github.com/bamzi/go-ethereum@v1.6.7-0.20170704111104-138f26c93af1/les/odr.go (about)

     1  // Copyright 2016 The go-ethereum Authors
     2  // This file is part of the go-ethereum library.
     3  //
     4  // The go-ethereum library is free software: you can redistribute it and/or modify
     5  // it under the terms of the GNU Lesser General Public License as published by
     6  // the Free Software Foundation, either version 3 of the License, or
     7  // (at your option) any later version.
     8  //
     9  // The go-ethereum library is distributed in the hope that it will be useful,
    10  // but WITHOUT ANY WARRANTY; without even the implied warranty of
    11  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    12  // GNU Lesser General Public License for more details.
    13  //
    14  // You should have received a copy of the GNU Lesser General Public License
    15  // along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
    16  
    17  package les
    18  
    19  import (
    20  	"context"
    21  
    22  	"github.com/ethereum/go-ethereum/ethdb"
    23  	"github.com/ethereum/go-ethereum/light"
    24  	"github.com/ethereum/go-ethereum/log"
    25  )
    26  
    27  // LesOdr implements light.OdrBackend
    28  type LesOdr struct {
    29  	db        ethdb.Database
    30  	stop      chan struct{}
    31  	retriever *retrieveManager
    32  }
    33  
    34  func NewLesOdr(db ethdb.Database, retriever *retrieveManager) *LesOdr {
    35  	return &LesOdr{
    36  		db:        db,
    37  		retriever: retriever,
    38  		stop:      make(chan struct{}),
    39  	}
    40  }
    41  
    42  func (odr *LesOdr) Stop() {
    43  	close(odr.stop)
    44  }
    45  
    46  func (odr *LesOdr) Database() ethdb.Database {
    47  	return odr.db
    48  }
    49  
    50  const (
    51  	MsgBlockBodies = iota
    52  	MsgCode
    53  	MsgReceipts
    54  	MsgProofs
    55  	MsgHeaderProofs
    56  )
    57  
    58  // Msg encodes a LES message that delivers reply data for a request
    59  type Msg struct {
    60  	MsgType int
    61  	ReqID   uint64
    62  	Obj     interface{}
    63  }
    64  
    65  // Retrieve tries to fetch an object from the LES network.
    66  // If the network retrieval was successful, it stores the object in local db.
    67  func (self *LesOdr) Retrieve(ctx context.Context, req light.OdrRequest) (err error) {
    68  	lreq := LesRequest(req)
    69  
    70  	reqID := genReqID()
    71  	rq := &distReq{
    72  		getCost: func(dp distPeer) uint64 {
    73  			return lreq.GetCost(dp.(*peer))
    74  		},
    75  		canSend: func(dp distPeer) bool {
    76  			p := dp.(*peer)
    77  			return lreq.CanSend(p)
    78  		},
    79  		request: func(dp distPeer) func() {
    80  			p := dp.(*peer)
    81  			cost := lreq.GetCost(p)
    82  			p.fcServer.QueueRequest(reqID, cost)
    83  			return func() { lreq.Request(reqID, p) }
    84  		},
    85  	}
    86  
    87  	if err = self.retriever.retrieve(ctx, reqID, rq, func(p distPeer, msg *Msg) error { return lreq.Validate(self.db, msg) }); err == nil {
    88  		// retrieved from network, store in db
    89  		req.StoreResult(self.db)
    90  	} else {
    91  		log.Debug("Failed to retrieve data from network", "err", err)
    92  	}
    93  	return
    94  }