Statistics (Ehcache Core 2.6.11 API)

java.lang.Object
- net.sf.ehcache.Statistics

All Implemented Interfaces:

Serializable
```
public class Statistics
extends Object
implements Serializable
```
An immutable Cache statistics implementation
This is like a value object, with the added ability to clear cache statistics on the cache. That ability does not survive any Serialization of this class. On deserialization the cache can be considered disconnected.
The accuracy of these statistics are determined by the value of Cache.getStatisticsAccuracy() at the time the statistic was computed. This can be changed by setting Cache.setStatisticsAccuracy(int).
Because this class maintains a reference to an Ehcache, any references held to this class will prevent the Ehcache from getting garbage collected.
todo Add missCountExpired. Request from user.

Version:

$Id: Statistics.java 5631 2012-05-10 08:31:33Z teck $

Author:

Greg Luck

See Also:

Serialized Form

Field Summary

Fields
Modifier and Type	Field and Description
`static int`	`STATISTICS_ACCURACY_BEST_EFFORT` Best efforts accuracy setting.
`static int`	`STATISTICS_ACCURACY_GUARANTEED` Guaranteed accuracy setting.
`static int`	`STATISTICS_ACCURACY_NONE` Fast but not accurate setting.

Constructor Summary

Constructors
Constructor and Description
`Statistics(Ehcache cache, int statisticsAccuracy, long cacheHits, long onDiskHits, long offHeapHits, long inMemoryHits, long misses, long onDiskMisses, long offHeapMisses, long inMemoryMisses, long size, float averageGetTime, long evictionCount, long memoryStoreSize, long offHeapStoreSize, long diskStoreSize, long searchesPerSecond, long averageSearchTime, long writerQueueLength)` Creates a new statistics object, associated with a Cache

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`void`	`clearStatistics()` Clears the statistic counters to 0 for the associated Cache.
`Ehcache`	`getAssociatedCache()`
`String`	`getAssociatedCacheName()`
`float`	`getAverageGetTime()` The average get time.
`long`	`getAverageSearchTime()` Gets the average execution time (in milliseconds) within the last sample period
`long`	`getCacheHits()` The number of times a requested item was found in the cache.
`long`	`getCacheMisses()`
`long`	`getDiskStoreObjectCount()`
`long`	`getEvictionCount()` Gets the number of cache evictions, since the cache was created, or statistics were cleared.
`long`	`getInMemoryHits()` Number of times a requested item was found in the Memory Store.
`long`	`getInMemoryMisses()` Number of times a requested item was not found in the Memory Store.
`long`	`getMemoryStoreObjectCount()`
`long`	`getObjectCount()` Gets the number of elements stored in the cache.
`long`	`getOffHeapHits()` Number of times a requested item was found in the off-heap store.
`long`	`getOffHeapMisses()` Number of times a requested item was not found in the off-heap store.
`long`	`getOffHeapStoreObjectCount()`
`long`	`getOnDiskHits()` Number of times a requested item was found in the Disk Store.
`long`	`getOnDiskMisses()` Number of times a requested item was not found in the Disk Store.
`long`	`getSearchesPerSecond()` Get the number of search executions that have completed in the last second
`int`	`getStatisticsAccuracy()` Accurately measuring statistics can be expensive.
`String`	`getStatisticsAccuracyDescription()` Accurately measuring statistics can be expensive.
`long`	`getWriterQueueSize()` Gets the size of the write-behind queue, if any.
`static boolean`	`isValidStatisticsAccuracy(int statisticsAccuracy)` Utility method to determine if a given value is a valid statistics accuracy value or not
`String`	`toString()` Returns a `String` representation of the `Ehcache` statistics.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

- Field Detail
  - STATISTICS_ACCURACY_NONE
```
public static final int STATISTICS_ACCURACY_NONE
```
    Fast but not accurate setting.
    
    See Also:
    
    Constant Field Values
  - STATISTICS_ACCURACY_BEST_EFFORT
```
public static final int STATISTICS_ACCURACY_BEST_EFFORT
```
    Best efforts accuracy setting.
    
