/* * 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.transformations; import org.apache.flink.annotation.Internal; import org.apache.flink.api.dag.Transformation; import org.apache.flink.shaded.guava18.com.google.common.collect.Lists; import java.util.Collection; import java.util.List; /** * This transformation represents a union of several input * {@link Transformation Transformations}. * * <p>This does not create a physical operation, it only affects how upstream operations are * connected to downstream operations. * * @param <T> The type of the elements that result from this {@code UnionTransformation} */ @Internal public class UnionTransformation<T> extends Transformation<T> { private final List<Transformation<T>> inputs; /** * Creates a new {@code UnionTransformation} from the given input {@code Transformations}. * * <p>The input {@code Transformations} must all have the same type. * * @param inputs The list of input {@code Transformations} */ public UnionTransformation(List<Transformation<T>> inputs) { super("Union", inputs.get(0).getOutputType(), inputs.get(0).getParallelism()); for (Transformation<T> input: inputs) { if (!input.getOutputType().equals(getOutputType())) { throw new UnsupportedOperationException("Type mismatch in input " + input); } } this.inputs = Lists.newArrayList(inputs); } /** * Returns the list of input {@code Transformations}. */ public List<Transformation<T>> getInputs() { return inputs; } @Override public Collection<Transformation<?>> getTransitivePredecessors() { List<Transformation<?>> result = Lists.newArrayList(); result.add(this); for (Transformation<T> input: inputs) { result.addAll(input.getTransitivePredecessors()); } return result; } }