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 edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
  15 import java.util.Collections;
  16 import java.util.HashSet;
  17 import java.util.Set;
  18 import java.util.concurrent.ConcurrentHashMap;
  19 import java.util.function.Consumer;
  20 import java.util.stream.Stream;
  21 import org.eclipse.jdt.annotation.NonNullByDefault;
  22 import org.eclipse.jdt.annotation.Nullable;
  23 import org.opendaylight.yangtools.concepts.AbstractObjectRegistration;
  24 import org.opendaylight.yangtools.concepts.ObjectRegistration;
  25
  26 @Beta
  27 @NonNullByDefault
  28 public final class ObjectRegistry<T> {
  29     private final Set<ObjectRegistration<? extends T>> objects;
  30     private final Set<ObjectRegistration<? extends T>> unmodifiableView;
  31     private final String name;
  32
  33     private ObjectRegistry(final String name, final Set<ObjectRegistration<? extends T>> objects) {
  34         this.name = requireNonNull(name);
  35         this.objects = requireNonNull(objects);
  36         this.unmodifiableView = Collections.unmodifiableSet(objects);
  37     }
  38
  39     public static <T> ObjectRegistry<T> createConcurrent(final String name) {
  40         return new ObjectRegistry<>(name, ConcurrentHashMap.newKeySet());
  41     }
  42
  43     public static <T> ObjectRegistry<T> createSimple(final String name) {
  44         return new ObjectRegistry<>(name, new HashSet<>(1));
  45     }
  46
  47     public boolean isEmpty() {
  48         return objects.isEmpty();
  49     }
  50
  51     public Stream<? extends T> streamObjects() {
  52         return streamRegistrations().map(ObjectRegistration::getInstance);
  53     }
  54
  55     public Set<ObjectRegistration<? extends T>> getRegistrations() {
  56         return unmodifiableView;
  57     }
  58
  59     public Stream<ObjectRegistration<? extends T>> streamRegistrations() {
  60         return objects.stream();
  61     }
  62
  63     public <O extends T> ObjectRegistration<O> register(final O object) {
  64         final ObjectRegistration<O> ret = new Reg<>(object, objects::remove);
  65         objects.add(ret);
  66         return ret;
  67     }
  68
  69     @Override
  70     public String toString() {
  71         return MoreObjects.toStringHelper(this).add("name", name).add("objects", objects.size()).toString();
  72     }
  73
  74     private static final class Reg<T> extends AbstractObjectRegistration<T> {
  75         private @Nullable Consumer<ObjectRegistration<? super T>> removeCall;
  76
  77         Reg(final T instance, final Consumer<ObjectRegistration<? super T>> removeCall) {
  78             super(instance);
  79             this.removeCall = requireNonNull(removeCall);
  80         }
  81
  82         @Override
  83         @SuppressFBWarnings("NP_STORE_INTO_NONNULL_FIELD")
  84         protected void removeRegistration() {
  85             removeCall.accept(this);
  86             // Do not retail reference to that state
  87             removeCall = null;
  88         }
  89     }
  90 }