[GitHub] seojangho commented on a change in pull request #104: [NEMO-183] DAG-centric translation from Beam pipeline to IR DAG

[GitBox <gi...@apache.org>]

seojangho commented on a change in pull request #104: [NEMO-183] DAG-centric translation from Beam pipeline to IR DAG
URL: https://github.com/apache/incubator-nemo/pull/104#discussion_r210505301
 
 

 ##########
 File path: compiler/frontend/beam/src/main/java/edu/snu/nemo/compiler/frontend/beam/PipelineVisitor.java
 ##########
 @@ -0,0 +1,291 @@
+/*
+ * Copyright (C) 2018 Seoul National University
+ *
+ * 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 edu.snu.nemo.compiler.frontend.beam;
+
+import edu.snu.nemo.common.dag.DAG;
+import edu.snu.nemo.common.dag.DAGBuilder;
+import edu.snu.nemo.common.dag.Edge;
+import edu.snu.nemo.common.dag.Vertex;
+import org.apache.beam.sdk.Pipeline;
+import org.apache.beam.sdk.runners.TransformHierarchy;
+import org.apache.beam.sdk.transforms.ParDo;
+import org.apache.beam.sdk.transforms.View;
+import org.apache.beam.sdk.values.PValue;
+
+import java.util.*;
+
+/**
+ * Traverses through the given Beam pipeline to construct a DAG of Beam Transform,
+ * while preserving hierarchy of CompositeTransforms.
+ * This DAG will be later translated by {@link PipelineTranslator} into Nemo IR DAG.
+ */
+public final class PipelineVisitor extends Pipeline.PipelineVisitor.Defaults {
+
+  private static final String TRANSFORM = "Transform-";
+  private static final String DATAFLOW = "Dataflow-";
+
+  private final Stack<CompositeTransformVertex> compositeTransformVertexStack = new Stack<>();
+  private CompositeTransformVertex rootVertex = null;
+  private int nextIdx = 0;
+
+  @Override
+  public void visitPrimitiveTransform(final TransformHierarchy.Node node) {
+    final PrimitiveTransformVertex vertex = new PrimitiveTransformVertex(node, compositeTransformVertexStack.peek());
+    compositeTransformVertexStack.peek().addVertex(vertex);
+    vertex.getPValuesConsumed()
+        .forEach(pValue -> {
+          final TransformVertex dst = getDestinationOfDataFlowEdge(vertex, pValue);
+          dst.parent.addDataFlow(new DataFlowEdge(dst.parent.getProducerOf(pValue), dst));
+        });
+  }
+
+  @Override
+  public CompositeBehavior enterCompositeTransform(final TransformHierarchy.Node node) {
+    final CompositeTransformVertex vertex;
+    if (compositeTransformVertexStack.isEmpty()) {
+      // There is always a top-level CompositeTransform that encompasses the entire Beam pipeline.
+      vertex = new CompositeTransformVertex(node, null);
+    } else {
+      vertex = new CompositeTransformVertex(node, compositeTransformVertexStack.peek());
 
 Review comment:
   Transform A is the parent of Transform B if and only if Transform B is inserted into the pipeline as the result of 'expanding' CompositeTransform A. In short, DAG topology is not related to parent-child relationship.

----------------------------------------------------------------
This is an automated message from the Apache Git Service.
To respond to the message, please log on GitHub and use the
URL above to go to the specific comment.
 
For queries about this service, please contact Infrastructure at:
users@infra.apache.org


With regards,
Apache Git Services