feat: Waku v2 bridge

Issue #12610

vendor/github.com/anacrolix/chansync/set-once.go

@@ -0,0 +1,44 @@
+package chansync
+
+import (
+	"sync"
+	"sync/atomic"
+
+	"github.com/anacrolix/chansync/events"
+)
+
+// SetOnce is a boolean value that can only be flipped from false to true.
+type SetOnce struct {
+	ch chan struct{}
+	// Could be faster than trying to receive from ch
+	closed    uint32
+	initOnce  sync.Once
+	closeOnce sync.Once
+}
+
+// Returns a channel that is closed when the event is flagged.
+func (me *SetOnce) Done() events.Done {
+	me.init()
+	return me.ch
+}
+
+func (me *SetOnce) init() {
+	me.initOnce.Do(func() {
+		me.ch = make(chan struct{})
+	})
+}
+
+// Set only returns true the first time it is called.
+func (me *SetOnce) Set() (first bool) {
+	me.closeOnce.Do(func() {
+		me.init()
+		first = true
+		atomic.StoreUint32(&me.closed, 1)
+		close(me.ch)
+	})
+	return
+}
+
+func (me *SetOnce) IsSet() bool {
+	return atomic.LoadUint32(&me.closed) != 0
+}