    See Also:
    
    Constant Field Values
  - STATISTICS_ACCURACY_GUARANTEED
```
public static final int STATISTICS_ACCURACY_GUARANTEED
```
    Guaranteed accuracy setting.
    
    See Also:
    
    Constant Field Values
- Constructor Detail
  - Statistics
```
public Statistics(Ehcache cache,
                  int statisticsAccuracy,
                  long cacheHits,
                  long onDiskHits,
                  long offHeapHits,
                  long inMemoryHits,
                  long misses,
                  long onDiskMisses,
                  long offHeapMisses,
                  long inMemoryMisses,
                  long size,
                  float averageGetTime,
                  long evictionCount,
                  long memoryStoreSize,
                  long offHeapStoreSize,
                  long diskStoreSize,
                  long searchesPerSecond,
                  long averageSearchTime,
                  long writerQueueLength)
```
    Creates a new statistics object, associated with a Cache
    
    Parameters:
    
    cache - The cache that clearStatistics() will call, if not disconnected
    
    statisticsAccuracy -
    
    cacheHits -
    
    onDiskHits -
    
    offHeapHits -
    
    inMemoryHits -
    
    misses -
    
    size -
- Method Detail
  - clearStatistics
```
public void clearStatistics()
```
    Clears the statistic counters to 0 for the associated Cache.
  - getCacheHits
```
public long getCacheHits()
```
    The number of times a requested item was found in the cache.
    
    Returns:
    
    the number of times a requested item was found in the cache
  - getInMemoryHits
```
public long getInMemoryHits()
```
    Number of times a requested item was found in the Memory Store.
    
    Returns:
    
    the number of times a requested item was found in memory
  - getOffHeapHits
```
public long getOffHeapHits()
```
    Number of times a requested item was found in the off-heap store.
    
    Returns:
    
    the number of times a requested item was found in off-heap
  - getOnDiskHits
```
public long getOnDiskHits()
```
    Number of times a requested item was found in the Disk Store.
    
    Returns:
    
    the number of times a requested item was found on Disk, or 0 if there is no disk storage configured.
  - getCacheMisses
```
public long getCacheMisses()
```
    Returns:
    
    the number of times a requested element was not found in the cache
  - getInMemoryMisses
```
public long getInMemoryMisses()
```
    Number of times a requested item was not found in the Memory Store.
    
    Returns:
    
    the number of times a requested item was not found in memory
  - getOffHeapMisses
```
public long getOffHeapMisses()
```
    Number of times a requested item was not found in the off-heap store.
    
    Returns:
    
    the number of times a requested item was not found in off-heap
  - getOnDiskMisses
```
public long getOnDiskMisses()
```
    Number of times a requested item was not found in the Disk Store.
    
    Returns:
    
    the number of times a requested item was not found on Disk, or 0 if there is no disk storage configured.
  - getObjectCount
```
public long getObjectCount()
```
    Gets the number of elements stored in the cache. Caclulating this can be expensive. Accordingly, this method will return three different values, depending on the statistics accuracy setting.
    Best Effort Size
    This result is returned when the statistics accuracy setting is STATISTICS_ACCURACY_BEST_EFFORT.
    The size is the number of Elements in the MemoryStore plus the number of Elements in the DiskStore.
    This number is the actual number of elements, including expired elements that have not been removed. Any duplicates between stores are accounted for.
    Expired elements are removed from the the memory store when getting an expired element, or when attempting to spool an expired element to disk.
    Expired elements are removed from the disk store when getting an expired element, or when the expiry thread runs, which is once every five minutes.
    
    Guaranteed Accuracy Size
    This result is returned when the statistics accuracy setting is STATISTICS_ACCURACY_GUARANTEED.
    This method accounts for elements which might be expired or duplicated between stores. It take approximately 200ms per 1000 elements to execute.
    Fast but non-accurate Size
    This result is returned when the statistics accuracy setting is STATISTICS_ACCURACY_NONE.
    The number given may contain expired elements. In addition if the DiskStore is used it may contain some double counting of elements. It takes 6ms for 1000 elements to execute. Time to execute is O(log n). 50,000 elements take 36ms.
    
