path: root/les/server.go

// Copyright 2016 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 les implements the Light Ethereum Subprotocol.
package les

import (
    "encoding/binary"
    "math"
    "sync"
    "time"

    "github.com/ethereum/go-ethereum/common"
    "github.com/ethereum/go-ethereum/core"
    "github.com/ethereum/go-ethereum/core/types"
    "github.com/ethereum/go-ethereum/eth"
    "github.com/ethereum/go-ethereum/ethdb"
    "github.com/ethereum/go-ethereum/les/flowcontrol"
    "github.com/ethereum/go-ethereum/light"
    "github.com/ethereum/go-ethereum/log"
    "github.com/ethereum/go-ethereum/p2p"
    "github.com/ethereum/go-ethereum/rlp"
    "github.com/ethereum/go-ethereum/trie"
)

type LesServer struct {
    protocolManager *ProtocolManager
    fcManager       *flowcontrol.ClientManager // nil if our node is client only
    fcCostStats     *requestCostStats
    defParams       *flowcontrol.ServerParams
    stopped         bool
}

func NewLesServer(eth *eth.Ethereum, config *eth.Config) (*LesServer, error) {
    pm, err := NewProtocolManager(eth.BlockChain().Config(), false, config.NetworkId, eth.EventMux(), eth.Engine(), eth.BlockChain(), eth.TxPool(), eth.ChainDb(), nil, nil)
    if err != nil {
        return nil, err
    }
    pm.blockLoop()

    srv := &LesServer{protocolManager: pm}
    pm.server = srv

    srv.defParams = &flowcontrol.ServerParams{
        BufLimit:    300000000,
        MinRecharge: 50000,
    }
    srv.fcManager = flowcontrol.NewClientManager(uint64(config.LightServ), 10, 1000000000)
    srv.fcCostStats = newCostStats(eth.ChainDb())
    return srv, nil
}

func (s *LesServer) Protocols() []p2p.Protocol {
    return s.protocolManager.SubProtocols
}

// Start starts the LES server
func (s *LesServer) Start(srvr *p2p.Server) {
    s.protocolManager.Start(srvr)
}

// Stop stops the LES service
func (s *LesServer) Stop() {
    s.fcCostStats.store()
    s.fcManager.Stop()
    go func() {
        <-s.protocolManager.noMorePeers
    }()
    s.protocolManager.Stop()
}

type requestCosts struct {
    baseCost, reqCost uint64
}

type requestCostTable map[uint64]*requestCosts

type RequestCostList []struct {
    MsgCode, BaseCost, ReqCost uint64
}

func (list RequestCostList) decode() requestCostTable {
    table := make(requestCostTable)
    for _, e := range list {
        table[e.MsgCode] = &requestCosts{
            baseCost: e.BaseCost,
            reqCost:  e.ReqCost,
        }
    }
    return table
}

func (table requestCostTable) encode() RequestCostList {
    list := make(RequestCostList, len(table))
    for idx, code := range reqList {
        list[idx].MsgCode = code
        list[idx].BaseCost = table[code].baseCost
        list[idx].ReqCost = table[code].reqCost
    }
    return list
}

type linReg struct {
    sumX, sumY, sumXX, sumXY float64
    cnt                      uint64
}

const linRegMaxCnt = 100000

func (l *linReg) add(x, y float64) {
    if l.cnt >= linRegMaxCnt {
        sub := float64(l.cnt+1-linRegMaxCnt) / linRegMaxCnt
        l.sumX -= l.sumX * sub
        l.sumY -= l.sumY * sub
        l.sumXX -= l.sumXX * sub
        l.sumXY -= l.sumXY * sub
        l.cnt = linRegMaxCnt - 1
    }
    l.cnt++
    l.sumX += x
    l.sumY += y
    l.sumXX += x * x
    l.sumXY += x * y
}

func (l *linReg) calc() (b, m float64) {
    if l.cnt == 0 {
        return 0, 0
    }
    cnt := float64(l.cnt)
    d := cnt*l.sumXX - l.sumX*l.sumX
    if d < 0.001 {
        return l.sumY / cnt, 0
    }
    m = (cnt*l.sumXY - l.sumX*l.sumY) / d
    b = (l.sumY / cnt) - (m * l.sumX / cnt)
    return b, m
}

