src/main/java/org/apache/datasketches/memory/MapHandle.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.datasketches.memory;

/**
 * A Handle for a memory-mapped, read-only file resource.
 * Please read Javadocs for {@link Handle}.
 *
 * @author Lee Rhodes
 * @author Roman Leventov
 */
//Joins a Read-only Handle with an AutoCloseable Map resource.
public class MapHandle implements Map, Handle {
  /**
   * Having at least one final field makes this class safe for concurrent publication.
   */
  final AllocateDirectMap dirMap;
  private BaseWritableMemoryImpl wMem;

  MapHandle(final AllocateDirectMap dirMap, final BaseWritableMemoryImpl wMem) {
    this.dirMap = dirMap;
    this.wMem = wMem;
  }

  @Override
  public Memory get() {
    return wMem;
  }

  @Override
  public void close() {
    if (dirMap.doClose()) {
      wMem = null;
    }
  }

  @Override
  public void load() {
    dirMap.load();
  }

  @Override
  public boolean isLoaded() {
    return dirMap.isLoaded();
  }

}