| /* |
| * 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.tests; |
| |
| import org.apache.flink.api.common.functions.RichFlatMapFunction; |
| import org.apache.flink.api.common.state.ValueState; |
| import org.apache.flink.api.common.state.ValueStateDescriptor; |
| import org.apache.flink.configuration.Configuration; |
| import org.apache.flink.util.Collector; |
| |
| import java.io.Serializable; |
| |
| /** |
| * This mapper validates exactly-once and at-least-once semantics in connection with {@link SequenceGeneratorSource}. |
| */ |
| public class SemanticsCheckMapper extends RichFlatMapFunction<Event, String> { |
| |
| private static final long serialVersionUID = -744070793650644485L; |
| |
| /** This value state tracks the current sequence number per key. */ |
| private volatile ValueState<Long> sequenceValue; |
| |
| /** This defines how semantics are checked for each update. */ |
| private final ValidatorFunction validator; |
| |
| SemanticsCheckMapper(ValidatorFunction validator) { |
| this.validator = validator; |
| } |
| |
| @Override |
| public void flatMap(Event event, Collector<String> out) throws Exception { |
| |
| Long currentValue = sequenceValue.value(); |
| if (currentValue == null) { |
| currentValue = 0L; |
| } |
| |
| long nextValue = event.getSequenceNumber(); |
| |
| if (validator.check(currentValue, nextValue)) { |
| sequenceValue.update(nextValue); |
| } else { |
| out.collect("Alert: " + currentValue + " -> " + nextValue + " (" + event.getKey() + ")"); |
| } |
| } |
| |
| @Override |
| public void open(Configuration parameters) throws Exception { |
| ValueStateDescriptor<Long> sequenceStateDescriptor = |
| new ValueStateDescriptor<>("sequenceState", Long.class); |
| |
| sequenceValue = getRuntimeContext().getState(sequenceStateDescriptor); |
| } |
| |
| interface ValidatorFunction extends Serializable { |
| boolean check(long current, long update); |
| |
| static ValidatorFunction exactlyOnce() { |
| return (current, update) -> (update - current) == 1; |
| } |
| |
| static ValidatorFunction atLeastOnce() { |
| return (current, update) -> (update - current) <= 1; |
| } |
| } |
| } |