1 package com.atlassian.cache;
2
3 import java.util.Comparator;
4
5 import javax.annotation.Nonnull;
6
7 import static com.atlassian.cache.StatisticsType.COUNTER;
8 import static com.atlassian.cache.StatisticsType.GAUGE;
9 import static com.atlassian.util.concurrent.Assertions.notNull;
10
11 /**
12 * An immutable representation of a statistics key for a Cache.
13 *
14 * This class is used by {@link ManagedCache#getStatistics()} to dynamically distinguish different cache
15 * statistics available for a {@link com.atlassian.cache.Cache}.
16 *
17 * @since v2.4.0
18 */
19 public enum CacheStatisticsKey
20 {
21 /**
22 * Returns the number of cached objects kept referenced by the {@link Cache} (depends on the cache implementation)
23 */
24 SIZE("size", GAUGE),
25
26 /**
27 * Returns the number of bytes used by the {@link Cache}.
28 * <p>
29 * Note: This is likely to be a very expensive statistic in some implementations, so consumers may want
30 * to discard it when it hasn't been explicitly requested. Even where available, the reported heap size
31 * is almost certain to be only an approximation of the cache's total memory use.
32 * </p>
33 */
34 HEAP_SIZE("heapSize", GAUGE),
35
36 /**
37 * Returns the number of times {@link Cache} lookup methods have returned a cached value.
38 */
39 HIT_COUNT("hitCount", COUNTER),
40
41 /**
42 * Returns the number of times {@link Cache} put methods have added a cached value.
43 */
44 PUT_COUNT("putCount", COUNTER),
45
46 /**
47 * Returns the number of times {@link Cache} remove methods have removed a cached value.
48 */
49 REMOVE_COUNT("removeCount", COUNTER),
50
51 /**
52 * Returns the number of times {@link Cache} lookup methods have returned an uncached (newly
53 * loaded) value, or null. Multiple concurrent calls to {@link Cache} lookup methods on an absent
54 * value can result in multiple misses, all returning the results of a single cache load
55 * operation.
56 */
57 MISS_COUNT("missCount", COUNTER),
58
59 /**
60 * Returns the number of times an entry has been evicted.
61 */
62 EVICTION_COUNT("evictionCount", COUNTER);
63
64
65
66 /** Sorts cache statistics keys by {@link #getLabel() label}. */
67 public static Comparator<CacheStatisticsKey> SORT_BY_LABEL = new Comparator<CacheStatisticsKey>()
68 {
69 @Override
70 public int compare(CacheStatisticsKey key1, CacheStatisticsKey key2)
71 {
72 return key1.getLabel().compareTo(key2.getLabel());
73 }
74 };
75
76 private final String label;
77 private final StatisticsType type;
78
79 private CacheStatisticsKey(String label, StatisticsType type)
80 {
81 this.label = notNull("label", label);
82 this.type = notNull("type", type);
83 }
84
85 /**
86 * Returns the label for this cache statistics key.
87 * This is intended to be the same as the {@link #name()}, except written in {@code camelCase}.
88 * @return the label for this cache statistics key.
89 */
90 @Nonnull
91 public String getLabel()
92 {
93 return label;
94 }
95
96 /**
97 * Returns the type of statistic that this is.
98 * Different types of statistics might render differently in a user interface.
99 * @return the type of statistic that this is.
100 */
101 @Nonnull
102 public StatisticsType getType()
103 {
104 return type;
105 }
106 }