add conn limiter

limiter/conn/limiter.go

@@ -0,0 +1,30 @@
+package conn
+
+import (
+	"sync/atomic"
+
+	limiter "github.com/go-gost/core/limiter/conn"
+)
+
+type llimiter struct {
+	limit   int
+	current int64
+}
+
+func NewLimiter(n int) limiter.Limiter {
+	return &llimiter{limit: n}
+}
+
+func (l *llimiter) Limit() int {
+	return l.limit
+}
+
+func (l *llimiter) Allow(n int) bool {
+	if atomic.AddInt64(&l.current, int64(n)) >= int64(l.limit) {
+		if n > 0 {
+			atomic.AddInt64(&l.current, -int64(n))
+		}
+		return false
+	}
+	return true
+}