Package com.hazelcast.cache

Interface CacheStatistics

public interface CacheStatistics
Cache statistics

Cache statistics are accumulated starting from the time a cache is created.
An instance of this class represents local node values only! For an accumulated view on cluster level, the user has to retrieve all nodes statistics and aggregate values on his own.

Sample code: 

       ICache<Key, Value> unwrappedCache =  cache.unwrap( ICache.class );
       CacheStatistics cacheStatistics = unwrappedCache.getLocalCacheStatistics();
       long cacheHits = cacheStatistics.getCacheHits();
Since:
3.3.1

  • Method Details

    • getCreationTime

      long getCreationTime()
      Gets the cache creation time.
      Returns:
      the cache creation time

    • getLastAccessTime

      long getLastAccessTime()
      Gets the last access time to cache.
      Returns:
      the last access time to cache

    • getLastUpdateTime

      long getLastUpdateTime()
      Gets the last update time to cache.
      Returns:
      the last update time to cache

    • getOwnedEntryCount

      long getOwnedEntryCount()
      Returns the owned entry count in the cache.
      Returns:
      the owned entry count in the cache

    • getCacheHits

      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 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.

      Returns:
      the number of hits (get requests that were satisfied by the cache)

    • getCacheHitPercentage

      float getCacheHitPercentage()
      This is a measure of cache efficiency.

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

      Returns:
      the percentage of successful hits as a decimal, such as 75

    • getCacheMisses

      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 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.

      Returns:
      the number of misses (get requests that were not satisfied)

    • getCacheMissPercentage

      float getCacheMissPercentage()
      Returns the percentage of cache accesses that did not find a requested entry in the cache.

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

      Returns:
      the percentage of cache 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.

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

      Returns:
      the number of gets to the cache

    • getCachePuts

      long getCachePuts()
      The total number of puts to the cache.

      A put is counted even if it is immediately evicted.

      Replaces are where a put occurs which overrides an existing mapping, and they are counted as a put.

      Returns:
      the number of puts to the cache

    • 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.
      Returns:
      the number of removals from the cache

    • 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 total number of evictions from the cache

    • getAverageGetTime

      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.

      Returns:
      the mean time in microseconds to execute gets

    • getAveragePutTime

      float getAveragePutTime()
      The mean time to execute puts.
      Returns:
      the mean time in microseconds to execute puts

    • getAverageRemoveTime

      float getAverageRemoveTime()
      The mean time to execute removes.
      Returns:
      the mean time in microseconds to execute removes

    • getNearCacheStatistics

      NearCacheStats getNearCacheStatistics()
      Gets the Near Cache statistics.
      Returns:
      the Near Cache statistics

    • getReplicationStats

      LocalReplicationStats getReplicationStats()
      Returns:
      replication statistics.
      Since:
      5.0