Change: proxy gruop strategy improvement

common/singledo/singledo.go

@@ -0,0 +1,54 @@
+package singledo
+
+import (
+	"sync"
+	"time"
+)
+
+type call struct {
+	wg  sync.WaitGroup
+	val interface{}
+	err error
+}
+
+type Single struct {
+	mux    sync.Mutex
+	last   int64
+	wait   int64
+	call   *call
+	result *Result
+}
+
+type Result struct {
+	Val interface{}
+	Err error
+}
+
+func (s *Single) Do(fn func() (interface{}, error)) (v interface{}, err error, shared bool) {
+	s.mux.Lock()
+	now := time.Now().Unix()
+	if now < s.last+s.wait {
+		s.mux.Unlock()
+		return s.result.Val, s.result.Err, true
+	}
+
+	if call := s.call; call != nil {
+		s.mux.Unlock()
+		call.wg.Wait()
+		return call.val, call.err, true
+	}
+
+	call := &call{}
+	call.wg.Add(1)
+	s.call = call
+	s.mux.Unlock()
+	call.val, call.err = fn()
+	s.call = nil
+	s.result = &Result{call.val, call.err}
+	s.last = now
+	return call.val, call.err, false
+}
+
+func NewSingle(wait time.Duration) *Single {
+	return &Single{wait: int64(wait)}
+}