Class CacheStats
Cache
.
Cache statistics are incremented according to the following rules:
- When a cache lookup encounters an existing cache entry
hitCount
is incremented. - When a cache lookup first encounters a missing cache entry, a new entry is loaded.
- After successfully loading an entry
missCount
andloadSuccessCount
are incremented, and the total loading time, in nanoseconds, is added tototalLoadTime
. - When an exception is thrown while loading an entry,
missCount
andloadFailureCount
are incremented, and the total loading time, in nanoseconds, is added tototalLoadTime
. - Cache lookups that encounter a missing cache entry that is still loading will wait
for loading to complete (whether successful or not) and then increment
missCount
.
- After successfully loading an entry
- When an entry is computed through the asMap the
loadSuccessCount
orloadFailureCount
is incremented. - When an entry is evicted from the cache,
evictionCount
is incremented and the weight added toevictionWeight
. - No stats are modified when a cache entry is invalidated or manually removed.
- No stats are modified by non-computing operations invoked on the asMap view of the cache.
A lookup is specifically defined as an invocation of one of the methods
LoadingCache.get(Object)
, Cache.get(Object, java.util.function.Function)
, or
LoadingCache.getAll(Iterable)
.
This is a value-based class; use of identity-sensitive operations (including reference
equality (==
), identity hash code, or synchronization) on instances of CacheStats
may have unpredictable results and should be avoided.
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Field Summary
FieldsModifier and TypeFieldDescriptionprivate static final CacheStats
private final long
private final long
private final long
private final long
private final long
private final long
private final long
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Constructor Summary
ConstructorsConstructorDescriptionCacheStats
(@org.checkerframework.checker.index.qual.NonNegative long hitCount, @org.checkerframework.checker.index.qual.NonNegative long missCount, @org.checkerframework.checker.index.qual.NonNegative long loadSuccessCount, @org.checkerframework.checker.index.qual.NonNegative long loadFailureCount, @org.checkerframework.checker.index.qual.NonNegative long totalLoadTime, @org.checkerframework.checker.index.qual.NonNegative long evictionCount) Deprecated.This constructor is scheduled for removal in version 3.0.0.CacheStats
(@org.checkerframework.checker.index.qual.NonNegative long hitCount, @org.checkerframework.checker.index.qual.NonNegative long missCount, @org.checkerframework.checker.index.qual.NonNegative long loadSuccessCount, @org.checkerframework.checker.index.qual.NonNegative long loadFailureCount, @org.checkerframework.checker.index.qual.NonNegative long totalLoadTime, @org.checkerframework.checker.index.qual.NonNegative long evictionCount, @org.checkerframework.checker.index.qual.NonNegative long evictionWeight) Deprecated. -
Method Summary
Modifier and TypeMethodDescription@org.checkerframework.checker.index.qual.NonNegative double
Returns the average time spent loading new values.static @NonNull CacheStats
empty()
Returns a statistics instance where no cache events have been recorded.boolean
@org.checkerframework.checker.index.qual.NonNegative long
Returns the number of times an entry has been evicted.@org.checkerframework.checker.index.qual.NonNegative long
Returns the sum of weights of evicted entries.int
hashCode()
@org.checkerframework.checker.index.qual.NonNegative long
hitCount()
Returns the number of timesCache
lookup methods have returned a cached value.@org.checkerframework.checker.index.qual.NonNegative double
hitRate()
Returns the ratio of cache requests which were hits.@org.checkerframework.checker.index.qual.NonNegative long
Returns the total number of times thatCache
lookup methods attempted to load new values.@org.checkerframework.checker.index.qual.NonNegative long
Returns the number of timesCache
lookup methods failed to load a new value, either because no value was found or an exception was thrown while loading.@org.checkerframework.checker.index.qual.NonNegative double
Returns the ratio of cache loading attempts which threw exceptions.@org.checkerframework.checker.index.qual.NonNegative long
Returns the number of timesCache
lookup methods have successfully loaded a new value.@NonNull CacheStats
minus
(@NonNull CacheStats other) Returns a newCacheStats
representing the difference between thisCacheStats
andother
.@org.checkerframework.checker.index.qual.NonNegative long
Returns the number of timesCache
lookup methods have returned an uncached (newly loaded) value, or null.@org.checkerframework.checker.index.qual.NonNegative double
missRate()
Returns the ratio of cache requests which were misses.static CacheStats
of
(@org.checkerframework.checker.index.qual.NonNegative long hitCount, @org.checkerframework.checker.index.qual.NonNegative long missCount, @org.checkerframework.checker.index.qual.NonNegative long loadSuccessCount, @org.checkerframework.checker.index.qual.NonNegative long loadFailureCount, @org.checkerframework.checker.index.qual.NonNegative long totalLoadTime, @org.checkerframework.checker.index.qual.NonNegative long evictionCount, @org.checkerframework.checker.index.qual.NonNegative long evictionWeight) Returns aCacheStats
representing the specified statistics.@NonNull CacheStats
plus
(@NonNull CacheStats other) Returns a newCacheStats
representing the sum of thisCacheStats
andother
.@org.checkerframework.checker.index.qual.NonNegative long
Returns the number of timesCache
lookup methods have returned either a cached or uncached value.private static long
saturatedAdd
(long a, long b) Returns the sum ofa
andb
unless it would overflow or underflow in which caseLong.MAX_VALUE
orLong.MIN_VALUE
is returned, respectively.private static long
saturatedSubtract
(long a, long b) Returns the difference ofa
andb
unless it would overflow or underflow in which caseLong.MAX_VALUE
orLong.MIN_VALUE
is returned, respectively.toString()
@org.checkerframework.checker.index.qual.NonNegative long
Returns the total number of nanoseconds the cache has spent loading new values.
