go-pulse/les/lespay/client/valuetracker.go
Felföldi Zsolt b4a2681120
les, les/lespay: implement new server pool (#20758)
This PR reimplements the light client server pool. It is also a first step
to move certain logic into a new lespay package. This package will contain
the implementation of the lespay token sale functions, the token buying and
selling logic and other components related to peer selection/prioritization
and service quality evaluation. Over the long term this package will be
reusable for incentivizing future protocols.

Since the LES peer logic is now based on enode.Iterator, it can now use
DNS-based fallback discovery to find servers.

This document describes the function of the new components:
https://gist.github.com/zsfelfoldi/3c7ace895234b7b345ab4f71dab102d4
2020-05-22 13:46:34 +02:00

512 lines
16 KiB
Go

// Copyright 2020 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
package client
import (
"bytes"
"fmt"
"math"
"sync"
"time"
"github.com/ethereum/go-ethereum/common/mclock"
"github.com/ethereum/go-ethereum/ethdb"
"github.com/ethereum/go-ethereum/les/utils"
"github.com/ethereum/go-ethereum/log"
"github.com/ethereum/go-ethereum/p2p/enode"
"github.com/ethereum/go-ethereum/rlp"
)
const (
vtVersion = 1 // database encoding format for ValueTracker
nvtVersion = 1 // database encoding format for NodeValueTracker
)
var (
vtKey = []byte("vt:")
vtNodeKey = []byte("vtNode:")
)
// NodeValueTracker collects service value statistics for a specific server node
type NodeValueTracker struct {
lock sync.Mutex
rtStats, lastRtStats ResponseTimeStats
lastTransfer mclock.AbsTime
basket serverBasket
reqCosts []uint64
reqValues *[]float64
}
// init initializes a NodeValueTracker.
// Note that the contents of the referenced reqValues slice will not change; a new
// reference is passed if the values are updated by ValueTracker.
func (nv *NodeValueTracker) init(now mclock.AbsTime, reqValues *[]float64) {
reqTypeCount := len(*reqValues)
nv.reqCosts = make([]uint64, reqTypeCount)
nv.lastTransfer = now
nv.reqValues = reqValues
nv.basket.init(reqTypeCount)
}
// updateCosts updates the request cost table of the server. The request value factor
// is also updated based on the given cost table and the current reference basket.
// Note that the contents of the referenced reqValues slice will not change; a new
// reference is passed if the values are updated by ValueTracker.
func (nv *NodeValueTracker) updateCosts(reqCosts []uint64, reqValues *[]float64, rvFactor float64) {
nv.lock.Lock()
defer nv.lock.Unlock()
nv.reqCosts = reqCosts
nv.reqValues = reqValues
nv.basket.updateRvFactor(rvFactor)
}
// transferStats returns request basket and response time statistics that should be
// added to the global statistics. The contents of the server's own request basket are
// gradually transferred to the main reference basket and removed from the server basket
// with the specified transfer rate.
// The response time statistics are retained at both places and therefore the global
// distribution is always the sum of the individual server distributions.
func (nv *NodeValueTracker) transferStats(now mclock.AbsTime, transferRate float64) (requestBasket, ResponseTimeStats) {
nv.lock.Lock()
defer nv.lock.Unlock()
dt := now - nv.lastTransfer
nv.lastTransfer = now
if dt < 0 {
dt = 0
}
recentRtStats := nv.rtStats
recentRtStats.SubStats(&nv.lastRtStats)
nv.lastRtStats = nv.rtStats
return nv.basket.transfer(-math.Expm1(-transferRate * float64(dt))), recentRtStats
}
// RtStats returns the node's own response time distribution statistics
func (nv *NodeValueTracker) RtStats() ResponseTimeStats {
nv.lock.Lock()
defer nv.lock.Unlock()
return nv.rtStats
}
// ValueTracker coordinates service value calculation for individual servers and updates
// global statistics
type ValueTracker struct {
clock mclock.Clock
lock sync.Mutex
quit chan chan struct{}
db ethdb.KeyValueStore
connected map[enode.ID]*NodeValueTracker
reqTypeCount int
refBasket referenceBasket
mappings [][]string
currentMapping int
initRefBasket requestBasket
rtStats ResponseTimeStats
transferRate float64
statsExpLock sync.RWMutex
statsExpRate, offlineExpRate float64
statsExpirer utils.Expirer
statsExpFactor utils.ExpirationFactor
}
type valueTrackerEncV1 struct {
Mappings [][]string
RefBasketMapping uint
RefBasket requestBasket
RtStats ResponseTimeStats
ExpOffset, SavedAt uint64
}
type nodeValueTrackerEncV1 struct {
RtStats ResponseTimeStats
ServerBasketMapping uint
ServerBasket requestBasket
}
// RequestInfo is an initializer structure for the service vector.
