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les: move client pool to les/vflux/server (#22495)

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* les: move client pool to les/vflux/server

* les/vflux/server: un-expose NodeBalance, remove unused fn, fix bugs

* tests/fuzzers/vflux: add ClientPool fuzzer

* les/vflux/server: fixed balance tests

* les: rebase fix

* les/vflux/server: fixed more bugs

* les/vflux/server: unexported NodeStateMachine fields and flags

* les/vflux/server: unexport all internal components and functions

* les/vflux/server: fixed priorityPool test

* les/vflux/server: polish balance

* les/vflux/server: fixed mutex locking error

* les/vflux/server: priorityPool bug fixed

* common/prque: make Prque wrap-around priority handling optional

* les/vflux/server: rename funcs, small optimizations

* les/vflux/server: fixed timeUntil

* les/vflux/server: separated balance.posValue and negValue

* les/vflux/server: polish setup

* les/vflux/server: enforce capacity curve monotonicity

* les/vflux/server: simplified requestCapacity

* les/vflux/server: requestCapacity with target range, no iterations in SetCapacity

* les/vflux/server: minor changes

* les/vflux/server: moved default factors to balanceTracker

* les/vflux/server: set inactiveFlag in priorityPool

* les/vflux/server: moved related metrics to vfs package

* les/vflux/client: make priorityPool temp state logic cleaner

* les/vflux/server: changed log.Crit to log.Error

* add vflux fuzzer to oss-fuzz

Co-authored-by: rjl493456442 <garyrong0905@gmail.com>
This commit is contained in:
Felföldi Zsolt
2021-04-06 20:42:50 +02:00
committed by GitHub
parent e275b1a293
commit 2d89fe0883
27 changed files with 1987 additions and 1545 deletions
Download Patch File Download Diff File Expand all files Collapse all files

