heron/api/src/java/com/twitter/heron/api/windowing/EvictionContext.java

//  Copyright 2017 Twitter. All rights reserved.
//
//  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 com.twitter.heron.api.windowing;

/**
 * Context information that can be used by the eviction policy
 */
public interface EvictionContext {
  /**
   * Returns the reference time that the eviction policy could use to
   * evict the events. In the case of event time processing, this would be
   * the watermark time.
   *
   * @return the reference time in millis
   */
  Long getReferenceTime();

  /**
   * Returns the sliding count for count based windows
   *
   * @return the sliding count
   */
  Long getSlidingCount();


  /**
   * Returns the sliding interval for time based windows
   *
   * @return the sliding interval
   */
  Long getSlidingInterval();

  /**
   * Returns the current count of events in the queue up to the reference time
   * based on which count based evictions can be performed.
   *
   * @return the current count
   */
  Long getCurrentCount();
}