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valuetracker.go
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valuetracker.go
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// 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/Thurston00/go-rethereum/common/mclock"
"github.com/Thurston00/go-rethereum/ethdb"
"github.com/Thurston00/go-rethereum/les/utils"
"github.com/Thurston00/go-rethereum/log"
"github.com/Thurston00/go-rethereum/p2p/enode"
"github.com/Thurston00/go-rethereum/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
vt *ValueTracker
rtStats, lastRtStats ResponseTimeStats
lastTransfer mclock.AbsTime
basket serverBasket
reqCosts []uint64
reqValues []float64
}
// UpdateCosts updates the node value tracker's request cost table
func (nv *NodeValueTracker) UpdateCosts(reqCosts []uint64) {
nv.vt.lock.Lock()
defer nv.vt.lock.Unlock()
nv.updateCosts(reqCosts, nv.vt.refBasket.reqValues, nv.vt.refBasket.reqValueFactor(reqCosts))
}
// 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
}
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 (nv *NodeValueTracker) Served(reqs []ServedRequest, respTime time.Duration) {
nv.vt.statsExpLock.RLock()
expFactor := nv.vt.statsExpFactor
nv.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, expFactor)
}
// 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
}
// StatsExpFactor 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)
reqTypeCount := len(vt.refBasket.reqValues)
nv.reqCosts = make([]uint64, reqTypeCount)
nv.lastTransfer = vt.clock.Now()
nv.reqValues = vt.refBasket.reqValues
nv.basket.init(reqTypeCount)
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{vt: vt, 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)
}
}
// 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 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
}