| /* |
| * 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.learning.katas.util; |
| |
| import org.apache.beam.sdk.transforms.DoFn; |
| import org.apache.beam.sdk.transforms.PTransform; |
| import org.apache.beam.sdk.transforms.ParDo; |
| import org.apache.beam.sdk.transforms.windowing.BoundedWindow; |
| import org.apache.beam.sdk.transforms.windowing.GlobalWindow; |
| import org.apache.beam.sdk.values.PCollection; |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| public class Log { |
| |
| private static final Logger LOGGER = LoggerFactory.getLogger(Log.class); |
| |
| private Log() { |
| } |
| |
| public static <T> PTransform<PCollection<T>, PCollection<T>> ofElements() { |
| return new LoggingTransform<>(); |
| } |
| |
| public static <T> PTransform<PCollection<T>, PCollection<T>> ofElements(String prefix) { |
| return new LoggingTransform<>(prefix); |
| } |
| |
| private static class LoggingTransform<T> extends PTransform<PCollection<T>, PCollection<T>> { |
| |
| private String prefix; |
| |
| private LoggingTransform() { |
| prefix = ""; |
| } |
| |
| private LoggingTransform(String prefix) { |
| this.prefix = prefix; |
| } |
| |
| @Override |
| public PCollection<T> expand(PCollection<T> input) { |
| return input.apply(ParDo.of(new DoFn<T, T>() { |
| |
| @ProcessElement |
| public void processElement(@Element T element, OutputReceiver<T> out, |
| BoundedWindow window) { |
| |
| String message = prefix + element.toString(); |
| |
| if (!(window instanceof GlobalWindow)) { |
| message = message + " Window:" + window.toString(); |
| } |
| |
| LOGGER.info(message); |
| |
| out.output(element); |
| } |
| |
| })); |
| } |
| |
| } |
| |
| } |