493
les/vflux/server/balance.go
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@@ -47,21 +47,57 @@ type PriceFactors struct {
TimeFactor, CapacityFactor, RequestFactor float64
}
// timePrice returns the price of connection per nanosecond at the given capacity
func (p PriceFactors) timePrice(cap uint64) float64 {
return p.TimeFactor + float64(cap)*p.CapacityFactor/1000000
// connectionPrice returns the price of connection per nanosecond at the given capacity
// and the estimated average request cost.
func (p PriceFactors) connectionPrice(cap uint64, avgReqCost float64) float64 {
return p.TimeFactor + float64(cap)*p.CapacityFactor/1000000 + p.RequestFactor*avgReqCost
}
// NodeBalance keeps track of the positive and negative balances of a connected
type (
// nodePriority interface provides current and estimated future priorities on demand
nodePriority interface {
// priority should return the current priority of the node (higher is better)
priority(cap uint64) int64
// estimatePriority should return a lower estimate for the minimum of the node priority
// value starting from the current moment until the given time. If the priority goes
// under the returned estimate before the specified moment then it is the caller's
// responsibility to signal with updateFlag.
estimatePriority(cap uint64, addBalance int64, future, bias time.Duration, update bool) int64
}
// ReadOnlyBalance provides read-only operations on the node balance
ReadOnlyBalance interface {
nodePriority
GetBalance() (uint64, uint64)
GetRawBalance() (utils.ExpiredValue, utils.ExpiredValue)
GetPriceFactors() (posFactor, negFactor PriceFactors)
}
// ConnectedBalance provides operations permitted on connected nodes (non-read-only
// operations are not permitted inside a BalanceOperation)
ConnectedBalance interface {
ReadOnlyBalance
SetPriceFactors(posFactor, negFactor PriceFactors)
RequestServed(cost uint64) uint64
}
// AtomicBalanceOperator provides operations permitted in an atomic BalanceOperation
AtomicBalanceOperator interface {
ReadOnlyBalance
AddBalance(amount int64) (uint64, uint64, error)
SetBalance(pos, neg uint64) error
}
)
// nodeBalance keeps track of the positive and negative balances of a connected
// client and calculates actual and projected future priority values.
// Implements nodePriority interface.
type NodeBalance struct {
bt *BalanceTracker
type nodeBalance struct {
bt *balanceTracker
lock sync.RWMutex
node *enode.Node
connAddress string
active bool
priority bool
active, hasPriority, setFlags bool
capacity uint64
balance balance
posFactor, negFactor PriceFactors
@@ -78,7 +114,62 @@ type NodeBalance struct {
// balance represents a pair of positive and negative balances
type balance struct {
pos, neg utils.ExpiredValue
pos, neg utils.ExpiredValue
posExp, negExp utils.ValueExpirer
}
// posValue returns the value of positive balance at a given timestamp.
func (b balance) posValue(now mclock.AbsTime) uint64 {
return b.pos.Value(b.posExp.LogOffset(now))
}
// negValue returns the value of negative balance at a given timestamp.
func (b balance) negValue(now mclock.AbsTime) uint64 {
return b.neg.Value(b.negExp.LogOffset(now))
}
// addValue adds the value of a given amount to the balance. The original value and
// updated value will also be returned if the addition is successful.
// Returns the error if the given value is too large and the value overflows.
func (b *balance) addValue(now mclock.AbsTime, amount int64, pos bool, force bool) (uint64, uint64, int64, error) {
var (
val utils.ExpiredValue
offset utils.Fixed64
)
if pos {
offset, val = b.posExp.LogOffset(now), b.pos
} else {
offset, val = b.negExp.LogOffset(now), b.neg
}
old := val.Value(offset)
if amount > 0 && (amount > maxBalance || old > maxBalance-uint64(amount)) {
if !force {
return old, 0, 0, errBalanceOverflow
}
val = utils.ExpiredValue{}
amount = maxBalance
}
net := val.Add(amount, offset)
if pos {
b.pos = val
} else {
b.neg = val
}
return old, val.Value(offset), net, nil
}
// setValue sets the internal balance amount to the given values. Returns the
// error if the given value is too large.
func (b *balance) setValue(now mclock.AbsTime, pos uint64, neg uint64) error {
if pos > maxBalance || neg > maxBalance {
