/*
 * Copyright (c) 1997, 2018 Oracle and/or its affiliates. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Distribution License v. 1.0, which is available at
 * http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */

package org.glassfish.pfl.tf.timer.impl ;

import java.util.Collection ;
import java.util.Iterator ;
import java.util.Set ;
import java.util.HashSet ;

This is an implementation of the Set interface that keeps track
of its version so that we can tell when it is modified.
Each time an element is added to or removed from the set, the
version is incremented.
This implementation is synchronized so that the version
is consistently updated whenever the set is modified.
/** This is an implementation of the Set interface that keeps track
 * of its version so that we can tell when it is modified.
 * Each time an element is added to or removed from the set, the
 * version is incremented.
 * This implementation is synchronized so that the version
 * is consistently updated whenever the set is modified.
 */
public class VersionedHashSet<E> extends HashSet<E> {
    private long version = 0 ;

    public synchronized long version() {
	return version ;
    }

    public VersionedHashSet() {
	super() ;
    }

    public VersionedHashSet( Collection<? extends E> c ) {
	super( c ) ;
    }

    public VersionedHashSet( int initialCapacity, float loadFactor ) {
	super( initialCapacity, loadFactor ) ;
    }

    public VersionedHashSet( int initialCapacity ) {
	super( initialCapacity ) ;
    }

    public synchronized boolean add( E e ) {
	boolean result = super.add( e ) ;
	if (result) 
	    version++ ;
	return result ;
    }

    public synchronized boolean remove( Object o ) {
	boolean result = super.remove( o ) ;
	if (result)
	    version++ ;
	return result ;
    }

    public Iterator<E> iterator() {
	final Iterator<E> state = super.iterator() ;

	return new Iterator<E>() {
	    public boolean hasNext() {
		return state.hasNext() ;
	    }

	    public E next() {
		return state.next() ;
	    }

	    public void remove() {
		synchronized (VersionedHashSet.this) {
		    state.remove() ;
		    version++ ;
		}
	    }
	} ;
    }
}