Merge branch 'upstream-mirror' into sync-updates

# Conflicts:
#	layeredcache_test.go

cache.go

@@ -141,6 +141,9 @@ func (c *Cache) Replace(key string, value interface{}) bool {
 // Attempts to get the value from the cache and calles fetch on a miss (missing
 // or stale item). If fetch returns an error, no value is cached and the error
 // is returned back to the caller.
+// Note that Fetch merely calls the public Get and Set functions. If you want
+// a different Fetch behavior, such as thundering herd protection or returning
+// expired items, implement it in your application.
 func (c *Cache) Fetch(key string, duration time.Duration, fetch func() (interface{}, error)) (*Item, error) {
 	item := c.Get(key)
 	if item != nil && !item.Expired() {
@@ -373,7 +376,13 @@ func (c *Cache) doPromote(item *Item) bool {
 func (c *Cache) gc() int {
 	dropped := 0
 	element := c.list.Back()
-	for i := 0; i < c.itemsToPrune; i++ {
+
+	itemsToPrune := int64(c.itemsToPrune)
+	if min := c.size - c.maxSize; min > itemsToPrune {
+		itemsToPrune = min
+	}
+
+	for i := int64(0); i < itemsToPrune; i++ {
 		if element == nil {
 			return dropped
 		}