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

    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 Details

    • 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

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

    • 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