# Class ConcurrentLruCache<T>

java.lang.Object
org.apache.tomcat.util.collections.ConcurrentLruCache<T>

Type Parameters:
  `T` - the type of entries stored in the cache

public class ConcurrentLruCache<T> extends Object
A thread-safe LRU (Least Recently Used) cache with a configurable size limit. Entries beyond the limit are evicted in LRU order.

- ## Constructor Summary

  Constructors
  Constructor
  Description
  `ConcurrentLruCache(int limit)`
  Creates a new LRU cache with the specified size limit.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `void`
  `add(T entry)`
  Adds an entry to the cache.
  `void`
  `clear()`
  Removes all entries from the cache.
  `boolean`
  `contains(T entry)`
  Checks whether the cache contains the given entry.
  `int`
  `getLimit()`
  Returns the current maximum number of entries allowed in the cache.
  `void`
  `setLimit(int limit)`
  Sets the maximum number of entries in the cache.

  ### Methods inherited from class Object

  `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- ## Constructor Details

  - ### ConcurrentLruCache

    public ConcurrentLruCache(int limit)
    Creates a new LRU cache with the specified size limit.
    Parameters:
      `limit` - the maximum number of entries in the cache

- ## Method Details

  - ### add

    public void add(T entry)
    Adds an entry to the cache. If the cache is at its limit, the least recently used entry will be evicted.
    Parameters:
      `entry` - the entry to add

  - ### contains

    public boolean contains(T entry)
    Checks whether the cache contains the given entry. Accessing an entry through this method updates its recency.
    Parameters:
      `entry` - the entry to check
    Returns:
      `true` if the entry is in the cache

  - ### clear

    public void clear()
    Removes all entries from the cache.

  - ### setLimit

    public void setLimit(int limit)
    Sets the maximum number of entries in the cache. If the new limit is smaller than the current size, the least recently used entries will be evicted. A limit of 0 or less disables the cache.
    Parameters:
      `limit` - the new maximum number of entries

  - ### getLimit

    public int getLimit()
    Returns the current maximum number of entries allowed in the cache.
    Returns:
      the cache limit, or -1 if the cache is disabled