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les, les/flowcontrol: implement LES/3 (#19329)

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les, les/flowcontrol: implement LES/3
This commit is contained in:
Felföldi Zsolt
2019-05-30 20:51:13 +02:00
committed by GitHub
parent 3d58268bba
commit 58497f46bd
22 changed files with 1539 additions and 614 deletions
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195
les/flowcontrol/manager.go
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@ -47,9 +47,9 @@ type cmNodeFields struct {
const FixedPointMultiplier = 1000000
var (
capFactorDropTC = 1 / float64(time.Second*10) // time constant for dropping the capacity factor
capFactorRaiseTC = 1 / float64(time.Hour) // time constant for raising the capacity factor
capFactorRaiseThreshold = 0.75 // connected / total capacity ratio threshold for raising the capacity factor
capacityDropFactor = 0.1
capacityRaiseTC = 1 / (3 * float64(time.Hour)) // time constant for raising the capacity factor
capacityRaiseThresholdRatio = 1.125 // total/connected capacity ratio threshold for raising the capacity factor
)
// ClientManager controls the capacity assigned to the clients of a server.
@ -61,10 +61,14 @@ type ClientManager struct {
clock mclock.Clock
lock sync.Mutex
enabledCh chan struct{}
stop chan chan struct{}
curve PieceWiseLinear
sumRecharge, totalRecharge, totalConnected uint64
capLogFactor, totalCapacity float64
logTotalCap, totalCapacity float64
logTotalCapRaiseLimit float64
minLogTotalCap, maxLogTotalCap float64
capacityRaiseThreshold uint64
capLastUpdate mclock.AbsTime
totalCapacityCh chan uint64
@ -106,13 +110,35 @@ func NewClientManager(curve PieceWiseLinear, clock mclock.Clock) *ClientManager
clock: clock,
rcQueue: prque.New(func(a interface{}, i int) { a.(*ClientNode).queueIndex = i }),
capLastUpdate: clock.Now(),
stop: make(chan chan struct{}),
}
if curve != nil {
cm.SetRechargeCurve(curve)
}
go func() {
// regularly recalculate and update total capacity
for {
select {
case <-time.After(time.Minute):
cm.lock.Lock()
cm.updateTotalCapacity(cm.clock.Now(), true)
cm.lock.Unlock()
case stop := <-cm.stop:
close(stop)
return
}
}
}()
return cm
}
// Stop stops the client manager
func (cm *ClientManager) Stop() {
stop := make(chan struct{})
cm.stop <- stop
<-stop
}
// SetRechargeCurve updates the recharge curve
func (cm *ClientManager) SetRechargeCurve(curve PieceWiseLinear) {
cm.lock.Lock()
@ -120,13 +146,29 @@ func (cm *ClientManager) SetRechargeCurve(curve PieceWiseLinear) {
now := cm.clock.Now()
cm.updateRecharge(now)
cm.updateCapFactor(now, false)
cm.curve = curve
if len(curve) > 0 {
cm.totalRecharge = curve[len(curve)-1].Y
} else {
cm.totalRecharge = 0
}
}
// SetCapacityRaiseThreshold sets a threshold value used for raising capFactor.
// Either if the difference between total allowed and connected capacity is less
// than this threshold or if their ratio is less than capacityRaiseThresholdRatio
// then capFactor is allowed to slowly raise.
func (cm *ClientManager) SetCapacityLimits(min, max, raiseThreshold uint64) {
if min < 1 {
min = 1
}
cm.minLogTotalCap = math.Log(float64(min))
if max < 1 {
max = 1
}
cm.maxLogTotalCap = math.Log(float64(max))
cm.logTotalCap = cm.maxLogTotalCap
cm.capacityRaiseThreshold = raiseThreshold
cm.refreshCapacity()
}
@ -141,8 +183,9 @@ func (cm *ClientManager) connect(node *ClientNode) {
node.corrBufValue = int64(node.params.BufLimit)
node.rcLastIntValue = cm.rcLastIntValue
node.queueIndex = -1
cm.updateCapFactor(now, true)
cm.updateTotalCapacity(now, true)
cm.totalConnected += node.params.MinRecharge
cm.updateRaiseLimit()
}
// disconnect should be called when a client is disconnected
@ -152,8 +195,9 @@ func (cm *ClientManager) disconnect(node *ClientNode) {
now := cm.clock.Now()
cm.updateRecharge(cm.clock.Now())
cm.updateCapFactor(now, true)
cm.updateTotalCapacity(now, true)
cm.totalConnected -= node.params.MinRecharge
cm.updateRaiseLimit()
}
// accepted is called when a request with given maximum cost is accepted.
