CounterGenerator.java

/**                                                                                                                                                                                
 * Copyright (c) 2010 Yahoo! Inc. All rights reserved.                                                                                                                             
 *                                                                                                                                                                                 
 * Licensed 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. See accompanying                                                                                                                 
 * LICENSE file.                                                                                                                                                                   
 */

package com.yahoo.ycsb.generator;

import java.util.concurrent.atomic.AtomicInteger;

/**
 * Generates a sequence of integers 0, 1, ...
 */
public class CounterGenerator extends IntegerGenerator
{
	final AtomicInteger counter;

	/**
	 * Create a counter that starts at countstart
	 */
	public CounterGenerator(int countstart)
	{
		counter=new AtomicInteger(countstart);
		setLastInt(counter.get()-1);
	}
	
	/**
	 * If the generator returns numeric (integer) values, return the next value as an int. Default is to return -1, which
	 * is appropriate for generators that do not return numeric values.
	 */
	public int nextInt() 
	{
		int ret = counter.getAndIncrement();
		setLastInt(ret);
		return ret;
	}
	@Override
	public int lastInt()
	{
	                return counter.get() - 1;
	}
	@Override
	public double mean() {
		throw new UnsupportedOperationException("Can't compute mean of non-stationary distribution!");
	}
}