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   * 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.spark;
  
  import static org.junit.Assert.assertEquals;
  import static org.junit.Assert.assertFalse;
  import static org.junit.Assert.assertTrue;
  import static org.mockito.Mockito.mock;
  
  import java.util.List;
  import org.apache.beam.runners.spark.translation.Dataset;
  import org.apache.beam.runners.spark.translation.EvaluationContext;
  import org.apache.beam.runners.spark.translation.TransformTranslator;
  import org.apache.beam.sdk.Pipeline;
  import org.apache.beam.sdk.coders.Coder;
  import org.apache.beam.sdk.transforms.Count;
  import org.apache.beam.sdk.transforms.Create;
  import org.apache.beam.sdk.transforms.Create.Values;
  import org.apache.beam.sdk.transforms.DoFn;
  import org.apache.beam.sdk.transforms.GroupByKey;
  import org.apache.beam.sdk.transforms.ParDo;
  import org.apache.beam.sdk.transforms.View;
  import org.apache.beam.sdk.values.PCollection;
  import org.apache.beam.sdk.values.PCollectionView;
  import org.junit.ClassRule;
  import org.junit.Test;
  
  /** Tests of {@link Dataset#cache(String, Coder)}} scenarios. */
  @SuppressWarnings({
    "rawtypes", // TODO(https://github.com/apache/beam/issues/20447)
  })
  public class CacheTest {
  
    @ClassRule public static SparkContextRule contextRule = new SparkContextRule();
  
    /**
     * Test checks how the cache candidates map is populated by the runner when evaluating the
     * pipeline.
     */
    @Test
    public void cacheCandidatesUpdaterTest() {
      SparkPipelineOptions options = contextRule.createPipelineOptions();
      Pipeline pipeline = Pipeline.create(options);
      PCollection<String> pCollection = pipeline.apply(Create.of("foo", "bar"));
  
      // First use of pCollection.
      pCollection.apply(Count.globally());
      // Second use of pCollection.
      PCollectionView<List<String>> view = pCollection.apply(View.asList());
  
      // Internally View.asList() creates a PCollection that underlies the PCollectionView, that
      // PCollection should not be cached as the SparkRunner does not access that PCollection to
      // access the PCollectionView.
      pipeline
          .apply(Create.of("foo", "baz"))
          .apply(
              ParDo.of(
                      new DoFn<String, String>() {
                        @ProcessElement
                        public void processElement(ProcessContext processContext) {
                          if (processContext.sideInput(view).contains(processContext.element())) {
                            processContext.output(processContext.element());
                          }
                        }
                      })
                  .withSideInputs(view));
  
      EvaluationContext ctxt =
          new EvaluationContext(contextRule.getSparkContext(), pipeline, options);
      SparkRunner.CacheVisitor cacheVisitor =
          new SparkRunner.CacheVisitor(new TransformTranslator.Translator(), ctxt);
      pipeline.traverseTopologically(cacheVisitor);
      assertEquals(2L, (long) ctxt.getCacheCandidates().get(pCollection));
      assertEquals(1L, ctxt.getCacheCandidates().values().stream().filter(l -> l > 1).count());
    }
  
    @Test
    public void shouldCacheTest() {
      SparkPipelineOptions options = contextRule.createPipelineOptions();
      options.setCacheDisabled(true);
      Pipeline pipeline = Pipeline.create(options);
  
      Values<String> valuesTransform = Create.of("foo", "bar");
      PCollection pCollection = mock(PCollection.class);
  
      EvaluationContext ctxt =
          new EvaluationContext(contextRule.getSparkContext(), pipeline, options);
      ctxt.getCacheCandidates().put(pCollection, 2L);
  
      assertFalse(ctxt.shouldCache(valuesTransform, pCollection));
  
      options.setCacheDisabled(false);
      assertTrue(ctxt.shouldCache(valuesTransform, pCollection));
  
      GroupByKey<String, String> gbkTransform = GroupByKey.create();
      assertFalse(ctxt.shouldCache(gbkTransform, pCollection));
    }
  }
  