const (
// Default2QRecentRatio is the ratio of the 2Q cache dedicated
// to recently added entries that have only been accessed once.
Default2QRecentRatio = 0.25
// Default2QGhostEntries is the default ratio of ghost
// entries kept to track entries recently evicted
Default2QGhostEntries = 0.50
)
const (
// DefaultEvictedBufferSize defines the default buffer size to store evicted key/val
DefaultEvictedBufferSize = 16
)
Cache is a thread-safe fixed size LRU cache.
type Cache[K comparable, V any] struct { // contains filtered or unexported fields }
func New[K comparable, V any](size int) (*Cache[K, V], error)
New creates an LRU of the given size.
func NewWithEvict[K comparable, V any](size int, onEvicted func(key K, value V)) (c *Cache[K, V], err error)
NewWithEvict constructs a fixed size cache with the given eviction callback.
func (c *Cache[K, V]) Add(key K, value V) (evicted bool)
Add adds a value to the cache. Returns true if an eviction occurred.
func (c *Cache[K, V]) Contains(key K) bool
Contains checks if a key is in the cache, without updating the recent-ness or deleting it for being stale.
func (c *Cache[K, V]) ContainsOrAdd(key K, value V) (ok, evicted bool)
ContainsOrAdd checks if a key is in the cache without updating the recent-ness or deleting it for being stale, and if not, adds the value. Returns whether found and whether an eviction occurred.
func (c *Cache[K, V]) Get(key K) (value V, ok bool)
Get looks up a key's value from the cache.
func (c *Cache[K, V]) GetOldest() (key K, value V, ok bool)
GetOldest returns the oldest entry
func (c *Cache[K, V]) Keys() []K
Keys returns a slice of the keys in the cache, from oldest to newest.
func (c *Cache[K, V]) Len() int
Len returns the number of items in the cache.
func (c *Cache[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 (c *Cache[K, V]) PeekOrAdd(key K, value V) (previous V, ok, evicted bool)
PeekOrAdd checks if a key is in the cache without updating the recent-ness or deleting it for being stale, and if not, adds the value. Returns whether found and whether an eviction occurred.
func (c *Cache[K, V]) Purge()
Purge is used to completely clear the cache.
func (c *Cache[K, V]) Remove(key K) (present bool)
Remove removes the provided key from the cache.
func (c *Cache[K, V]) RemoveOldest() (key K, value V, ok bool)
RemoveOldest removes the oldest item from the cache.
func (c *Cache[K, V]) Resize(size int) (evicted int)
Resize changes the cache size.
func (c *Cache[K, V]) Values() []V
Values returns a slice of the values in the cache, from oldest to newest.
TwoQueueCache is a thread-safe fixed size 2Q cache. 2Q is an enhancement over the standard LRU cache in that it tracks both frequently and recently used entries separately. This avoids a burst in access to new entries from evicting frequently used entries. It adds some additional tracking overhead to the standard LRU cache, and is computationally about 2x the cost, and adds some metadata over head. The ARCCache is similar, but does not require setting any parameters.
type TwoQueueCache[K comparable, V any] struct { // contains filtered or unexported fields }
func New2Q[K comparable, V any](size int) (*TwoQueueCache[K, V], error)
New2Q creates a new TwoQueueCache using the default values for the parameters.
func New2QParams[K comparable, V any](size int, recentRatio, ghostRatio float64) (*TwoQueueCache[K, V], error)
New2QParams creates a new TwoQueueCache using the provided parameter values.
func (c *TwoQueueCache[K, V]) Add(key K, value V)
Add adds a value to the cache.
func (c *TwoQueueCache[K, V]) Contains(key K) bool
Contains is used to check if the cache contains a key without updating recency or frequency.
func (c *TwoQueueCache[K, V]) Get(key K) (value V, ok bool)
Get looks up a key's value from the cache.
func (c *TwoQueueCache[K, V]) Keys() []K
Keys returns a slice of the keys in the cache. The frequently used keys are first in the returned slice.
func (c *TwoQueueCache[K, V]) Len() int
Len returns the number of items in the cache.
func (c *TwoQueueCache[K, V]) Peek(key K) (value V, ok bool)
Peek is used to inspect the cache value of a key without updating recency or frequency.
func (c *TwoQueueCache[K, V]) Purge()
Purge is used to completely clear the cache.
func (c *TwoQueueCache[K, V]) Remove(key K)
Remove removes the provided key from the cache.
func (c *TwoQueueCache[K, V]) Resize(size int) (evicted int)
Resize changes the cache size.
func (c *TwoQueueCache[K, V]) Values() []V
Values returns a slice of the values in the cache. The frequently used values are first in the returned slice.