refactor Group.Do implement via Group.Dochan call

Author: gleonid

singleflight/singleflight.go

@@ -49,23 +49,8 @@ type Result struct {
 // original to complete and receives the same results.
 // The return value shared indicates whether v was given to multiple callers.
 func (g *Group) Do(key string, fn func() (interface{}, error)) (v interface{}, err error, shared bool) {
-	g.mu.Lock()
-	if g.m == nil {
-		g.m = make(map[string]*call)
-	}
-	if c, ok := g.m[key]; ok {
-		c.dups++
-		g.mu.Unlock()
-		c.wg.Wait()
-		return c.val, c.err, true
-	}
-	c := new(call)
-	c.wg.Add(1)
-	g.m[key] = c
-	g.mu.Unlock()
-
-	g.doCall(c, key, fn)
-	return c.val, c.err, c.dups > 0
+	r := <-g.DoChan(key, fn)
+	return r.Val, r.Err, r.Shared
 }
 
 // DoChan is like Do but returns a channel that will receive the