backend.go

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//版权所有2016 Go Ethereum作者
//此文件是Go以太坊库的一部分。
//
//Go-Ethereum库是免费软件：您可以重新分发它和/或修改
//根据GNU发布的较低通用公共许可证的条款
//自由软件基金会，或者许可证的第3版，或者
//（由您选择）任何更高版本。
//
//Go以太坊图书馆的发行目的是希望它会有用，
//但没有任何保证；甚至没有
//适销性或特定用途的适用性。见
//GNU较低的通用公共许可证，了解更多详细信息。
//
//你应该收到一份GNU较低级别的公共许可证副本
//以及Go以太坊图书馆。如果没有，请参见<http://www.gnu.org/licenses/>。

//包les实现轻以太坊子协议。
package les

import (
	"fmt"
	"sync"
	"time"

	"github.com/ethereum/go-ethereum/accounts"
	"github.com/ethereum/go-ethereum/common"
	"github.com/ethereum/go-ethereum/common/hexutil"
	"github.com/ethereum/go-ethereum/consensus"
	"github.com/ethereum/go-ethereum/core"
	"github.com/ethereum/go-ethereum/core/bloombits"
	"github.com/ethereum/go-ethereum/core/rawdb"
	"github.com/ethereum/go-ethereum/core/types"
	"github.com/ethereum/go-ethereum/eth"
	"github.com/ethereum/go-ethereum/eth/downloader"
	"github.com/ethereum/go-ethereum/eth/filters"
	"github.com/ethereum/go-ethereum/eth/gasprice"
	"github.com/ethereum/go-ethereum/event"
	"github.com/ethereum/go-ethereum/internal/ethapi"
	"github.com/ethereum/go-ethereum/light"
	"github.com/ethereum/go-ethereum/log"
	"github.com/ethereum/go-ethereum/node"
	"github.com/ethereum/go-ethereum/p2p"
	"github.com/ethereum/go-ethereum/consensus/dpos"
	"github.com/ethereum/go-ethereum/p2p/discv5"
	"github.com/ethereum/go-ethereum/params"
	rpc "github.com/ethereum/go-ethereum/rpc"
)

type LightEthereum struct {
	lesCommons

	odr         *LesOdr
	relay       *LesTxRelay
	chainConfig *params.ChainConfig
//关闭服务的通道
	shutdownChan chan bool

//处理程序
	peers      *peerSet
	txPool     *light.TxPool
	blockchain *light.LightChain
	serverPool *serverPool
	reqDist    *requestDistributor
	retriever  *retrieveManager

bloomRequests chan chan *bloombits.Retrieval //接收Bloom数据检索请求的通道
	bloomIndexer  *core.ChainIndexer

	ApiBackend *LesApiBackend

	eventMux       *event.TypeMux
	engine         consensus.Engine
	accountManager *accounts.Manager

	networkId     uint64
	netRPCService *ethapi.PublicNetAPI

	wg sync.WaitGroup
}

func New(ctx *node.ServiceContext, config *eth.Config) (*LightEthereum, error) {
	chainDb, err := eth.CreateDB(ctx, config, "lightchaindata")
	if err != nil {
		return nil, err
	}
	chainConfig, genesisHash, genesisErr := core.SetupGenesisBlock(chainDb, config.Genesis)
	if _, isCompat := genesisErr.(*params.ConfigCompatError); genesisErr != nil && !isCompat {
		return nil, genesisErr
	}
	log.Info("Initialised chain configuration", "config", chainConfig)

	peers := newPeerSet()
	quitSync := make(chan struct{})

	leth := &LightEthereum{
		lesCommons: lesCommons{
			chainDb: chainDb,
			config:  config,
		},
		chainConfig:    chainConfig,
		eventMux:       ctx.EventMux,
		peers:          peers,
		reqDist:        newRequestDistributor(peers, quitSync),
		accountManager: ctx.AccountManager,
		engine:           dpos.New(chainConfig.Dpos, chainDb),
		shutdownChan:   make(chan bool),
		networkId:      config.NetworkId,
		bloomRequests:  make(chan chan *bloombits.Retrieval),
		bloomIndexer:   eth.NewBloomIndexer(chainDb, light.BloomTrieFrequency, light.HelperTrieConfirmations),
	}

	leth.relay = NewLesTxRelay(peers, leth.reqDist)
	leth.serverPool = newServerPool(chainDb, quitSync, &leth.wg)
	leth.retriever = newRetrieveManager(peers, leth.reqDist, leth.serverPool)

	leth.odr = NewLesOdr(chainDb, leth.retriever)
	leth.chtIndexer = light.NewChtIndexer(chainDb, true, leth.odr)
	leth.bloomTrieIndexer = light.NewBloomTrieIndexer(chainDb, true, leth.odr)
	leth.odr.SetIndexers(leth.chtIndexer, leth.bloomTrieIndexer, leth.bloomIndexer)

