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writesched_random.go (2051B)

      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, closed, or emptied, it's deleted
     23 	// from the map.
     24 	sq map[uint32]*writeQueue
     25 
     26 	// pool of empty queues for reuse.
     27 	queuePool writeQueuePool
     28 }
     29 
     30 func (ws *randomWriteScheduler) OpenStream(streamID uint32, options OpenStreamOptions) {
     31 	// no-op: idle streams are not tracked
     32 }
     33 
     34 func (ws *randomWriteScheduler) CloseStream(streamID uint32) {
     35 	q, ok := ws.sq[streamID]
     36 	if !ok {
     37 		return
     38 	}
     39 	delete(ws.sq, streamID)
     40 	ws.queuePool.put(q)
     41 }
     42 
     43 func (ws *randomWriteScheduler) AdjustStream(streamID uint32, priority PriorityParam) {
     44 	// no-op: priorities are ignored
     45 }
     46 
     47 func (ws *randomWriteScheduler) Push(wr FrameWriteRequest) {
     48 	if wr.isControl() {
     49 		ws.zero.push(wr)
     50 		return
     51 	}
     52 	id := wr.StreamID()
     53 	q, ok := ws.sq[id]
     54 	if !ok {
     55 		q = ws.queuePool.get()
     56 		ws.sq[id] = q
     57 	}
     58 	q.push(wr)
     59 }
     60 
     61 func (ws *randomWriteScheduler) Pop() (FrameWriteRequest, bool) {
     62 	// Control and RST_STREAM frames first.
     63 	if !ws.zero.empty() {
     64 		return ws.zero.shift(), true
     65 	}
     66 	// Iterate over all non-idle streams until finding one that can be consumed.
     67 	for streamID, q := range ws.sq {
     68 		if wr, ok := q.consume(math.MaxInt32); ok {
     69 			if q.empty() {
     70 				delete(ws.sq, streamID)
     71 				ws.queuePool.put(q)
     72 			}
     73 			return wr, true
     74 		}
     75 	}
     76 	return FrameWriteRequest{}, false
     77 }