content: /**
   * 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 variable that contains information about a (possibly changing) value.
   *
   * @author William Farner
   */
  interface RecordingStat<T extends Number> extends Stat<T> {
  
    /**
     * Called by the variable sampler when a sample is being taken.  Only calls to this method should
     * be used to store variable history.
     *
     * Note - if the sampling of this value depends on other variables, it is imperative that those
     * variables values are updated first (and available via {@link Stat#read()}.
     *
     * @return A new sample of the variable.
     */
    public T sample();
  }
  