Package org.apache.solr.util

Class ConcurrentLRUCache<K,V>

java.lang.Object
org.apache.solr.util.ConcurrentLRUCache<K,V>
All Implemented Interfaces:
org.apache.lucene.util.Accountable, org.apache.solr.common.util.Cache<K,V>
public class ConcurrentLRUCache<K,V> extends Object implements org.apache.solr.common.util.Cache<K,V>, org.apache.lucene.util.Accountable
A LRU cache implementation based upon ConcurrentHashMap and other techniques to reduce contention and synchronization overhead to utilize multiple CPU cores more effectively.

Note that the implementation does not follow a true LRU (least-recently-used) eviction strategy. Instead it strives to remove least recently used items but when the initial cleanup does not remove enough items to reach the 'acceptableWaterMark' limit, it can remove more items forcefully regardless of access order.

Since:
solr 1.4

  • Constructor Details

    • ConcurrentLRUCache

      public ConcurrentLRUCache(long ramLowerWatermark, long ramUpperWatermark, boolean runCleanupThread, ConcurrentLRUCache.EvictionListener<K,V> evictionListener)

    • ConcurrentLRUCache

      public ConcurrentLRUCache(long ramLowerWatermark, long ramUpperWatermark, boolean runCleanupThread, ConcurrentLRUCache.EvictionListener<K,V> evictionListener, int maxIdleTimeSec)

    • ConcurrentLRUCache

      public ConcurrentLRUCache(int upperWaterMark, int lowerWaterMark, int acceptableWaterMark, int initialSize, boolean runCleanupThread, boolean runNewThreadForCleanup, ConcurrentLRUCache.EvictionListener<K,V> evictionListener)

    • ConcurrentLRUCache

      public ConcurrentLRUCache(int upperWaterMark, int lowerWaterMark, int acceptableWaterMark, int initialSize, boolean runCleanupThread, boolean runNewThreadForCleanup, ConcurrentLRUCache.EvictionListener<K,V> evictionListener, int maxIdleTimeSec)

    • ConcurrentLRUCache

      public ConcurrentLRUCache(int size, int lowerWaterMark)

  • Method Details

    • setAlive

      public void setAlive(boolean live)

    • setUpperWaterMark

      public void setUpperWaterMark(int upperWaterMark)

    • setLowerWaterMark

      public void setLowerWaterMark(int lowerWaterMark)

    • setAcceptableWaterMark

      public void setAcceptableWaterMark(int acceptableWaterMark)

    • setRamUpperWatermark

      public void setRamUpperWatermark(long ramUpperWatermark)

    • setRamLowerWatermark

      public void setRamLowerWatermark(long ramLowerWatermark)

    • setMaxIdleTime

      public void setMaxIdleTime(int maxIdleTime)

    • setRunCleanupThread

      public void setRunCleanupThread(boolean runCleanupThread)

    • get

      public V get(K key)
      Specified by:
      get in interface org.apache.solr.common.util.Cache<K,V>

    • remove

      public V remove(K key)
      Specified by:
      remove in interface org.apache.solr.common.util.Cache<K,V>

    • computeIfAbsent

      public V computeIfAbsent(K key, Function<? super K,? extends V> mappingFunction)
      Specified by:
      computeIfAbsent in interface org.apache.solr.common.util.Cache<K,V>

    • put

      public V put(K key, V val)
      Specified by:
      put in interface org.apache.solr.common.util.Cache<K,V>

    • putCacheEntry

      public V putCacheEntry(ConcurrentLRUCache.CacheEntry<K,V> e)
      Visible for testing to create synthetic cache entries.
      NOTE: This API is for internal purposes only and might change in incompatible ways in the next release.

    • markAndSweep

      public void markAndSweep()
      Removes items from the cache to bring the size down to an acceptable value.

      Visible for unit testing.

      NOTE: This API is for internal purposes only and might change in incompatible ways in the next release.

    • getOldestAccessedItems

      public Map<K,V> getOldestAccessedItems(int n)
      Returns 'n' number of oldest accessed entries present in this cache.

      This uses a TreeSet to collect the 'n' oldest items ordered by ascending last access time and returns a LinkedHashMap containing 'n' or less than 'n' entries.

      Parameters:
      n - the number of oldest items needed
      Returns:
      a LinkedHashMap containing 'n' or less than 'n' entries

    • getLatestAccessedItems

      public Map<K,V> getLatestAccessedItems(int n)

    • size

      public int size()

    • clear

      public void clear()
      Specified by:
      clear in interface org.apache.solr.common.util.Cache<K,V>

    • getMap

      public Map<Object,ConcurrentLRUCache.CacheEntry<K,V>> getMap()

    • destroy

      public void destroy()

    • getStats

      public ConcurrentLRUCache.Stats getStats()

    • ramBytesUsed

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

    • getChildResources

      public Collection<org.apache.lucene.util.Accountable> getChildResources()
      Specified by:
      getChildResources in interface org.apache.lucene.util.Accountable