Class CacheLRU

java.lang.Object
org.h2.util.CacheLRU
All Implemented Interfaces:
Cache
public class CacheLRU extends Object implements Cache
A cache implementation based on the last recently used (LRU) algorithm.

  • Field Details

    • TYPE_NAME

      static final String TYPE_NAME
      See Also:

    • writer

      private final CacheWriter writer

    • fifo

      private final boolean fifo
      Use First-In-First-Out (don't move recently used items to the front of the queue).

    • mask

      private final int mask

    • values

      private CacheObject[] values

    • recordCount

      private int recordCount

    • len

      private final int len
      The number of cache buckets.

    • maxMemory

      private long maxMemory
      The maximum memory, in words (4 bytes each).

    • memory

      private long memory
      The current memory used in this cache, in words (4 bytes each).

  • Constructor Details

    • CacheLRU

      CacheLRU(CacheWriter writer, int maxMemoryKb, boolean fifo)

  • Method Details

    • getCache

      public static Cache getCache(CacheWriter writer, String cacheType, int cacheSize)
      Create a cache of the given type and size.
      Parameters:
      writer - the cache writer
      cacheType - the cache type
      cacheSize - the size
      Returns:
      the cache object

    • clear

      public void clear()
      Description copied from interface: Cache
      Clear the cache.
      Specified by:
      clear in interface Cache

    • put

      public void put(CacheObject rec)
      Description copied from interface: Cache
      Add an element to the cache. Other items may fall out of the cache because of this. It is not allowed to add the same record twice.
      Specified by:
      put in interface Cache
      Parameters:
      rec - the object

    • update

      public CacheObject update(int pos, CacheObject rec)
      Description copied from interface: Cache
      Update an element in the cache. This will move the item to the front of the list.
      Specified by:
      update in interface Cache
      Parameters:
      pos - the unique key of the element
      rec - the element
      Returns:
      the element

    • removeOldIfRequired

      private void removeOldIfRequired()

    • removeOld

      private void removeOld()

    • addToFront

      private void addToFront(CacheObject rec)

    • removeFromLinkedList

      private void removeFromLinkedList(CacheObject rec)

    • remove

      public boolean remove(int pos)
      Description copied from interface: Cache
      Remove an object from the cache.
      Specified by:
      remove in interface Cache
      Parameters:
      pos - the unique key of the element
      Returns:
      true if the key was in the cache

    • find

      public CacheObject find(int pos)
      Description copied from interface: Cache
      Get an element from the cache if it is available. This will not move the item to the front of the list.
      Specified by:
      find in interface Cache
      Parameters:
      pos - the unique key of the element
      Returns:
      the element or null

    • get

      public CacheObject get(int pos)
      Description copied from interface: Cache
      Get an element in the cache if it is available. This will move the item to the front of the list.
      Specified by:
      get in interface Cache
      Parameters:
      pos - the unique key of the element
      Returns:
      the element or null

    • getAllChanged

      public ArrayList<CacheObject> getAllChanged()
      Description copied from interface: Cache
      Get all objects in the cache that have been changed.
      Specified by:
      getAllChanged in interface Cache
      Returns:
      the list of objects

    • setMaxMemory

      public void setMaxMemory(int maxKb)
      Description copied from interface: Cache
      Set the maximum memory to be used by this cache.
      Specified by:
      setMaxMemory in interface Cache
      Parameters:
      maxKb - the maximum size in KB

    • getMaxMemory

      public int getMaxMemory()
      Description copied from interface: Cache
      Get the maximum memory to be used.
      Specified by:
      getMaxMemory in interface Cache
      Returns:
      the maximum size in KB

    • getMemory

      public int getMemory()
      Description copied from interface: Cache
      Get the used size in KB.
      Specified by:
      getMemory in interface Cache
      Returns:
      the current size in KB