add Stop method to stop the background worker and make it possible for the GC to reap the object

cache.go

@@ -115,6 +115,12 @@ func (c *Cache) Clear() {
 	c.list = list.New()
 }
 
+// Stops the background worker. Operations performed on the cache after Stop
+// is called are likely to panic
+func (c *Cache) Stop() {
+	close(c.promotables)
+}
+
 func (c *Cache) deleteItem(bucket *bucket, item *Item) {
 	bucket.delete(item.key) //stop other GETs from getting it
 	c.deletables <- item
@@ -142,7 +148,10 @@ func (c *Cache) promote(item *Item) {
 func (c *Cache) worker() {
 	for {
 		select {
-		case item := <-c.promotables:
+		case item, ok := <-c.promotables:
+			if ok == false {
+				return
+			}
 			if c.doPromote(item) && c.size > c.maxSize {
 				c.gc()
 			}

readme.md

@@ -101,6 +101,10 @@ cache.Replace("user:4", user)
 
 `Replace` returns true if the item existed (and thus was replaced). In the case where the key was not in the cache, the value *is not* inserted and false is returned.
 
+### Stop
+The cache's background worker can be stopped by calling `Stop`. Once `Stop` is called
+the cache should not be used (calls are likely to panic). Stop must be called in order to allow the garbage collector to reap the cache.
+
 ## Tracking
 CCache supports a special tracking mode which is meant to be used in conjunction with other pieces of your code that maintains a long-lived reference to data.