com.hazelcast.cache.impl

Class CacheStatisticsImpl

java.lang.Object

com.hazelcast.cache.impl.CacheStatisticsImpl

All Implemented Interfaces:

CacheStatistics, DataSerializable

public class CacheStatisticsImpl
extends Object
implements DataSerializable, CacheStatistics

Some statistics of a ICache Statistics accumulated in this data object is published through MxBean

See Also:

CacheMXBeanImpl

Constructor Summary

Constructors

Constructor and Description
CacheStatisticsImpl()

Method Summary

Methods

Modifier and Type	Method and Description
CacheStatisticsImpl	accumulate(CacheStatisticsImpl other) Simple CacheStatistics adder.
void	addGetTimeNano(long duration) Increments the getCache time accumulator
void	addPutTimeNano(long duration) Increments the put time accumulator
void	addRemoveTimeNano(long duration) Increments the remove time accumulator
void	clear() implementation of CacheStatisticsMXBean.clear()
float	getAverageGetTime() The mean time to execute gets.
float	getAveragePutTime() The mean time to execute puts.
float	getAverageRemoveTime() The mean time to execute removes.
long	getCacheEvictions() The total number of evictions from the cache.
long	getCacheExpiries() The total number of expiries from the cache.
long	getCacheGets() The total number of requests to the cache.
long	getCacheGetTimeTakenNanos()
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 that 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	getCachePutTimeTakenNanos()
long	getCacheRemovals() The total number of removals from the cache.
long	getCacheRemoveTimeTakenNanos()
void	increaseCacheEvictions(long number) Increases the counter by the number specified.
void	increaseCacheExpiries(long number) Increases the counter by the number specified.
void	increaseCacheHits(long number) Increases the counter by the number specified.
void	increaseCacheMisses(long number) Increases the counter by the number specified.
void	increaseCachePuts(long number) Increases the counter by the number specified.
void	increaseCacheRemovals(long number) Increases the counter by the number specified.
void	readData(ObjectDataInput in) Reads fields from the input stream
void	writeData(ObjectDataOutput out) Writes object fields to output stream

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

getCacheRemovals

public 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.

Specified by:

getCacheRemovals in interface CacheStatistics

Returns:

the number of removals

getCacheExpiries

public long getCacheExpiries()

The total number of expiries from the cache. An expiry may or may not be evicted. This number represent the entries that fail evaluation and may not include the entries which are not yet evaluated for expiry or not accessed.

Returns:

the number of expiries

getCacheGets

public 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.

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()

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 puts

getCacheHits

public long getCacheHits()

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

Cache.containsKey(Object) is not a get request for statistics purposes.

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

For an EntryProcessor, a hit occurs when the key exists and an entry processor can be invoked against it, even if no methods of Cache.Entry or MutableEntry are called.

Specified by:

getCacheHits in interface CacheStatistics

Returns:

the number of hits

getCacheMisses

public long getCacheMisses()

A miss is a get request that is not satisfied.

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

Cache.containsKey(Object) is not a get request for statistics purposes.

For an EntryProcessor, a miss occurs when the key does not exist and therefore an entry processor cannot be invoked against it.

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 that 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

getCacheEvictions

public 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.

Specified by:

getCacheEvictions in interface CacheStatistics

Returns:

the number of evictions

getCachePutTimeTakenNanos

public long getCachePutTimeTakenNanos()

getCacheGetTimeTakenNanos

public long getCacheGetTimeTakenNanos()

getCacheRemoveTimeTakenNanos

public long getCacheRemoveTimeTakenNanos()

getCacheHitPercentage

public float getCacheHitPercentage()

This is a measure of cache efficiency.

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

Specified by:

getCacheHitPercentage in interface CacheStatistics

Returns:

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

getCacheMissPercentage

public float getCacheMissPercentage()

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

getAverageGetTime

public float getAverageGetTime()

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:

getAverageGetTime in interface CacheStatistics

Returns:

the time in µs

getAveragePutTime

public float getAveragePutTime()

The mean time to execute puts.

Specified by:

getAveragePutTime in interface CacheStatistics

Returns:

the time in µs

getAverageRemoveTime

public float getAverageRemoveTime()

The mean time to execute removes.

Specified by:

getAverageRemoveTime in interface CacheStatistics

Returns:

the time in µs

clear

public void clear()

implementation of CacheStatisticsMXBean.clear()

See Also:

CacheStatisticsMXBean.clear()

increaseCacheRemovals

public void increaseCacheRemovals(long number)

Increases the counter by the number specified.

Parameters:

number - the number to increase the counter by

increaseCacheExpiries

public void increaseCacheExpiries(long number)

Increases the counter by the number specified.

Parameters:

number - the number to increase the counter by

increaseCachePuts

public void increaseCachePuts(long number)

Increases the counter by the number specified.

Parameters:

number - the number to increase the counter by

increaseCacheHits

public void increaseCacheHits(long number)

Increases the counter by the number specified.

Parameters:

number - the number to increase the counter by

increaseCacheMisses

public void increaseCacheMisses(long number)

Increases the counter by the number specified.

Parameters:

number - the number to increase the counter by

increaseCacheEvictions

public void increaseCacheEvictions(long number)

Increases the counter by the number specified.

Parameters:

number - the number to increase the counter by

addGetTimeNano

public void addGetTimeNano(long duration)

Increments the getCache time accumulator

Parameters:

duration - the time taken in nanoseconds

addPutTimeNano

public void addPutTimeNano(long duration)

Increments the put time accumulator

Parameters:

duration - the time taken in nanoseconds

addRemoveTimeNano

public void addRemoveTimeNano(long duration)

Increments the remove time accumulator

Parameters:

duration - the time taken in nanoseconds

accumulate

public CacheStatisticsImpl accumulate(CacheStatisticsImpl other)

Simple CacheStatistics adder. Can be used to merge two statistics data, such as the ones collected from multiple nodes.

Parameters:

other - CacheStatisticsImpl to be merged

Returns:

CacheStatisticsImpl with merged data

writeData

public void writeData(ObjectDataOutput out)
               throws IOException

Description copied from interface: DataSerializable

Writes object fields to output stream

Specified by:

writeData in interface DataSerializable

Parameters:

out - output

Throws:

IOException

readData

public void readData(ObjectDataInput in)
              throws IOException

Reads fields from the input stream

Specified by:

readData in interface DataSerializable

Parameters:

in - input

Throws:

IOException