ceph/src/rocksdb/java/src/main/java/org/rocksdb/CompactionPriority.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  * Compaction Priorities
  10  */
  11 public enum CompactionPriority {
  12
  13   /**
  14    * Slightly Prioritize larger files by size compensated by #deletes
  15    */
  16   ByCompensatedSize((byte)0x0),
  17
  18   /**
  19    * First compact files whose data's latest update time is oldest.
  20    * Try this if you only update some hot keys in small ranges.
  21    */
  22   OldestLargestSeqFirst((byte)0x1),
  23
  24   /**
  25    * First compact files whose range hasn't been compacted to the next level
  26    * for the longest. If your updates are random across the key space,
  27    * write amplification is slightly better with this option.
  28    */
  29   OldestSmallestSeqFirst((byte)0x2),
  30
  31   /**
  32    * First compact files whose ratio between overlapping size in next level
  33    * and its size is the smallest. It in many cases can optimize write
  34    * amplification.
  35    */
  36   MinOverlappingRatio((byte)0x3),
  37
  38   /**
  39    * Keeps a cursor(s) of the successor of the file (key range) was/were
  40    * compacted before, and always picks the next files (key range) in that
  41    * level. The file picking process will cycle through all the files in a
  42    * round-robin manner.
  43    */
  44   RoundRobin((byte)0x4);
  45
  46
  47   private final byte value;
  48
  49   CompactionPriority(final byte value) {
  50     this.value = value;
  51   }
  52
  53   /**
  54    * Returns the byte value of the enumerations value
  55    *
  56    * @return byte representation
  57    */
  58   public byte getValue() {
  59     return value;
  60   }
  61
  62   /**
  63    * Get CompactionPriority by byte value.
  64    *
  65    * @param value byte representation of CompactionPriority.
  66    *
  67    * @return {@link org.rocksdb.CompactionPriority} instance or null.
  68    * @throws java.lang.IllegalArgumentException if an invalid
  69    *     value is provided.
  70    */
  71   public static CompactionPriority getCompactionPriority(final byte value) {
  72     for (final CompactionPriority compactionPriority :
  73         CompactionPriority.values()) {
  74       if (compactionPriority.getValue() == value){
  75         return compactionPriority;
  76       }
  77     }
  78     throw new IllegalArgumentException(
  79         "Illegal value provided for CompactionPriority.");
  80   }
  81 }