exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/values/ValuesBatchCreator.java

/*
 * 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.values;

import java.io.ByteArrayInputStream;
import java.io.InputStream;
import java.nio.charset.StandardCharsets;
import java.util.Collections;
import java.util.List;

import org.apache.drill.common.exceptions.ExecutionSetupException;
import org.apache.drill.common.exceptions.UserException;
import org.apache.drill.common.types.TypeProtos;
import org.apache.drill.common.types.Types;
import org.apache.drill.exec.ops.ExecutorFragmentContext;
import org.apache.drill.exec.physical.config.Values;
import org.apache.drill.exec.physical.impl.BatchCreator;
import org.apache.drill.exec.physical.impl.scan.framework.BasicScanFactory;
import org.apache.drill.exec.physical.impl.scan.framework.ManagedReader;
import org.apache.drill.exec.physical.impl.scan.framework.ManagedScanFramework;
import org.apache.drill.exec.physical.impl.scan.framework.SchemaNegotiator;
import org.apache.drill.exec.record.CloseableRecordBatch;
import org.apache.drill.exec.record.RecordBatch;
import org.apache.drill.exec.store.easy.json.JsonStreamBatchReader;

public class ValuesBatchCreator implements BatchCreator<Values> {

  @Override
  public CloseableRecordBatch getBatch(ExecutorFragmentContext context,
    Values subScan, List<RecordBatch> children) throws ExecutionSetupException {
    assert children.isEmpty();
    try {
      ManagedScanFramework.ScanFrameworkBuilder builder = createBuilder(subScan);
      return builder.buildScanOperator(context, subScan);
    } catch (UserException e) {
      // Rethrow user exceptions directly
      throw e;
    } catch (Throwable e) {
      // Wrap all others
      throw new ExecutionSetupException(e);
    }
  }

  private ManagedScanFramework.ScanFrameworkBuilder createBuilder(Values subScan) {
    ManagedScanFramework.ScanFrameworkBuilder builder = new ManagedScanFramework.ScanFrameworkBuilder();
    builder.setUserName(subScan.getUserName());
    builder.providedSchema(subScan.getSchema());

    ManagedScanFramework.ReaderFactory readerFactory = new BasicScanFactory(Collections.singletonList(
      getRecordReader(new ByteArrayInputStream(subScan.getContent().getBytes(StandardCharsets.UTF_8)))).iterator());
    builder.setReaderFactory(readerFactory);
    builder.nullType(Types.optional(TypeProtos.MinorType.VARCHAR));
    return builder;
  }

  private static ManagedReader<SchemaNegotiator> getRecordReader(InputStream source) {
    return new JsonStreamBatchReader(source);
  }
}