io.druid.query.ReferenceCountingSegmentQueryRunner Maven / Gradle / Ivy

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A module that is everything required to understands Druid Segments

There is a newer version: 0.12.3

/*
 * Licensed to Metamarkets Group Inc. (Metamarkets) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. Metamarkets 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 io.druid.query;

import com.metamx.common.guava.CloseQuietly;
import com.metamx.common.guava.ResourceClosingSequence;
import com.metamx.common.guava.Sequence;
import io.druid.segment.ReferenceCountingSegment;

import java.io.Closeable;
import java.util.Map;

/**
 */
public class ReferenceCountingSegmentQueryRunner implements QueryRunner
{
  private final QueryRunnerFactory> factory;
  private final ReferenceCountingSegment adapter;
  private final SegmentDescriptor descriptor;

  public ReferenceCountingSegmentQueryRunner(
      QueryRunnerFactory> factory,
      ReferenceCountingSegment adapter,
      SegmentDescriptor descriptor
  )
  {
    this.factory = factory;
    this.adapter = adapter;
    this.descriptor = descriptor;
  }

  @Override
  public Sequence run(final Query query, Map responseContext)
  {
    final Closeable closeable = adapter.increment();
    if (closeable != null) {
      try {
        final Sequence baseSequence = factory.createRunner(adapter).run(query, responseContext);

        return new ResourceClosingSequence(baseSequence, closeable);
      }
      catch (RuntimeException e) {
        CloseQuietly.close(closeable);
        throw e;
      }
    } else {
      // Segment was closed before we had a chance to increment the reference count
      return new ReportTimelineMissingSegmentQueryRunner(descriptor).run(query, responseContext);
    }
  }
}