/*
* 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 org.apache.beam.sdk.state;
import org.apache.beam.sdk.annotations.Internal;
import org.apache.beam.sdk.transforms.windowing.TimestampCombiner;
import org.joda.time.Instant;
/**
* <b><i>For internal use only; no backwards-compatibility guarantees.</i></b>
*
* <p>A {@link State} accepting and aggregating timestamps according to a {@link TimestampCombiner},
* holding the output watermark to the resulting timestamp.
*/
@Internal
public interface WatermarkHoldState extends GroupingState<Instant, Instant> {
/**
* Return the {@link TimestampCombiner} which will be used to determine a watermark hold time
* given an element timestamp, and to combine watermarks from windows which are about to be
* merged.
*/
TimestampCombiner getTimestampCombiner();
@Override
WatermarkHoldState readLater();
}