| // 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; |
| |
| import java.util.List; |
| |
| /** |
| * A view of events in a sliding window. |
| * |
| * @param <T> the type of event that this window contains. E.g. {@link org.apache.storm.tuple.Tuple} |
| */ |
| public interface Window<T> { |
| /** |
| * Gets the list of events in the window. |
| * <p> |
| * <b>Note: </b> If the number of tuples in windows is huge, invoking {@code get} would |
| * load all the tuples into memory and may throw an OOM exception. Use windowing with persistence |
| * </p> |
| * |
| * @return the list of events in the window. |
| */ |
| List<T> get(); |
| |
| /** |
| * Get the list of newly added events in the window since the last time the window was generated. |
| * |
| * @return the list of newly added events in the window. |
| */ |
| List<T> getNew(); |
| |
| /** |
| * Get the list of events expired from the window since the last time the window was generated. |
| * |
| * @return the list of events expired from the window. |
| */ |
| List<T> getExpired(); |
| |
| /** |
| * If processing based on event time, returns the window end time based on watermark otherwise |
| * returns the window end time based on processing time. |
| * |
| * @return the window end timestamp |
| */ |
| Long getEndTimestamp(); |
| |
| /** |
| * Returns the window start timestamp. Will return null if the window length is not based on |
| * time duration. |
| * |
| * @return the window start timestamp or null if the window length is not time based |
| */ |
| Long getStartTimestamp(); |
| } |