    Returns:
    
    the number of elements in the ehcache, with a varying degree of accuracy, depending on accuracy setting.
  - getMemoryStoreObjectCount
```
public long getMemoryStoreObjectCount()
```
    Returns:
    
    the number of objects in the memory store
  - getOffHeapStoreObjectCount
```
public long getOffHeapStoreObjectCount()
```
    Returns:
    
    the number of objects in the off-heap store
  - getDiskStoreObjectCount
```
public long getDiskStoreObjectCount()
```
    Returns:
    
    the number of objects in the disk store
  - getStatisticsAccuracy
```
public int getStatisticsAccuracy()
```
    Accurately measuring statistics can be expensive. Returns the current accuracy setting.
    
    Returns:
    
    one of STATISTICS_ACCURACY_BEST_EFFORT, STATISTICS_ACCURACY_GUARANTEED, STATISTICS_ACCURACY_NONE
  - getStatisticsAccuracyDescription
```
public String getStatisticsAccuracyDescription()
```
    Accurately measuring statistics can be expensive. Returns the current accuracy setting.
    
    Returns:
    
    a human readable description of the accuracy setting. One of "None", "Best Effort" or "Guaranteed".
  - getAssociatedCacheName
```
public String getAssociatedCacheName()
```
    Returns:
    
    the name of the Ehcache, or null if a reference is no longer held to the cache, as, it would be after deserialization.
  - getAssociatedCache
```
public Ehcache getAssociatedCache()
```
    Returns:
    
    the name of the Ehcache, or null if a reference is no longer held to the cache, as, it would be after deserialization.
  - toString
```
public final String toString()
```
    Returns a String representation of the Ehcache statistics.
    
    Overrides:
    
    toString in class Object
  - getAverageGetTime
```
public float getAverageGetTime()
```
    The average get time. Because ehcache support JDK1.4.2, each get time uses System.currentTimeMilis, rather than nanoseconds. The accuracy is thus limited.
  - getEvictionCount
```
public long getEvictionCount()
```
    Gets the number of cache evictions, since the cache was created, or statistics were cleared.
  - getAverageSearchTime
```
public long getAverageSearchTime()
```
    Gets the average execution time (in milliseconds) within the last sample period
  - getSearchesPerSecond
```
public long getSearchesPerSecond()
```
    Get the number of search executions that have completed in the last second
  - isValidStatisticsAccuracy
```
public static boolean isValidStatisticsAccuracy(int statisticsAccuracy)
```
    Utility method to determine if a given value is a valid statistics accuracy value or not
    
    Parameters:
    
    statisticsAccuracy -
    
    Returns:
    
    true if the value is one of STATISTICS_ACCURACY_BEST_EFFORT, STATISTICS_ACCURACY_GUARANTEED, STATISTICS_ACCURACY_NONE
  - getWriterQueueSize
```
public long getWriterQueueSize()
```
    Gets the size of the write-behind queue, if any. The value is for all local buckets
    
    Returns:
    
    Elements waiting to be processed by the write behind writer. -1 if no write-behind

Class Statistics

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

STATISTICS_ACCURACY_NONE

STATISTICS_ACCURACY_BEST_EFFORT

STATISTICS_ACCURACY_GUARANTEED

Constructor Detail

Statistics

Method Detail

clearStatistics

getCacheHits

getInMemoryHits

getOffHeapHits

getOnDiskHits

getCacheMisses

getInMemoryMisses

getOffHeapMisses

getOnDiskMisses

getObjectCount

Best Effort Size

Guaranteed Accuracy Size

Fast but non-accurate Size

getMemoryStoreObjectCount

getOffHeapStoreObjectCount

getDiskStoreObjectCount

getStatisticsAccuracy

getStatisticsAccuracyDescription

getAssociatedCacheName

getAssociatedCache

toString

getAverageGetTime

getEvictionCount

getAverageSearchTime

getSearchesPerSecond

isValidStatisticsAccuracy

getWriterQueueSize