javax.cache
Interface CacheStatistics

@MXBean
public interface CacheStatistics

A management bean for cache statistics.

Statistics are accumulated from the time a cache is created. They can be reset to zero using clearStatistics().

There are no defined consistency semantics for statistics. Refer to the implementation for precise semantics.

Each cache's statistics object must be registered with an ObjectName that is unique and has the following:

Type: javax.cache:type=CacheStatistics

Required Attributes:

• CacheManager Name
• Cache Name

Since:

1.0

Author:

Greg Luck

Method Summary

void	clearStatistics() Clears the statistics counters to 0 for the associated Cache.
long	getAverageGetMillis() The mean time to execute gets.
long	getAveragePutMillis() The mean time to execute puts.
long	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() getCacheHits() divided by the total number of gets.
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.
String	getName()
String	getStatus() Gets the CacheStatus attribute of the Cache expressed as a String.
Date	statsAccumulatingFrom() The date from which statistics have been accumulated.

Method Detail

getName

String getName()

Returns:

the name of the Cache these statistics are for

getStatus

String getStatus()

Gets the CacheStatus attribute of the Cache expressed as a String.

Returns:

The status value from the CacheStatus enum class

clearStatistics

void clearStatistics()

Clears the statistics counters to 0 for the associated Cache.

statsAccumulatingFrom

Date statsAccumulatingFrom()

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

Returns:

the date statistics started being accumulated

getCacheHits

long getCacheHits()

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

Returns:

the number of hits

getCacheHitPercentage

float getCacheHitPercentage()

getCacheHits() divided by the total number of gets. This is a measure of cache efficiency.

Returns:

the percentage of successful hits, as a decimal

getCacheMisses

long getCacheMisses()

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 teh 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.

Returns:

the number of misses

getCacheMissPercentage

float getCacheMissPercentage()

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

Returns:

the percentage of accesses that failed to find anything

getCacheGets

long getCacheGets()

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.

Returns:

the number of gets

getCachePuts

long getCachePuts()

The total number of puts to the cache.

A put is counted even if it is immediately evicted. A replace includes a put and remove.

Returns:

the number of hits

getCacheRemovals

long getCacheRemovals()

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

A replace is a put that overwrites a mapping and is not considered a remove.

Returns:

the number of hits

getCacheEvictions

long getCacheEvictions()

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.

Returns:

the number of evictions from the cache

getAverageGetMillis

long getAverageGetMillis()

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.

Returns:

the time in milliseconds

getAveragePutMillis

long getAveragePutMillis()

The mean time to execute puts.

Returns:

the time in milliseconds

getAverageRemoveMillis

long getAverageRemoveMillis()

The mean time to execute removes.

Returns:

the time in milliseconds