package expirable

import "github.com/hashicorp/golang-lru/v2/expirable"

Index ¶

• type EvictCallback
• type LRU
• func NewLRU[K comparable, V any](size int, onEvict EvictCallback[K, V], ttl time.Duration) *LRU[K, V]
• func (c *LRU[K, V]) Add(key K, value V) (evicted bool)
• func (c *LRU[K, V]) Contains(key K) (ok bool)
• func (c *LRU[K, V]) Get(key K) (value V, ok bool)
• func (c *LRU[K, V]) GetOldest() (key K, value V, ok bool)
• func (c *LRU[K, V]) Keys() []K
• func (c *LRU[K, V]) Len() int
• func (c *LRU[K, V]) Peek(key K) (value V, ok bool)
• func (c *LRU[K, V]) Purge()
• func (c *LRU[K, V]) Remove(key K) bool
• func (c *LRU[K, V]) RemoveOldest() (key K, value V, ok bool)
• func (c *LRU[K, V]) Resize(size int) (evicted int)
• func (c *LRU[K, V]) Values() []V

Examples ¶

• LRU

Types ¶

type EvictCallback ¶

type EvictCallback[K comparable, V any] func(key K, value V)

EvictCallback is used to get a callback when a cache entry is evicted

type LRU ¶

type LRU[K comparable, V any] struct {
	// contains filtered or unexported fields
}

LRU implements a thread-safe LRU with expirable entries.

{
	// make cache with 10ms TTL and 5 max keys
	cache := NewLRU[string, string](5, nil, time.Millisecond*10)

	// set value under key1.
	cache.Add("key1", "val1")

	// get value under key1
	r, ok := cache.Get("key1")

	// check for OK value
	if ok {
		fmt.Printf("value before expiration is found: %v, value: %q\n", ok, r)
	}

	// wait for cache to expire
	time.Sleep(time.Millisecond * 100)

	// get value under key1 after key expiration
	r, ok = cache.Get("key1")
	fmt.Printf("value after expiration is found: %v, value: %q\n", ok, r)

	// set value under key2, would evict old entry because it is already expired.
	cache.Add("key2", "val2")

	fmt.Printf("Cache len: %d\n", cache.Len())
	// Output:
	// value before expiration is found: true, value: "val1"
	// value after expiration is found: false, value: ""
	// Cache len: 1
}

value before expiration is found: true, value: "val1"
value after expiration is found: false, value: ""
Cache len: 1

func NewLRU ¶

func NewLRU[K comparable, V any](size int, onEvict EvictCallback[K, V], ttl time.Duration) *LRU[K, V]

NewLRU returns a new thread-safe cache with expirable entries.

Size parameter set to 0 makes cache of unlimited size, e.g. turns LRU mechanism off.

Providing 0 TTL turns expiring off.

Delete expired entries every 1/100th of ttl value. Goroutine which deletes expired entries runs indefinitely.

func (*LRU[K, V]) Add ¶

func (c *LRU[K, V]) Add(key K, value V) (evicted bool)

Add adds a value to the cache. Returns true if an eviction occurred. Returns false if there was no eviction: the item was already in the cache, or the size was not exceeded.

func (*LRU[K, V]) Contains ¶

func (c *LRU[K, V]) Contains(key K) (ok bool)

Contains checks if a key is in the cache, without updating the recent-ness or deleting it for being stale.

func (*LRU[K, V]) Get ¶

func (c *LRU[K, V]) Get(key K) (value V, ok bool)

Get looks up a key's value from the cache.

func (*LRU[K, V]) GetOldest ¶

func (c *LRU[K, V]) GetOldest() (key K, value V, ok bool)

GetOldest returns the oldest entry

func (*LRU[K, V]) Keys ¶

func (c *LRU[K, V]) Keys() []K

Keys returns a slice of the keys in the cache, from oldest to newest.

func (*LRU[K, V]) Len ¶

func (c *LRU[K, V]) Len() int

Len returns the number of items in the cache.

func (*LRU[K, V]) Peek ¶

func (c *LRU[K, V]) Peek(key K) (value V, ok bool)

Peek returns the key value (or undefined if not found) without updating the "recently used"-ness of the key.

func (*LRU[K, V]) Purge ¶

func (c *LRU[K, V]) Purge()

Purge clears the cache completely. onEvict is called for each evicted key.

func (*LRU[K, V]) Remove ¶

func (c *LRU[K, V]) Remove(key K) bool

Remove removes the provided key from the cache, returning if the key was contained.

func (*LRU[K, V]) RemoveOldest ¶

func (c *LRU[K, V]) RemoveOldest() (key K, value V, ok bool)

RemoveOldest removes the oldest item from the cache.

func (*LRU[K, V]) Resize ¶

func (c *LRU[K, V]) Resize(size int) (evicted int)

Resize changes the cache size. Size of 0 means unlimited.

func (*LRU[K, V]) Values ¶

func (c *LRU[K, V]) Values() []V

Values returns a slice of the values in the cache, from oldest to newest. Expired entries are filtered out.

Source Files ¶

expirable_lru.go