694 lines
22 KiB
Go
694 lines
22 KiB
Go
// Copyright 2020 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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package server
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import (
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"errors"
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"math"
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"sync"
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"time"
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"github.com/ethereum/go-ethereum/common/mclock"
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"github.com/ethereum/go-ethereum/les/utils"
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"github.com/ethereum/go-ethereum/p2p/enode"
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"github.com/ethereum/go-ethereum/p2p/nodestate"
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)
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var errBalanceOverflow = errors.New("balance overflow")
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const maxBalance = math.MaxInt64 // maximum allowed balance value
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const (
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balanceCallbackUpdate = iota // called when priority drops below the last minimum estimate
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balanceCallbackZero // called when priority drops to zero (positive balance exhausted)
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balanceCallbackCount // total number of balance callbacks
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)
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// PriceFactors determine the pricing policy (may apply either to positive or
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// negative balances which may have different factors).
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// - TimeFactor is cost unit per nanosecond of connection time
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// - CapacityFactor is cost unit per nanosecond of connection time per 1000000 capacity
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// - RequestFactor is cost unit per request "realCost" unit
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type PriceFactors struct {
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TimeFactor, CapacityFactor, RequestFactor float64
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}
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// connectionPrice returns the price of connection per nanosecond at the given capacity
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// and the estimated average request cost.
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func (p PriceFactors) connectionPrice(cap uint64, avgReqCost float64) float64 {
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return p.TimeFactor + float64(cap)*p.CapacityFactor/1000000 + p.RequestFactor*avgReqCost
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}
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type (
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// nodePriority interface provides current and estimated future priorities on demand
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nodePriority interface {
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// priority should return the current priority of the node (higher is better)
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priority(cap uint64) int64
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// estimatePriority should return a lower estimate for the minimum of the node priority
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// value starting from the current moment until the given time. If the priority goes
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// under the returned estimate before the specified moment then it is the caller's
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// responsibility to signal with updateFlag.
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estimatePriority(cap uint64, addBalance int64, future, bias time.Duration, update bool) int64
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}
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// ReadOnlyBalance provides read-only operations on the node balance
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ReadOnlyBalance interface {
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nodePriority
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GetBalance() (uint64, uint64)
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GetRawBalance() (utils.ExpiredValue, utils.ExpiredValue)
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GetPriceFactors() (posFactor, negFactor PriceFactors)
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}
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// ConnectedBalance provides operations permitted on connected nodes (non-read-only
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// operations are not permitted inside a BalanceOperation)
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ConnectedBalance interface {
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ReadOnlyBalance
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SetPriceFactors(posFactor, negFactor PriceFactors)
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RequestServed(cost uint64) uint64
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}
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// AtomicBalanceOperator provides operations permitted in an atomic BalanceOperation
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AtomicBalanceOperator interface {
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ReadOnlyBalance
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AddBalance(amount int64) (uint64, uint64, error)
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SetBalance(pos, neg uint64) error
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}
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)
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// nodeBalance keeps track of the positive and negative balances of a connected
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// client and calculates actual and projected future priority values.
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// Implements nodePriority interface.
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type nodeBalance struct {
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bt *balanceTracker
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lock sync.RWMutex
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node *enode.Node
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connAddress string
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active, hasPriority, setFlags bool
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capacity uint64
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balance balance
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posFactor, negFactor PriceFactors
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sumReqCost uint64
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lastUpdate, nextUpdate, initTime mclock.AbsTime
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updateEvent mclock.Timer
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// since only a limited and fixed number of callbacks are needed, they are
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// stored in a fixed size array ordered by priority threshold.
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callbacks [balanceCallbackCount]balanceCallback
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// callbackIndex maps balanceCallback constants to callbacks array indexes (-1 if not active)
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callbackIndex [balanceCallbackCount]int
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callbackCount int // number of active callbacks
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}
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// balance represents a pair of positive and negative balances
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type balance struct {
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pos, neg utils.ExpiredValue
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posExp, negExp utils.ValueExpirer
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}
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// posValue returns the value of positive balance at a given timestamp.
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func (b balance) posValue(now mclock.AbsTime) uint64 {
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return b.pos.Value(b.posExp.LogOffset(now))
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}
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// negValue returns the value of negative balance at a given timestamp.
