| /* |
| * 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.portable; |
| |
| import javax.annotation.Nullable; |
| import org.apache.beam.runners.core.construction.graph.PipelineNode.PTransformNode; |
| import org.apache.beam.sdk.Pipeline; |
| import org.apache.beam.sdk.io.Read; |
| import org.apache.beam.sdk.transforms.PTransform; |
| |
| /** |
| * A factory for creating instances of {@link TransformEvaluator} for the application of a {@link |
| * PTransform}. |
| * |
| * <p>{@link TransformEvaluatorFactory TransformEvaluatorFactories} will be reused within a single |
| * execution of a {@link Pipeline} but will not be reused across executions. |
| */ |
| interface TransformEvaluatorFactory { |
| /** |
| * Create a new {@link TransformEvaluator} for the application of the {@link PTransform}. |
| * |
| * <p>Any work that must be done before input elements are processed (such as calling {@code |
| * DoFn.StartBundle}) must be done before the {@link TransformEvaluator} is made available to the |
| * caller. |
| * |
| * <p>May return null if the application cannot produce an evaluator (for example, it is a {@link |
| * Read} {@link PTransform} where all evaluators are in-use). |
| * |
| * @return An evaluator capable of processing the transform on the bundle, or null if no evaluator |
| * can be constructed. |
| * @throws Exception whenever constructing the underlying evaluator throws an exception |
| */ |
| @Nullable |
| <InputT> TransformEvaluator<InputT> forApplication( |
| PTransformNode application, CommittedBundle<?> inputBundle) throws Exception; |
| |
| /** |
| * Cleans up any state maintained by this {@link TransformEvaluatorFactory}. Called after a {@link |
| * Pipeline} is shut down. No more calls to {@link #forApplication(PTransformNode, |
| * CommittedBundle)} will be made after a call to {@link #cleanup()}. |
| */ |
| void cleanup() throws Exception; |
| } |