/**
* 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.apache.aurora.common.stats;
/**
* A convenience class to perform the basic tasks needed for a {@link RecordingStat} except the
* actual value calculation.
*
* @author William Farner
*/
public abstract class SampledStat<T extends Number> extends StatImpl<T> implements RecordingStat<T> {
private volatile T prevValue;
public SampledStat(String name, T defaultValue) {
super(name);
this.prevValue = defaultValue; /* Don't forbid null. */
}
public abstract T doSample();
@Override
public final T sample() {
prevValue = doSample();
return prevValue;
}
@Override
public T read() {
return prevValue;
}
}