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func (b balance) negValue(now mclock.AbsTime) uint64 {
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return b.neg.Value(b.negExp.LogOffset(now))
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}
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// addValue adds the value of a given amount to the balance. The original value and
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// updated value will also be returned if the addition is successful.
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// Returns the error if the given value is too large and the value overflows.
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func (b *balance) addValue(now mclock.AbsTime, amount int64, pos bool, force bool) (uint64, uint64, int64, error) {
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var (
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val utils.ExpiredValue
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offset utils.Fixed64
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)
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if pos {
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offset, val = b.posExp.LogOffset(now), b.pos
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} else {
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offset, val = b.negExp.LogOffset(now), b.neg
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}
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old := val.Value(offset)
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if amount > 0 && (amount > maxBalance || old > maxBalance-uint64(amount)) {
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if !force {
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return old, 0, 0, errBalanceOverflow
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}
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val = utils.ExpiredValue{}
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amount = maxBalance
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}
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net := val.Add(amount, offset)
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if pos {
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b.pos = val
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} else {
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b.neg = val
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}
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return old, val.Value(offset), net, nil
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}
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// setValue sets the internal balance amount to the given values. Returns the
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// error if the given value is too large.
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func (b *balance) setValue(now mclock.AbsTime, pos uint64, neg uint64) error {
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if pos > maxBalance || neg > maxBalance {
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return errBalanceOverflow
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}
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var pb, nb utils.ExpiredValue
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pb.Add(int64(pos), b.posExp.LogOffset(now))
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nb.Add(int64(neg), b.negExp.LogOffset(now))
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b.pos = pb
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b.neg = nb
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return nil
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}
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// balanceCallback represents a single callback that is activated when client priority
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// reaches the given threshold
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type balanceCallback struct {
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id int
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threshold int64
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callback func()
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}
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// GetBalance returns the current positive and negative balance.
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func (n *nodeBalance) GetBalance() (uint64, uint64) {
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n.lock.Lock()
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defer n.lock.Unlock()
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now := n.bt.clock.Now()
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n.updateBalance(now)
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return n.balance.posValue(now), n.balance.negValue(now)
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}
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// GetRawBalance returns the current positive and negative balance
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// but in the raw(expired value) format.
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func (n *nodeBalance) GetRawBalance() (utils.ExpiredValue, utils.ExpiredValue) {
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n.lock.Lock()
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defer n.lock.Unlock()
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now := n.bt.clock.Now()
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n.updateBalance(now)
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return n.balance.pos, n.balance.neg
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}
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// AddBalance adds the given amount to the positive balance and returns the balance
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// before and after the operation. Exceeding maxBalance results in an error (balance is
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// unchanged) while adding a negative amount higher than the current balance results in
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// zero balance.
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// Note: this function should run inside a NodeStateMachine operation
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func (n *nodeBalance) AddBalance(amount int64) (uint64, uint64, error) {
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var (
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err error
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old, new uint64
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now = n.bt.clock.Now()
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callbacks []func()
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setPriority bool
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)
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// Operation with holding the lock
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n.bt.updateTotalBalance(n, func() bool {
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n.updateBalance(now)
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if old, new, _, err = n.balance.addValue(now, amount, true, false); err != nil {
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return false
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}
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callbacks, setPriority = n.checkCallbacks(now), n.checkPriorityStatus()
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n.storeBalance(true, false)
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return true
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})
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if err != nil {
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return old, old, err
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}
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// Operation without holding the lock
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for _, cb := range callbacks {
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cb()
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}
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if n.setFlags {
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if setPriority {
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n.bt.ns.SetStateSub(n.node, n.bt.setup.priorityFlag, nodestate.Flags{}, 0)
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}
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// Note: priority flag is automatically removed by the zero priority callback if necessary
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n.signalPriorityUpdate()
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}
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return old, new, nil
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}
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// SetBalance sets the positive and negative balance to the given values
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// Note: this function should run inside a NodeStateMachine operation
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func (n *nodeBalance) SetBalance(pos, neg uint64) error {
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var (
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now = n.bt.clock.Now()
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callbacks []func()
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setPriority bool
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)
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// Operation with holding the lock
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n.bt.updateTotalBalance(n, func() bool {
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n.updateBalance(now)
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if err := n.balance.setValue(now, pos, neg); err != nil {
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return false
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}
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callbacks, setPriority = n.checkCallbacks(now), n.checkPriorityStatus()
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n.storeBalance(true, true)
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return true
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})
