geode-core/src/main/java/org/apache/geode/cache/EvictionAction.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.geode.cache;

import java.io.Serializable;

import javax.print.attribute.EnumSyntax;

import org.apache.geode.annotations.Immutable;

/**
 * The action that an {@link org.apache.geode.cache.EvictionAlgorithm} takes.
 *
 * @since GemFire 5.0
 * @see org.apache.geode.cache.EvictionAlgorithm
 * @see org.apache.geode.internal.cache.EvictionAttributesImpl
 */
@Immutable
public final class EvictionAction extends EnumSyntax implements Serializable {
  private static final long serialVersionUID = -98840597493242980L;
  /**
   * Canonical EvictionAction that represents no eviction
   */
  @Immutable
  public static final EvictionAction NONE = new EvictionAction(0);

  /**
   * Perform a {@link org.apache.geode.cache.Region#localDestroy(Object) localDestory} on the least
   * recently used region entry.
   */
  @Immutable
  public static final EvictionAction LOCAL_DESTROY = new EvictionAction(1);

  /**
   * Write the value of the least recently used region entry to disk and <code>null</code>-out its
   * value in the VM to free up heap space. Note that this action is only available when the region
   * has been configured to access data on disk.
   */
  @Immutable
  public static final EvictionAction OVERFLOW_TO_DISK = new EvictionAction(2);

  /**
   * The default eviction action is to {@linkplain #LOCAL_DESTROY locally destroy} an Entry.
   */
  @Immutable
  public static final EvictionAction DEFAULT_EVICTION_ACTION = LOCAL_DESTROY;

  private EvictionAction(int val) {
    super(val);
  }

  private static final String[] stringTable = {"none", "local-destroy", "overflow-to-disk",};

  @Override
  protected String[] getStringTable() {
    return stringTable;
  }

  // TODO post Java 1.8.0u45 uncomment final flag, see JDK-8076152
  @Immutable
  private static final EvictionAction[] enumValueTable = {NONE, LOCAL_DESTROY, OVERFLOW_TO_DISK};

  @Override
  protected EnumSyntax[] getEnumValueTable() {
    return enumValueTable;
  }

  public boolean isLocalDestroy() {
    return this == LOCAL_DESTROY;
  }

  public boolean isOverflowToDisk() {
    return this == OVERFLOW_TO_DISK;
  }

  public boolean isNone() {
    return this == NONE;
  }

  /**
   * Returns the eviction action the corresponds to the given parameter. Returns <code>null</code>
   * if no action corresponds.
   *
   * @since GemFire 6.5
   */
  public static EvictionAction parseValue(int v) {
    if (v < 0 || v >= enumValueTable.length) {
      return null;
    } else {
      return enumValueTable[v];
    }
  }

  /**
   *
   * @return the action parsed from the provided string. If there are problems with parsing NONE is
   *         returned.
   */
  public static EvictionAction parseAction(String s) {
    if (s == null)
      return NONE;
    if (s.length() < 1)
      return NONE;
    for (int i = 0; i < stringTable.length; ++i) {
      if (s.equals(stringTable[i])) {
        return enumValueTable[i];
      }
    }
    return NONE;
  }
}