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Field Details
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EMPTY_STATS
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hitCount
private final long hitCount -
missCount
private final long missCount -
loadSuccessCount
private final long loadSuccessCount -
loadFailureCount
private final long loadFailureCount -
totalLoadTime
private final long totalLoadTime -
evictionCount
private final long evictionCount -
evictionWeight
private final long evictionWeight
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Constructor Details
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CacheStats
@Deprecated public CacheStats(@org.checkerframework.checker.index.qual.NonNegative long hitCount, @org.checkerframework.checker.index.qual.NonNegative long missCount, @org.checkerframework.checker.index.qual.NonNegative long loadSuccessCount, @org.checkerframework.checker.index.qual.NonNegative long loadFailureCount, @org.checkerframework.checker.index.qual.NonNegative long totalLoadTime, @org.checkerframework.checker.index.qual.NonNegative long evictionCount) Deprecated.This constructor is scheduled for removal in version 3.0.0.Constructs a newCacheStats
instance.- Parameters:
hitCount
- the number of cache hitsmissCount
- the number of cache missesloadSuccessCount
- the number of successful cache loadsloadFailureCount
- the number of failed cache loadstotalLoadTime
- the total load time (success and failure)evictionCount
- the number of entries evicted from the cache
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CacheStats
@Deprecated public CacheStats(@org.checkerframework.checker.index.qual.NonNegative long hitCount, @org.checkerframework.checker.index.qual.NonNegative long missCount, @org.checkerframework.checker.index.qual.NonNegative long loadSuccessCount, @org.checkerframework.checker.index.qual.NonNegative long loadFailureCount, @org.checkerframework.checker.index.qual.NonNegative long totalLoadTime, @org.checkerframework.checker.index.qual.NonNegative long evictionCount, @org.checkerframework.checker.index.qual.NonNegative long evictionWeight) Deprecated.Constructs a newCacheStats
instance.Many parameters of the same type in a row is a bad thing, but this class is not constructed by end users and is too fine-grained for a builder.
- Parameters:
hitCount
- the number of cache hitsmissCount
- the number of cache missesloadSuccessCount
- the number of successful cache loadsloadFailureCount
- the number of failed cache loadstotalLoadTime
- the total load time (success and failure)evictionCount
- the number of entries evicted from the cacheevictionWeight
- the sum of weights of entries evicted from the cache
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Method Details
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of
public static CacheStats of(@org.checkerframework.checker.index.qual.NonNegative long hitCount, @org.checkerframework.checker.index.qual.NonNegative long missCount, @org.checkerframework.checker.index.qual.NonNegative long loadSuccessCount, @org.checkerframework.checker.index.qual.NonNegative long loadFailureCount, @org.checkerframework.checker.index.qual.NonNegative long totalLoadTime, @org.checkerframework.checker.index.qual.NonNegative long evictionCount, @org.checkerframework.checker.index.qual.NonNegative long evictionWeight) Returns aCacheStats
representing the specified statistics.- Parameters:
hitCount
- the number of cache hitsmissCount
- the number of cache missesloadSuccessCount
- the number of successful cache loadsloadFailureCount
- the number of failed cache loadstotalLoadTime
- the total load time (success and failure)evictionCount
- the number of entries evicted from the cacheevictionWeight
- the sum of weights of entries evicted from the cache
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empty
Returns a statistics instance where no cache events have been recorded.- Returns:
- an empty statistics instance
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requestCount
public @org.checkerframework.checker.index.qual.NonNegative long requestCount()Returns the number of timesCache
lookup methods have returned either a cached or uncached value. This is defined ashitCount + missCount
.Note: the values of the metrics are undefined in case of overflow (though it is guaranteed not to throw an exception). If you require specific handling, we recommend implementing your own stats collector.