type RequestInfo struct {
// Name identifies the request type and is used for re-mapping the service vector if necessary
Name string
// InitAmount and InitValue are used to initialize the reference basket
InitAmount, InitValue float64
}
// NewValueTracker creates a new ValueTracker and loads its previously saved state from
// the database if possible.
func NewValueTracker(db ethdb.KeyValueStore, clock mclock.Clock, reqInfo []RequestInfo, updatePeriod time.Duration, transferRate, statsExpRate, offlineExpRate float64) *ValueTracker {
now := clock.Now()
initRefBasket := requestBasket{items: make([]basketItem, len(reqInfo))}
mapping := make([]string, len(reqInfo))
var sumAmount, sumValue float64
for _, req := range reqInfo {
sumAmount += req.InitAmount
sumValue += req.InitAmount * req.InitValue
}
scaleValues := sumAmount * basketFactor / sumValue
for i, req := range reqInfo {
mapping[i] = req.Name
initRefBasket.items[i].amount = uint64(req.InitAmount * basketFactor)
initRefBasket.items[i].value = uint64(req.InitAmount * req.InitValue * scaleValues)
}
vt := &ValueTracker{
clock: clock,
connected: make(map[enode.ID]*NodeValueTracker),
quit: make(chan chan struct{}),
db: db,
reqTypeCount: len(initRefBasket.items),
initRefBasket: initRefBasket,
transferRate: transferRate,
statsExpRate: statsExpRate,
offlineExpRate: offlineExpRate,
}
if vt.loadFromDb(mapping) != nil {
// previous state not saved or invalid, init with default values
vt.refBasket.basket = initRefBasket
vt.mappings = [][]string{mapping}
vt.currentMapping = 0
}
vt.statsExpirer.SetRate(now, statsExpRate)
vt.refBasket.init(vt.reqTypeCount)
vt.periodicUpdate()
go func() {
for {
select {
case <-clock.After(updatePeriod):
vt.lock.Lock()
vt.periodicUpdate()
vt.lock.Unlock()
case quit := <-vt.quit:
close(quit)
return
}
}
}()
return vt
}
// StatsExpirer returns the statistics expirer so that other values can be expired
// with the same rate as the service value statistics.
func (vt *ValueTracker) StatsExpirer() *utils.Expirer {
return &vt.statsExpirer
}
// StatsExpirer returns the current expiration factor so that other values can be expired
// with the same rate as the service value statistics.
func (vt *ValueTracker) StatsExpFactor() utils.ExpirationFactor {
vt.statsExpLock.RLock()
defer vt.statsExpLock.RUnlock()
return vt.statsExpFactor
}
// loadFromDb loads the value tracker's state from the database and converts saved
// request basket index mapping if it does not match the specified index to name mapping.
func (vt *ValueTracker) loadFromDb(mapping []string) error {
enc, err := vt.db.Get(vtKey)
if err != nil {
return err
}
r := bytes.NewReader(enc)
var version uint
if err := rlp.Decode(r, &version); err != nil {
log.Error("Decoding value tracker state failed", "err", err)
return err
}
if version != vtVersion {
log.Error("Unknown ValueTracker version", "stored", version, "current", nvtVersion)
return fmt.Errorf("Unknown ValueTracker version %d (current version is %d)", version, vtVersion)
}
var vte valueTrackerEncV1
if err := rlp.Decode(r, &vte); err != nil {
log.Error("Decoding value tracker state failed", "err", err)
return err
}
logOffset := utils.Fixed64(vte.ExpOffset)
dt := time.Now().UnixNano() - int64(vte.SavedAt)
if dt > 0 {
