Add Inner Ring code

pkg/local_object_storage/bucket/fsbucket/queue.go

@@ -0,0 +1,44 @@
+package fsbucket
+
+import "sync"
+
+type (
+	queue struct {
+		*sync.RWMutex
+		buf []elem
+	}
+
+	elem struct {
+		depth  int
+		prefix string
+		path   string
+	}
+)
+
+func newQueue(n int) *queue {
+	return &queue{
+		RWMutex: new(sync.RWMutex),
+		buf:     make([]elem, 0, n),
+	}
+}
+
+func (q *queue) Len() int {
+	return len(q.buf)
+}
+
+func (q *queue) Push(s elem) {
+	q.Lock()
+	q.buf = append(q.buf, s)
+	q.Unlock()
+}
+
+func (q *queue) Pop() (s elem) {
+	q.Lock()
+	if len(q.buf) > 0 {
+		s = q.buf[0]
+		q.buf = q.buf[1:]
+	}
+	q.Unlock()
+
+	return
+}