initial import

core/collection/fifo.go

@@ -0,0 +1,60 @@
+package collection
+
+import "sync"
+
+type Queue struct {
+	lock     sync.Mutex
+	elements []interface{}
+	size     int
+	head     int
+	tail     int
+	count    int
+}
+
+func NewQueue(size int) *Queue {
+	return &Queue{
+		elements: make([]interface{}, size),
+		size:     size,
+	}
+}
+
+func (q *Queue) Empty() bool {
+	q.lock.Lock()
+	empty := q.count == 0
+	q.lock.Unlock()
+
+	return empty
+}
+
+func (q *Queue) Put(element interface{}) {
+	q.lock.Lock()
+	defer q.lock.Unlock()
+
+	if q.head == q.tail && q.count > 0 {
+		nodes := make([]interface{}, len(q.elements)+q.size)
+		copy(nodes, q.elements[q.head:])
+		copy(nodes[len(q.elements)-q.head:], q.elements[:q.head])
+		q.head = 0
+		q.tail = len(q.elements)
+		q.elements = nodes
+	}
+
+	q.elements[q.tail] = element
+	q.tail = (q.tail + 1) % len(q.elements)
+	q.count++
+}
+
+func (q *Queue) Take() (interface{}, bool) {
+	q.lock.Lock()
+	defer q.lock.Unlock()
+
+	if q.count == 0 {
+		return nil, false
+	}
+
+	element := q.elements[q.head]
+	q.head = (q.head + 1) % len(q.elements)
+	q.count--
+
+	return element, true
+}