Get now returns the *Item rather than the item's value. Get no longer actively

purges stale items.

Combining these two changes, CCache can now be used to implement both of
Varnish's grace and saint mode.

layeredcache.go

@@ -35,32 +35,24 @@ func Layered(config *Configuration) *LayeredCache {
 	return c
 }
 
-func (c *LayeredCache) Get(primary, secondary string) interface{} {
-	if item := c.get(primary, secondary); item != nil {
-		return item.value
-	}
-	return nil
-}
-
-func (c *LayeredCache) TrackingGet(primary, secondary string) TrackedItem {
-	item := c.get(primary, secondary)
-	if item == nil {
-		return NilTracked
-	}
-	item.track()
-	return item
-}
-
-func (c *LayeredCache) get(primary, secondary string) *Item {
+func (c *LayeredCache) Get(primary, secondary string) *Item {
 	bucket := c.bucket(primary)
 	item := bucket.get(primary, secondary)
 	if item == nil {
 		return nil
 	}
-	if item.expires < time.Now().Unix() {
-		return nil
+	if item.expires > time.Now().Unix() {
+		c.conditionalPromote(item)
 	}
-	c.conditionalPromote(item)
+	return item
+}
+
+func (c *LayeredCache) TrackingGet(primary, secondary string) TrackedItem {
+	item := c.Get(primary, secondary)
+	if item == nil {
+		return NilTracked
+	}
+	item.track()
 	return item
 }