/*
* 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.api.functions;
import org.apache.flink.streaming.api.watermark.Watermark;
/**
* A timestamp assigner that assigns timestamps based on the machine's wall clock.
*
* <p>If this assigner is used after a stream source, it realizes "ingestion time" semantics.
*
* @param <T> The elements that get timestamps assigned.
*/
public class IngestionTimeExtractor<T> implements AssignerWithPeriodicWatermarks<T> {
private static final long serialVersionUID = -4072216356049069301L;
private long maxTimestamp;
@Override
public long extractTimestamp(T element, long previousElementTimestamp) {
// make sure timestamps are monotonously increasing, even when the system clock re-syncs
final long now = Math.max(System.currentTimeMillis(), maxTimestamp);
maxTimestamp = now;
return now;
}
@Override
public Watermark getCurrentWatermark() {
// make sure timestamps are monotonously increasing, even when the system clock re-syncs
final long now = Math.max(System.currentTimeMillis(), maxTimestamp);
maxTimestamp = now;
return new Watermark(now - 1);
}
}