arc

README

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arc

An Adaptive Replacement Cache (ARC) written in Go.

GoDoc

This project implements "ARC", a self-tuning, low overhead replacement cache. The goal of this project is to expose an interface compareable to common LRU cache management systems. ARC uses a learning rule to adaptively and continually revise its assumptions about the workload in order to adjust the internal LRU and LFU cache sizes.

This implementation is based on Nimrod Megiddo and Dharmendra S. Modha's "ARC: A SELF-TUNING, LOW OVERHEAD REPLACEMENT CACHE", while definitely useable and thread safe, this is still an experiment and shouldn't be considered production-ready.

<------- cache size c ------>
+-----------------+----------
| LFU             | LRU     |
+-----------------+----------
                  ^
                  |
                  p (dynamically adjusted by learning rule)

B1 [...]
B2 [...]

The cache is implemented using two internal caching systems L1 and L2. The cache size c defines the maximum number of entries stored (excluding ghost entries). Ghost entries are being stored in two "ghost registries" B1 and B1. Ghost entries no longer have a value associated with them.

Ghost entries are being used in order to keep track of expelled pages. They no longer have a value associated with them, but can be promoted into the internal LRU cache.

Frequently requested pages are being promoted into the LFU.

Documentation

Overview

Package arc implements an Adaptive replacement cache

Index

• type ARC
  • func New(c int) *ARC
  • func (a *ARC) Get(key interface{}) (value interface{}, ok bool)
  • func (a *ARC) Len() int
  • func (a *ARC) Put(key, value interface{}) bool

Types

type ARC

type ARC struct {
	// contains filtered or unexported fields
}

func New

func New(c int) *ARC

New returns a new Adaptive Replacement Cache (ARC).

func (*ARC) Get

func (a *ARC) Get(key interface{}) (value interface{}, ok bool)

Get retrieves a previously via Set inserted entry. This optimizes future access to this entry (side effect).

func (*ARC) Len

func (a *ARC) Len() int

Len determines the number of currently cached entries. This method is side-effect free in the sense that it does not attempt to optimize random cache access.

func (*ARC) Put

func (a *ARC) Put(key, value interface{}) bool

Put inserts a new key-value pair into the cache. This optimizes future access to this entry (side effect).