/* * Copyright 2016 Google. * * Licensed 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 com.google.cloud.genomics.dockerflow.transform; import com.google.cloud.dataflow.sdk.transforms.Combine; import com.google.cloud.dataflow.sdk.transforms.DoFn; import com.google.cloud.dataflow.sdk.transforms.PTransform; import com.google.cloud.dataflow.sdk.transforms.ParDo; import com.google.cloud.dataflow.sdk.transforms.SerializableFunction; import com.google.cloud.dataflow.sdk.transforms.Values; import com.google.cloud.dataflow.sdk.values.KV; import com.google.cloud.dataflow.sdk.values.PCollection; /** Break Dataflow fusion. */ @SuppressWarnings("serial") public class BreakFusion<T> extends PTransform<PCollection<T>, PCollection<T>> { public BreakFusion() {} public BreakFusion(String name) { super(name); } @Override public PCollection<T> apply(PCollection<T> input) { return input .apply(ParDo.named("BreakFusion").of(new DummyMapFn<T>())) .apply(Combine.<String, T>perKey(new First<T>())) .apply(Values.<T>create()); } static class DummyMapFn<T> extends DoFn<T, KV<String, T>> { @Override public void processElement(DoFn<T, KV<String, T>>.ProcessContext c) throws Exception { c.output(KV.of(String.valueOf(c.element().hashCode()), c.element())); } } /** * Return the first element. Since ordering is not guaranteed, it should be treated as effectively * a random element. */ static class First<T> implements SerializableFunction<Iterable<T>, T> { @Override public T apply(Iterable<T> input) { return input.iterator() != null && input.iterator().hasNext() ? input.iterator().next() : null; } } }