From 3fa767d9ffa9cc9bcdfecbe97c046fa1077d7a60 Mon Sep 17 00:00:00 2001
From: Karl Seguin <karl@viki.com>
Date: Thu, 31 Oct 2013 11:45:22 +0800
Subject: [PATCH] added non-threadsafe Clear (for tests), fixed Fetch

---
 bucket.go |  6 ++++++
 cache.go  | 22 ++++++++++++++++------
 2 files changed, 22 insertions(+), 6 deletions(-)

diff --git a/bucket.go b/bucket.go
index 43e4973..81ab787 100755
--- a/bucket.go
+++ b/bucket.go
@@ -45,3 +45,9 @@ func (b *Bucket) getAndDelete(key string) *Item{
   delete(b.lookup, key)
   return item
 }
+
+func (b *Bucket) clear() {
+  b.Lock()
+  defer b.Unlock()
+  b.lookup = make(map[string]*Item)
+}
diff --git a/cache.go b/cache.go
index ccb15c5..c4284ae 100755
--- a/cache.go
+++ b/cache.go
@@ -18,7 +18,7 @@ type Cache struct {
 
 func New(config *Configuration) *Cache {
   c := &Cache{
-    list: new(list.List),
+    list: list.New(),
     Configuration: config,
     bucketCount: uint32(config.buckets),
     buckets: make([]*Bucket, config.buckets),
@@ -51,12 +51,14 @@ func (c *Cache) Set(key string, value interface{}, duration time.Duration) {
   c.promote(item)
 }
 
-func (c *Cache) Fetch(key string, duration time.Duration, fetch func() interface{}) interface{} {
+func (c *Cache) Fetch(key string, duration time.Duration, fetch func() (interface{}, error)) (interface{}, error) {
   item := c.Get(key)
-  if item != nil { return item }
-  value := fetch()
-  c.Set(key, value, duration)
-  return value
+  if item != nil { return item, nil }
+  value, err := fetch()
+  if err == nil {
+    c.Set(key, value, duration)
+  }
+  return value, err
 }
 
 func (c *Cache) Delete(key string) {
@@ -66,6 +68,14 @@ func (c *Cache) Delete(key string) {
   }
 }
 
+//this isn't thread safe. It's meant to be called from non-concurrent tests
+func (c *Cache) Clear() {
+  for _, bucket := range c.buckets {
+    bucket.clear()
+  }
+  c.list = list.New()
+}
+
 func (c *Cache) deleteItem(bucket *Bucket, item *Item) {
   bucket.delete(item.key) //stop othe GETs from getting it
   c.deletables <- item