logOffset += utils.Float64ToFixed64(float64(dt) * vt.offlineExpRate / math.Log(2))
}
vt.statsExpirer.SetLogOffset(vt.clock.Now(), logOffset)
vt.rtStats = vte.RtStats
vt.mappings = vte.Mappings
vt.currentMapping = -1
loop:
for i, m := range vt.mappings {
if len(m) != len(mapping) {
continue loop
}
for j, s := range mapping {
if m[j] != s {
continue loop
}
}
vt.currentMapping = i
break
}
if vt.currentMapping == -1 {
vt.currentMapping = len(vt.mappings)
vt.mappings = append(vt.mappings, mapping)
}
if int(vte.RefBasketMapping) == vt.currentMapping {
vt.refBasket.basket = vte.RefBasket
} else {
if vte.RefBasketMapping >= uint(len(vt.mappings)) {
log.Error("Unknown request basket mapping", "stored", vte.RefBasketMapping, "current", vt.currentMapping)
return fmt.Errorf("Unknown request basket mapping %d (current version is %d)", vte.RefBasketMapping, vt.currentMapping)
}
vt.refBasket.basket = vte.RefBasket.convertMapping(vt.mappings[vte.RefBasketMapping], mapping, vt.initRefBasket)
}
return nil
}
// saveToDb saves the value tracker's state to the database
func (vt *ValueTracker) saveToDb() {
vte := valueTrackerEncV1{
Mappings: vt.mappings,
RefBasketMapping: uint(vt.currentMapping),
RefBasket: vt.refBasket.basket,
RtStats: vt.rtStats,
ExpOffset: uint64(vt.statsExpirer.LogOffset(vt.clock.Now())),
SavedAt: uint64(time.Now().UnixNano()),
}
enc1, err := rlp.EncodeToBytes(uint(vtVersion))
if err != nil {
log.Error("Encoding value tracker state failed", "err", err)
return
}
enc2, err := rlp.EncodeToBytes(&vte)
if err != nil {
log.Error("Encoding value tracker state failed", "err", err)
return
}
if err := vt.db.Put(vtKey, append(enc1, enc2...)); err != nil {
log.Error("Saving value tracker state failed", "err", err)
}
}
// Stop saves the value tracker's state and each loaded node's individual state and
// returns after shutting the internal goroutines down.
func (vt *ValueTracker) Stop() {
quit := make(chan struct{})
vt.quit <- quit
<-quit
vt.lock.Lock()
vt.periodicUpdate()
for id, nv := range vt.connected {
vt.saveNode(id, nv)
}
vt.connected = nil
vt.saveToDb()
vt.lock.Unlock()
}
// Register adds a server node to the value tracker
func (vt *ValueTracker) Register(id enode.ID) *NodeValueTracker {
vt.lock.Lock()
defer vt.lock.Unlock()
if vt.connected == nil {
// ValueTracker has already been stopped
return nil
}
nv := vt.loadOrNewNode(id)
nv.init(vt.clock.Now(), &vt.refBasket.reqValues)
vt.connected[id] = nv
return nv
}
// Unregister removes a server node from the value tracker
func (vt *ValueTracker) Unregister(id enode.ID) {
vt.lock.Lock()
defer vt.lock.Unlock()
if nv := vt.connected[id]; nv != nil {
vt.saveNode(id, nv)
delete(vt.connected, id)
}
}
// GetNode returns an individual server node's value tracker. If it did not exist before
// then a new node is created.
func (vt *ValueTracker) GetNode(id enode.ID) *NodeValueTracker {
vt.lock.Lock()
defer vt.lock.Unlock()
return vt.loadOrNewNode(id)
}
// loadOrNewNode returns an individual server node's value tracker. If it did not exist before
// then a new node is created.
func (vt *ValueTracker) loadOrNewNode(id enode.ID) *NodeValueTracker {
if nv, ok := vt.connected[id]; ok {
return nv
}
nv := &NodeValueTracker{lastTransfer: vt.clock.Now()}
enc, err := vt.db.Get(append(vtNodeKey, id[:]...))
