjectRegistry.java

   1 /*
   2  * Copyright (c) 2018 Pantheon Technologies, s.r.o. 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.yangtools.util;
   9
  10 import static java.util.Objects.requireNonNull;
  11
  12 import com.google.common.annotations.Beta;
  13 import com.google.common.base.MoreObjects;
  14 import java.util.Collections;
  15 import java.util.HashSet;
  16 import java.util.Set;
  17 import java.util.concurrent.ConcurrentHashMap;
  18 import java.util.function.Consumer;
  19 import java.util.stream.Stream;
  20 import org.eclipse.jdt.annotation.NonNullByDefault;
  21 import org.eclipse.jdt.annotation.Nullable;
  22 import org.opendaylight.yangtools.concepts.AbstractObjectRegistration;
  23 import org.opendaylight.yangtools.concepts.ObjectRegistration;
  24
  25 @Beta
  26 @NonNullByDefault
  27 public final class ObjectRegistry<T> {
  28     private final Set<ObjectRegistration<? extends T>> objects;
  29     private final Set<ObjectRegistration<? extends T>> unmodifiableView;
  30     private final String name;
  31
  32     private ObjectRegistry(final String name, Set<ObjectRegistration<? extends T>> objects) {
  33         this.name = requireNonNull(name);
  34         this.objects = requireNonNull(objects);
  35         this.unmodifiableView = Collections.unmodifiableSet(objects);
  36     }
  37
  38     public static <T> ObjectRegistry<T> createConcurrent(final String name) {
  39         return new ObjectRegistry<>(name, ConcurrentHashMap.newKeySet());
  40     }
  41
  42     public static <T> ObjectRegistry<T> createSimple(final String name) {
  43         return new ObjectRegistry<>(name, new HashSet<>(1));
  44     }
  45
  46     public boolean isEmpty() {
  47         return objects.isEmpty();
  48     }
  49
  50     public Stream<? extends T> streamObjects() {
  51         return streamRegistrations().map(ObjectRegistration::getInstance);
  52     }
  53
  54     public Set<ObjectRegistration<? extends T>> getRegistrations() {
  55         return unmodifiableView;
  56     }
  57
  58     public Stream<ObjectRegistration<? extends T>> streamRegistrations() {
  59         return objects.stream();
  60     }
  61
  62     public <O extends T> ObjectRegistration<O> register(final O object) {
  63         final ObjectRegistration<O> ret = new Reg<>(object, objects::remove);
  64         objects.add(ret);
  65         return ret;
  66     }
  67
  68     @Override
  69     public String toString() {
  70         return MoreObjects.toStringHelper(this).add("name", name).add("objects", objects.size()).toString();
  71     }
  72
  73     private static final class Reg<T> extends AbstractObjectRegistration<T> {
  74         private @Nullable @javax.annotation.Nullable Consumer<ObjectRegistration<? super T>> removeCall;
  75
  76         Reg(final T instance, final Consumer<ObjectRegistration<? super T>> removeCall) {
  77             super(instance);
  78             this.removeCall = requireNonNull(removeCall);
  79         }
  80
  81         @Override
  82         protected void removeRegistration() {
  83             removeCall.accept(this);
  84             // Do not retail reference to that state
  85             removeCall = null;
  86         }
  87     }
  88 }