/*
* 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.runners.direct;
import java.util.Collection;
import java.util.Collections;
import org.apache.beam.sdk.runners.AppliedPTransform;
import org.apache.beam.sdk.transforms.Flatten;
import org.apache.beam.sdk.values.PCollection;
import org.apache.beam.sdk.values.PCollectionList;
/** A {@link RootInputProvider} that provides a singleton empty bundle. */
class EmptyInputProvider<T>
implements RootInputProvider<T, Void, PCollectionList<T>, Flatten.PCollections<T>> {
EmptyInputProvider() {}
/**
* {@inheritDoc}.
*
* <p>Returns an empty collection.
*/
@Override
public Collection<CommittedBundle<Void>> getInitialInputs(
AppliedPTransform<PCollectionList<T>, PCollection<T>, Flatten.PCollections<T>>
transform,
int targetParallelism) {
return Collections.emptyList();
}
}