Interface CacheStatisticsMXBean


  • @MXBean
    public interface CacheStatisticsMXBean
    Cache statistics.

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

    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 and attributes:

    Type: javax.cache:type=CacheStatistics

    Required Attributes:

    • CacheManager the URI of the CacheManager
    • Cache the name of the Cache
    Since:
    1.0
    Author:
    Greg Luck
    • Method Detail

      • clear

        void clear()
        Clears the statistics counters to 0 for the associated 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 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.

        Returns:
        the number of hits
      • 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 e.g 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 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.

        Returns:
        the number of misses
      • 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 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 a caches with multiple tiered storage, a gets may be implemented as a get to the cache or to the first tier.

        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.

        Replaces, where a put occurs which overrides an existing mapping is counted as a put.

        Returns:
        the number of puts
      • 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
      • 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
      • 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 time in µs
      • getAveragePutTime

        float getAveragePutTime()
        The mean time to execute puts.
        Returns:
        the time in µs
      • getAverageRemoveTime

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