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package cn.alotus.core.collection;

import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.atomic.AtomicLong;

import cn.alotus.core.lang.Assert;

/**
 * 集合索引环形获取工具类
 *
 * @author ZhouChuGang
 * @since 5.7.15
 */
public class RingIndexUtil {

	/**
	 * 通过cas操作 实现对指定值内的回环累加
	 *
	 * @param object        集合
	 *                      
    *
  • Collection - the collection size *
  • Map - the map size *
  • Array - the array size *
  • Iterator - the number of elements remaining in the iterator *
  • Enumeration - the number of elements remaining in the enumeration *
* @param atomicInteger 原子操作类 * @return 索引位置 */ public static int ringNextIntByObj(Object object, AtomicInteger atomicInteger) { Assert.notNull(object); int modulo = CollUtil.size(object); return ringNextInt(modulo, atomicInteger); } /** * 通过cas操作 实现对指定值内的回环累加 * * @param modulo 回环周期值 * @param atomicInteger 原子操作类 * @return 索引位置 */ public static int ringNextInt(int modulo, AtomicInteger atomicInteger) { Assert.notNull(atomicInteger); Assert.isTrue(modulo > 0); if (modulo <= 1) { return 0; } for (; ; ) { int current = atomicInteger.get(); int next = (current + 1) % modulo; if (atomicInteger.compareAndSet(current, next)) { return next; } } } /** * 通过cas操作 实现对指定值内的回环累加
* 此方法一般用于大量数据完成回环累加(如数据库中的值大于int最大值) * * @param modulo 回环周期值 * @param atomicLong 原子操作类 * @return 索引位置 */ public static long ringNextLong(long modulo, AtomicLong atomicLong) { Assert.notNull(atomicLong); Assert.isTrue(modulo > 0); if (modulo <= 1) { return 0; } for (; ; ) { long current = atomicLong.get(); long next = (current + 1) % modulo; if (atomicLong.compareAndSet(current, next)) { return next; } } } }




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