| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more contributor license |
| * agreements. See the NOTICE file distributed with this work for additional information regarding |
| * copyright ownership. The ASF licenses this file to You 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 org.apache.geode.distributed.internal; |
| |
| import java.util.concurrent.atomic.AtomicLong; |
| |
| import org.apache.geode.Statistics; |
| |
| /** |
| * This class holds the max value of a stat inside an AtomicLong. Every time a higher value is found |
| * the class will forward the delta between the old max and the new max to the statistics class. |
| * This pattern is a lock-less alternative to calling Statistics.getLong and then updating the max. |
| */ |
| class MaxLongGauge { |
| private final int statId; |
| private final Statistics stats; |
| private final AtomicLong max; |
| |
| public MaxLongGauge(int statId, Statistics stats) { |
| this.statId = statId; |
| this.stats = stats; |
| max = new AtomicLong(); |
| } |
| |
| public void recordMax(long currentValue) { |
| boolean done = false; |
| while (!done) { |
| long maxValue = max.get(); |
| if (currentValue <= maxValue) { |
| done = true; |
| } else { |
| done = max.compareAndSet(maxValue, currentValue); |
| if (done) { |
| stats.incLong(statId, currentValue - maxValue); |
| } |
| } |
| } |
| } |
| } |