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priority.go
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priority.go
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/*
Copyright 2014-2021 Docker Inc.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
package spdystream
import (
"container/heap"
"sync"
"github.com/moby/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()
}