tinylru

README

tinylru

A fast little LRU cache.

Getting Started

Installing

To start using tinylru, install Go and run go get:

$ go get -u github.com/tidwall/tinylru

This will retrieve the library.

Usage

Keys are strings, values are interfaces.

// Create an LRU cache
var cache tinylru.LRU

// Set the cache size. This is the maximum number of items that the cache can
// hold before evicting old items. The default size is 256.
cache.Resize(1024)

// Set a key. Returns the previous value and ok if a previous value exists.
prev, ok := cache.Set("hello", "world")

// Get a key. Returns the value and ok if the value exists.
value, ok := cache.Get("hello")

// Delete a key. Returns the deleted value and ok if a previous value exists.
prev, ok := tr.Delete("hello")

A Set function may evict old items when adding a new item while LRU is at capacity. If you want to know what was evicted then use the SetEvicted function.

// Set a key and return the evicted item, if any.
prev, ok, evictedKey, evictedValue, evicted := cache.SetEvicted("hello")

Contact

Josh Baker @tidwall

License

tinybtree source code is available under the MIT License.

Documentation

Index

• Constants
• type LRU
  • func (lru *LRU) Delete(key string) (prev interface{}, deleted bool)
  • func (lru *LRU) Get(key string) (value interface{}, ok bool)
  • func (lru *LRU) Len() int
  • func (lru *LRU) Range(iter func(key string, value interface{}) bool)
  • func (lru *LRU) Resize(size int) (evictedKeys []string, evictedValues []interface{})
  • func (lru *LRU) Reverse(iter func(key string, value interface{}) bool)
  • func (lru *LRU) Set(key string, value interface{}) (prev interface{}, replaced bool)
  • func (lru *LRU) SetEvicted(key string, value interface{}) (prev interface{}, replaced bool, evictedKey string, evictedValue interface{}, ...)

Constants

const DefaultSize = 256

DefaultSize is the default maximum size of an LRU cache before older items get automatically evicted.

Types

type LRU

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

LRU implements an LRU cache

func (*LRU) Delete

func (lru *LRU) Delete(key string) (prev interface{}, deleted bool)

Delete a value for a key

func (*LRU) Get

func (lru *LRU) Get(key string) (value interface{}, ok bool)

Get a value for key

func (*LRU) Len

func (lru *LRU) Len() int

Len returns the length of the lru cache

func (*LRU) Range

func (lru *LRU) Range(iter func(key string, value interface{}) bool)

Range iterates over all key/values in the order of most recently to least recently used items. It's not safe to call other LRU operations while ranging.

func (*LRU) Resize

func (lru *LRU) Resize(size int) (evictedKeys []string,
	evictedValues []interface{})

Resize sets the maximum size of an LRU cache. If this value is less than the number of items currently in the cache, then items will be evicted. Returns evicted items. This operation will panic if the size is less than one.

func (*LRU) Reverse

func (lru *LRU) Reverse(iter func(key string, value interface{}) bool)

Reverse iterates over all key/values in the order of least recently to most recently used items. It's not safe to call other LRU operations while ranging.

func (*LRU) Set

func (lru *LRU) Set(key string, value interface{}) (prev interface{},
	replaced bool)

Set or replace a value for a key.

func (*LRU) SetEvicted

func (lru *LRU) SetEvicted(key string, value interface{}) (prev interface{},
	replaced bool, evictedKey string, evictedValue interface{}, evicted bool)

SetEvicted sets or replaces a value for a key. If this operation causes an eviction then the evicted item is returned.