org.wso2.carbon.caching.impl

Class CacheStatisticsImpl

java.lang.Object

org.wso2.carbon.caching.impl.CacheStatisticsImpl

All Implemented Interfaces:

CacheStatistics

public class CacheStatisticsImpl
extends Object
implements CacheStatistics

TODO: class description

Constructor Summary

Constructors

Constructor and Description
CacheStatisticsImpl()

Method Summary

Methods

Modifier and Type	Method and Description
void	clear() Clears the statistics counters to 0 for the associated Cache.
float	getAverageGetMillis() The mean time to execute gets.
float	getAveragePutMillis() The mean time to execute puts.
float	getAverageRemoveMillis() The mean time to execute removes.
long	getCacheEvictions() The total number of evictions from the cache.
long	getCacheGets() The total number of requests to the cache.
float	getCacheHitPercentage() This is a measure of cache efficiency.
long	getCacheHits() The number of get requests that were satisfied by the cache.
long	getCacheMisses() A miss is a get request which is not satisfied.
float	getCacheMissPercentage() Returns the percentage of cache accesses that did not find a requested entry in the cache.
long	getCachePuts() The total number of puts to the cache.
long	getCacheRemovals() The total number of removals from the cache.
Date	getStartAccumulationDate() The date from which statistics have been accumulated.

Methods inherited from class java.lang.Object

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

Constructor Detail

CacheStatisticsImpl

public CacheStatisticsImpl()

Method Detail

clear

public void clear()

Description copied from interface: CacheStatistics

Clears the statistics counters to 0 for the associated Cache.

Specified by:

clear in interface CacheStatistics

getStartAccumulationDate

public Date getStartAccumulationDate()

Description copied from interface: CacheStatistics

The date from which statistics have been accumulated. Because statistics can be cleared, this is not necessarily since the cache was started.

Specified by:

getStartAccumulationDate in interface CacheStatistics

Returns:

the date statistics started being accumulated

getCacheHits

public long getCacheHits()

Description copied from interface: CacheStatistics

The number of get requests that were satisfied by the cache.

In a caches with multiple tiered storage, a hit may be implemented as a hit to the cache or to the first tier.

Specified by:

getCacheHits in interface CacheStatistics

Returns:

the number of hits

getCacheHitPercentage

public float getCacheHitPercentage()

Description copied from interface: CacheStatistics

This is a measure of cache efficiency.

It is calculated as CacheStatistics.getCacheHits() divided by CacheStatistics.getCacheGets() * 100.

Specified by:

getCacheHitPercentage in interface CacheStatistics

Returns:

the percentage of successful hits, as a decimal e.g 75.

getCacheMisses

public long getCacheMisses()

Description copied from interface: CacheStatistics

A miss is a get request which is not satisfied.

In a simple cache a miss occurs when the cache does not satisfy the request.

In a caches with multiple tiered storage, a miss may be implemented as a miss to the cache or to the first tier.

In a read-through cache a miss is an absence of the key in the cache which will trigger a call to a CacheLoader. So it is still a miss even though the cache will load and return the value.

Refer to the implementation for precise semantics.

Specified by:

getCacheMisses in interface CacheStatistics

Returns:

the number of misses

getCacheMissPercentage

public float getCacheMissPercentage()

Description copied from interface: CacheStatistics

Returns the percentage of cache accesses that did not find a requested entry in the cache.

This is calculated as CacheStatistics.getCacheMisses() divided by CacheStatistics.getCacheGets() * 100.

Specified by:

getCacheMissPercentage in interface CacheStatistics

Returns:

the percentage of accesses that failed to find anything

getCacheGets

public long getCacheGets()

Description copied from interface: CacheStatistics

The total number of requests to the cache. This will be equal to the sum of the hits and misses.

A "get" is an operation that returns the current or previous value. It does not include checking for the existence of a key.

In a caches with multiple tiered storage, a gets may be implemented as a get to the cache or to the first tier.

Specified by:

getCacheGets in interface CacheStatistics

Returns:

the number of gets

getCachePuts

public long getCachePuts()

Description copied from interface: CacheStatistics

The total number of puts to the cache.

A put is counted even if it is immediately evicted.

Replaces, where a put occurs which overrides an existing mapping is counted as a put.

Specified by:

getCachePuts in interface CacheStatistics

Returns:

the number of hits

getCacheRemovals

public long getCacheRemovals()

Description copied from interface: CacheStatistics

The total number of removals from the cache. This does not include evictions, where the cache itself initiates the removal to make space.

Specified by:

getCacheRemovals in interface CacheStatistics

Returns:

the number of hits

getCacheEvictions

public long getCacheEvictions()

Description copied from interface: CacheStatistics

The total number of evictions from the cache. An eviction is a removal initiated by the cache itself to free up space. An eviction is not treated as a removal and does not appear in the removal counts.

Specified by:

getCacheEvictions in interface CacheStatistics

Returns:

the number of evictions from the cache

getAverageGetMillis

public float getAverageGetMillis()

Description copied from interface: CacheStatistics

The mean time to execute gets.

In a read-through cache the time taken to load an entry on miss is not included in get time.

Specified by:

getAverageGetMillis in interface CacheStatistics

Returns:

the time in milliseconds

getAveragePutMillis

public float getAveragePutMillis()

Description copied from interface: CacheStatistics

The mean time to execute puts.

Specified by:

getAveragePutMillis in interface CacheStatistics

Returns:

the time in milliseconds

getAverageRemoveMillis

public float getAverageRemoveMillis()

Description copied from interface: CacheStatistics

The mean time to execute removes.

Specified by:

getAverageRemoveMillis in interface CacheStatistics

Returns:

the time in milliseconds