@ -174,18 +218,24 @@ func (cm *ClientManager) accepted(node *ClientNode, maxCost uint64, now mclock.A
//
// Note: processed should always be called for all accepted requests
func (cm *ClientManager) processed(node *ClientNode, maxCost, realCost uint64, now mclock.AbsTime) {
cm.lock.Lock()
defer cm.lock.Unlock()
if realCost > maxCost {
realCost = maxCost
}
cm.updateNodeRc(node, int64(maxCost-realCost), &node.params, now)
if uint64(node.corrBufValue) > node.bufValue {
cm.updateBuffer(node, int64(maxCost-realCost), now)
}
// updateBuffer recalulates the corrected buffer value, adds the given value to it
// and updates the node's actual buffer value if possible
func (cm *ClientManager) updateBuffer(node *ClientNode, add int64, now mclock.AbsTime) {
cm.lock.Lock()
defer cm.lock.Unlock()
cm.updateNodeRc(node, add, &node.params, now)
if node.corrBufValue > node.bufValue {
if node.log != nil {
node.log.add(now, fmt.Sprintf("corrected bv=%d oldBv=%d", node.corrBufValue, node.bufValue))
}
node.bufValue = uint64(node.corrBufValue)
node.bufValue = node.corrBufValue
}
}
@ -195,11 +245,30 @@ func (cm *ClientManager) updateParams(node *ClientNode, params ServerParams, now
defer cm.lock.Unlock()
cm.updateRecharge(now)
cm.updateCapFactor(now, true)
cm.updateTotalCapacity(now, true)
cm.totalConnected += params.MinRecharge - node.params.MinRecharge
cm.updateRaiseLimit()
cm.updateNodeRc(node, 0, &params, now)
}
// updateRaiseLimit recalculates the limiting value until which logTotalCap
// can be raised when no client freeze events occur
func (cm *ClientManager) updateRaiseLimit() {
if cm.capacityRaiseThreshold == 0 {
cm.logTotalCapRaiseLimit = 0
return
}
limit := float64(cm.totalConnected + cm.capacityRaiseThreshold)
limit2 := float64(cm.totalConnected) * capacityRaiseThresholdRatio
if limit2 > limit {
limit = limit2
}
if limit < 1 {
limit = 1
}
cm.logTotalCapRaiseLimit = math.Log(limit)
}
// updateRecharge updates the recharge integrator and checks the recharge queue
// for nodes with recently filled buffers
func (cm *ClientManager) updateRecharge(now mclock.AbsTime) {
@ -208,9 +277,15 @@ func (cm *ClientManager) updateRecharge(now mclock.AbsTime) {
// updating is done in multiple steps if node buffers are filled and sumRecharge
// is decreased before the given target time
for cm.sumRecharge > 0 {
bonusRatio := cm.curve.ValueAt(cm.sumRecharge) / float64(cm.sumRecharge)
if bonusRatio < 1 {
bonusRatio = 1
sumRecharge := cm.sumRecharge
if sumRecharge > cm.totalRecharge {
sumRecharge = cm.totalRecharge
}
bonusRatio := float64(1)
v := cm.curve.ValueAt(sumRecharge)
s := float64(sumRecharge)
if v > s && s > 0 {
bonusRatio = v / s
}
dt := now - lastUpdate
// fetch the client that finishes first
@ -228,7 +303,6 @@ func (cm *ClientManager) updateRecharge(now mclock.AbsTime) {
// finished recharging, update corrBufValue and sumRecharge if necessary and do next step
if rcqNode.corrBufValue < int64(rcqNode.params.BufLimit) {
rcqNode.corrBufValue = int64(rcqNode.params.BufLimit)
cm.updateCapFactor(lastUpdate, true)
cm.sumRecharge -= rcqNode.params.MinRecharge
}
cm.rcLastIntValue = rcqNode.rcFullIntValue
@ -249,9 +323,6 @@ func (cm *ClientManager) updateNodeRc(node *ClientNode, bvc int64, params *Serve
node.rcLastIntValue = cm.rcLastIntValue
}
node.corrBufValue += bvc
if node.corrBufValue < 0 {
node.corrBufValue = 0
}
diff := int64(params.BufLimit - node.params.BufLimit)
if diff > 0 {
node.corrBufValue += diff
@ -261,15 +332,14 @@ func (cm *ClientManager) updateNodeRc(node *ClientNode, bvc int64, params *Serve
node.corrBufValue = int64(params.BufLimit)
isFull = true
}
sumRecharge := cm.sumRecharge
if !wasFull {
sumRecharge -= node.params.MinRecharge
cm.sumRecharge -= node.params.MinRecharge
}
if params != &node.params {
node.params = *params
}
if !isFull {
sumRecharge += node.params.MinRecharge
cm.sumRecharge += node.params.MinRecharge
if node.queueIndex != -1 {
cm.rcQueue.Remove(node.queueIndex)
}
@ -277,63 +347,54 @@ func (cm *ClientManager) updateNodeRc(node *ClientNode, bvc int64, params *Serve
node.rcFullIntValue = cm.rcLastIntValue + (int64(node.params.BufLimit)-node.corrBufValue)*FixedPointMultiplier/int64(node.params.MinRecharge)
cm.rcQueue.Push(node, -node.rcFullIntValue)
}
if sumRecharge != cm.sumRecharge {
cm.updateCapFactor(now, true)
cm.sumRecharge = sumRecharge
}
}
// updateCapFactor updates the total capacity factor. The capacity factor allows
// the total capacity of the system to go over the allowed total recharge value
// if the sum of momentarily recharging clients only exceeds the total recharge
// allowance in a very small fraction of time.
