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A module that is everything required to understands Druid Segments

There is a newer version: 30.0.1

/*
 * 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.druid.collections;

import com.google.common.base.Preconditions;
import org.apache.druid.java.util.common.ISE;
import org.apache.druid.utils.CloseableUtils;

import java.io.Closeable;
import java.util.concurrent.atomic.AtomicReference;

public class CloseableResourceHolder implements ResourceHolder
{
  private final AtomicReference resource;

  /**
   * Use {@link ResourceHolder#fromCloseable}.
   */
  CloseableResourceHolder(T resource)
  {
    this.resource = new AtomicReference<>(Preconditions.checkNotNull(resource, "resource"));
  }

  @Override
  public T get()
  {
    final T retVal = resource.get();
    if (retVal == null) {
      throw new ISE("Already closed");
    }
    return retVal;
  }

  @Override
  public void close()
  {
    final T oldResource = resource.getAndSet(null);
    CloseableUtils.closeAndWrapExceptions(oldResource);
  }
}