return errBalanceOverflow
}
var pb, nb utils.ExpiredValue
pb.Add(int64(pos), b.posExp.LogOffset(now))
nb.Add(int64(neg), b.negExp.LogOffset(now))
b.pos = pb
b.neg = nb
return nil
}
// balanceCallback represents a single callback that is activated when client priority
@@ -90,18 +181,18 @@ type balanceCallback struct {
}
// GetBalance returns the current positive and negative balance.
func (n *NodeBalance) GetBalance() (uint64, uint64) {
func (n *nodeBalance) GetBalance() (uint64, uint64) {
n.lock.Lock()
defer n.lock.Unlock()
now := n.bt.clock.Now()
n.updateBalance(now)
return n.balance.pos.Value(n.bt.posExp.LogOffset(now)), n.balance.neg.Value(n.bt.negExp.LogOffset(now))
return n.balance.posValue(now), n.balance.negValue(now)
}
// GetRawBalance returns the current positive and negative balance
// but in the raw(expired value) format.
func (n *NodeBalance) GetRawBalance() (utils.ExpiredValue, utils.ExpiredValue) {
func (n *nodeBalance) GetRawBalance() (utils.ExpiredValue, utils.ExpiredValue) {
n.lock.Lock()
defer n.lock.Unlock()
@@ -114,164 +205,147 @@ func (n *NodeBalance) GetRawBalance() (utils.ExpiredValue, utils.ExpiredValue) {
// before and after the operation. Exceeding maxBalance results in an error (balance is
// unchanged) while adding a negative amount higher than the current balance results in
// zero balance.
func (n *NodeBalance) AddBalance(amount int64) (uint64, uint64, error) {
// Note: this function should run inside a NodeStateMachine operation
func (n *nodeBalance) AddBalance(amount int64) (uint64, uint64, error) {
var (
err error
old, new uint64
err error
old, new uint64
now = n.bt.clock.Now()
callbacks []func()
setPriority bool
)
n.bt.ns.Operation(func() {
var (
callbacks []func()
setPriority bool
)
n.bt.updateTotalBalance(n, func() bool {
now := n.bt.clock.Now()
n.updateBalance(now)
// Ensure the given amount is valid to apply.
offset := n.bt.posExp.LogOffset(now)
old = n.balance.pos.Value(offset)
if amount > 0 && (amount > maxBalance || old > maxBalance-uint64(amount)) {
err = errBalanceOverflow
return false
}
// Update the total positive balance counter.
n.balance.pos.Add(amount, offset)
callbacks = n.checkCallbacks(now)
setPriority = n.checkPriorityStatus()
new = n.balance.pos.Value(offset)
n.storeBalance(true, false)
return true
})
for _, cb := range callbacks {
cb()
// Operation with holding the lock
n.bt.updateTotalBalance(n, func() bool {
n.updateBalance(now)
if old, new, _, err = n.balance.addValue(now, amount, true, false); err != nil {
return false
}
if setPriority {
n.bt.ns.SetStateSub(n.node, n.bt.PriorityFlag, nodestate.Flags{}, 0)
}
n.signalPriorityUpdate()
callbacks, setPriority = n.checkCallbacks(now), n.checkPriorityStatus()
n.storeBalance(true, false)
return true
})
if err != nil {
return old, old, err
}
// Operation without holding the lock
for _, cb := range callbacks {
cb()
}
if n.setFlags {
if setPriority {
n.bt.ns.SetStateSub(n.node, n.bt.setup.priorityFlag, nodestate.Flags{}, 0)
}
// Note: priority flag is automatically removed by the zero priority callback if necessary
n.signalPriorityUpdate()
}
return old, new, nil
}
// SetBalance sets the positive and negative balance to the given values
func (n *NodeBalance) SetBalance(pos, neg uint64) error {
if pos > maxBalance || neg > maxBalance {
return errBalanceOverflow
}
n.bt.ns.Operation(func() {
var (
callbacks []func()
setPriority bool
)
n.bt.updateTotalBalance(n, func() bool {
now := n.bt.clock.Now()
n.updateBalance(now)
var pb, nb utils.ExpiredValue
pb.Add(int64(pos), n.bt.posExp.LogOffset(now))
nb.Add(int64(neg), n.bt.negExp.LogOffset(now))
n.balance.pos = pb
n.balance.neg = nb
callbacks = n.checkCallbacks(now)
setPriority = n.checkPriorityStatus()
n.storeBalance(true, true)
return true
})
for _, cb := range callbacks {
cb()
// Note: this function should run inside a NodeStateMachine operation
func (n *nodeBalance) SetBalance(pos, neg uint64) error {
var (
now = n.bt.clock.Now()
callbacks []func()
setPriority bool
)
// Operation with holding the lock
n.bt.updateTotalBalance(n, func() bool {
n.updateBalance(now)
if err := n.balance.setValue(now, pos, neg); err != nil {
return false
}
if setPriority {
