Package com.github.javaparser.symbolsolver.cache

Class DefaultCacheStats

java.lang.Object

com.github.javaparser.symbolsolver.cache.DefaultCacheStats

All Implemented Interfaces:

CacheStats

public class DefaultCacheStats
extends Object
implements CacheStats

Statistics about the performance of a Cache. Instances of this class are immutable.

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 loadExceptionCount 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 evicted from the cache, evictionCount is incremented.
• No stats are modified when a cache entry is invalidated or manually removed.
• No stats are modified by operations invoked on the asMap view of the cache.

Constructor Summary

Constructors

Constructor	Description
DefaultCacheStats()	Constructs a new ICacheStats instance.
DefaultCacheStats(long hitCount, long missCount, long loadSuccessCount, long loadExceptionCount, long totalLoadTime, long evictionCount)	Constructs a new ICacheStats instance.

Method Summary

Modifier and Type	Method	Description
double	averageLoadPenalty()	Returns the average time spent loading new values.
boolean	equals(Object object)
long	evictionCount()	Returns the number of times an entry has been evicted.
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	loadExceptionCount()	Returns the number of times Cache lookup methods threw an exception while loading a new value.
double	loadExceptionRate()	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.
CacheStats	minus(CacheStats other)	Returns a new ICacheStats representing the difference between this ICacheStats 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.
CacheStats	plus(CacheStats other)	Returns a new ICacheStats representing the sum of this ICacheStats 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

DefaultCacheStats

public DefaultCacheStats()

Constructs a new ICacheStats instance.

DefaultCacheStats

public DefaultCacheStats(long hitCount,
                         long missCount,
                         long loadSuccessCount,
                         long loadExceptionCount,
                         long totalLoadTime,
                         long evictionCount)

Constructs a new ICacheStats instance.

Method Detail

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.

Specified by:

requestCount in interface CacheStats

hitCount

public long hitCount()

Returns the number of times Cache lookup methods have returned a cached value.

Specified by:

hitCount in interface CacheStats

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.

Specified by:

hitRate in interface CacheStats

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.

Specified by:

missCount in interface CacheStats

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 + loadExceptionCount. Multiple concurrent misses for the same key will result in a single load operation.

Specified by:

missRate in interface CacheStats

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 and those that threw exceptions. This is defined as loadSuccessCount + loadExceptionCount.

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.

Specified by:

loadCount in interface CacheStats

loadSuccessCount

public long loadSuccessCount()

Returns the number of times Cache lookup methods have successfully loaded a new value. This is usually incremented in conjunction with missCount, though missCount is also incremented when an exception is encountered during cache loading (see loadExceptionCount). Multiple concurrent misses for the same key will result in a single load operation. This may be incremented not in conjunction with missCount if the load occurs as a result of a refresh or if the cache loader returned more items than was requested. missCount may also be incremented not in conjunction with this (nor loadExceptionCount) on calls to getIfPresent.

Specified by:

loadSuccessCount in interface CacheStats

loadExceptionCount

public long loadExceptionCount()

Returns the number of times Cache lookup methods threw an exception while loading a new value. This is usually 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. This may be incremented not in conjunction with missCount if the load occurs as a result of a refresh or if the cache loader returned more items than was requested. missCount may also be incremented not in conjunction with this (nor loadSuccessCount) on calls to getIfPresent.

Specified by:

loadExceptionCount in interface CacheStats

loadExceptionRate

public double loadExceptionRate()

Returns the ratio of cache loading attempts which threw exceptions. This is defined as loadExceptionCount / (loadSuccessCount + loadExceptionCount), or 0.0 when loadSuccessCount + loadExceptionCount == 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.

Specified by:

loadExceptionRate in interface CacheStats

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 loadExceptionCount is incremented.

Specified by:

totalLoadTime in interface CacheStats

averageLoadPenalty

public double averageLoadPenalty()

Returns the average time spent loading new values. This is defined as totalLoadTime / (loadSuccessCount + loadExceptionCount).

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.

Specified by:

averageLoadPenalty in interface CacheStats

evictionCount

public long evictionCount()

Returns the number of times an entry has been evicted. This count does not include manual invalidations.

Specified by:

evictionCount in interface CacheStats

minus

public CacheStats minus(CacheStats other)

Returns a new ICacheStats representing the difference between this ICacheStats and other. Negative values, which aren't supported by ICacheStats will be rounded up to zero.

Specified by:

minus in interface CacheStats

plus

public CacheStats plus(CacheStats other)

Returns a new ICacheStats representing the sum of this ICacheStats 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.

Specified by:

plus in interface CacheStats

Since:

11.0

hashCode

public int hashCode()

Overrides:

hashCode in class Object

equals

public boolean equals(@CheckForNull
                      Object object)

Overrides:

equals in class Object

toString

public String toString()

Overrides:

toString in class Object