/*
* 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.flink.streaming.runtime.operators;
import org.apache.flink.streaming.api.functions.AssignerWithPunctuatedWatermarks;
import org.apache.flink.streaming.api.operators.AbstractUdfStreamOperator;
import org.apache.flink.streaming.api.operators.ChainingStrategy;
import org.apache.flink.streaming.api.operators.OneInputStreamOperator;
import org.apache.flink.streaming.api.watermark.Watermark;
import org.apache.flink.streaming.runtime.streamrecord.StreamRecord;
/**
* A stream operator that extracts timestamps from stream elements and
* generates watermarks based on punctuation elements.
*
* @param <T> The type of the input elements
*/
public class TimestampsAndPunctuatedWatermarksOperator<T>
extends AbstractUdfStreamOperator<T, AssignerWithPunctuatedWatermarks<T>>
implements OneInputStreamOperator<T, T> {
private static final long serialVersionUID = 1L;
private long currentWatermark = Long.MIN_VALUE;
public TimestampsAndPunctuatedWatermarksOperator(AssignerWithPunctuatedWatermarks<T> assigner) {
super(assigner);
this.chainingStrategy = ChainingStrategy.ALWAYS;
}
@Override
public void processElement(StreamRecord<T> element) throws Exception {
final T value = element.getValue();
final long newTimestamp = userFunction.extractTimestamp(value,
element.hasTimestamp() ? element.getTimestamp() : Long.MIN_VALUE);
output.collect(element.replace(element.getValue(), newTimestamp));
final Watermark nextWatermark = userFunction.checkAndGetNextWatermark(value, newTimestamp);
if (nextWatermark != null && nextWatermark.getTimestamp() > currentWatermark) {
currentWatermark = nextWatermark.getTimestamp();
output.emitWatermark(nextWatermark);
}
}
/**
* Override the base implementation to completely ignore watermarks propagated from
* upstream (we rely only on the {@link AssignerWithPunctuatedWatermarks} to emit
* watermarks from here).
*/
@Override
public void processWatermark(Watermark mark) throws Exception {
// if we receive a Long.MAX_VALUE watermark we forward it since it is used
// to signal the end of input and to not block watermark progress downstream
if (mark.getTimestamp() == Long.MAX_VALUE && currentWatermark != Long.MAX_VALUE) {
currentWatermark = Long.MAX_VALUE;
output.emitWatermark(mark);
}
}
}