Package org.atlanmod.commons.cache

Class CacheStats

  • @Immutable
@ParametersAreNonnullByDefault
public final class CacheStats
extends Object
    Statistics about the performance of a Cache.

    • Constructor Summary

      Constructors 
      Modifier Constructor Description
      protected CacheStats​(long hitCount, long missCount, long loadSuccessCount, long loadFailureCount, long totalLoadTime, long evictionCount)
      Constructs a new CacheStats.

    • Constructor Detail

      • CacheStats

        protected CacheStats​(@Nonnegative
                     long hitCount,
                     @Nonnegative
                     long missCount,
                     @Nonnegative
                     long loadSuccessCount,
                     @Nonnegative
                     long loadFailureCount,
                     @Nonnegative
                     long totalLoadTime,
                     @Nonnegative
                     long evictionCount)
        Constructs a new CacheStats.
        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) in nanoseconds
        evictionCount - the number of entries evicted from the cache

    • Method Detail

      • requestCount

        @Nonnegative
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.
        Returns:
        the hitCount + missCount

      • hitCount

        @Nonnegative
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

        @Nonnegative
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

        @Nonnegative
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

        @Nonnegative
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

        @Nonnegative
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.
        Returns:
        the loadSuccessCount + loadFailureCount

      • loadSuccessCount

        @Nonnegative
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

        @Nonnegative
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

        @Nonnegative
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.
        Returns:
        the ratio of cache loading attempts which threw exceptions

      • totalLoadTime

        @Nonnegative
public Duration 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

        @Nonnegative
public double averageLoadPenalty()
        Returns the average time spent loading new values. This is defined as totalLoadTime / (loadSuccessCount + loadFailureCount).
        Returns:
        the average time spent loading new values

      • evictionCount

        @Nonnegative
public long evictionCount()
        Returns the number of times an entry has been evicted. This count does not include manual Cache.invalidate(K).
        Returns:
        the number of times an entry has been evicted

      • minus

        @Nonnull
public CacheStats minus​(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

        @Nonnull
public CacheStats plus​(CacheStats other)
        Returns a new CacheStats representing the sum of this CacheStats and other.
        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​(@Nullable
                      Object o)
        Overrides:
        equals in class Object