n.bt.ns.SetStateSub(n.node, n.bt.PriorityFlag, nodestate.Flags{}, 0)
}
n.signalPriorityUpdate()
callbacks, setPriority = n.checkCallbacks(now), n.checkPriorityStatus()
n.storeBalance(true, true)
return true
})
// Operation without holding the lock
for _, cb := range callbacks {
cb()
}
if n.setFlags {
if setPriority {
n.bt.ns.SetStateSub(n.node, n.bt.setup.priorityFlag, nodestate.Flags{}, 0)
}
// Note: priority flag is automatically removed by the zero priority callback if necessary
n.signalPriorityUpdate()
}
return nil
}
// RequestServed should be called after serving a request for the given peer
func (n *NodeBalance) RequestServed(cost uint64) uint64 {
func (n *nodeBalance) RequestServed(cost uint64) (newBalance uint64) {
n.lock.Lock()
var callbacks []func()
defer func() {
n.lock.Unlock()
if callbacks != nil {
n.bt.ns.Operation(func() {
for _, cb := range callbacks {
cb()
}
})
}
}()
now := n.bt.clock.Now()
var (
check bool
fcost = float64(cost)
now = n.bt.clock.Now()
)
n.updateBalance(now)
fcost := float64(cost)
posExp := n.bt.posExp.LogOffset(now)
var check bool
if !n.balance.pos.IsZero() {
if n.posFactor.RequestFactor != 0 {
c := -int64(fcost * n.posFactor.RequestFactor)
cc := n.balance.pos.Add(c, posExp)
if c == cc {
posCost := -int64(fcost * n.posFactor.RequestFactor)
if posCost == 0 {
fcost = 0
newBalance = n.balance.posValue(now)
} else {
var net int64
_, newBalance, net, _ = n.balance.addValue(now, posCost, true, false)
if posCost == net {
fcost = 0
} else {
fcost *= 1 - float64(cc)/float64(c)
fcost *= 1 - float64(net)/float64(posCost)
}
check = true
} else {
fcost = 0
}
}
if fcost > 0 {
if n.negFactor.RequestFactor != 0 {
n.balance.neg.Add(int64(fcost*n.negFactor.RequestFactor), n.bt.negExp.LogOffset(now))
check = true
}
if fcost > 0 && n.negFactor.RequestFactor != 0 {
n.balance.addValue(now, int64(fcost*n.negFactor.RequestFactor), false, false)
check = true
}
n.sumReqCost += cost
var callbacks []func()
if check {
callbacks = n.checkCallbacks(now)
}
n.sumReqCost += cost
return n.balance.pos.Value(posExp)
n.lock.Unlock()
if callbacks != nil {
n.bt.ns.Operation(func() {
for _, cb := range callbacks {
cb()
}
})
}
return
}
// Priority returns the actual priority based on the current balance
func (n *NodeBalance) Priority(capacity uint64) int64 {
// priority returns the actual priority based on the current balance
func (n *nodeBalance) priority(capacity uint64) int64 {
n.lock.Lock()
defer n.lock.Unlock()
n.updateBalance(n.bt.clock.Now())
return n.balanceToPriority(n.balance, capacity)
now := n.bt.clock.Now()
n.updateBalance(now)
return n.balanceToPriority(now, n.balance, capacity)
}
// EstMinPriority gives a lower estimate for the priority at a given time in the future.
// An average request cost per time is assumed that is twice the average cost per time
// in the current session.
// If update is true then a priority callback is added that turns UpdateFlag on and off
// If update is true then a priority callback is added that turns updateFlag on and off
// in case the priority goes below the estimated minimum.
func (n *NodeBalance) EstimatePriority(capacity uint64, addBalance int64, future, bias time.Duration, update bool) int64 {
func (n *nodeBalance) estimatePriority(capacity uint64, addBalance int64, future, bias time.Duration, update bool) int64 {
n.lock.Lock()
defer n.lock.Unlock()
now := n.bt.clock.Now()
n.updateBalance(now)
b := n.balance
b := n.balance // copy the balance
if addBalance != 0 {
offset := n.bt.posExp.LogOffset(now)
old := n.balance.pos.Value(offset)
if addBalance > 0 && (addBalance > maxBalance || old > maxBalance-uint64(addBalance)) {
b.pos = utils.ExpiredValue{}
b.pos.Add(maxBalance, offset)
} else {
b.pos.Add(addBalance, offset)
}
b.addValue(now, addBalance, true, true)
}
if future > 0 {
var avgReqCost float64
@@ -284,52 +358,20 @@ func (n *NodeBalance) EstimatePriority(capacity uint64, addBalance int64, future
if bias > 0 {
b = n.reducedBalance(b, now+mclock.AbsTime(future), bias, capacity, 0)
}
pri := n.balanceToPriority(b, capacity)
// Note: we subtract one from the estimated priority in order to ensure that biased
// estimates are always lower than actual priorities, even if the bias is very small.
