CacheStats (caffeine 2.8.0 API)

java.lang.Object
- com.github.benmanes.caffeine.cache.stats.CacheStats

```
@Immutable
public final class CacheStats
extends Object
```
Statistics about the performance of a 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 and loadSuccessCount are incremented, and the total loading time, in nanoseconds, is added to totalLoadTime.
  - When an exception is thrown while loading an entry, missCount and loadFailureCount are incremented, and the total loading time, in nanoseconds, is added to totalLoadTime.
  - 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.
- When an entry is computed through the asMap the loadSuccessCount or loadFailureCount is incremented.
- When an entry is evicted from the cache, evictionCount is incremented and the weight added to evictionWeight.
- 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).

Constructor Summary

Constructors
Constructor and Description
`CacheStats(long hitCount, long missCount, long loadSuccessCount, long loadFailureCount, long totalLoadTime, long evictionCount)` Deprecated. This constructor is scheduled for removal in version 3.0.0.
`CacheStats(long hitCount, long missCount, long loadSuccessCount, long loadFailureCount, long totalLoadTime, long evictionCount, long evictionWeight)` Constructs a new `CacheStats` instance.

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`double`	`averageLoadPenalty()` Returns the average time spent loading new values.
`static @NonNull CacheStats`	`empty()` Returns a statistics instance where no cache events have been recorded.
`boolean`	`equals(Object o)`
`long`	`evictionCount()` Returns the number of times an entry has been evicted.
`long`	`evictionWeight()` Returns the sum of weights of evicted entries.
`int`	`hashCode()`
`long`	`hitCount()` Returns the number of times `Cache` lookup methods have returned a cached value.
`double`	`hitRate()` Returns the ratio of cache requests which were hits.
`long`	`loadCount()` Returns the total number of times that `Cache` lookup methods attempted to load new values.
`long`	`loadFailureCount()` Returns the number of times `Cache` lookup methods failed to load a new value, either because no value was found or an exception was thrown while loading.
`double`	`loadFailureRate()` Returns the ratio of cache loading attempts which threw exceptions.
`long`	`loadSuccessCount()` Returns the number of times `Cache` lookup methods have successfully loaded a new value.
`@NonNull CacheStats`	`minus(@NonNull CacheStats other)` Returns a new `CacheStats` representing the difference between this `CacheStats` and `other`.
`long`	`missCount()` Returns the number of times `Cache` lookup methods have returned an uncached (newly loaded) value, or null.
`double`	`missRate()` Returns the ratio of cache requests which were misses.
`@NonNull CacheStats`	`plus(@NonNull CacheStats other)` Returns a new `CacheStats` representing the sum of this `CacheStats` and `other`.
`long`	`requestCount()` Returns the number of times `Cache` lookup methods have returned either a cached or uncached value.
`String`	`toString()`
`long`	`totalLoadTime()` Returns the total number of nanoseconds the cache has spent loading new values.

Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait

- Constructor Detail
  - CacheStats
```
@Deprecated
public CacheStats(long hitCount,
                              long missCount,
                              long loadSuccessCount,
                              long loadFailureCount,
                              long totalLoadTime,
                              long evictionCount)
```
    Deprecated. This constructor is scheduled for removal in version 3.0.0.
    
    Constructs a new CacheStats instance.
    
    Parameters:
    
    hitCount - the number of cache hits
    
    missCount - the number of cache misses
    
    loadSuccessCount - the number of successful cache loads
    
    loadFailureCount - the number of failed cache loads
    
    totalLoadTime - the total load time (success and failure)
    
    evictionCount - the number of entries evicted from the cache
  - CacheStats
```
public CacheStats(long hitCount,
                  long missCount,
                  long loadSuccessCount,
                  long loadFailureCount,
                  long totalLoadTime,
                  long evictionCount,
                  long evictionWeight)
```
    Constructs a new CacheStats 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 hits
    
    missCount - the number of cache misses
    
    loadSuccessCount - the number of successful cache loads
    
    loadFailureCount - the number of failed cache loads
    
    totalLoadTime - the total load time (success and failure)
    
    evictionCount - the number of entries evicted from the cache
    
    evictionWeight - the sum of weights of entries evicted from the cache
- Method Detail
  - empty
```
public static @NonNull CacheStats empty()
```
    Returns a statistics instance where no cache events have been recorded.
    