func (l *linReg) toBytes() []byte {
    var arr [40]byte
    binary.BigEndian.PutUint64(arr[0:8], math.Float64bits(l.sumX))
    binary.BigEndian.PutUint64(arr[8:16], math.Float64bits(l.sumY))
    binary.BigEndian.PutUint64(arr[16:24], math.Float64bits(l.sumXX))
    binary.BigEndian.PutUint64(arr[24:32], math.Float64bits(l.sumXY))
    binary.BigEndian.PutUint64(arr[32:40], l.cnt)
    return arr[:]
}

func linRegFromBytes(data []byte) *linReg {
    if len(data) != 40 {
        return nil
    }
    l := &linReg{}
    l.sumX = math.Float64frombits(binary.BigEndian.Uint64(data[0:8]))
    l.sumY = math.Float64frombits(binary.BigEndian.Uint64(data[8:16]))
    l.sumXX = math.Float64frombits(binary.BigEndian.Uint64(data[16:24]))
    l.sumXY = math.Float64frombits(binary.BigEndian.Uint64(data[24:32]))
    l.cnt = binary.BigEndian.Uint64(data[32:40])
    return l
}

type requestCostStats struct {
    lock  sync.RWMutex
    db    ethdb.Database
    stats map[uint64]*linReg
}

type requestCostStatsRlp []struct {
    MsgCode uint64
    Data    []byte
}

var rcStatsKey = []byte("_requestCostStats")

func newCostStats(db ethdb.Database) *requestCostStats {
    stats := make(map[uint64]*linReg)
    for _, code := range reqList {
        stats[code] = &linReg{cnt: 100}
    }

    if db != nil {
        data, err := db.Get(rcStatsKey)
        var statsRlp requestCostStatsRlp
        if err == nil {
            err = rlp.DecodeBytes(data, &statsRlp)
        }
        if err == nil {
            for _, r := range statsRlp {
                if stats[r.MsgCode] != nil {
                    if l := linRegFromBytes(r.Data); l != nil {
                        stats[r.MsgCode] = l
                    }
                }
            }
        }
    }

    return &requestCostStats{
        db:    db,
        stats: stats,
    }
}

func (s *requestCostStats) store() {
    s.lock.Lock()
    defer s.lock.Unlock()

    statsRlp := make(requestCostStatsRlp, len(reqList))
    for i, code := range reqList {
        statsRlp[i].MsgCode = code
        statsRlp[i].Data = s.stats[code].toBytes()
    }

    if data, err := rlp.EncodeToBytes(statsRlp); err == nil {
        s.db.Put(rcStatsKey, data)
    }
}

func (s *requestCostStats) getCurrentList() RequestCostList {
    s.lock.Lock()
    defer s.lock.Unlock()

    list := make(RequestCostList, len(reqList))
    //fmt.Println("RequestCostList")
    for idx, code := range reqList {
        b, m := s.stats[code].calc()
        //fmt.Println(code, s.stats[code].cnt, b/1000000, m/1000000)
        if m < 0 {
            b += m
            m = 0
        }
        if b < 0 {
            b = 0
        }

        list[idx].MsgCode = code
        list[idx].BaseCost = uint64(b * 2)
        list[idx].ReqCost = uint64(m * 2)
    }
    return list
}

func (s *requestCostStats) update(msgCode, reqCnt, cost uint64) {
    s.lock.Lock()
    defer s.lock.Unlock()

    c, ok := s.stats[msgCode]
    if !ok || reqCnt == 0 {
        return
    }
    c.add(float64(reqCnt), float64(cost))
}

