path: root/les/txrelay.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

import (
    "sync"

    "github.com/dexon-foundation/dexon/common"
    "github.com/dexon-foundation/dexon/core/types"
    "github.com/dexon-foundation/dexon/rlp"
)

type ltrInfo struct {
    tx     *types.Transaction
    sentTo map[*peer]struct{}
}

type LesTxRelay struct {
    txSent       map[common.Hash]*ltrInfo
    txPending    map[common.Hash]struct{}
    ps           *peerSet
    peerList     []*peer
    peerStartPos int
    lock         sync.RWMutex

    reqDist *requestDistributor
}

func NewLesTxRelay(ps *peerSet, reqDist *requestDistributor) *LesTxRelay {
    r := &LesTxRelay{
        txSent:    make(map[common.Hash]*ltrInfo),
        txPending: make(map[common.Hash]struct{}),
        ps:        ps,
        reqDist:   reqDist,
    }
    ps.notify(r)
    return r
}

func (self *LesTxRelay) registerPeer(p *peer) {
    self.lock.Lock()
    defer self.lock.Unlock()

    self.peerList = self.ps.AllPeers()
}

func (self *LesTxRelay) unregisterPeer(p *peer) {
    self.lock.Lock()
    defer self.lock.Unlock()

    self.peerList = self.ps.AllPeers()
}

// send sends a list of transactions to at most a given number of peers at
// once, never resending any particular transaction to the same peer twice
func (self *LesTxRelay) send(txs types.Transactions, count int) {
    sendTo := make(map[*peer]types.Transactions)

    self.peerStartPos++ // rotate the starting position of the peer list
    if self.peerStartPos >= len(self.peerList) {
        self.peerStartPos = 0
    }

    for _, tx := range txs {
        hash := tx.Hash()
        ltr, ok := self.txSent[hash]
        if !ok {
            ltr = &ltrInfo{
                tx:     tx,
                sentTo: make(map[*peer]struct{}),
            }
            self.txSent[hash] = ltr
            self.txPending[hash] = struct{}{}
        }

        if len(self.peerList) > 0 {
            cnt := count
            pos := self.peerStartPos
            for {
                peer := self.peerList[pos]
                if _, ok := ltr.sentTo[peer]; !ok {
                    sendTo[peer] = append(sendTo[peer], tx)
                    ltr.sentTo[peer] = struct{}{}
                    cnt--
                }
                if cnt == 0 {
                    break // sent it to the desired number of peers
                }
                pos++
                if pos == len(self.peerList) {
                    pos = 0
                }
                if pos == self.peerStartPos {
                    break // tried all available peers
                }
            }
        }
    }

    for p, list := range sendTo {
        pp := p
        ll := list
        enc, _ := rlp.EncodeToBytes(ll)

        reqID := genReqID()
        rq := &distReq{
            getCost: func(dp distPeer) uint64 {
                peer := dp.(*peer)
                return peer.GetTxRelayCost(len(ll), len(enc))
            },
            canSend: func(dp distPeer) bool {
                return dp.(*peer) == pp
            },
            request: func(dp distPeer) func() {
                peer := dp.(*peer)
                cost := peer.GetTxRelayCost(len(ll), len(enc))
                peer.fcServer.QueueRequest(reqID, cost)
                return func() { peer.SendTxs(reqID, cost, enc) }
            },
        }
        self.reqDist.queue(rq)
    }
}

func (self *LesTxRelay) Send(txs types.Transactions) {
    self.lock.Lock()
    defer self.lock.Unlock()

    self.send(txs, 3)
}

func (self *LesTxRelay) NewHead(head common.Hash, mined []common.Hash, rollback []common.Hash) {
    self.lock.Lock()
    defer self.lock.Unlock()

    for _, hash := range mined {
        delete(self.txPending, hash)
    }

    for _, hash := range rollback {
        self.txPending[hash] = struct{}{}
    }

    if len(self.txPending) > 0 {
        txs := make(types.Transactions, len(self.txPending))
        i := 0
        for hash := range self.txPending {
            txs[i] = self.txSent[hash].tx
            i++
        }
        self.send(txs, 1)
    }
}

func (self *LesTxRelay) Discard(hashes []common.Hash) {
    self.lock.Lock()
    defer self.lock.Unlock()

    for _, hash := range hashes {
        delete(self.txSent, hash)
        delete(self.txPending, hash)
    }
}