org.apache.jackrabbit.oak.cache

Class AbstractCacheStats

java.lang.Object

javax.management.StandardMBean

org.apache.jackrabbit.oak.commons.jmx.AnnotatedStandardMBean

org.apache.jackrabbit.oak.cache.AbstractCacheStats

All Implemented Interfaces:

javax.management.DynamicMBean, javax.management.MBeanRegistration, CacheStatsMBean

Direct Known Subclasses:

CacheStats

public abstract class AbstractCacheStats
extends AnnotatedStandardMBean
implements CacheStatsMBean

Abstract base class for providing cache statistic via the CacheStatsMBean.

Field Summary

Fields inherited from interface org.apache.jackrabbit.oak.api.jmx.CacheStatsMBean

TYPE

Method Summary

Modifier and Type	Method and Description
java.lang.String	cacheInfoAsString() Gathers the stats of the cache for logging.
double	getAverageLoadPenalty() Returns the average time spent loading new values.
long	getEvictionCount() Returns the number of times an entry has been evicted.
long	getHitCount() Returns the number of times com.google.common.cache.Cache lookup methods have returned a cached value.
double	getHitRate() Returns the ratio of cache requests which were hits.
long	getLoadCount() Returns the total number of times that com.google.common.cache.Cache lookup methods attempted to load new values.
long	getLoadExceptionCount() Returns the number of times com.google.common.cache.Cache lookup methods threw an exception while loading a new value.
double	getLoadExceptionRate() Returns the ratio of cache loading attempts which threw exceptions.
long	getLoadSuccessCount() Returns the number of times com.google.common.cache.Cache lookup methods have successfully loaded a new value.
long	getMissCount() Returns the number of times com.google.common.cache.Cache lookup methods have returned an uncached (newly loaded) value, or null.
double	getMissRate() Returns the ratio of cache requests which were misses.
@NotNull java.lang.String	getName()
long	getRequestCount() Returns the number of times com.google.common.cache.Cache lookup methods have returned either a cached or uncached value.
long	getTotalLoadTime() Returns the total number of nanoseconds the cache has spent loading new values.
void	resetStats() Reset the cache stats
static java.lang.String	timeInWords(long nanos)

Methods inherited from class javax.management.StandardMBean

getAttribute, getAttributes, getImplementation, getImplementationClass, getMBeanInfo, getMBeanInterface, invoke, postDeregister, postRegister, preDeregister, preRegister, setAttribute, setAttributes, setImplementation

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface org.apache.jackrabbit.oak.api.jmx.CacheStatsMBean

estimateCurrentWeight, getElementCount, getMaxTotalWeight

Method Detail

resetStats

public void resetStats()

Description copied from interface: CacheStatsMBean

Reset the cache stats

Specified by:

resetStats in interface CacheStatsMBean

getName

@NotNull
public @NotNull java.lang.String getName()

Specified by:

getName in interface CacheStatsMBean

getRequestCount

public long getRequestCount()

Description copied from interface: CacheStatsMBean

Returns the number of times com.google.common.cache.Cache lookup methods have returned either a cached or uncached value. This is defined as getHitCount + getMissCount.

Specified by:

getRequestCount in interface CacheStatsMBean

getHitCount

public long getHitCount()

Description copied from interface: CacheStatsMBean

Returns the number of times com.google.common.cache.Cache lookup methods have returned a cached value.

Specified by:

getHitCount in interface CacheStatsMBean

getHitRate

public double getHitRate()

Description copied from interface: CacheStatsMBean

Returns the ratio of cache requests which were hits. This is defined as getHitCount / getRequestCount, or 1.0 when getRequestCount == 0. Note that getHitRate + getMissRate =~ 1.0.

Specified by:

getHitRate in interface CacheStatsMBean

getMissCount

public long getMissCount()

Description copied from interface: CacheStatsMBean

Returns the number of times com.google.common.cache.Cache lookup methods have returned an uncached (newly loaded) value, or null. Multiple concurrent calls to com.google.common.cache.Cache lookup methods on an absent value can result in multiple misses, all returning the results of a single cache load operation.

Specified by:

getMissCount in interface CacheStatsMBean

getMissRate

public double getMissRate()

Description copied from interface: CacheStatsMBean

Returns the ratio of cache requests which were misses. This is defined as getMissCount / getRequestCount, or 0.0 when getRequestCount == 0. Note that getHitRate + getMissRate =~ 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 getMissCount >= getLoadSuccessCount + getLoadExceptionCount. Multiple concurrent misses for the same key will result in a single load operation.

Specified by:

getMissRate in interface CacheStatsMBean

getLoadCount

public long getLoadCount()

Description copied from interface: CacheStatsMBean

Returns the total number of times that com.google.common.cache.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 getLoadSuccessCount + getLoadExceptionCount.

Specified by:

getLoadCount in interface CacheStatsMBean

getLoadSuccessCount

public long getLoadSuccessCount()

Description copied from interface: CacheStatsMBean

Returns the number of times com.google.common.cache.Cache lookup methods have successfully loaded a new value. This is always incremented in conjunction with CacheStatsMBean.getMissCount(), though getMissCount is also incremented when an exception is encountered during cache loading (see CacheStatsMBean.getLoadExceptionCount()). Multiple concurrent misses for the same key will result in a single load operation.

Specified by:

getLoadSuccessCount in interface CacheStatsMBean

getLoadExceptionCount

public long getLoadExceptionCount()

Description copied from interface: CacheStatsMBean

Returns the number of times com.google.common.cache.Cache lookup methods threw an exception while loading a new value. This is always incremented in conjunction with getMissCount, though getMissCount is also incremented when cache loading completes successfully (see CacheStatsMBean.getLoadSuccessCount()). Multiple concurrent misses for the same key will result in a single load operation.

Specified by:

getLoadExceptionCount in interface CacheStatsMBean

getLoadExceptionRate

public double getLoadExceptionRate()

Description copied from interface: CacheStatsMBean

Returns the ratio of cache loading attempts which threw exceptions. This is defined as getLoadExceptionCount / (getLoadSuccessCount + getLoadExceptionCount), or 0.0 when getLoadSuccessCount + getLoadExceptionCount == 0.

Specified by:

getLoadExceptionRate in interface CacheStatsMBean

getTotalLoadTime

public long getTotalLoadTime()

Description copied from interface: CacheStatsMBean

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 getLoadSuccessCount or getLoadExceptionCount is incremented.

Specified by:

getTotalLoadTime in interface CacheStatsMBean

getAverageLoadPenalty

public double getAverageLoadPenalty()

Description copied from interface: CacheStatsMBean

Returns the average time spent loading new values. This is defined as getTotalLoadTime / (getLoadSuccessCount + getLoadExceptionCount).

Specified by:

getAverageLoadPenalty in interface CacheStatsMBean

getEvictionCount

public long getEvictionCount()

Description copied from interface: CacheStatsMBean

Returns the number of times an entry has been evicted. This count does not include manual com.google.common.cache.Cache#invalidate invalidations.

Specified by:

getEvictionCount in interface CacheStatsMBean

cacheInfoAsString

public java.lang.String cacheInfoAsString()

Description copied from interface: CacheStatsMBean

Gathers the stats of the cache for logging.

Specified by:

cacheInfoAsString in interface CacheStatsMBean

timeInWords

public static java.lang.String timeInWords(long nanos)