package com.atlassian.cache.impl;
   
   import java.util.Set;
   import java.util.concurrent.CopyOnWriteArraySet;
   
   import com.atlassian.cache.CachedReferenceListener;
   
   import static com.google.common.base.Preconditions.checkNotNull;
   
  /**
   * A utility class which:
   * <ul>
   *     <li>Manages a set of {@code CachedReferenceListener}s</li>
   *     <li>Provides a way to notify these listeners about different events</li>
   * </ul>
   */
  public class DefaultCachedReferenceListenerSupport<V> implements CachedReferenceListenerSupport<V>
  {
      private final Set<CachedReferenceListener<V>> listeners = new CopyOnWriteArraySet<CachedReferenceListener<V>>();
      private final CachedReferenceNotificationSupport notificationSupport =
              CachedReferenceNotificationSupport.getInstance();
  
      @Override
      public void add(CachedReferenceListener<V> listener, boolean includeValues)
      {
          listeners.add(checkNotNull(listener));
      }
  
      @Override
      public void remove(CachedReferenceListener<V> listener)
      {
          listeners.remove(checkNotNull(listener));
      }
  
      @Override
      public void notifyEvict(V oldValue)
      {
          notificationSupport.notifyEvict(listeners, new DefaultCachedReferenceEvent<V>(oldValue));
      }
  
      @Override
      public void notifySet(V value)
      {
          notificationSupport.notifySet(listeners, new DefaultCachedReferenceEvent<V>(value));
      }
  
      @Override
      public void notifyReset(V oldValue)
      {
          notificationSupport.notifyReset(listeners, new DefaultCachedReferenceEvent<V>(oldValue));
      }
  }