// This ensures that two nodes will not ping-pong update signals forever if both of
// them have zero estimated priority drop in the projected future.
pri := n.balanceToPriority(now, b, capacity) - 1
if update {
n.addCallback(balanceCallbackUpdate, pri, n.signalPriorityUpdate)
}
return pri
}
// PosBalanceMissing calculates the missing amount of positive balance in order to
// connect at targetCapacity, stay connected for the given amount of time and then
// still have a priority of targetPriority
func (n *NodeBalance) PosBalanceMissing(targetPriority int64, targetCapacity uint64, after time.Duration) uint64 {
n.lock.Lock()
defer n.lock.Unlock()
now := n.bt.clock.Now()
if targetPriority < 0 {
timePrice := n.negFactor.timePrice(targetCapacity)
timeCost := uint64(float64(after) * timePrice)
negBalance := n.balance.neg.Value(n.bt.negExp.LogOffset(now))
if timeCost+negBalance < uint64(-targetPriority) {
return 0
}
if uint64(-targetPriority) > negBalance && timePrice > 1e-100 {
if negTime := time.Duration(float64(uint64(-targetPriority)-negBalance) / timePrice); negTime < after {
after -= negTime
} else {
after = 0
}
}
targetPriority = 0
}
timePrice := n.posFactor.timePrice(targetCapacity)
posRequired := uint64(float64(targetPriority)*float64(targetCapacity)+float64(after)*timePrice) + 1
if posRequired >= maxBalance {
return math.MaxUint64 // target not reachable
}
posBalance := n.balance.pos.Value(n.bt.posExp.LogOffset(now))
if posRequired > posBalance {
return posRequired - posBalance
}
return 0
}
// SetPriceFactors sets the price factors. TimeFactor is the price of a nanosecond of
// connection while RequestFactor is the price of a request cost unit.
func (n *NodeBalance) SetPriceFactors(posFactor, negFactor PriceFactors) {
func (n *nodeBalance) SetPriceFactors(posFactor, negFactor PriceFactors) {
n.lock.Lock()
now := n.bt.clock.Now()
n.updateBalance(now)
@@ -346,7 +388,7 @@ func (n *NodeBalance) SetPriceFactors(posFactor, negFactor PriceFactors) {
}
// GetPriceFactors returns the price factors
func (n *NodeBalance) GetPriceFactors() (posFactor, negFactor PriceFactors) {
func (n *nodeBalance) GetPriceFactors() (posFactor, negFactor PriceFactors) {
n.lock.Lock()
defer n.lock.Unlock()
@@ -354,7 +396,7 @@ func (n *NodeBalance) GetPriceFactors() (posFactor, negFactor PriceFactors) {
}
// activate starts time/capacity cost deduction.
func (n *NodeBalance) activate() {
func (n *nodeBalance) activate() {
n.bt.updateTotalBalance(n, func() bool {
if n.active {
return false
@@ -366,7 +408,7 @@ func (n *NodeBalance) activate() {
}
// deactivate stops time/capacity cost deduction and saves the balances in the database
func (n *NodeBalance) deactivate() {
func (n *nodeBalance) deactivate() {
n.bt.updateTotalBalance(n, func() bool {
if !n.active {
return false
@@ -383,7 +425,7 @@ func (n *NodeBalance) deactivate() {
}
// updateBalance updates balance based on the time factor
func (n *NodeBalance) updateBalance(now mclock.AbsTime) {
func (n *nodeBalance) updateBalance(now mclock.AbsTime) {
if n.active && now > n.lastUpdate {
n.balance = n.reducedBalance(n.balance, n.lastUpdate, time.Duration(now-n.lastUpdate), n.capacity, 0)
n.lastUpdate = now
@@ -391,7 +433,7 @@ func (n *NodeBalance) updateBalance(now mclock.AbsTime) {
}
// storeBalance stores the positive and/or negative balance of the node in the database
func (n *NodeBalance) storeBalance(pos, neg bool) {
func (n *nodeBalance) storeBalance(pos, neg bool) {
if pos {
n.bt.storeBalance(n.node.ID().Bytes(), false, n.balance.pos)
}
@@ -405,7 +447,7 @@ func (n *NodeBalance) storeBalance(pos, neg bool) {
// immediately.
// Note: should be called while n.lock is held
// Note 2: the callback function runs inside a NodeStateMachine operation
func (n *NodeBalance) addCallback(id int, threshold int64, callback func()) {
func (n *nodeBalance) addCallback(id int, threshold int64, callback func()) {
n.removeCallback(id)
idx := 0
for idx < n.callbackCount && threshold > n.callbacks[idx].threshold {
@@ -425,7 +467,7 @@ func (n *NodeBalance) addCallback(id int, threshold int64, callback func()) {
// removeCallback removes the given callback and returns true if it was active
// Note: should be called while n.lock is held
func (n *NodeBalance) removeCallback(id int) bool {
