implement a StreamFrame Queue to handle high priority StreamFrames for retransmission

fixes #21

stream_frame_queue.go

@@ -0,0 +1,66 @@
+package quic
+
+import (
+	"sync"
+
+	"github.com/lucas-clemente/quic-go/frames"
+)
+
+// StreamFrameQueue is a Queue that handles StreamFrames
+type StreamFrameQueue struct {
+	prioFrames []*frames.StreamFrame
+	frames     []*frames.StreamFrame
+	mutex      sync.Mutex
+}
+
+// Push adds a new StreamFrame to the queue
+func (q *StreamFrameQueue) Push(frame *frames.StreamFrame, prio bool) {
+	q.mutex.Lock()
+	defer q.mutex.Unlock()
+
+	if prio {
+		q.prioFrames = append(q.prioFrames, frame)
+	} else {
+		q.frames = append(q.frames, frame)
+	}
+}
+
+// Len returns the total number of queued StreamFrames
+func (q *StreamFrameQueue) Len() int {
+	q.mutex.Lock()
+	defer q.mutex.Unlock()
+
+	return len(q.prioFrames) + len(q.frames)
+}
+
+// Pop returns the next element and deletes it from the queue
+func (q *StreamFrameQueue) Pop() *frames.StreamFrame {
+	q.mutex.Lock()
+	defer q.mutex.Unlock()
+
+	if len(q.prioFrames) > 0 {
+		frame := q.prioFrames[0]
+		q.prioFrames = q.prioFrames[1:]
+		return frame
+	}
+	if len(q.frames) > 0 {
+		frame := q.frames[0]
+		q.frames = q.frames[1:]
+		return frame
+	}
+	return nil
+}
+
+// Front returns the next element without modifying the queue
+func (q *StreamFrameQueue) Front() *frames.StreamFrame {
+	q.mutex.Lock()
+	defer q.mutex.Unlock()
+
+	if len(q.prioFrames) > 0 {
+		return q.prioFrames[0]
+	}
+	if len(q.frames) > 0 {
+		return q.frames[0]
+	}
+	return nil
+}