    Returns:
    
    an empty statistics instance
  - requestCount
```
public long requestCount()
```
    Returns the number of times Cache lookup methods have returned either a cached or uncached value. This is defined as hitCount + 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
  - hitCount
```
public long hitCount()
```
    Returns the number of times Cache lookup methods have returned a cached value.
    
    Returns:
    
    the number of times Cache lookup methods have returned a cached value
  - hitRate
```
public double hitRate()
```
    Returns the ratio of cache requests which were hits. This is defined as hitCount / requestCount, or 1.0 when requestCount == 0. Note that hitRate + missRate =~ 1.0.
    
    Returns:
    
    the ratio of cache requests which were hits
  - missCount
```
public long missCount()
```
    Returns the number of times Cache lookup methods have returned an uncached (newly loaded) value, or null. Multiple concurrent calls to Cache 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
  - missRate
```
public double missRate()
```
    Returns the ratio of cache requests which were misses. This is defined as missCount / requestCount, or 0.0 when requestCount == 0. Note that hitRate + 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 that missCount >= 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
  - loadCount
```
public long loadCount()
```
    Returns the total number of times that Cache lookup methods attempted to load new values. This includes both successful load operations, as well as those that threw exceptions. This is defined as 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 loadSuccessCount + loadFailureCount
  - loadSuccessCount
```
public long loadSuccessCount()
```
    Returns the number of times Cache lookup methods have successfully loaded a new value. This is always incremented in conjunction with missCount, though missCount is also incremented when an exception is encountered during cache loading (see loadFailureCount). 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
  - loadFailureCount
```
public long loadFailureCount()
```
    Returns the number of times Cache 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 with missCount, though missCount is also incremented when cache loading completes successfully (see loadSuccessCount). 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
  - loadFailureRate
```
public double loadFailureRate()
```
    Returns the ratio of cache loading attempts which threw exceptions. This is defined as loadFailureCount / (loadSuccessCount + loadFailureCount), or 0.0 when loadSuccessCount + 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
  - totalLoadTime
```
public 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 time loadSuccessCount or loadFailureCount is incremented.
    
    Returns:
    
    the total number of nanoseconds the cache has spent loading new values
  - averageLoadPenalty
```
public double averageLoadPenalty()
```
    Returns the average time spent loading new values. This is defined as totalLoadTime / (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
  - evictionCount
```
public 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
  - evictionWeight
```
public 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
  - minus
```
public @NonNull CacheStats minus(@NonNull CacheStats other)
```
    Returns a new CacheStats representing the difference between this CacheStats and other. Negative values, which aren't supported by CacheStats will be rounded up to zero.
    
    Parameters:
    
    other - the statistics to subtract with
    
    Returns:
    
    the difference between this instance and other
  - plus
```
public @NonNull CacheStats plus(@NonNull CacheStats other)
```
    Returns a new CacheStats representing the sum of this CacheStats and other.
    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
  - hashCode
```
public int hashCode()
```
    Overrides:
    
    hashCode in class Object
  - equals
```
public boolean equals(Object o)
```
    Overrides:
    
    equals in class Object
  - toString
```
public String toString()
```
    Overrides:
    
    toString in class Object

Class CacheStats

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

CacheStats

CacheStats

Method Detail

empty

requestCount

hitCount

hitRate

missCount

missRate

loadCount

loadSuccessCount

loadFailureCount

loadFailureRate

totalLoadTime

averageLoadPenalty

evictionCount

evictionWeight

minus

plus

hashCode

equals

toString