func (n *nodeBalance) removeCallback(id int) bool {
idx := n.callbackIndex[id]
if idx == -1 {
return false
@@ -442,11 +484,11 @@ func (n *NodeBalance) removeCallback(id int) bool {
// checkCallbacks checks whether the threshold of any of the active callbacks
// have been reached and returns triggered callbacks.
// Note: checkCallbacks assumes that the balance has been recently updated.
func (n *NodeBalance) checkCallbacks(now mclock.AbsTime) (callbacks []func()) {
func (n *nodeBalance) checkCallbacks(now mclock.AbsTime) (callbacks []func()) {
if n.callbackCount == 0 || n.capacity == 0 {
return
}
pri := n.balanceToPriority(n.balance, n.capacity)
pri := n.balanceToPriority(now, n.balance, n.capacity)
for n.callbackCount != 0 && n.callbacks[n.callbackCount-1].threshold >= pri {
n.callbackCount--
n.callbackIndex[n.callbacks[n.callbackCount].id] = -1
@@ -458,7 +500,7 @@ func (n *NodeBalance) checkCallbacks(now mclock.AbsTime) (callbacks []func()) {
// scheduleCheck sets up or updates a scheduled event to ensure that it will be called
// again just after the next threshold has been reached.
func (n *NodeBalance) scheduleCheck(now mclock.AbsTime) {
func (n *nodeBalance) scheduleCheck(now mclock.AbsTime) {
if n.callbackCount != 0 {
d, ok := n.timeUntil(n.callbacks[n.callbackCount-1].threshold)
if !ok {
@@ -484,7 +526,7 @@ func (n *NodeBalance) scheduleCheck(now mclock.AbsTime) {
}
// updateAfter schedules a balance update and callback check in the future
func (n *NodeBalance) updateAfter(dt time.Duration) {
func (n *nodeBalance) updateAfter(dt time.Duration) {
if n.updateEvent == nil || n.updateEvent.Stop() {
if dt == 0 {
n.updateEvent = nil
@@ -512,20 +554,22 @@ func (n *NodeBalance) updateAfter(dt time.Duration) {
// balanceExhausted should be called when the positive balance is exhausted (priority goes to zero/negative)
// Note: this function should run inside a NodeStateMachine operation
func (n *NodeBalance) balanceExhausted() {
func (n *nodeBalance) balanceExhausted() {
n.lock.Lock()
n.storeBalance(true, false)
n.priority = false
n.hasPriority = false
n.lock.Unlock()
n.bt.ns.SetStateSub(n.node, nodestate.Flags{}, n.bt.PriorityFlag, 0)
if n.setFlags {
n.bt.ns.SetStateSub(n.node, nodestate.Flags{}, n.bt.setup.priorityFlag, 0)
}
}
// checkPriorityStatus checks whether the node has gained priority status and sets the priority
// callback and flag if necessary. It assumes that the balance has been recently updated.
// Note that the priority flag has to be set by the caller after the mutex has been released.
func (n *NodeBalance) checkPriorityStatus() bool {
if !n.priority && !n.balance.pos.IsZero() {
n.priority = true
func (n *nodeBalance) checkPriorityStatus() bool {
if !n.hasPriority && !n.balance.pos.IsZero() {
n.hasPriority = true
n.addCallback(balanceCallbackZero, 0, func() { n.balanceExhausted() })
return true
}
@@ -534,15 +578,15 @@ func (n *NodeBalance) checkPriorityStatus() bool {
// signalPriorityUpdate signals that the priority fell below the previous minimum estimate
// Note: this function should run inside a NodeStateMachine operation
func (n *NodeBalance) signalPriorityUpdate() {
n.bt.ns.SetStateSub(n.node, n.bt.UpdateFlag, nodestate.Flags{}, 0)
n.bt.ns.SetStateSub(n.node, nodestate.Flags{}, n.bt.UpdateFlag, 0)
func (n *nodeBalance) signalPriorityUpdate() {
n.bt.ns.SetStateSub(n.node, n.bt.setup.updateFlag, nodestate.Flags{}, 0)
n.bt.ns.SetStateSub(n.node, nodestate.Flags{}, n.bt.setup.updateFlag, 0)
}
// setCapacity updates the capacity value used for priority calculation
// Note: capacity should never be zero
// Note 2: this function should run inside a NodeStateMachine operation
func (n *NodeBalance) setCapacity(capacity uint64) {
func (n *nodeBalance) setCapacity(capacity uint64) {
n.lock.Lock()
now := n.bt.clock.Now()
n.updateBalance(now)
@@ -557,74 +601,89 @@ func (n *NodeBalance) setCapacity(capacity uint64) {
// balanceToPriority converts a balance to a priority value. Lower priority means
// first to disconnect. Positive balance translates to positive priority. If positive
// balance is zero then negative balance translates to a negative priority.
func (n *NodeBalance) balanceToPriority(b balance, capacity uint64) int64 {
