diff --git a/fetcher.go b/fetcher.go
new file mode 100644
index 0000000..4d4b06f
--- /dev/null
+++ b/fetcher.go
@@ -0,0 +1,84 @@
+package go-cache
+
+const (
+	errInvalidKey = "type:[invalid_key] key:[%s]"
+)
+type callbackFunc func(key string)(interface{},error)
+
+type fetcher struct {
+	cb map[string]callbackFunc
+	prefixLen int
+}
+
+func NewFetcher(prefixLen int) *fetcher {
+	return &fetcher{
+		cb : make(map[string]callbackFunc),
+		prefixLen: prefixLen,
+	}
+}
+
+func (f *fetcher) Register(keyPrefix string, cbf callbackFunc) bool{
+	if len(keyPrefix) != f.prefixLen {
+		return false
+	}
+	f.cb[keyPrefix] = cbf
+	return true
+}
+
+func (f *fetcher) execute(key string) (interface{},error) {
+	if len(key) < f.prefixLen {
+		return nil, fmt.Errorf(errInvalidKey,key)
+	}
+	keyPrefix := key[:f.prefixLen]
+	cbf, ok := f.cb[keyPrefix]
+	if !ok {
+		return nil, fmt.Errorf(errInvalidKey,key)
+	}
+	return cbf(key)
+}
+
+
+/*
+
+//header bidding
+sample keys
+
+Key_Prefix_PUB_SLOT_INFO  = "AAA00"
+Key_Prefix_PUB_HB_PARTNER = "AAB00"
+Key_Prefix_PubAdunitConfig = "AAC00"
+Key_Prefix_PubSlotHashInfo = "AAD00"
+Key_Prefix_PubSlotRegex    = "AAE00"
+Key_Prefix_PubSlotNameHash = "AAF00"
+Key_Prefix_PubVASTTags     = "AAG00"
+
+
+PUB_SLOT_INFO  = Key_Prefix_PUB_SLOT_INFO + "_%d_%d_%d_%d" // publisher slot mapping at publisher, profile, display version and adapter level
+PUB_HB_PARTNER = Key_Prefix_PUB_HB_PARTNER + "_%d_%d_%d"  // header bidding partner list at publishr,profile, display version level
+PubAdunitConfig = Key_Prefix_PubAdunitConfig + "_%d_%d_%d"
+PubSlotHashInfo = Key_Prefix_PubSlotHashInfo + "_%d_%d_%d_%d"     // slot and its hash info at publisher, profile, display version and adapter level
+PubSlotRegex    = Key_Prefix_PubSlotRegex + "_%d_%d_%d_%d_%s" // slot and its matching regex info at publisher, profile, display version and adapter level
+PubSlotNameHash = Key_Prefix_PubSlotNameHash + "_%d"       //publisher slotname hash mapping cache key
+PubVASTTags     = Key_Prefix_PubVASTTags + "_%d"
+
+func DBGetVASTTags(key string) (interface{},error) {
+	strings.Split(key,"_")
+	key[0] // keyprefix
+	key[1] //publisherid
+}
+
+//hb
+fetcher.Register(Key_Prefix_PUB_SLOT_INFO, DBGetVASTTags)
+
+type AsyncCache struct {
+	c *cache
+	f *fetcher
+	ks *keystatus
+}
+
+func (c *AsycCache) aget(key string) {
+	data, err := c.f.execute(key)
+	if err != nil {
+		c.c.set(key, data)
+	}
+}
+*/
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