com.twitter.heron.api.windowing.EvictionContext Maven / Gradle / Ivy

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// 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.

/**
 * 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 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();
}