exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/scan/v3/lifecycle/ScanEventListener.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.scan.v3.lifecycle;

import org.apache.drill.exec.ops.OperatorContext;
import org.apache.drill.exec.physical.impl.scan.RowBatchReader;
import org.apache.drill.exec.physical.impl.scan.ScanOperatorEvents;
import org.apache.drill.exec.physical.impl.scan.v3.ScanLifecycleBuilder;

/**
 * Binds the scan lifeycle to the scan operator. Defers creating
 * the scan lifecycle until the operator context is available
 * to allow most fields in the scan lifecycle to be immutable.
 */
public class ScanEventListener implements ScanOperatorEvents {

  private final ScanLifecycleBuilder scanOptions;
  private ScanLifecycle scanLifecycle;

  public ScanEventListener(ScanLifecycleBuilder scanOptions) {
    this.scanOptions = scanOptions;
  }

  @Override
  public void bind(OperatorContext context) {
    scanLifecycle = scanOptions.build(context);
  }

  @Override
  public RowBatchReader nextReader() {
    return scanLifecycle.nextReader();
  }

  @Override
  public void close() {
    if (scanLifecycle != null) {
      scanLifecycle.close();
      scanLifecycle = null;
    }
  }
}