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// Operation without holding the lock
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for _, cb := range callbacks {
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cb()
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}
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if n.setFlags {
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if setPriority {
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n.bt.ns.SetStateSub(n.node, n.bt.setup.priorityFlag, nodestate.Flags{}, 0)
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}
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// Note: priority flag is automatically removed by the zero priority callback if necessary
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n.signalPriorityUpdate()
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}
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return nil
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}
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// RequestServed should be called after serving a request for the given peer
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func (n *nodeBalance) RequestServed(cost uint64) (newBalance uint64) {
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n.lock.Lock()
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var (
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check bool
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fcost = float64(cost)
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now = n.bt.clock.Now()
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)
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n.updateBalance(now)
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if !n.balance.pos.IsZero() {
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posCost := -int64(fcost * n.posFactor.RequestFactor)
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if posCost == 0 {
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fcost = 0
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newBalance = n.balance.posValue(now)
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} else {
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var net int64
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_, newBalance, net, _ = n.balance.addValue(now, posCost, true, false)
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if posCost == net {
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fcost = 0
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} else {
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fcost *= 1 - float64(net)/float64(posCost)
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}
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check = true
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}
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}
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if fcost > 0 && n.negFactor.RequestFactor != 0 {
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n.balance.addValue(now, int64(fcost*n.negFactor.RequestFactor), false, false)
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check = true
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}
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n.sumReqCost += cost
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var callbacks []func()
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if check {
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callbacks = n.checkCallbacks(now)
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}
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n.lock.Unlock()
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if callbacks != nil {
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n.bt.ns.Operation(func() {
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for _, cb := range callbacks {
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cb()
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}
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})
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}
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return
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}
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// priority returns the actual priority based on the current balance
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func (n *nodeBalance) priority(capacity uint64) int64 {
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n.lock.Lock()
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defer n.lock.Unlock()
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now := n.bt.clock.Now()
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n.updateBalance(now)
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return n.balanceToPriority(now, n.balance, capacity)
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}
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// EstMinPriority gives a lower estimate for the priority at a given time in the future.
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// An average request cost per time is assumed that is twice the average cost per time
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// in the current session.
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// If update is true then a priority callback is added that turns updateFlag on and off
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// in case the priority goes below the estimated minimum.
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func (n *nodeBalance) estimatePriority(capacity uint64, addBalance int64, future, bias time.Duration, update bool) int64 {
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n.lock.Lock()
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defer n.lock.Unlock()
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now := n.bt.clock.Now()
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n.updateBalance(now)
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b := n.balance // copy the balance
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if addBalance != 0 {
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b.addValue(now, addBalance, true, true)
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}
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if future > 0 {
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var avgReqCost float64
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dt := time.Duration(n.lastUpdate - n.initTime)
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if dt > time.Second {
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avgReqCost = float64(n.sumReqCost) * 2 / float64(dt)
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}
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b = n.reducedBalance(b, now, future, capacity, avgReqCost)
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}
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if bias > 0 {
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b = n.reducedBalance(b, now.Add(future), bias, capacity, 0)
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}
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pri := n.balanceToPriority(now, b, capacity)
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// Ensure that biased estimates are always lower than actual priorities, even if
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// the bias is very small.
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// This ensures that two nodes will not ping-pong update signals forever if both of
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// them have zero estimated priority drop in the projected future.
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current := n.balanceToPriority(now, n.balance, capacity)
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if pri >= current {
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pri = current - 1
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}
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if update {
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n.addCallback(balanceCallbackUpdate, pri, n.signalPriorityUpdate)
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}
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return pri
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}
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// SetPriceFactors sets the price factors. TimeFactor is the price of a nanosecond of
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// connection while RequestFactor is the price of a request cost unit.
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func (n *nodeBalance) SetPriceFactors(posFactor, negFactor PriceFactors) {
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n.lock.Lock()
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now := n.bt.clock.Now()
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n.updateBalance(now)
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n.posFactor, n.negFactor = posFactor, negFactor
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callbacks := n.checkCallbacks(now)
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n.lock.Unlock()
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if callbacks != nil {
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n.bt.ns.Operation(func() {
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for _, cb := range callbacks {
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cb()
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}
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})
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}
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}
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// GetPriceFactors returns the price factors
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func (n *nodeBalance) GetPriceFactors() (posFactor, negFactor PriceFactors) {
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n.lock.Lock()
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defer n.lock.Unlock()
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return n.posFactor, n.negFactor
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}
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// activate starts time/capacity cost deduction.
