Package org.apache.ignite.cache.eviction.lru

Class LruEvictionPolicy<K,​V>

  • All Implemented Interfaces:
    Externalizable, Serializable, EvictionPolicy<K,​V>, IgniteMBeanAware
    public class LruEvictionPolicy<K,​V>
extends AbstractEvictionPolicy<K,​V>
implements IgniteMBeanAware
    Eviction policy based on Least Recently Used (LRU) algorithm and supports batch eviction.

    The eviction starts in the following cases:

    • The cache size becomes batchSize elements greater than the maximum size.
    • The size of cache entries in bytes becomes greater than the maximum memory size. The size of cache entry calculates as sum of key size and value size.
    Note:Batch eviction is enabled only if maximum memory limit isn't set (maxMemSize == 0). batchSize elements will be evicted in this case. The default batchSize value is 1. This implementation is very efficient since it is lock-free and does not create any additional table-like data structures. The LRU ordering information is maintained by attaching ordering metadata to cache entries.
    See Also:
    Serialized Form

    • Constructor Detail

      • LruEvictionPolicy

        public LruEvictionPolicy()
        Constructs LRU eviction policy with all defaults.

      • LruEvictionPolicy

        public LruEvictionPolicy​(int max)
        Constructs LRU eviction policy with maximum size.
        Parameters:
        max - Maximum allowed size of cache before entry will start getting evicted.

    • Method Detail

      • setMaxSize

        public LruEvictionPolicy<K,​V> setMaxSize​(int max)
        Sets maximum allowed size of cache before entry will start getting evicted.
        Overrides:
        setMaxSize in class AbstractEvictionPolicy<K,​V>
        Parameters:
        max - Maximum allowed size of cache before entry will start getting evicted.
        Returns:
        this for chaining.

      • queue

        public Collection<EvictableEntry<K,​V>> queue()
        Gets read-only view on internal FIFO queue in proper order.
        Returns:
        Read-only view ono internal 'FIFO' queue.

      • removeMeta

        protected boolean removeMeta​(Object meta)
        Specified by:
        removeMeta in class AbstractEvictionPolicy<K,​V>
        Parameters:
        meta - Meta-information shipped to an entry.
        Returns:
        True if meta was successfully removed from the container.

      • touch

        protected boolean touch​(EvictableEntry<K,​V> entry)
        Specified by:
        touch in class AbstractEvictionPolicy<K,​V>
        Parameters:
        entry - Entry to touch.
        Returns:
        True if new node has been added to queue by this call.

      • shrink0

        protected int shrink0()
        Tries to remove one item from queue.
        Specified by:
        shrink0 in class AbstractEvictionPolicy<K,​V>
        Returns:
        number of bytes that was free. -1 if queue is empty.