func (pm *ProtocolManager) blockLoop() {
    pm.wg.Add(1)
    sub := pm.eventMux.Subscribe(core.ChainHeadEvent{})
    newCht := make(chan struct{}, 10)
    newCht <- struct{}{}
    go func() {
        var mu sync.Mutex
        var lastHead *types.Header
        lastBroadcastTd := common.Big0
        for {
            select {
            case ev := <-sub.Chan():
                peers := pm.peers.AllPeers()
                if len(peers) > 0 {
                    header := ev.Data.(core.ChainHeadEvent).Block.Header()
                    hash := header.Hash()
                    number := header.Number.Uint64()
                    td := core.GetTd(pm.chainDb, hash, number)
                    if td != nil && td.Cmp(lastBroadcastTd) > 0 {
                        var reorg uint64
                        if lastHead != nil {
                            reorg = lastHead.Number.Uint64() - core.FindCommonAncestor(pm.chainDb, header, lastHead).Number.Uint64()
                        }
                        lastHead = header
                        lastBroadcastTd = td

                        log.Debug("Announcing block to peers", "number", number, "hash", hash, "td", td, "reorg", reorg)

                        announce := announceData{Hash: hash, Number: number, Td: td, ReorgDepth: reorg}
                        for _, p := range peers {
                            select {
                            case p.announceChn <- announce:
                            default:
                                pm.removePeer(p.id)
                            }
                        }
                    }
                }
                newCht <- struct{}{}
            case <-newCht:
                go func() {
                    mu.Lock()
                    more := makeCht(pm.chainDb)
                    mu.Unlock()
                    if more {
                        time.Sleep(time.Millisecond * 10)
                        newCht <- struct{}{}
                    }
                }()
            case <-pm.quitSync:
                sub.Unsubscribe()
                pm.wg.Done()
                return
            }
        }
    }()
}

var (
    lastChtKey = []byte("LastChtNumber") // chtNum (uint64 big endian)
    chtPrefix  = []byte("cht")           // chtPrefix + chtNum (uint64 big endian) -> trie root hash
)

func getChtRoot(db ethdb.Database, num uint64) common.Hash {
    var encNumber [8]byte
    binary.BigEndian.PutUint64(encNumber[:], num)
    data, _ := db.Get(append(chtPrefix, encNumber[:]...))
    return common.BytesToHash(data)
}

func storeChtRoot(db ethdb.Database, num uint64, root common.Hash) {
    var encNumber [8]byte
    binary.BigEndian.PutUint64(encNumber[:], num)
    db.Put(append(chtPrefix, encNumber[:]...), root[:])
}

func makeCht(db ethdb.Database) bool {
    headHash := core.GetHeadBlockHash(db)
    headNum := core.GetBlockNumber(db, headHash)

    var newChtNum uint64
    if headNum > light.ChtConfirmations {
        newChtNum = (headNum - light.ChtConfirmations) / light.ChtFrequency
    }

    var lastChtNum uint64
    data, _ := db.Get(lastChtKey)
    if len(data) == 8 {
        lastChtNum = binary.BigEndian.Uint64(data[:])
    }
    if newChtNum <= lastChtNum {
        return false
    }

    var t *trie.Trie
    if lastChtNum > 0 {
        var err error
        t, err = trie.New(getChtRoot(db, lastChtNum), db)
        if err != nil {
            lastChtNum = 0
        }
    }
    if lastChtNum == 0 {
        t, _ = trie.New(common.Hash{}, db)
    }

    for num := lastChtNum * light.ChtFrequency; num < (lastChtNum+1)*light.ChtFrequency; num++ {
        hash := core.GetCanonicalHash(db, num)
        if hash == (common.Hash{}) {
            panic("Canonical hash not found")
        }
        td := core.GetTd(db, hash, num)
        if td == nil {
            panic("TD not found")
        }
        var encNumber [8]byte
        binary.BigEndian.PutUint64(encNumber[:], num)
        var node light.ChtNode
        node.Hash = hash
        node.Td = td
        data, _ := rlp.EncodeToBytes(node)
        t.Update(encNumber[:], data)
    }

    root, err := t.Commit()
    if err != nil {
        lastChtNum = 0
    } else {
        lastChtNum++

        log.Trace("Generated CHT", "number", lastChtNum, "root", root.Hex())

        storeChtRoot(db, lastChtNum, root)
        var data [8]byte
        binary.BigEndian.PutUint64(data[:], lastChtNum)
        db.Put(lastChtKey, data[:])
    }

    return newChtNum > lastChtNum
}