/*
    * Licensed to the Apache Software Foundation (ASF) under one or more
    * contributor license agreements.  See the NOTICE file distributed with
    * this work for additional information regarding copyright ownership.
    * The ASF licenses this file to You under the Apache License, Version 2.0
    * (the "License"); you may not use this file except in compliance with
    * the License.  You may obtain a copy of the License at
    *
    *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package org.apache.commons.collections.collection;
  
  import java.io.Serializable;
  import java.util.Collection;
  import java.util.Iterator;
  
  /**
   * Decorates another {@link Collection} to synchronize its behaviour
   * for a multi-threaded environment.
   * <p>
   * Iterators must be manually synchronized:
   * <pre>
   * synchronized (coll) {
   *   Iterator it = coll.iterator();
   *   // do stuff with iterator
   * }
   * </pre>
   * <p>
   * This class is Serializable from Commons Collections 3.1.
   *
   * @param <E> the type of the elements in the collection
   * @since 3.0
   * @version $Id: SynchronizedCollection.java 1443602 2013-02-07 17:00:23Z tn $
   */
  public class SynchronizedCollection<E> implements Collection<E>, Serializable {
  
      /** Serialization version */
      private static final long serialVersionUID = 2412805092710877986L;
  
      /** The collection to decorate */
      protected final Collection<E> collection;
      /** The object to lock on, needed for List/SortedSet views */
      protected final Object lock;
  
      /**
       * Factory method to create a synchronized collection.
       * 
       * @param <T> the type of the elements in the collection
       * @param coll  the collection to decorate, must not be null
       * @return a new synchronized collection
       * @throws IllegalArgumentException if collection is null
       */
      public static <T> SynchronizedCollection<T> synchronizedCollection(final Collection<T> coll) {
          return new SynchronizedCollection<T>(coll);
      }
  
      //-----------------------------------------------------------------------
      /**
       * Constructor that wraps (not copies).
       * 
       * @param collection  the collection to decorate, must not be null
       * @throws IllegalArgumentException if the collection is null
       */
      protected SynchronizedCollection(final Collection<E> collection) {
          if (collection == null) {
              throw new IllegalArgumentException("Collection must not be null");
          }
          this.collection = collection;
          this.lock = this;
      }
  
      /**
       * Constructor that wraps (not copies).
       * 
       * @param collection  the collection to decorate, must not be null
       * @param lock  the lock object to use, must not be null
       * @throws IllegalArgumentException if the collection is null
       */
      protected SynchronizedCollection(final Collection<E> collection, final Object lock) {
          if (collection == null) {
              throw new IllegalArgumentException("Collection must not be null");
          }
          this.collection = collection;
          this.lock = lock;
      }
  
      /**
       * Gets the collection being decorated.
       * 
       * @return the decorated collection
       */
      protected Collection<E> decorated() {
          return collection;
     }
 
     //-----------------------------------------------------------------------
     
     public boolean add(final E object) {
         synchronized (lock) {
             return decorated().add(object);
         }
     }
 
     public boolean addAll(final Collection<? extends E> coll) {
         synchronized (lock) {
             return decorated().addAll(coll);
         }
     }
 
     public void clear() {
         synchronized (lock) {
             decorated().clear();
         }
     }
 
     public boolean contains(final Object object) {
         synchronized (lock) {
             return decorated().contains(object);
         }
     }
 
     public boolean containsAll(final Collection<?> coll) {
         synchronized (lock) {
             return decorated().containsAll(coll);
         }
     }
 
     public boolean isEmpty() {
         synchronized (lock) {
             return decorated().isEmpty();
         }
     }
 
     /**
      * Iterators must be manually synchronized.
      * <pre>
      * synchronized (coll) {
      *   Iterator it = coll.iterator();
      *   // do stuff with iterator
      * }
      * 
      * @return an iterator that must be manually synchronized on the collection
      */
     public Iterator<E> iterator() {
         return decorated().iterator();
     }
 
     public Object[] toArray() {
         synchronized (lock) {
             return decorated().toArray();
         }
     }
 
     public <T> T[] toArray(final T[] object) {
         synchronized (lock) {
             return decorated().toArray(object);
         }
     }
 
     public boolean remove(final Object object) {
         synchronized (lock) {
             return decorated().remove(object);
         }
     }
 
     public boolean removeAll(final Collection<?> coll) {
         synchronized (lock) {
             return decorated().removeAll(coll);
         }
     }
 
     public boolean retainAll(final Collection<?> coll) {
         synchronized (lock) {
             return decorated().retainAll(coll);
         }
     }
 
     public int size() {
         synchronized (lock) {
             return decorated().size();
         }
     }
 
     @Override
     public boolean equals(final Object object) {
         synchronized (lock) {
             if (object == this) {
                 return true;
             }
             return object == this || decorated().equals(object);
         }
     }
 
     @Override
     public int hashCode() {
         synchronized (lock) {
             return decorated().hashCode();
         }
     }
 
     @Override
     public String toString() {
         synchronized (lock) {
             return decorated().toString();
         }
     }
 
 }