refactor channel registration

irc/utils/sync.go

@@ -0,0 +1,35 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package utils
+
+import (
+	"sync"
+	"sync/atomic"
+)
+
+// Once is a fork of sync.Once to expose a Done() method.
+type Once struct {
+	done uint32
+	m    sync.Mutex
+}
+
+func (o *Once) Do(f func()) {
+	if atomic.LoadUint32(&o.done) == 0 {
+		o.doSlow(f)
+	}
+}
+
+func (o *Once) doSlow(f func()) {
+	o.m.Lock()
+	defer o.m.Unlock()
+	if o.done == 0 {
+		defer atomic.StoreUint32(&o.done, 1)
+		f()
+	}
+}
+
+func (o *Once) Done() bool {
+	return atomic.LoadUint32(&o.done) == 1
+}