mosche commented on code in PR #24009:
URL: https://github.com/apache/beam/pull/24009#discussion_r1025008863
##########
runners/spark/3/src/main/java/org/apache/beam/runners/spark/structuredstreaming/translation/PipelineTranslator.java:
##########
@@ -17,170 +17,336 @@
*/
package org.apache.beam.runners.spark.structuredstreaming.translation;
+import static
org.apache.beam.sdk.Pipeline.PipelineVisitor.CompositeBehavior.DO_NOT_ENTER_TRANSFORM;
+import static
org.apache.beam.sdk.Pipeline.PipelineVisitor.CompositeBehavior.ENTER_TRANSFORM;
+import static org.apache.beam.sdk.util.Preconditions.checkStateNotNull;
+import static org.apache.beam.sdk.values.PCollection.IsBounded.UNBOUNDED;
+
import java.io.IOException;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Map;
+import java.util.Set;
+import javax.annotation.Nullable;
import org.apache.beam.runners.core.construction.PTransformTranslation;
+import org.apache.beam.runners.core.construction.SerializablePipelineOptions;
+import org.apache.beam.runners.spark.SparkCommonPipelineOptions;
+import
org.apache.beam.runners.spark.structuredstreaming.translation.helpers.EncoderProvider;
import org.apache.beam.sdk.Pipeline;
+import org.apache.beam.sdk.Pipeline.PipelineVisitor;
+import org.apache.beam.sdk.annotations.Internal;
+import org.apache.beam.sdk.coders.Coder;
import org.apache.beam.sdk.options.StreamingOptions;
import org.apache.beam.sdk.runners.AppliedPTransform;
-import org.apache.beam.sdk.runners.TransformHierarchy;
+import org.apache.beam.sdk.runners.TransformHierarchy.Node;
import org.apache.beam.sdk.transforms.PTransform;
+import org.apache.beam.sdk.transforms.View;
+import org.apache.beam.sdk.util.WindowedValue;
import org.apache.beam.sdk.values.PCollection;
import org.apache.beam.sdk.values.PInput;
import org.apache.beam.sdk.values.POutput;
import org.apache.beam.sdk.values.PValue;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import org.apache.beam.sdk.values.TupleTag;
+import org.apache.spark.sql.Dataset;
+import org.apache.spark.sql.Encoder;
+import org.apache.spark.sql.SparkSession;
+import org.apache.spark.sql.catalyst.encoders.ExpressionEncoder;
+import org.apache.spark.storage.StorageLevel;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
- * {@link Pipeline.PipelineVisitor} that translates the Beam operators to
their Spark counterparts.
- * It also does the pipeline preparation: mode detection, transforms
replacement, classpath
- * preparation.
+ * The pipeline translator translates a Beam {@link Pipeline} into a Spark
correspondence, that can
+ * then be evaluated.
+ *
+ * <p>The translation involves traversing the hierarchy of a pipeline multiple
times:
+ *
+ * <ol>
+ * <li>Detect if {@link StreamingOptions#setStreaming streaming} mode is
required.
+ * <li>Identify datasets that are repeatedly used as input and should be
cached.
+ * <li>And finally, translate each primitive or composite {@link PTransform}
that is {@link
+ * #getTransformTranslator known} and {@link
TransformTranslator#canTranslate supported} into
+ * its Spark correspondence. If a composite is not supported, it will be
expanded further into
+ * its parts and translated then.
+ * </ol>
*/
-@SuppressWarnings({
- "nullness" // TODO(https://github.com/apache/beam/issues/20497)
-})
-public abstract class PipelineTranslator extends
Pipeline.PipelineVisitor.Defaults {
+@Internal
+public abstract class PipelineTranslator {
private static final Logger LOG =
LoggerFactory.getLogger(PipelineTranslator.class);
- protected TranslationContext translationContext;
- //
--------------------------------------------------------------------------------------------
- // Pipeline preparation methods
- //
--------------------------------------------------------------------------------------------
public static void replaceTransforms(Pipeline pipeline, StreamingOptions
options) {
pipeline.replaceAll(SparkTransformOverrides.getDefaultOverrides(options.isStreaming()));
}
/**
- * Visit the pipeline to determine the translation mode (batch/streaming)
and update options
- * accordingly.
+ * Analyse the pipeline to determine if we have to switch to streaming mode
for the pipeline
+ * translation and update {@link StreamingOptions} accordingly.
*/
- public static void detectTranslationMode(Pipeline pipeline, StreamingOptions
options) {
- TranslationModeDetector detector = new TranslationModeDetector();
+ public static void detectStreamingMode(Pipeline pipeline, StreamingOptions
options) {
+ StreamingModeDetector detector = new
StreamingModeDetector(options.isStreaming());
pipeline.traverseTopologically(detector);
- if (detector.getTranslationMode().equals(TranslationMode.STREAMING)) {
- options.setStreaming(true);
+ options.setStreaming(detector.streaming);
+ }
+
+ /** Returns a {@link TransformTranslator} for the given {@link PTransform}
if known. */
+ protected abstract @Nullable <
+ InT extends PInput, OutT extends POutput, TransformT extends
PTransform<InT, OutT>>
+ TransformTranslator<InT, OutT, TransformT>
getTransformTranslator(TransformT transform);
+
+ /**
+ * Translates a Beam pipeline into its Spark correspondence using the Spark
SQL / Dataset API.
+ *
+ * <p>Note, in some cases this involves the early evaluation of some parts
of the pipeline. For
+ * example, in order to use a side-input {@link
org.apache.beam.sdk.values.PCollectionView
+ * PCollectionView} in a translation the corresponding Spark {@link
+ * org.apache.beam.runners.spark.translation.Dataset Dataset} might have to
be collected and
+ * broadcasted to be able to continue with the translation.
+ *
+ * @return The result of the translation is an {@link EvaluationContext}
that can trigger the
+ * evaluation of the Spark pipeline.
+ */
+ public EvaluationContext translate(
+ Pipeline pipeline, SparkSession session, SparkCommonPipelineOptions
options) {
+ LOG.debug("starting translation of the pipeline using {}",
getClass().getName());
+ DependencyVisitor dependencies = new DependencyVisitor();
+ pipeline.traverseTopologically(dependencies);
+
+ TranslatingVisitor translator = new TranslatingVisitor(session, options,
dependencies.results);
+ pipeline.traverseTopologically(translator);
+
+ return new EvaluationContext(translator.leaves, session);
+ }
+
+ /**
+ * The correspondence of a {@link PCollection} as result of translating a
{@link PTransform}
+ * including additional metadata (such as name and dependents).
+ */
+ private static final class TranslationResult<T> implements
EvaluationContext.NamedDataset<T> {
+ private final String name;
+ private @Nullable Dataset<WindowedValue<T>> dataset = null;
+ private final Set<PTransform<?, ?>> dependentTransforms = new HashSet<>();
+
+ private TranslationResult(PCollection<?> pCol) {
+ this.name = pCol.getName();
+ }
+
+ @Override
+ public String name() {
+ return name;
+ }
+
+ @Override
+ public @Nullable Dataset<WindowedValue<T>> dataset() {
+ return dataset;
}
}
- /** The translation mode of the Beam Pipeline. */
- private enum TranslationMode {
+ /** Shared, mutable state during the translation of a pipeline and omitted
afterwards. */
+ interface TranslationState extends EncoderProvider {
Review Comment:
👍
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