if !b.pos.IsZero() {
return int64(b.pos.Value(n.bt.posExp.LogOffset(n.bt.clock.Now())) / capacity)
func (n *nodeBalance) balanceToPriority(now mclock.AbsTime, b balance, capacity uint64) int64 {
pos := b.posValue(now)
if pos > 0 {
return int64(pos / capacity)
}
return -int64(b.neg.Value(n.bt.negExp.LogOffset(n.bt.clock.Now())))
return -int64(b.negValue(now))
}
// priorityToBalance converts a target priority to a requested balance value.
// If the priority is negative, then minimal negative balance is returned;
// otherwise the minimal positive balance is returned.
func (n *nodeBalance) priorityToBalance(priority int64, capacity uint64) (uint64, uint64) {
if priority > 0 {
return uint64(priority) * n.capacity, 0
}
return 0, uint64(-priority)
}
// reducedBalance estimates the reduced balance at a given time in the fututre based
// on the given balance, the time factor and an estimated average request cost per time ratio
func (n *NodeBalance) reducedBalance(b balance, start mclock.AbsTime, dt time.Duration, capacity uint64, avgReqCost float64) balance {
func (n *nodeBalance) reducedBalance(b balance, start mclock.AbsTime, dt time.Duration, capacity uint64, avgReqCost float64) balance {
// since the costs are applied continuously during the dt time period we calculate
// the expiration offset at the middle of the period
at := start + mclock.AbsTime(dt/2)
dtf := float64(dt)
var (
at = start + mclock.AbsTime(dt/2)
dtf = float64(dt)
)
if !b.pos.IsZero() {
factor := n.posFactor.timePrice(capacity) + n.posFactor.RequestFactor*avgReqCost
factor := n.posFactor.connectionPrice(capacity, avgReqCost)
diff := -int64(dtf * factor)
dd := b.pos.Add(diff, n.bt.posExp.LogOffset(at))
if dd == diff {
_, _, net, _ := b.addValue(at, diff, true, false)
if net == diff {
dtf = 0
} else {
dtf += float64(dd) / factor
dtf += float64(net) / factor
}
}
if dt > 0 {
factor := n.negFactor.timePrice(capacity) + n.negFactor.RequestFactor*avgReqCost
b.neg.Add(int64(dtf*factor), n.bt.negExp.LogOffset(at))
if dtf > 0 {
factor := n.negFactor.connectionPrice(capacity, avgReqCost)
b.addValue(at, int64(dtf*factor), false, false)
}
return b
}
// timeUntil calculates the remaining time needed to reach a given priority level
// assuming that no requests are processed until then. If the given level is never
// reached then (0, false) is returned.
// reached then (0, false) is returned. If it has already been reached then (0, true)
// is returned.
// Note: the function assumes that the balance has been recently updated and
// calculates the time starting from the last update.
func (n *NodeBalance) timeUntil(priority int64) (time.Duration, bool) {
now := n.bt.clock.Now()
var dt float64
if !n.balance.pos.IsZero() {
posBalance := n.balance.pos.Value(n.bt.posExp.LogOffset(now))
timePrice := n.posFactor.timePrice(n.capacity)
func (n *nodeBalance) timeUntil(priority int64) (time.Duration, bool) {
var (
now = n.bt.clock.Now()
pos = n.balance.posValue(now)
targetPos, targetNeg = n.priorityToBalance(priority, n.capacity)
diffTime float64
)
if pos > 0 {
timePrice := n.posFactor.connectionPrice(n.capacity, 0)
if timePrice < 1e-100 {
return 0, false
}
if priority > 0 {
newBalance := uint64(priority) * n.capacity
if newBalance > posBalance {
return 0, false
if targetPos > 0 {
if targetPos > pos {
return 0, true
}
dt = float64(posBalance-newBalance) / timePrice
return time.Duration(dt), true
diffTime = float64(pos-targetPos) / timePrice
return time.Duration(diffTime), true
} else {
dt = float64(posBalance) / timePrice
diffTime = float64(pos) / timePrice
}
} else {
if priority > 0 {
return 0, false
if targetPos > 0 {
return 0, true
}
}
// if we have a positive balance then dt equals the time needed to get it to zero
negBalance := n.balance.neg.Value(n.bt.negExp.LogOffset(now))
timePrice := n.negFactor.timePrice(n.capacity)
if uint64(-priority) > negBalance {
neg := n.balance.negValue(now)
if targetNeg > neg {
timePrice := n.negFactor.connectionPrice(n.capacity, 0)
if timePrice < 1e-100 {
return 0, false
}
dt += float64(uint64(-priority)-negBalance) / timePrice
diffTime += float64(targetNeg-neg) / timePrice
}
return time.Duration(dt), true
return time.Duration(diffTime), true
}