com.google.cloud.dataflow.sdk.runners.worker.DataflowExecutionContext Maven / Gradle / Ivy

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/*
 * Copyright (C) 2015 Google Inc.
 *
 * 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.dataflow.sdk.runners.worker;

import com.google.api.services.dataflow.model.SideInputInfo;
import com.google.cloud.dataflow.sdk.util.BatchModeExecutionContext;
import com.google.cloud.dataflow.sdk.util.SideInputReader;
import com.google.cloud.dataflow.sdk.values.PCollectionView;

/**
 * Extensions to {@link com.google.cloud.dataflow.sdk.util.BatchModeExecutionContext} specific to
 * the Dataflow worker.
 */
public abstract class DataflowExecutionContext extends BatchModeExecutionContext {
  /**
   * Returns a {@link SideInputReader} for all the side inputs described in the given
   * {@link SideInputInfo} descriptors. By default, throws {@link UnsupportedOperationException}.
   * Individual workers should override this behavior.
   */
  public abstract SideInputReader getSideInputReader(
      Iterable sideInputInfos) throws Exception;

  /**
   * Returns a {@link SideInputReader} for all the provided views, where the execution context
   * itself knows how to read data for the view. By default, throws
   * {@code UnsupportedOperationException}. Particular workers should override this behavior.
   */
  public abstract SideInputReader getSideInputReaderForViews(
      Iterable> views) throws Exception;

  /**
   * Returns a {@link DataflowExecutionContext} that does not support side inputs at all, for
   * situations when side inputs are not relevant, such as testing.
   */
  public static DataflowExecutionContext withoutSideInputs() {
    return new DataflowExecutionContext() {
      @Override
      public SideInputReader getSideInputReader(
          Iterable sideInputInfos) throws Exception {
        throw new UnsupportedOperationException(
            "DataflowExecutionContext.withoutSideInputs().getSideInputReader(...)");
      }

      @Override
      public SideInputReader getSideInputReaderForViews(
          Iterable> views) throws Exception {
        throw new UnsupportedOperationException(
            "DataflowExecutionContext.withoutSideInputs().getSideInputReaderForViews(...)");
      }
    };
  }
}