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func (n *nodeBalance) activate() {
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n.bt.updateTotalBalance(n, func() bool {
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if n.active {
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return false
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}
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n.active = true
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n.lastUpdate = n.bt.clock.Now()
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return true
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})
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}
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// deactivate stops time/capacity cost deduction and saves the balances in the database
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func (n *nodeBalance) deactivate() {
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n.bt.updateTotalBalance(n, func() bool {
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if !n.active {
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return false
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}
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n.updateBalance(n.bt.clock.Now())
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if n.updateEvent != nil {
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n.updateEvent.Stop()
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n.updateEvent = nil
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}
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n.storeBalance(true, true)
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n.active = false
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return true
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})
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}
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// updateBalance updates balance based on the time factor
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func (n *nodeBalance) updateBalance(now mclock.AbsTime) {
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if n.active && now > n.lastUpdate {
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n.balance = n.reducedBalance(n.balance, n.lastUpdate, time.Duration(now-n.lastUpdate), n.capacity, 0)
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n.lastUpdate = now
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}
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}
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// storeBalance stores the positive and/or negative balance of the node in the database
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func (n *nodeBalance) storeBalance(pos, neg bool) {
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if pos {
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n.bt.storeBalance(n.node.ID().Bytes(), false, n.balance.pos)
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}
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if neg {
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n.bt.storeBalance([]byte(n.connAddress), true, n.balance.neg)
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}
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}
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// addCallback sets up a one-time callback to be called when priority reaches
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// the threshold. If it has already reached the threshold the callback is called
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// immediately.
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// Note: should be called while n.lock is held
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// Note 2: the callback function runs inside a NodeStateMachine operation
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func (n *nodeBalance) addCallback(id int, threshold int64, callback func()) {
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n.removeCallback(id)
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idx := 0
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for idx < n.callbackCount && threshold > n.callbacks[idx].threshold {
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idx++
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}
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for i := n.callbackCount - 1; i >= idx; i-- {
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n.callbackIndex[n.callbacks[i].id]++
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n.callbacks[i+1] = n.callbacks[i]
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}
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n.callbackCount++
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n.callbackIndex[id] = idx
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n.callbacks[idx] = balanceCallback{id, threshold, callback}
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now := n.bt.clock.Now()
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n.updateBalance(now)
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n.scheduleCheck(now)
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}
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// removeCallback removes the given callback and returns true if it was active
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// Note: should be called while n.lock is held
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func (n *nodeBalance) removeCallback(id int) bool {
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idx := n.callbackIndex[id]
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if idx == -1 {
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return false
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}
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n.callbackIndex[id] = -1
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for i := idx; i < n.callbackCount-1; i++ {
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n.callbackIndex[n.callbacks[i+1].id]--
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n.callbacks[i] = n.callbacks[i+1]
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}
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n.callbackCount--
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return true
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}
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// checkCallbacks checks whether the threshold of any of the active callbacks
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// have been reached and returns triggered callbacks.
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// Note: checkCallbacks assumes that the balance has been recently updated.
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func (n *nodeBalance) checkCallbacks(now mclock.AbsTime) (callbacks []func()) {
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if n.callbackCount == 0 || n.capacity == 0 {
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return
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}
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pri := n.balanceToPriority(now, n.balance, n.capacity)
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for n.callbackCount != 0 && n.callbacks[n.callbackCount-1].threshold >= pri {
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n.callbackCount--
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n.callbackIndex[n.callbacks[n.callbackCount].id] = -1
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callbacks = append(callbacks, n.callbacks[n.callbackCount].callback)
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}
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n.scheduleCheck(now)
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return
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}
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// scheduleCheck sets up or updates a scheduled event to ensure that it will be called
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// again just after the next threshold has been reached.
