143 lines
3.0 KiB
Go
143 lines
3.0 KiB
Go
// Copyright 2023 LiveKit, Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package pacer
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import (
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"sync"
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"time"
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"github.com/frostbyte73/core"
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"github.com/gammazero/deque"
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"github.com/livekit/livekit-server/pkg/sfu/bwe"
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"github.com/livekit/protocol/logger"
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)
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const (
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maxOvershootFactor = 2.0
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)
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type LeakyBucket struct {
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*Base
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logger logger.Logger
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lock sync.RWMutex
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packets deque.Deque[*Packet]
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interval time.Duration
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bitrate int
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stop core.Fuse
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}
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func NewLeakyBucket(logger logger.Logger, bwe bwe.BWE, interval time.Duration, bitrate int) *LeakyBucket {
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l := &LeakyBucket{
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Base: NewBase(logger, bwe),
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logger: logger,
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interval: interval,
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bitrate: bitrate,
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}
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l.packets.SetBaseCap(512)
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go l.sendWorker()
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return l
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}
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func (l *LeakyBucket) SetInterval(interval time.Duration) {
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l.lock.Lock()
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defer l.lock.Unlock()
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l.interval = interval
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}
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func (l *LeakyBucket) SetBitrate(bitrate int) {
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l.lock.Lock()
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defer l.lock.Unlock()
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l.bitrate = bitrate
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}
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func (l *LeakyBucket) Stop() {
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l.stop.Break()
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}
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func (l *LeakyBucket) Enqueue(p *Packet) {
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l.lock.Lock()
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l.packets.PushBack(p)
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l.lock.Unlock()
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}
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func (l *LeakyBucket) sendWorker() {
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l.lock.RLock()
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interval := l.interval
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l.lock.RUnlock()
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var bitrate int
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timer := time.NewTimer(interval)
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overage := 0
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for {
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<-timer.C
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l.lock.RLock()
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interval = l.interval
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bitrate = l.bitrate
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l.lock.RUnlock()
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// calculate number of bytes that can be sent in this interval
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// adjusting for overage.
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intervalBytes := int(interval.Seconds() * float64(bitrate) / 8.0)
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maxOvershootBytes := int(float64(intervalBytes) * maxOvershootFactor)
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toSendBytes := intervalBytes - overage
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if toSendBytes < 0 {
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// too much overage, wait for next interval
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overage = -toSendBytes
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timer.Reset(interval)
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continue
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}
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// do not allow too much overshoot in an interval
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if toSendBytes > maxOvershootBytes {
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toSendBytes = maxOvershootBytes
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}
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for {
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if l.stop.IsBroken() {
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return
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}
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l.lock.Lock()
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if l.packets.Len() == 0 {
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l.lock.Unlock()
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// allow overshoot in next interval with shortage in this interval
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overage = -toSendBytes
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timer.Reset(interval)
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break
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}
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p := l.packets.PopFront()
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l.lock.Unlock()
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written, _ := l.Base.SendPacket(p)
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toSendBytes -= written
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if toSendBytes < 0 {
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// overage, wait for next interval
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overage = -toSendBytes
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timer.Reset(interval)
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break
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}
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}
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}
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}
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// ------------------------------------------------
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