EvictionAlgorithm.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 javax.print.attribute.EnumSyntax;

/**
 * The algorithm used to determine when to perform an {@link org.apache.geode.cache.EvictionAction}
 * 
 * @since GemFire 5.0
 * @see org.apache.geode.cache.EvictionAction
 * @see org.apache.geode.internal.cache.EvictionAttributesImpl
 */
public final class EvictionAlgorithm extends EnumSyntax {
  private static final long serialVersionUID = 5778669432033106789L;
  /**
   * The canonical EvictionAction that represents no eviction action
   */
  public static final EvictionAlgorithm NONE = new EvictionAlgorithm(0);

  /**
   * An algorithm that considers the number of Entries in the Region before invoking its
   * {@link EvictionAction}
   */
  public static final EvictionAlgorithm LRU_ENTRY = new EvictionAlgorithm(1);

  /**
   * An algorithm that considers the JVM heap size before invoking its {@link EvictionAction}
   */
  public static final EvictionAlgorithm LRU_HEAP = new EvictionAlgorithm(2);

  /**
   * An algorithm that considers the amount of bytes consumed by the Region before invoking its
   * {@link EvictionAction}
   */
  public static final EvictionAlgorithm LRU_MEMORY = new EvictionAlgorithm(3);

  /**
   * An algorithm that considers the number of Entries in the Region before invoking its
   * {@link EvictionAction}
   * 
   * @deprecated
   */
  public static final EvictionAlgorithm LIFO_ENTRY = new EvictionAlgorithm(4);

  /**
   * An algorithm that considers the amount of bytes consumed by the Region before invoking its
   * {@link EvictionAction}
   * 
   * @deprecated
   */
  public static final EvictionAlgorithm LIFO_MEMORY = new EvictionAlgorithm(5);

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

  private static final String[] stringTable = {"none", "lru-entry-count", "lru-heap-percentage",
      "lru-memory-size", "lifo-entry-count", "lifo-memory-size"};

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

  // TODO post Java 1.8.0u45 uncomment final flag, see JDK-8076152
  private static /* final */ EvictionAlgorithm[] enumValueTable =
      {NONE, LRU_ENTRY, LRU_HEAP, LRU_MEMORY, LIFO_ENTRY, LIFO_MEMORY,};

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

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

  public static EvictionAlgorithm parseAction(String s) {
    if (s == null)
      return null;
    if (s.length() < 1)
      return null;
    for (int i = 0; i < stringTable.length; ++i) {
      if (s.equals(stringTable[i])) {
        return enumValueTable[i];
      }
    }
    return null;
  }

  public final boolean isLRUEntry() {
    return this == LRU_ENTRY;
  }

  public final boolean isLRUMemory() {
    return this == LRU_MEMORY;
  }

  public final boolean isLRUHeap() {
    return this == LRU_HEAP;
  }

  /** returns true if this object uses a least-recently-used algorithm */
  public boolean isLRU() {
    return this.isLRUEntry() || this.isLRUMemory() || this.isLRUHeap();
  }

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

  /**
   * @deprecated
   */
  public boolean isLIFO() {
    return this == LIFO_ENTRY || this == LIFO_MEMORY;
  }
}