updates to identity site

src/pkg/cache/cache.go

@@ -0,0 +1,77 @@
+package cache
+
+import (
+	"time"
+
+	lru "github.com/hashicorp/golang-lru"
+)
+
+type Key interface {
+	Key() interface{}
+}
+type Value interface {
+	Stale() bool
+	Value() interface{}
+}
+type item struct {
+	key      interface{}
+	value    interface{}
+	expireOn time.Time
+}
+
+func NewItem(key, value interface{}, expires time.Duration) *item {
+	return &item{
+		key:      key,
+		value:    value,
+		expireOn: time.Now().Add(expires),
+	}
+}
+func (e *item) Stale() bool {
+	if e == nil || e.value == nil {
+		return true
+	}
+
+	return time.Now().After(e.expireOn)
+}
+func (s *item) Value() interface{} {
+	return s.value
+}
+
+type Cacher interface {
+	Add(Key, Value)
+	Has(Key) bool
+	Get(Key) (Value, bool)
+	Remove(Key)
+}
+
+type arcCache struct {
+	cache *lru.ARCCache
+}
+
+func NewARC(size int) (Cacher, error) {
+	arc, err := lru.NewARC(size)
+	if err != nil {
+		return nil, err
+	}
+
+	return &arcCache{cache: arc}, nil
+}
+func (c *arcCache) Add(key Key, value Value) {
+	c.cache.Add(key.Key(), value)
+}
+func (c *arcCache) Get(key Key) (Value, bool) {
+	if v, ok := c.cache.Get(key.Key()); ok {
+		if value, ok := v.(Value); ok && !value.Stale() {
+			return value, true
+		}
+		c.cache.Remove(key.Key())
+	}
+	return nil, false
+}
+func (c *arcCache) Has(key Key) bool {
+	_, ok := c.Get(key)
+	return ok
+}
+func (c *arcCache) Remove(key Key) {
+	c.cache.Remove(key.Key())
+}