- Returns:
- the
hitCount + missCount
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hitCount
public @org.checkerframework.checker.index.qual.NonNegative long hitCount()Returns the number of timesCache
lookup methods have returned a cached value.- Returns:
- the number of times
Cache
lookup methods have returned a cached value
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hitRate
public @org.checkerframework.checker.index.qual.NonNegative double hitRate()Returns the ratio of cache requests which were hits. This is defined ashitCount / requestCount
, or1.0
whenrequestCount == 0
. Note thathitRate + missRate =~ 1.0
.- Returns:
- the ratio of cache requests which were hits
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missCount
public @org.checkerframework.checker.index.qual.NonNegative long missCount()Returns the number of timesCache
lookup methods have returned an uncached (newly loaded) value, or null. Multiple concurrent calls toCache
lookup methods on an absent value can result in multiple misses, all returning the results of a single cache load operation.- Returns:
- the number of times
Cache
lookup methods have returned an uncached (newly loaded) value, or null
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missRate
public @org.checkerframework.checker.index.qual.NonNegative double missRate()Returns the ratio of cache requests which were misses. This is defined asmissCount / requestCount
, or0.0
whenrequestCount == 0
. Note thathitRate + missRate =~ 1.0
. Cache misses include all requests which weren't cache hits, including requests which resulted in either successful or failed loading attempts, and requests which waited for other threads to finish loading. It is thus the case thatmissCount >= loadSuccessCount + loadFailureCount
. Multiple concurrent misses for the same key will result in a single load operation.- Returns:
- the ratio of cache requests which were misses
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loadCount
public @org.checkerframework.checker.index.qual.NonNegative long loadCount()Returns the total number of times thatCache
lookup methods attempted to load new values. This includes both successful load operations, as well as those that threw exceptions. This is defined asloadSuccessCount + loadFailureCount
.Note: the values of the metrics are undefined in case of overflow (though it is guaranteed not to throw an exception). If you require specific handling, we recommend implementing your own stats collector.
- Returns:
- the
loadSuccessCount + loadFailureCount
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loadSuccessCount
public @org.checkerframework.checker.index.qual.NonNegative long loadSuccessCount()Returns the number of timesCache
lookup methods have successfully loaded a new value. This is always incremented in conjunction withmissCount
, thoughmissCount
is also incremented when an exception is encountered during cache loading (seeloadFailureCount
). Multiple concurrent misses for the same key will result in a single load operation.- Returns:
- the number of times
Cache
lookup methods have successfully loaded a new value
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loadFailureCount
public @org.checkerframework.checker.index.qual.NonNegative long loadFailureCount()Returns the number of timesCache
lookup methods failed to load a new value, either because no value was found or an exception was thrown while loading. This is always incremented in conjunction withmissCount
, thoughmissCount
is also incremented when cache loading completes successfully (seeloadSuccessCount
). Multiple concurrent misses for the same key will result in a single load operation.- Returns:
- the number of times
Cache
lookup methods failed to load a new value
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loadFailureRate
public @org.checkerframework.checker.index.qual.NonNegative double loadFailureRate()Returns the ratio of cache loading attempts which threw exceptions. This is defined asloadFailureCount / (loadSuccessCount + loadFailureCount)
, or0.0
whenloadSuccessCount + loadFailureCount == 0
.Note: the values of the metrics are undefined in case of overflow (though it is guaranteed not to throw an exception). If you require specific handling, we recommend implementing your own stats collector.
- Returns:
- the ratio of cache loading attempts which threw exceptions
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totalLoadTime
public @org.checkerframework.checker.index.qual.NonNegative long totalLoadTime()Returns the total number of nanoseconds the cache has spent loading new values. This can be used to calculate the miss penalty. This value is increased every timeloadSuccessCount
orloadFailureCount
is incremented.- Returns:
- the total number of nanoseconds the cache has spent loading new values
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averageLoadPenalty
public @org.checkerframework.checker.index.qual.NonNegative double averageLoadPenalty()Returns the average time spent loading new values. This is defined astotalLoadTime / (loadSuccessCount + loadFailureCount)
.Note: the values of the metrics are undefined in case of overflow (though it is guaranteed not to throw an exception). If you require specific handling, we recommend implementing your own stats collector.
- Returns:
- the average time spent loading new values
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evictionCount
public @org.checkerframework.checker.index.qual.NonNegative long evictionCount()Returns the number of times an entry has been evicted. This count does not include manual invalidations.- Returns:
- the number of times an entry has been evicted
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evictionWeight
public @org.checkerframework.checker.index.qual.NonNegative long evictionWeight()Returns the sum of weights of evicted entries. This total does not include manual invalidations.- Returns:
- the sum of weights of evicted entities
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minus
Returns a newCacheStats
representing the difference between thisCacheStats
andother
. Negative values, which aren't supported byCacheStats
will be rounded up to zero.- Parameters:
other
- the statistics to subtract with- Returns:
- the difference between this instance and
other
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plus
Returns a newCacheStats
representing the sum of thisCacheStats
andother
.Note: the values of the metrics are undefined in case of overflow (though it is guaranteed not to throw an exception). If you require specific handling, we recommend implementing your own stats collector.
- Parameters:
other
- the statistics to add with- Returns:
- the sum of the statistics
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saturatedSubtract
private static long saturatedSubtract(long a, long b) Returns the difference ofa
andb
unless it would overflow or underflow in which caseLong.MAX_VALUE
orLong.MIN_VALUE
is returned, respectively. -
saturatedAdd
private static long saturatedAdd(long a, long b) Returns the sum ofa
andb
unless it would overflow or underflow in which caseLong.MAX_VALUE
orLong.MIN_VALUE
is returned, respectively. -
hashCode
public int hashCode() -
equals
-
toString
-