Package org.apache.solr.search

Class CaffeineCache<K,​V>

  • All Implemented Interfaces:
    com.github.benmanes.caffeine.cache.RemovalListener<K,​V>, AutoCloseable, org.apache.lucene.util.Accountable, SolrInfoBean, SolrMetricProducer, SolrCache<K,​V>
    public class CaffeineCache<K,​V>
extends SolrCacheBase
implements SolrCache<K,​V>, org.apache.lucene.util.Accountable, com.github.benmanes.caffeine.cache.RemovalListener<K,​V>
    A SolrCache backed by the Caffeine caching library [1]. By default it uses the Window TinyLFU (W-TinyLFU) eviction policy.

    This cache supports either maximum size limit (the number of items) or maximum ram bytes limit, but not both. If both values are set then only maxRamMB limit is used and maximum size limit is ignored.

    W-TinyLFU [2] is a near optimal policy that uses recency and frequency to determine which entry to evict in O(1) time. The estimated frequency is retained in a Count-Min Sketch and entries reside on LRU priority queues [3]. By capturing the historic frequency of an entry, the cache is able to outperform classic policies like LRU and LFU, as well as modern policies like ARC and LIRS. This policy performed particularly well in search workloads.

    [1] https://github.com/ben-manes/caffeine [2] http://arxiv.org/pdf/1512.00727.pdf [3] http://highscalability.com/blog/2016/1/25/design-of-a-modern-cache.html

    • Constructor Detail

      • CaffeineCache

        public CaffeineCache()

    • Method Detail

      • init

        public Object init​(Map<String,​String> args,
                   Object persistence,
                   CacheRegenerator regenerator)
        Description copied from interface: SolrCache
        The initialization routine. Instance specific arguments are passed in the args map.

        The persistence object will exist across different lifetimes of similar caches. For example, all filter caches will share the same persistence object, sometimes at the same time (it must be thread-safe). If null is passed, then the cache implementation should create and return a new persistence object. If not null, the passed in object should be returned again.

        Since it will exist across the lifetime of many caches, care should be taken to not reference any particular cache instance and prevent it from being garbage collected (no using inner classes unless they are static).

        The persistence object is designed to be used as a way for statistics to accumulate across all instances of the same type of cache, however the object may be of any type desired by the cache implementation.

        The CacheRegenerator is what the cache uses during auto-warming to regenerate an item in the new cache from an entry in the old cache.

        Specified by:
        init in interface SolrCache<K,​V>

      • onRemoval

        public void onRemoval​(K key,
                      V value,
                      com.github.benmanes.caffeine.cache.RemovalCause cause)
        Specified by:
        onRemoval in interface com.github.benmanes.caffeine.cache.RemovalListener<K,​V>

      • ramBytesUsed

        public long ramBytesUsed()
        Specified by:
        ramBytesUsed in interface org.apache.lucene.util.Accountable

      • get

        public V get​(K key)
        Description copied from interface: SolrCache
        :TODO: copy from Map
        Specified by:
        get in interface SolrCache<K,​V>

      • computeIfAbsent

        public V computeIfAbsent​(K key,
                         IOFunction<? super K,​? extends V> mappingFunction)
                  throws IOException
        Description copied from interface: SolrCache
        Get an existing element or atomically compute it if missing.
        Specified by:
        computeIfAbsent in interface SolrCache<K,​V>
        Parameters:
        key - key
        mappingFunction - function to compute the element. If the function returns a null result the cache mapping will not be created. NOTE: this function must NOT attempt to modify any mappings in the cache.
        Returns:
        existing or newly computed value, null if there was no existing value and it was not possible to compute a new value (in which case the new mapping won't be created).
        Throws:
        IOException - if and only if mappingFunction threw an IOException. A cache mapping will not be created in this case

      • put

        public V put​(K key,
             V val)
        Description copied from interface: SolrCache
        :TODO: copy from Map
        Specified by:
        put in interface SolrCache<K,​V>

      • clear

        public void clear()
        Description copied from interface: SolrCache
        :TODO: copy from Map
        Specified by:
        clear in interface SolrCache<K,​V>

      • size

        public int size()
        Description copied from interface: SolrCache
        :TODO: copy from Map
        Specified by:
        size in interface SolrCache<K,​V>

      • getMaxSize

        public int getMaxSize()
        Description copied from interface: SolrCache
        Returns maximum size limit (number of items) if set and supported, -1 otherwise.
        Specified by:
        getMaxSize in interface SolrCache<K,​V>

      • setMaxSize

        public void setMaxSize​(int maxSize)
        Description copied from interface: SolrCache
        Set maximum size limit (number of items), or -1 for unlimited. Note: this has effect only on implementations that support it, it's a no-op otherwise
        Specified by:
        setMaxSize in interface SolrCache<K,​V>

      • getMaxRamMB

        public int getMaxRamMB()
        Description copied from interface: SolrCache
        Returns maximum size limit (in MB) if set and supported, -1 otherwise.
        Specified by:
        getMaxRamMB in interface SolrCache<K,​V>

      • setMaxRamMB

        public void setMaxRamMB​(int maxRamMB)
        Description copied from interface: SolrCache
        Set maximum size limit (in MB), or -1 for unlimited. Note: this has effect only on implementations that support it, it's a no-op otherwise.
        Specified by:
        setMaxRamMB in interface SolrCache<K,​V>

      • warm

        public void warm​(SolrIndexSearcher searcher,
                 SolrCache<K,​V> old)
        Description copied from interface: SolrCache
        Warm this cache associated with searcher using the old cache object. this and old will have the same concrete type.
        Specified by:
        warm in interface SolrCache<K,​V>

      • getName

        public String getName()
        Description copied from interface: SolrInfoBean
        Simple common usage name, e.g. BasicQueryHandler, or fully qualified class name.
        Specified by:
        getName in interface SolrInfoBean