// Copyright (c) HashiCorp, Inc.
// SPDX-License-Identifier: MPL-2.0

// Package lru provides three different LRU caches of varying sophistication.
//
// Cache is a simple LRU cache. It is based on the LRU implementation in
// groupcache: https://github.com/golang/groupcache/tree/master/lru
//
// TwoQueueCache tracks frequently used and recently used entries separately.
// This avoids a burst of accesses from taking out frequently used entries, at
// the cost of about 2x computational overhead and some extra bookkeeping.
//
// ARCCache is an adaptive replacement cache. It tracks recent evictions as well
// as recent usage in both the frequent and recent caches. Its computational
// overhead is comparable to TwoQueueCache, but the memory overhead is linear
// with the size of the cache.
//
// ARC has been patented by IBM, so do not use it if that is problematic for
// your program. For this reason, it is in a separate go module contained within
// this repository.
//
// All caches in this package take locks while operating, and are therefore
// thread-safe for consumers.
package lru