/*
* All content copyright Terracotta, Inc., unless otherwise indicated.
*
* 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 org.terracotta.statistics;
import java.io.Serializable;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicLong;
import java.util.concurrent.atomic.AtomicReference;
Author: Mathieu Carbou
/**
* @author Mathieu Carbou
*/
public class MemoizingValueStatistic<T extends Serializable> implements ValueStatistic<T> {
private final long delayNs;
private final AtomicReference<T> memoized = new AtomicReference<>();
private final AtomicLong expiration = new AtomicLong();
private final ValueStatistic<T> delegate;
public MemoizingValueStatistic(long delay, TimeUnit unit, ValueStatistic<T> delegate) {
this.delayNs = TimeUnit.NANOSECONDS.convert(delay, unit);
this.delegate = delegate;
}
@Override
public StatisticType type() {
return delegate.type();
}
@Override
public T value() {
long now = Time.time();
long exp = expiration.get();
if (now >= exp && expiration.compareAndSet(exp, now + delayNs)) {
memoized.set(delegate.value());
}
return memoized.get();
}
}