Module org.apache.derby.engine
Package org.apache.derby.mbeans

Interface CacheManagerMBean

  • public interface CacheManagerMBean
    This is an MBean that provides information about one of Derby's cache managers.

    • Method Summary

      All Methods Instance Methods Abstract Methods 
      Modifier and Type Method Description
      long getAllocatedEntries()
      Get the number of entries currently allocated in the cache.
      boolean getCollectAccessCounts()
      Check if collection of cache access counts is enabled.
      long getEvictionCount()
      Get the number of cached objects that have been evicted from the cache in order to make room for other objects.
      long getHitCount()
      Get the number of cache accesses where the requested object was already in the cache.
      long getMaxEntries()
      Get the maximum number of entries that could be held by this cache.
      long getMissCount()
      Get the number of cache accesses where the requested object was not already in the cache.
      long getUsedEntries()
      Get the number of objects that are currently in the cache.
      void setCollectAccessCounts​(boolean collect)
      Enable or disable collection of cache access counts.

    • Method Detail

      • setCollectAccessCounts

        void setCollectAccessCounts​(boolean collect)
        Enable or disable collection of cache access counts. That is, whether or not each hit, miss and eviction should be counted. Enabling it might impose a small overhead on cache accesses, and might reduce the system performance. Access counts are disabled by default.
        Parameters:
        collect - true if access counts should be collected, or false otherwise
        See Also:
        getCollectAccessCounts(), getHitCount(), getMissCount(), getEvictionCount()

      • getCollectAccessCounts

        boolean getCollectAccessCounts()
        Check if collection of cache access counts is enabled.
        Returns:
        true if access counts are enabled, false otherwise
        See Also:
        setCollectAccessCounts(boolean)

      • getHitCount

        long getHitCount()
        Get the number of cache accesses where the requested object was already in the cache.
        Returns:
        the number of cache hits

      • getMissCount

        long getMissCount()
        Get the number of cache accesses where the requested object was not already in the cache.
        Returns:
        the number of cache misses

      • getEvictionCount

        long getEvictionCount()
        Get the number of cached objects that have been evicted from the cache in order to make room for other objects.
        Returns:
        the number of evicted objects

      • getMaxEntries

        long getMaxEntries()
        Get the maximum number of entries that could be held by this cache.
        Returns:
        the maximum number of entries in the cache

      • getAllocatedEntries

        long getAllocatedEntries()
        Get the number of entries currently allocated in the cache. This number includes entries for objects that have been removed from the cache, whose entries have not yet been reused for other objects.
        Returns:
        the number of entries in the cache

      • getUsedEntries

        long getUsedEntries()
        Get the number of objects that are currently in the cache.
        Returns:
        the number of objects in the cache