org.forstdb.LRUCache Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of forstjni Show documentation
ForSt fat jar with modifications specific for Apache Flink that contains .so files for linux32 and linux64 (glibc and musl-libc), jnilib files for Mac OSX, and a .dll for Windows x64.
There is a newer version: 0.1.2-beta
Show newest version
// Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
//  This source code is licensed under both the GPLv2 (found in the
//  COPYING file in the root directory) and Apache 2.0 License
//  (found in the LICENSE.Apache file in the root directory).

package org.forstdb;

/**
 * Least Recently Used Cache
 */
public class LRUCache extends Cache {

  /**
   * Create a new cache with a fixed size capacity
   *
   * @param capacity The fixed size capacity of the cache
   */
  public LRUCache(final long capacity) {
    this(capacity, -1, false, 0.0, 0.0);
  }

  /**
   * Create a new cache with a fixed size capacity. The cache is sharded
   * to 2^numShardBits shards, by hash of the key. The total capacity
   * is divided and evenly assigned to each shard.
   * numShardBits = -1 means it is automatically determined: every shard
   * will be at least 512KB and number of shard bits will not exceed 6.
   *
   * @param capacity The fixed size capacity of the cache
   * @param numShardBits The cache is sharded to 2^numShardBits shards,
   *     by hash of the key
   */
  public LRUCache(final long capacity, final int numShardBits) {
    super(newLRUCache(capacity, numShardBits, false, 0.0, 0.0));
  }

  /**
   * Create a new cache with a fixed size capacity. The cache is sharded
   * to 2^numShardBits shards, by hash of the key. The total capacity
   * is divided and evenly assigned to each shard. If strictCapacityLimit
   * is set, insert to the cache will fail when cache is full.
   * numShardBits = -1 means it is automatically determined: every shard
   * will be at least 512KB and number of shard bits will not exceed 6.
   *
   * @param capacity The fixed size capacity of the cache
   * @param numShardBits The cache is sharded to 2^numShardBits shards,
   *     by hash of the key
   * @param strictCapacityLimit insert to the cache will fail when cache is full
   */
  public LRUCache(final long capacity, final int numShardBits,
                  final boolean strictCapacityLimit) {
    super(newLRUCache(capacity, numShardBits, strictCapacityLimit, 0.0, 0.0));
  }

  /**
   * Create a new cache with a fixed size capacity. The cache is sharded
   * to 2^numShardBits shards, by hash of the key. The total capacity
   * is divided and evenly assigned to each shard. If strictCapacityLimit
   * is set, insert to the cache will fail when cache is full. User can also
   * set percentage of the cache reserves for high priority entries via
   * highPriPoolRatio.
   * numShardBits = -1 means it is automatically determined: every shard
   * will be at least 512KB and number of shard bits will not exceed 6.
   *
   * @param capacity The fixed size capacity of the cache
   * @param numShardBits The cache is sharded to 2^numShardBits shards,
   *     by hash of the key
   * @param strictCapacityLimit insert to the cache will fail when cache is full
   * @param highPriPoolRatio percentage of the cache reserves for high priority
   *     entries
   */
  public LRUCache(final long capacity, final int numShardBits, final boolean strictCapacityLimit,
      final double highPriPoolRatio) {
    super(newLRUCache(capacity, numShardBits, strictCapacityLimit, highPriPoolRatio, 0.0));
  }

  /**
   * Create a new cache with a fixed size capacity. The cache is sharded
   * to 2^numShardBits shards, by hash of the key. The total capacity
   * is divided and evenly assigned to each shard. If strictCapacityLimit
   * is set, insert to the cache will fail when cache is full. User can also
   * set percentage of the cache reserves for high priority entries and low
   * priority entries via highPriPoolRatio and lowPriPoolRatio.
   * numShardBits = -1 means it is automatically determined: every shard
   * will be at least 512KB and number of shard bits will not exceed 6.
   *
   * @param capacity The fixed size capacity of the cache
   * @param numShardBits The cache is sharded to 2^numShardBits shards,
   *     by hash of the key
   * @param strictCapacityLimit insert to the cache will fail when cache is full
   * @param highPriPoolRatio percentage of the cache reserves for high priority
   *     entries
   * @param lowPriPoolRatio percentage of the cache reserves for low priority
   *     entries
   */
  public LRUCache(final long capacity, final int numShardBits, final boolean strictCapacityLimit,
      final double highPriPoolRatio, final double lowPriPoolRatio) {
    super(newLRUCache(
        capacity, numShardBits, strictCapacityLimit, highPriPoolRatio, lowPriPoolRatio));
  }

  private static native long newLRUCache(final long capacity, final int numShardBits,
      final boolean strictCapacityLimit, final double highPriPoolRatio,
      final double lowPriPoolRatio);
  @Override protected final native void disposeInternal(final long handle);
}