cc.siyecao.uid.utils.PaddedAtomicLong Maven / Gradle / Ivy
/*
* Copyright (c) 2017 Baidu, Inc. All Rights Reserve.
*
* 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.
*/
package cc.siyecao.uid.utils;
import java.util.concurrent.atomic.AtomicLong;
/**
* Represents a padded {@link AtomicLong} to prevent the FalseSharing problem
*
* The CPU cache line commonly be 64 bytes, here is a sample of cache line after padding:
* 64 bytes = 8 bytes (object reference) + 6 * 8 bytes (padded long) + 8 bytes (a long value)
*
* @author yutianbao
*/
public class PaddedAtomicLong extends AtomicLong {
private static final long serialVersionUID = -3415778863941386253L;
/**
* Padded 6 long (48 bytes)
*/
public volatile long p1, p2, p3, p4, p5, p6 = 7L;
/**
* Constructors from {@link AtomicLong}
*/
public PaddedAtomicLong() {
super();
}
public PaddedAtomicLong(long initialValue) {
super( initialValue );
}
/**
* To prevent GC optimizations for cleaning unused padded references
*/
public long sumPaddingToPreventOptimization() {
return p1 + p2 + p3 + p4 + p5 + p6;
}
}