ceph/src/rocksdb/java/src/main/java/org/rocksdb/ClockCache.java

   1 // Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
   2 //  This source code is licensed under both the GPLv2 (found in the
   3 //  COPYING file in the root directory) and Apache 2.0 License
   4 //  (found in the LICENSE.Apache file in the root directory).
   5
   6 package org.rocksdb;
   7
   8 /**
   9  * Similar to {@link LRUCache}, but based on the CLOCK algorithm with
  10  * better concurrent performance in some cases
  11  */
  12 public class ClockCache extends Cache {
  13
  14   /**
  15    * Create a new cache with a fixed size capacity.
  16    *
  17    * @param capacity The fixed size capacity of the cache
  18    */
  19   public ClockCache(final long capacity) {
  20     super(newClockCache(capacity, -1, false));
  21   }
  22
  23   /**
  24    * Create a new cache with a fixed size capacity. The cache is sharded
  25    * to 2^numShardBits shards, by hash of the key. The total capacity
  26    * is divided and evenly assigned to each shard.
  27    * numShardBits = -1 means it is automatically determined: every shard
  28    * will be at least 512KB and number of shard bits will not exceed 6.
  29    *
  30    * @param capacity The fixed size capacity of the cache
  31    * @param numShardBits The cache is sharded to 2^numShardBits shards,
  32    *     by hash of the key
  33    */
  34   public ClockCache(final long capacity, final int numShardBits) {
  35     super(newClockCache(capacity, numShardBits, false));
  36   }
  37
  38   /**
  39    * Create a new cache with a fixed size capacity. The cache is sharded
  40    * to 2^numShardBits shards, by hash of the key. The total capacity
  41    * is divided and evenly assigned to each shard. If strictCapacityLimit
  42    * is set, insert to the cache will fail when cache is full.
  43    * numShardBits = -1 means it is automatically determined: every shard
  44    * will be at least 512KB and number of shard bits will not exceed 6.
  45    *
  46    * @param capacity The fixed size capacity of the cache
  47    * @param numShardBits The cache is sharded to 2^numShardBits shards,
  48    *     by hash of the key
  49    * @param strictCapacityLimit insert to the cache will fail when cache is full
  50    */
  51   public ClockCache(final long capacity, final int numShardBits,
  52       final boolean strictCapacityLimit) {
  53     super(newClockCache(capacity, numShardBits, strictCapacityLimit));
  54   }
  55
  56   private native static long newClockCache(final long capacity,
  57       final int numShardBits, final boolean strictCapacityLimit);
  58   @Override protected final native void disposeInternal(final long handle);
  59 }