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package spdystream
import (
"container/heap"
"sync"
"github.com/docker/spdystream/spdy"
)
type prioritizedFrame struct {
frame spdy.Frame
priority uint8
insertId uint64
}
type frameQueue []*prioritizedFrame
func (fq frameQueue) Len() int {
return len(fq)
}
func (fq frameQueue) Less(i, j int) bool {
if fq[i].priority == fq[j].priority {
return fq[i].insertId < fq[j].insertId
}
return fq[i].priority < fq[j].priority
}
func (fq frameQueue) Swap(i, j int) {
fq[i], fq[j] = fq[j], fq[i]
}
func (fq *frameQueue) Push(x interface{}) {
*fq = append(*fq, x.(*prioritizedFrame))
}
func (fq *frameQueue) Pop() interface{} {
old := *fq
n := len(old)
*fq = old[0 : n-1]
return old[n-1]
}
type PriorityFrameQueue struct {
queue *frameQueue
c *sync.Cond
size int
nextInsertId uint64
drain bool
}
func NewPriorityFrameQueue(size int) *PriorityFrameQueue {
queue := make(frameQueue, 0, size)
heap.Init(&queue)
return &PriorityFrameQueue{
queue: &queue,
size: size,
c: sync.NewCond(&sync.Mutex{}),
}
}
func (q *PriorityFrameQueue) Push(frame spdy.Frame, priority uint8) {
q.c.L.Lock()
defer q.c.L.Unlock()
for q.queue.Len() >= q.size {
q.c.Wait()
}
pFrame := &prioritizedFrame{
frame: frame,
priority: priority,
insertId: q.nextInsertId,
}
q.nextInsertId = q.nextInsertId + 1
heap.Push(q.queue, pFrame)
q.c.Signal()
}
func (q *PriorityFrameQueue) Pop() spdy.Frame {
q.c.L.Lock()
defer q.c.L.Unlock()
for q.queue.Len() == 0 {
if q.drain {
return nil
}
q.c.Wait()
}
frame := heap.Pop(q.queue).(*prioritizedFrame).frame
q.c.Signal()
return frame
}
func (q *PriorityFrameQueue) Drain() {
q.c.L.Lock()
defer q.c.L.Unlock()
q.drain = true
q.c.Broadcast()
}
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