path: root/les/odr.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 (
    "context"

    "github.com/ethereum/go-ethereum/ethdb"
    "github.com/ethereum/go-ethereum/light"
    "github.com/ethereum/go-ethereum/log"
)

// LesOdr implements light.OdrBackend
type LesOdr struct {
    db        ethdb.Database
    stop      chan struct{}
    retriever *retrieveManager
}

func NewLesOdr(db ethdb.Database, retriever *retrieveManager) *LesOdr {
    return &LesOdr{
        db:        db,
        retriever: retriever,
        stop:      make(chan struct{}),
    }
}

func (odr *LesOdr) Stop() {
    close(odr.stop)
}

func (odr *LesOdr) Database() ethdb.Database {
    return odr.db
}

const (
    MsgBlockBodies = iota
    MsgCode
    MsgReceipts
    MsgProofs
    MsgHeaderProofs
)

// Msg encodes a LES message that delivers reply data for a request
type Msg struct {
    MsgType int
    ReqID   uint64
    Obj     interface{}
}

// Retrieve tries to fetch an object from the LES network.
// If the network retrieval was successful, it stores the object in local db.
func (self *LesOdr) Retrieve(ctx context.Context, req light.OdrRequest) (err error) {
    lreq := LesRequest(req)

    reqID := genReqID()
    rq := &distReq{
        getCost: func(dp distPeer) uint64 {
            return lreq.GetCost(dp.(*peer))
        },
        canSend: func(dp distPeer) bool {
            p := dp.(*peer)
            return lreq.CanSend(p)
        },
        request: func(dp distPeer) func() {
            p := dp.(*peer)
            cost := lreq.GetCost(p)
            p.fcServer.QueueRequest(reqID, cost)
            return func() { lreq.Request(reqID, p) }
        },
    }

    if err = self.retriever.retrieve(ctx, reqID, rq, func(p distPeer, msg *Msg) error { return lreq.Validate(self.db, msg) }); err == nil {
        // retrieved from network, store in db
        req.StoreResult(self.db)
    } else {
        log.Debug("Failed to retrieve data from network", "err", err)
    }
    return
}