vendor/golang.org/x/net/http2/writesched_random.go

   1 // Copyright 2014 The Go Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style
   3 // license that can be found in the LICENSE file.
   4
   5 package http2
   6
   7 import "math"
   8
   9 // NewRandomWriteScheduler constructs a WriteScheduler that ignores HTTP/2
  10 // priorities. Control frames like SETTINGS and PING are written before DATA
  11 // frames, but if no control frames are queued and multiple streams have queued
  12 // HEADERS or DATA frames, Pop selects a ready stream arbitrarily.
  13 func NewRandomWriteScheduler() WriteScheduler {
  14         return &randomWriteScheduler{sq: make(map[uint32]*writeQueue)}
  15 }
  16
  17 type randomWriteScheduler struct {
  18         // zero are frames not associated with a specific stream.
  19         zero writeQueue
  20
  21         // sq contains the stream-specific queues, keyed by stream ID.
  22         // When a stream is idle or closed, it's deleted from the map.
  23         sq map[uint32]*writeQueue
  24
  25         // pool of empty queues for reuse.
  26         queuePool writeQueuePool
  27 }
  28
  29 func (ws *randomWriteScheduler) OpenStream(streamID uint32, options OpenStreamOptions) {
  30         // no-op: idle streams are not tracked
  31 }
  32
  33 func (ws *randomWriteScheduler) CloseStream(streamID uint32) {
  34         q, ok := ws.sq[streamID]
  35         if !ok {
  36                 return
  37         }
  38         delete(ws.sq, streamID)
  39         ws.queuePool.put(q)
  40 }
  41
  42 func (ws *randomWriteScheduler) AdjustStream(streamID uint32, priority PriorityParam) {
  43         // no-op: priorities are ignored
  44 }
  45
  46 func (ws *randomWriteScheduler) Push(wr FrameWriteRequest) {
  47         id := wr.StreamID()
  48         if id == 0 {
  49                 ws.zero.push(wr)
  50                 return
  51         }
  52         q, ok := ws.sq[id]
  53         if !ok {
  54                 q = ws.queuePool.get()
  55                 ws.sq[id] = q
  56         }
  57         q.push(wr)
  58 }
  59
  60 func (ws *randomWriteScheduler) Pop() (FrameWriteRequest, bool) {
  61         // Control frames first.
  62         if !ws.zero.empty() {
  63                 return ws.zero.shift(), true
  64         }
  65         // Iterate over all non-idle streams until finding one that can be consumed.
  66         for _, q := range ws.sq {
  67                 if wr, ok := q.consume(math.MaxInt32); ok {
  68                         return wr, true
  69                 }
  70         }
  71         return FrameWriteRequest{}, false
  72 }