package lru
import (
"sync"
"github.com/hashicorp/golang-lru/simplelru"
)
// Cache is a thread-safe fixed size LRU cache.
type Cache struct {
lru simplelru.LRUCache
lock sync.RWMutex
}
// New creates an LRU of the given size.
func New(size int) (*Cache, error) {
return NewWithEvict(size, nil)
}
// NewWithEvict constructs a fixed size cache with the given eviction
// callback.
func NewWithEvict(size int, onEvicted func(key interface{}, value interface{})) (*Cache, error) {
lru, err := simplelru.NewLRU(size, simplelru.EvictCallback(onEvicted))
if err != nil {
return nil, err
}
c := &Cache{
lru: lru,
}
return c, nil
}
// Purge is used to completely clear the cache.
func (c *Cache) Purge() {
c.lock.Lock()
c.lru.Purge()
c.lock.Unlock()
}
// Add adds a value to the cache. Returns true if an eviction occurred.
func (c *Cache) Add(key, value interface{}) (evicted bool) {
c.lock.Lock()
evicted = c.lru.Add(key, value)
c.lock.Unlock()
return evicted
}
// Get looks up a key's value from the cache.
func (c *Cache) Get(key interface{}) (value interface{}, ok bool) {
c.lock.Lock()
value, ok = c.lru.Get(key)
c.lock.Unlock()
return value, ok
}
// Contains checks if a key is in the cache, without updating the
// recent-ness or deleting it for being stale.
func (c *Cache) Contains(key interface{}) bool {
c.lock.RLock()
containKey := c.lru.Contains(key)
c.lock.RUnlock()
return containKey
}
// Peek returns the key value (or undefined if not found) without updating
// the "recently used"-ness of the key.
func (c *Cache) Peek(key interface{}) (value interface{}, ok bool) {
c.lock.RLock()
value, ok = c.lru.Peek(key)
c.lock.RUnlock()
return value, ok
}
// 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) ContainsOrAdd(key, value interface{}) (ok, evicted bool) {
c.lock.Lock()
defer c.lock.Unlock()
if c.lru.Contains(key) {
return true, false
}
evicted = c.lru.Add(key, value)
return false, evicted
}
// 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) PeekOrAdd(key, value interface{}) (previous interface{}, ok, evicted bool) {
c.lock.Lock()
defer c.lock.Unlock()
previous, ok = c.lru.Peek(key)
if ok {
return previous, true, false
}
evicted = c.lru.Add(key, value)
return nil, false, evicted
}
// Remove removes the provided key from the cache.
func (c *Cache) Remove(key interface{}) (present bool) {
c.lock.Lock()
present = c.lru.Remove(key)
c.lock.Unlock()
return
}
// Resize changes the cache size.
func (c *Cache) Resize(size int) (evicted int) {
c.lock.Lock()
evicted = c.lru.Resize(size)
c.lock.Unlock()
return evicted
}
// RemoveOldest removes the oldest item from the cache.
func (c *Cache) RemoveOldest() (key interface{}, value interface{}, ok bool) {
c.lock.Lock()
key, value, ok = c.lru.RemoveOldest()
c.lock.Unlock()
return
}
// GetOldest returns the oldest entry
func (c *Cache) GetOldest() (key interface{}, value interface{}, ok bool) {
c.lock.Lock()
key, value, ok = c.lru.GetOldest()
c.lock.Unlock()
return
}
// Keys returns a slice of the keys in the cache, from oldest to newest.
func (c *Cache) Keys() []interface{} {
c.lock.RLock()
keys := c.lru.Keys()
c.lock.RUnlock()
return keys
}
// Len returns the number of items in the cache.
func (c *Cache) Len() int {
c.lock.RLock()
length := c.lru.Len()
c.lock.RUnlock()
return length
}
