[feat] nazasync: 增加一个竞争失败时非阻塞的Once

pkg/nazasync/once.go

@@ -0,0 +1,32 @@
+// Copyright 2022, Chef.  All rights reserved.
+// https://github.com/q191201771/naza
+//
+// Use of this source code is governed by a MIT-style license
+// that can be found in the License file.
+//
+// Author: Chef (191201771@qq.com)
+
+package nazasync
+
+import (
+	"sync"
+	"sync/atomic"
+)
+
+type StdOnce struct {
+	core sync.Once
+}
+
+func (o *StdOnce) Do(f func()) {
+	o.core.Do(f)
+}
+
+type NonblockingOnce struct {
+	done uint32
+}
+
+func (o *NonblockingOnce) Do(f func()) {
+	if atomic.CompareAndSwapUint32(&o.done, 0, 1) {
+		f()
+	}
+}