From fc13e78cf0f3873ba5b7628a480f37caada76736 Mon Sep 17 00:00:00 2001
From: guonaihong <guonaihong@qq.com>
Date: Mon, 20 May 2024 21:27:31 +0800
Subject: [PATCH] add myonce

---
 frame/frame_v1.go |  3 ---
 myonce/myonce.go  | 33 +++++++++++++++++++++++++++++++++
 2 files changed, 33 insertions(+), 3 deletions(-)
 create mode 100644 myonce/myonce.go

diff --git a/frame/frame_v1.go b/frame/frame_v1.go
index f1956b3..98f2008 100644
--- a/frame/frame_v1.go
+++ b/frame/frame_v1.go
@@ -90,9 +90,6 @@ func ReadHeader(r io.Reader, headArray *[enum.MaxFrameHeaderSize]byte) (h FrameH
 	switch {
 	// 长度
 	case h.PayloadLen >= 0 && h.PayloadLen <= 125:
-		if h.PayloadLen == 0 && !h.Mask {
-			return
-		}
 	case h.PayloadLen == 126:
 		// 2字节长度
 		have += 2
diff --git a/myonce/myonce.go b/myonce/myonce.go
new file mode 100644
index 0000000..dc10519
--- /dev/null
+++ b/myonce/myonce.go
@@ -0,0 +1,33 @@
+package myonce
+
+import (
+	"sync"
+	"sync/atomic"
+)
+
+type MyOnce struct {
+	done uint32
+}
+
+func (o *MyOnce) Do(mu *sync.Mutex, f func()) {
+
+	if atomic.LoadUint32(&o.done) == 0 {
+
+		o.doSlow(mu, f)
+	}
+}
+
+// 这里与标准库的做法不一样，标准库是保证了f执行之后才会设置done为1
+// 这里是先设置done为1，然后再执行f
+// 标准库是站在资源必须初始化成功的角度设计，而这里主要是为了解决资源释放自己调用自己的死锁问题
+// 试想下这个场景;
+// 出错会调用用户的OnClose函数，这个函数会被包在sync.Once里面，而OnClose函数中又会调用Close函数，这个函数里面也会有调用OnClose的逻辑，这样就会死锁
+// 如果前置设置done为1，那么就不会有这个问题
+func (o *MyOnce) doSlow(mu *sync.Mutex, f func()) {
+	mu.Lock()
+	defer mu.Unlock()
+	if o.done == 0 {
+		atomic.StoreUint32(&o.done, 1)
+		f()
+	}
+}