blob: 36d7919f16ac1b51831ea4e798f511b758f533ef [file] [log] [blame]
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package http2
import "math"
// NewRandomWriteScheduler constructs a WriteScheduler that ignores HTTP/2
// priorities. Control frames like SETTINGS and PING are written before DATA
// frames, but if no control frames are queued and multiple streams have queued
// HEADERS or DATA frames, Pop selects a ready stream arbitrarily.
func NewRandomWriteScheduler() WriteScheduler {
return &randomWriteScheduler{sq: make(map[uint32]*writeQueue)}
type randomWriteScheduler struct {
// zero are frames not associated with a specific stream.
zero writeQueue
// sq contains the stream-specific queues, keyed by stream ID.
// When a stream is idle or closed, it's deleted from the map.
sq map[uint32]*writeQueue
// pool of empty queues for reuse.
queuePool writeQueuePool
func (ws *randomWriteScheduler) OpenStream(streamID uint32, options OpenStreamOptions) {
// no-op: idle streams are not tracked
func (ws *randomWriteScheduler) CloseStream(streamID uint32) {
q, ok := ws.sq[streamID]
if !ok {
delete(ws.sq, streamID)
func (ws *randomWriteScheduler) AdjustStream(streamID uint32, priority PriorityParam) {
// no-op: priorities are ignored
func (ws *randomWriteScheduler) Push(wr FrameWriteRequest) {
id := wr.StreamID()
if id == 0 {
q, ok := ws.sq[id]
if !ok {
q = ws.queuePool.get()
ws.sq[id] = q
func (ws *randomWriteScheduler) Pop() (FrameWriteRequest, bool) {
// Control frames first.
if ! {
return, true
// Iterate over all non-idle streams until finding one that can be consumed.
for _, q := range ws.sq {
if wr, ok := q.consume(math.MaxInt32); ok {
return wr, true
return FrameWriteRequest{}, false