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func (n *nodeBalance) scheduleCheck(now mclock.AbsTime) {
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if n.callbackCount != 0 {
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d, ok := n.timeUntil(n.callbacks[n.callbackCount-1].threshold)
|
|
if !ok {
|
|
n.nextUpdate = 0
|
|
n.updateAfter(0)
|
|
return
|
|
}
|
|
if n.nextUpdate == 0 || n.nextUpdate > now.Add(d) {
|
|
if d > time.Second {
|
|
// Note: if the scheduled update is not in the very near future then we
|
|
// schedule the update a bit earlier. This way we do need to update a few
|
|
// extra times but don't need to reschedule every time a processed request
|
|
// brings the expected firing time a little bit closer.
|
|
d = ((d - time.Second) * 7 / 8) + time.Second
|
|
}
|
|
n.nextUpdate = now.Add(d)
|
|
n.updateAfter(d)
|
|
}
|
|
} else {
|
|
n.nextUpdate = 0
|
|
n.updateAfter(0)
|
|
}
|
|
}
|
|
|
|
// updateAfter schedules a balance update and callback check in the future
|
|
func (n *nodeBalance) updateAfter(dt time.Duration) {
|
|
if n.updateEvent == nil || n.updateEvent.Stop() {
|
|
if dt == 0 {
|
|
n.updateEvent = nil
|
|
} else {
|
|
n.updateEvent = n.bt.clock.AfterFunc(dt, func() {
|
|
var callbacks []func()
|
|
n.lock.Lock()
|
|
if n.callbackCount != 0 {
|
|
now := n.bt.clock.Now()
|
|
n.updateBalance(now)
|
|
callbacks = n.checkCallbacks(now)
|
|
}
|
|
n.lock.Unlock()
|
|
if callbacks != nil {
|
|
n.bt.ns.Operation(func() {
|
|
for _, cb := range callbacks {
|
|
cb()
|
|
}
|
|
})
|
|
}
|
|
})
|
|
}
|
|
}
|
|
}
|
|
|
|
// 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() {
|
|
n.lock.Lock()
|
|
n.storeBalance(true, false)
|
|
n.hasPriority = false
|
|
n.lock.Unlock()
|
|
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.hasPriority && !n.balance.pos.IsZero() {
|
|
n.hasPriority = true
|
|
n.addCallback(balanceCallbackZero, 0, func() { n.balanceExhausted() })
|
|
return true
|
|
}
|
|
return false
|
|
}
|
|
|
|
// 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.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) {
|
|
n.lock.Lock()
|
|
now := n.bt.clock.Now()
|
|
n.updateBalance(now)
|
|
n.capacity = capacity
|
|
callbacks := n.checkCallbacks(now)
|
|
n.lock.Unlock()
|
|
for _, cb := range callbacks {
|
|
cb()
|
|
}
|
|
}
|
|
|
|
// 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(now mclock.AbsTime, b balance, capacity uint64) int64 {
|
|
pos := b.posValue(now)
|
|
if pos > 0 {
|
|
return int64(pos / capacity)
|
|
}
|
|
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 {
|
|
// since the costs are applied continuously during the dt time period we calculate
|
|
// the expiration offset at the middle of the period
|
|
var (
|
|
at = start.Add(dt / 2)
|
|
dtf = float64(dt)
|
|
)
|
|
if !b.pos.IsZero() {
|
|
factor := n.posFactor.connectionPrice(capacity, avgReqCost)
|
|
diff := -int64(dtf * factor)
|
|
_, _, net, _ := b.addValue(at, diff, true, false)
|
|
if net == diff {
|
|
dtf = 0
|
|
} else {
|
|
dtf += float64(net) / factor
|
|
}
|
|
}
|
|
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. 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) {
|
|
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 targetPos > 0 {
|
|
if targetPos > pos {
|
|
return 0, true
|
|
}
|
|
diffTime = float64(pos-targetPos) / timePrice
|
|
return time.Duration(diffTime), true
|
|
} else {
|
|
diffTime = float64(pos) / timePrice
|
|
}
|
|
} else {
|
|
if targetPos > 0 {
|
|
return 0, true
|
|
}
|
|
}
|
|
neg := n.balance.negValue(now)
|
|
if targetNeg > neg {
|
|
timePrice := n.negFactor.connectionPrice(n.capacity, 0)
|
|
if timePrice < 1e-100 {
|
|
return 0, false
|
|
}
|
|
diffTime += float64(targetNeg-neg) / timePrice
|
|
}
|
|
return time.Duration(diffTime), true
|
|
}
|