Github user ppadma commented on a diff in the pull request:
https://github.com/apache/drill/pull/1121#discussion_r168325765
--- Diff:
exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/protocol/OperatorRecordBatch.java
---
@@ -0,0 +1,167 @@
+/*
+ * 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.drill.exec.physical.impl.protocol;
+
+import java.util.Iterator;
+
+import org.apache.drill.common.exceptions.UserException;
+import org.apache.drill.common.expression.SchemaPath;
+import org.apache.drill.exec.ops.FragmentContext;
+import org.apache.drill.exec.ops.FragmentContextInterface;
+import org.apache.drill.exec.ops.OperatorContext;
+import org.apache.drill.exec.physical.base.PhysicalOperator;
+import org.apache.drill.exec.record.BatchSchema;
+import org.apache.drill.exec.record.CloseableRecordBatch;
+import org.apache.drill.exec.record.TypedFieldId;
+import org.apache.drill.exec.record.VectorContainer;
+import org.apache.drill.exec.record.VectorWrapper;
+import org.apache.drill.exec.record.WritableBatch;
+import org.apache.drill.exec.record.selection.SelectionVector2;
+import org.apache.drill.exec.record.selection.SelectionVector4;
+
+/**
+ * Modular implementation of the standard Drill record batch iterator
+ * protocol. The protocol has two parts: control of the operator and
+ * access to the record batch. Each is encapsulated in separate
+ * implementation classes to allow easier customization for each
+ * situation. The operator internals are, themselves, abstracted to
+ * yet another class with the steps represented as method calls rather
+ * than as internal states as in the record batch iterator protocol.
+ * <p>
+ * Note that downstream operators make an assumption that the
+ * same vectors will appear from one batch to the next. That is,
+ * not only must the schema be the same, but if column "a" appears
+ * in two batches, the same value vector must back "a" in both
+ * batches. The <tt>TransferPair</tt> abstraction fails if different
+ * vectors appear across batches.
+ */
+
+public class OperatorRecordBatch implements CloseableRecordBatch {
+ static final org.slf4j.Logger logger =
org.slf4j.LoggerFactory.getLogger(OperatorRecordBatch.class);
+
+ private final OperatorDriver driver;
+ private final BatchAccessor batchAccessor;
+
+ public OperatorRecordBatch(FragmentContext context, PhysicalOperator
config, OperatorExec opExec) {
+ OperatorContext opContext = context.newOperatorContext(config);
+ opContext.getStats().startProcessing();
+
+ // Chicken-and-egg binding: the two objects must know about each
other. Pass the
+ // context to the operator exec via a bind method.
+
+ try {
+ opExec.bind(opContext);
+ driver = new OperatorDriver(opContext, opExec);
+ batchAccessor = opExec.batchAccessor();
+ } catch (UserException e) {
+ opContext.close();
+ throw e;
+ } catch (Throwable t) {
+ opContext.close();
+ throw UserException.executionError(t)
+ .addContext("Exception thrown from",
opExec.getClass().getSimpleName() + ".bind()")
+ .build(logger);
+ }
+ finally {
+ opContext.getStats().stopProcessing();
+ }
+ }
+
+ @Override
+ public FragmentContext getContext() {
+
+ // Backward compatibility with the full server context. Awkward for
testing
+
+ FragmentContext fragmentContext = fragmentContext();
+ if (fragmentContext instanceof FragmentContext) {
--- End diff --
not clear what we are doing here. why can't we just return fragmentContext ?
---
