001/*
002 *  This file is part of the Jikes RVM project (http://jikesrvm.org).
003 *
004 *  This file is licensed to You under the Eclipse Public License (EPL);
005 *  You may not use this file except in compliance with the License. You
006 *  may obtain a copy of the License at
007 *
008 *      http://www.opensource.org/licenses/eclipse-1.0.php
009 *
010 *  See the COPYRIGHT.txt file distributed with this work for information
011 *  regarding copyright ownership.
012 */
013package org.mmtk.vm;
014
015import org.vmmagic.pragma.Uninterruptible;
016
017
018/**
019 * A counter that supports atomic increment and reset.
020 */
021@Uninterruptible public abstract class SynchronizedCounter {
022
023  /**
024   * Reset the counter to 0, returning its previous value.
025   *
026   * @return The value of the counter, prior to reset.
027   */
028  public abstract int reset();
029
030  /**
031   * Adds 1 to the counter.
032   *
033   * @return the value before the add
034   */
035  public abstract int increment();
036
037  /**
038   * Peek at the counter
039   *
040   * @return The current value of the counter.
041   */
042  public abstract int peek();
043}