net.sf.ehcache.management.CacheStatisticsMBean Maven / Gradle / Ivy
/**
* Copyright Terracotta, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package net.sf.ehcache.management;
/**
* @author Greg Luck
* @version $Id: CacheStatisticsMBean.java 5631 2012-05-10 08:31:33Z teck $
* @since 1.3
*/
public interface CacheStatisticsMBean {
/**
* Clears the statistic counters to 0 for the associated Cache.
*/
void clearStatistics();
/**
* The number of times a requested item was found in the cache.
*
* @return the number of times a requested item was found in the cache
*/
long getCacheHits();
/**
* Number of times a requested item was found in the Memory Store.
*
* @return the number of times a requested item was found in memory
*/
long getInMemoryHits();
/**
* Number of times a requested item was found in the off-heap store.
*
* @return the number of times a requested item was found off-heap, or 0 if there is no BigMemory storage configured.
*/
long getOffHeapHits();
/**
* Number of times a requested item was found in the Disk Store.
*
* @return the number of times a requested item was found on Disk, or 0 if there is no disk storage configured.
*/
long getOnDiskHits();
/**
* @return the number of times a requested element was not found in the cache
*/
long getCacheMisses();
/**
* @return the number of times a requested element was not found in the memory cache
*/
long getInMemoryMisses();
/**
* @return the number of times a requested element was not found in the off-heap cache
*/
long getOffHeapMisses();
/**
* @return the number of times a requested element was not found in the disk cache
*/
long getOnDiskMisses();
/**
* 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 {@link net.sf.ehcache.Statistics#STATISTICS_ACCURACY_BEST_EFFORT}.
*
* The size is the number of {@link net.sf.ehcache.Element}s in the {@link net.sf.ehcache.store.MemoryStore} plus
* the number of {@link net.sf.ehcache.Element}s in the {@link net.sf.ehcache.store.disk.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 {@link net.sf.ehcache.Statistics#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 {@link net.sf.ehcache.Statistics#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.
*
* @return the number of elements in the ehcache, with a varying degree of accuracy, depending on accuracy setting.
*/
long getObjectCount();
/**
* Gets the number of objects in the MemoryStore
* @return the MemoryStore size which is always a count unadjusted for duplicates or expiries
*/
long getMemoryStoreObjectCount();
/**
* Gets the number of objects in the OffHeapStore
* @return the OffHeapStore size which is always a count unadjusted for duplicates or expiries
*/
long getOffHeapStoreObjectCount();
/**
* Gets the number of objects in the DiskStore
* @return the DiskStore size which is always a count unadjusted for duplicates or expiries
*/
long getDiskStoreObjectCount();
/**
* Accurately measuring statistics can be expensive. Returns the current accuracy setting.
*
* @return one of {@link net.sf.ehcache.Statistics#STATISTICS_ACCURACY_BEST_EFFORT},
* {@link net.sf.ehcache.Statistics#STATISTICS_ACCURACY_GUARANTEED},
* {@link net.sf.ehcache.Statistics#STATISTICS_ACCURACY_NONE}
*/
int getStatisticsAccuracy();
/**
* Accurately measuring statistics can be expensive. Returns the current accuracy setting.
* @return a human readable description of the accuracy setting. One of "None", "Best Effort" or "Guaranteed".
*/
String getStatisticsAccuracyDescription();
/**
* @return the name of the Ehcache, or null is there no associated cache
*/
String getAssociatedCacheName();
/**
* Returns the percentage of cache accesses that found a requested item in the cache.
*
* @return the percentage of successful hits
*/
double getCacheHitPercentage();
/**
* Returns the percentage of cache accesses that did not find a requested element in the cache.
*
* @return the percentage of accesses that failed to find anything
*/
double getCacheMissPercentage();
/**
* Returns the percentage of cache accesses that found a requested item cached in-memory.
*
* @return the percentage of successful hits from the MemoryStore
*/
double getInMemoryHitPercentage();
/**
* Returns the percentage of cache accesses that found a requested item cached off-heap.
*
* @return the percentage of successful hits from the OffHeapStore
*/
double getOffHeapHitPercentage();
/**
* Returns the percentage of cache accesses that found a requested item cached on disk.
*
* @return the percentage of successful hits from the DiskStore.
*/
double getOnDiskHitPercentage();
/**
* Gets the size of the write-behind queue, if any.
* The value is for all local buckets
* @return Elements waiting to be processed by the write behind writer. -1 if no write-behind
*/
long getWriterQueueLength();
/**
* Gets the maximum size of the write-behind queue, if any.
* @return Maximum elements waiting to be processed by the write behind writer. -1 if no write-behind
*/
int getWriterMaxQueueSize();
}