if err != nil {
return nv
}
r := bytes.NewReader(enc)
var version uint
if err := rlp.Decode(r, &version); err != nil {
log.Error("Failed to decode node value tracker", "id", id, "err", err)
return nv
}
if version != nvtVersion {
log.Error("Unknown NodeValueTracker version", "stored", version, "current", nvtVersion)
return nv
}
var nve nodeValueTrackerEncV1
if err := rlp.Decode(r, &nve); err != nil {
log.Error("Failed to decode node value tracker", "id", id, "err", err)
return nv
}
nv.rtStats = nve.RtStats
nv.lastRtStats = nve.RtStats
if int(nve.ServerBasketMapping) == vt.currentMapping {
nv.basket.basket = nve.ServerBasket
} else {
if nve.ServerBasketMapping >= uint(len(vt.mappings)) {
log.Error("Unknown request basket mapping", "stored", nve.ServerBasketMapping, "current", vt.currentMapping)
return nv
}
nv.basket.basket = nve.ServerBasket.convertMapping(vt.mappings[nve.ServerBasketMapping], vt.mappings[vt.currentMapping], vt.initRefBasket)
}
return nv
}
// saveNode saves a server node's value tracker to the database
func (vt *ValueTracker) saveNode(id enode.ID, nv *NodeValueTracker) {
recentRtStats := nv.rtStats
recentRtStats.SubStats(&nv.lastRtStats)
vt.rtStats.AddStats(&recentRtStats)
nv.lastRtStats = nv.rtStats
nve := nodeValueTrackerEncV1{
RtStats: nv.rtStats,
ServerBasketMapping: uint(vt.currentMapping),
ServerBasket: nv.basket.basket,
}
enc1, err := rlp.EncodeToBytes(uint(nvtVersion))
if err != nil {
log.Error("Failed to encode service value information", "id", id, "err", err)
return
}
enc2, err := rlp.EncodeToBytes(&nve)
if err != nil {
log.Error("Failed to encode service value information", "id", id, "err", err)
return
}
if err := vt.db.Put(append(vtNodeKey, id[:]...), append(enc1, enc2...)); err != nil {
log.Error("Failed to save service value information", "id", id, "err", err)
}
}
// UpdateCosts updates the node value tracker's request cost table
func (vt *ValueTracker) UpdateCosts(nv *NodeValueTracker, reqCosts []uint64) {
vt.lock.Lock()
defer vt.lock.Unlock()
nv.updateCosts(reqCosts, &vt.refBasket.reqValues, vt.refBasket.reqValueFactor(reqCosts))
}
// RtStats returns the global response time distribution statistics
func (vt *ValueTracker) RtStats() ResponseTimeStats {
vt.lock.Lock()
defer vt.lock.Unlock()
vt.periodicUpdate()
return vt.rtStats
}
// periodicUpdate transfers individual node data to the global statistics, normalizes
// the reference basket and updates request values. The global state is also saved to
// the database with each update.
func (vt *ValueTracker) periodicUpdate() {
now := vt.clock.Now()
vt.statsExpLock.Lock()
vt.statsExpFactor = utils.ExpFactor(vt.statsExpirer.LogOffset(now))
vt.statsExpLock.Unlock()
for _, nv := range vt.connected {
basket, rtStats := nv.transferStats(now, vt.transferRate)
vt.refBasket.add(basket)
vt.rtStats.AddStats(&rtStats)
}
vt.refBasket.normalize()
vt.refBasket.updateReqValues()
for _, nv := range vt.connected {
nv.updateCosts(nv.reqCosts, &vt.refBasket.reqValues, vt.refBasket.reqValueFactor(nv.reqCosts))
}
vt.saveToDb()
}
type ServedRequest struct {
ReqType, Amount uint32
}
// Served adds a served request to the node's statistics. An actual request may be composed
// of one or more request types (service vector indices).
func (vt *ValueTracker) Served(nv *NodeValueTracker, reqs []ServedRequest, respTime time.Duration) {
vt.statsExpLock.RLock()
expFactor := vt.statsExpFactor
vt.statsExpLock.RUnlock()
nv.lock.Lock()
defer nv.lock.Unlock()
var value float64
for _, r := range reqs {
nv.basket.add(r.ReqType, r.Amount, nv.reqCosts[r.ReqType]*uint64(r.Amount), expFactor)
value += (*nv.reqValues)[r.ReqType] * float64(r.Amount)
}
nv.rtStats.Add(respTime, value, vt.statsExpFactor)
}
type RequestStatsItem struct {
Name string
ReqAmount, ReqValue float64
}
// RequestStats returns the current contents of the reference request basket, with
// request values meaning average per request rather than total.
func (vt *ValueTracker) RequestStats() []RequestStatsItem {
vt.statsExpLock.RLock()
expFactor := vt.statsExpFactor
vt.statsExpLock.RUnlock()
vt.lock.Lock()
defer vt.lock.Unlock()
vt.periodicUpdate()
res := make([]RequestStatsItem, len(vt.refBasket.basket.items))
for i, item := range vt.refBasket.basket.items {
res[i].Name = vt.mappings[vt.currentMapping][i]
res[i].ReqAmount = expFactor.Value(float64(item.amount)/basketFactor, vt.refBasket.basket.exp)
res[i].ReqValue = vt.refBasket.reqValues[i]
}
return res
}