// The capacity factor is dropped quickly (with a small time constant) if sumRecharge
// exceeds totalRecharge. It is raised slowly (with a large time constant) if most
// of the total capacity is used by connected clients (totalConnected is larger than
// totalCapacity*capFactorRaiseThreshold) and sumRecharge stays under
// totalRecharge*totalConnected/totalCapacity.
func (cm *ClientManager) updateCapFactor(now mclock.AbsTime, refresh bool) {
if cm.totalRecharge == 0 {
return
// reduceTotalCapacity reduces the total capacity allowance in case of a client freeze event
func (cm *ClientManager) reduceTotalCapacity(frozenCap uint64) {
cm.lock.Lock()
defer cm.lock.Unlock()
ratio := float64(1)
if frozenCap < cm.totalConnected {
ratio = float64(frozenCap) / float64(cm.totalConnected)
}
now := cm.clock.Now()
cm.updateTotalCapacity(now, false)
cm.logTotalCap -= capacityDropFactor * ratio
if cm.logTotalCap < cm.minLogTotalCap {
cm.logTotalCap = cm.minLogTotalCap
}
cm.updateTotalCapacity(now, true)
}
// updateTotalCapacity updates the total capacity factor. The capacity factor allows
// the total capacity of the system to go over the allowed total recharge value
// if clients go to frozen state sufficiently rarely.
// The capacity factor is dropped instantly by a small amount if a clients is frozen.
// It is raised slowly (with a large time constant) if the total connected capacity
// is close to the total allowed amount and no clients are frozen.
func (cm *ClientManager) updateTotalCapacity(now mclock.AbsTime, refresh bool) {
dt := now - cm.capLastUpdate
cm.capLastUpdate = now
var d float64
if cm.sumRecharge > cm.totalRecharge {
d = (1 - float64(cm.sumRecharge)/float64(cm.totalRecharge)) * capFactorDropTC
} else {
totalConnected := float64(cm.totalConnected)
var connRatio float64
if totalConnected < cm.totalCapacity {
connRatio = totalConnected / cm.totalCapacity
} else {
connRatio = 1
}
if connRatio > capFactorRaiseThreshold {
sumRecharge := float64(cm.sumRecharge)
limit := float64(cm.totalRecharge) * connRatio
if sumRecharge < limit {
d = (1 - sumRecharge/limit) * (connRatio - capFactorRaiseThreshold) * (1 / (1 - capFactorRaiseThreshold)) * capFactorRaiseTC
}
if cm.logTotalCap < cm.logTotalCapRaiseLimit {
cm.logTotalCap += capacityRaiseTC * float64(dt)
if cm.logTotalCap > cm.logTotalCapRaiseLimit {
cm.logTotalCap = cm.logTotalCapRaiseLimit
}
}
if d != 0 {
cm.capLogFactor += d * float64(dt)
if cm.capLogFactor < 0 {
cm.capLogFactor = 0
}
if refresh {
cm.refreshCapacity()
}
if cm.logTotalCap > cm.maxLogTotalCap {
cm.logTotalCap = cm.maxLogTotalCap
}
if refresh {
cm.refreshCapacity()
}
}
// refreshCapacity recalculates the total capacity value and sends an update to the subscription
// channel if the relative change of the value since the last update is more than 0.1 percent
func (cm *ClientManager) refreshCapacity() {
totalCapacity := float64(cm.totalRecharge) * math.Exp(cm.capLogFactor)
totalCapacity := math.Exp(cm.logTotalCap)
if totalCapacity >= cm.totalCapacity*0.999 && totalCapacity <= cm.totalCapacity*1.001 {
return
}