splitting ArrowEnumerator into sub-classes

arrow/src/main/java/org/apache/calcite/adapter/arrow/AbstractArrowEnumerator.java

@@ -0,0 +1,81 @@
+/*
+ * 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.calcite.adapter.arrow;
+
+import org.apache.calcite.linq4j.Enumerator;
+import org.apache.calcite.util.ImmutableIntList;
+import org.apache.calcite.util.Util;
+
+import org.apache.arrow.vector.ValueVector;
+import org.apache.arrow.vector.VectorSchemaRoot;
+import org.apache.arrow.vector.VectorUnloader;
+import org.apache.arrow.vector.ipc.ArrowFileReader;
+import org.apache.arrow.vector.ipc.message.ArrowRecordBatch;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * Enumerator that reads from a collection of Arrow value-vectors.
+ */
+abstract class AbstractArrowEnumerator implements Enumerator<Object> {
+  protected final ArrowFileReader arrowFileReader;
+  protected int currRowIndex = -1;
+  protected int rowCount;
+  protected final List<ValueVector> valueVectors;
+  protected final List<Integer> fields;
+
+  AbstractArrowEnumerator(ArrowFileReader arrowFileReader, ImmutableIntList fields) {
+    this.arrowFileReader = arrowFileReader;
+    this.fields = fields;
+    this.valueVectors = new ArrayList<>(fields.size());
+  }
+
+  abstract void evaluateOperator(ArrowRecordBatch arrowRecordBatch);
+
+  protected void loadNextArrowBatch() {
+    try {
+      final VectorSchemaRoot vsr = arrowFileReader.getVectorSchemaRoot();
+      for (int i : fields) {
+        this.valueVectors.add(vsr.getVector(i));
+      }
+      this.rowCount = vsr.getRowCount();
+      VectorUnloader vectorUnloader = new VectorUnloader(vsr);
+      ArrowRecordBatch arrowRecordBatch = vectorUnloader.getRecordBatch();
+      evaluateOperator(arrowRecordBatch);
+    } catch (IOException e) {
+      throw Util.toUnchecked(e);
+    }
+  }
+
+  @Override public Object current() {
+    if (fields.size() == 1) {
+      return this.valueVectors.get(0).getObject(currRowIndex);
+    }
+    Object[] current = new Object[valueVectors.size()];
+    for (int i = 0; i < valueVectors.size(); i++) {
+      ValueVector vector = this.valueVectors.get(i);
+      current[i] = vector.getObject(currRowIndex);
+    }
+    return current;
+  }
+
+  @Override public void reset() {
+    throw new UnsupportedOperationException();
+  }
+}

arrow/src/main/java/org/apache/calcite/adapter/arrow/ArrowEnumerable.java

@@ -32,13 +32,12 @@
  */
 class ArrowEnumerable extends AbstractEnumerable<Object> {
   private final ArrowFileReader arrowFileReader;
+  private final ImmutableIntList fields;
   private final @Nullable Projector projector;
   private final @Nullable Filter filter;
-  private final ImmutableIntList fields;
 
-  ArrowEnumerable(ArrowFileReader arrowFileReader,
-      @Nullable Projector projector, @Nullable Filter filter,
-      ImmutableIntList fields) {
+  ArrowEnumerable(ArrowFileReader arrowFileReader, ImmutableIntList fields,
+      @Nullable Projector projector, @Nullable Filter filter) {
     this.arrowFileReader = arrowFileReader;
     this.projector = projector;
     this.filter = filter;
@@ -47,7 +46,13 @@ class ArrowEnumerable extends AbstractEnumerable<Object> {
 
   @Override public Enumerator<Object> enumerator() {
     try {
-      return new ArrowEnumerator(projector, filter, fields, arrowFileReader);
+      if (projector != null) {
+        return new ArrowProjectEnumerator(arrowFileReader, fields, projector);
+      } else if (filter != null) {
+        return new ArrowFilterEnumerator(arrowFileReader, fields, filter);
+      }
+      throw new IllegalArgumentException(
+          "The arrow enumerator must have either a filter or a projection");
     } catch (Exception e) {
       throw Util.toUnchecked(e);
     }

arrow/src/main/java/org/apache/calcite/adapter/arrow/ArrowFilterEnumerator.java

@@ -0,0 +1,97 @@
+/*
+ * 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.calcite.adapter.arrow;
+
+import org.apache.arrow.gandiva.evaluator.Filter;
+import org.apache.arrow.gandiva.evaluator.SelectionVector;
+import org.apache.arrow.gandiva.evaluator.SelectionVectorInt16;
+import org.apache.arrow.gandiva.exceptions.GandivaException;
+import org.apache.arrow.memory.ArrowBuf;
+import org.apache.arrow.memory.BufferAllocator;
+import org.apache.arrow.memory.RootAllocator;
+import org.apache.arrow.vector.ipc.ArrowFileReader;
+import org.apache.arrow.vector.ipc.message.ArrowRecordBatch;
+
+import org.apache.calcite.util.ImmutableIntList;
+import org.apache.calcite.util.Util;
+
+import java.io.IOException;
+
+/**
+ * Enumerator that reads from a filtered collection of Arrow value-vectors.
+ */
+class ArrowFilterEnumerator extends AbstractArrowEnumerator {
+  private final BufferAllocator allocator;
+  private final Filter filter;
+  private ArrowBuf buf;
+  private SelectionVector selectionVector;
+  private int selectionVectorIndex;
+
+  ArrowFilterEnumerator(ArrowFileReader arrowFileReader, ImmutableIntList fields, Filter filter) {
+    super(arrowFileReader, fields);
+    this.allocator = new RootAllocator(Long.MAX_VALUE);
+    this.filter = filter;
+  }
+
+  void evaluateOperator(ArrowRecordBatch arrowRecordBatch) {
+    try {
+      this.buf = this.allocator.buffer((long) rowCount * 2);
+      this.selectionVector = new SelectionVectorInt16(buf);
+      filter.evaluate(arrowRecordBatch, selectionVector);
+    } catch (GandivaException e) {
+      throw Util.toUnchecked(e);
+    }
+  }
+
+  @Override public boolean moveNext() {
+    if (selectionVector == null
+        || selectionVectorIndex >= selectionVector.getRecordCount()) {
+      boolean hasNextBatch;
+      while (true) {
+        try {
+          hasNextBatch = arrowFileReader.loadNextBatch();
+        } catch (IOException e) {
+          throw Util.toUnchecked(e);
+        }
+        if (hasNextBatch) {
+          selectionVectorIndex = 0;
+          this.valueVectors.clear();
+          loadNextArrowBatch();
+          assert selectionVector != null;
+          if (selectionVectorIndex >= selectionVector.getRecordCount()) {
+            // the "filtered" batch is empty, but there may be more batches to fetch
+            continue;
+          }
+          currRowIndex = selectionVector.getIndex(selectionVectorIndex++);
+        }
+        return hasNextBatch;
+      }
+    } else {
+      currRowIndex = selectionVector.getIndex(selectionVectorIndex++);
+      return true;
+    }
+  }
+
+  @Override public void close() {
+    try {
+      buf.close();
+      filter.close();
+    } catch (GandivaException e) {
+      throw Util.toUnchecked(e);
+    }
+  }
+}