//注意：newlightchain添加了受信任的检查点，因此它需要具有
//索引器已设置，但尚未启动
	if leth.blockchain, err = light.NewLightChain(leth.odr, leth.chainConfig, leth.engine); err != nil {
		return nil, err
	}
//注意：AddChildIndexer启动子级的更新过程
	leth.bloomIndexer.AddChildIndexer(leth.bloomTrieIndexer)
	leth.chtIndexer.Start(leth.blockchain)
	leth.bloomIndexer.Start(leth.blockchain)

//在不兼容的配置升级时倒带链。
	if compat, ok := genesisErr.(*params.ConfigCompatError); ok {
		log.Warn("Rewinding chain to upgrade configuration", "err", compat)
		leth.blockchain.SetHead(compat.RewindTo)
		rawdb.WriteChainConfig(chainDb, genesisHash, chainConfig)
	}

	leth.txPool = light.NewTxPool(leth.chainConfig, leth.blockchain, leth.relay)
	if leth.protocolManager, err = NewProtocolManager(leth.chainConfig, true, config.NetworkId, leth.eventMux, leth.engine, leth.peers, leth.blockchain, nil, chainDb, leth.odr, leth.relay, leth.serverPool, quitSync, &leth.wg); err != nil {
		return nil, err
	}
	leth.ApiBackend = &LesApiBackend{leth, nil}
	gpoParams := config.GPO
	if gpoParams.Default == nil {
		gpoParams.Default = config.MinerGasPrice
	}
	leth.ApiBackend.gpo = gasprice.NewOracle(leth.ApiBackend, gpoParams)
	return leth, nil
}

func lesTopic(genesisHash common.Hash, protocolVersion uint) discv5.Topic {
	var name string
	switch protocolVersion {
	case lpv1:
		name = "LES"
	case lpv2:
		name = "LES2"
	default:
		panic(nil)
	}
	return discv5.Topic(name + "@" + common.Bytes2Hex(genesisHash.Bytes()[0:8]))
}

type LightDummyAPI struct{}

//CoinBase是采矿奖励将发送到的地址
func (s *LightDummyAPI) Coinbase() (common.Address, error) {
	return common.Address{}, fmt.Errorf("not supported")
}

//hashRate返回pow hashRate
func (s *LightDummyAPI) Hashrate() hexutil.Uint {
	return 0
}

//挖掘返回当前是否正在挖掘此节点的指示。
func (s *LightDummyAPI) Mining() bool {
	return false
}

//API返回以太坊包提供的RPC服务集合。
//注意，其中一些服务可能需要转移到其他地方。
func (s *LightEthereum) APIs() []rpc.API {
	return append(ethapi.GetAPIs(s.ApiBackend), []rpc.API{
		{
			Namespace: "eth",
			Version:   "1.0",
			Service:   &LightDummyAPI{},
			Public:    true,
		}, {
			Namespace: "eth",
			Version:   "1.0",
			Service:   downloader.NewPublicDownloaderAPI(s.protocolManager.downloader, s.eventMux),
			Public:    true,
		}, {
			Namespace: "eth",
			Version:   "1.0",
			Service:   filters.NewPublicFilterAPI(s.ApiBackend, true),
			Public:    true,
		}, {
			Namespace: "net",
			Version:   "1.0",
			Service:   s.netRPCService,
			Public:    true,
		},
	}...)
}

func (s *LightEthereum) ResetWithGenesisBlock(gb *types.Block) {
	s.blockchain.ResetWithGenesisBlock(gb)
}

func (s *LightEthereum) BlockChain() *light.LightChain      { return s.blockchain }
func (s *LightEthereum) TxPool() *light.TxPool              { return s.txPool }
func (s *LightEthereum) Engine() consensus.Engine           { return s.engine }
func (s *LightEthereum) LesVersion() int                    { return int(ClientProtocolVersions[0]) }
func (s *LightEthereum) Downloader() *downloader.Downloader { return s.protocolManager.downloader }
func (s *LightEthereum) EventMux() *event.TypeMux           { return s.eventMux }

//协议实现node.service，返回所有当前配置的
//要启动的网络协议。
func (s *LightEthereum) Protocols() []p2p.Protocol {
	return s.makeProtocols(ClientProtocolVersions)
}

//start实现node.service，启动
//以太坊协议实现。
func (s *LightEthereum) Start(srvr *p2p.Server) error {
	s.startBloomHandlers()
	log.Warn("Light client mode is an experimental feature")
	s.netRPCService = ethapi.NewPublicNetAPI(srvr, s.networkId)
//客户端正在搜索列表中的第一个公告协议
	protocolVersion := AdvertiseProtocolVersions[0]
	s.serverPool.start(srvr, lesTopic(s.blockchain.Genesis().Hash(), protocolVersion))
	s.protocolManager.Start(s.config.LightPeers)
	return nil
}

//停止实现node.service，终止由
//以太坊协议。
func (s *LightEthereum) Stop() error {
	s.odr.Stop()
	s.bloomIndexer.Close()
	s.chtIndexer.Close()
	s.blockchain.Stop()
	s.protocolManager.Stop()
	s.txPool.Stop()
	s.engine.Close()

	s.eventMux.Stop()

	time.Sleep(time.Millisecond * 200)
	s.chainDb.Close()
	close(s.shutdownChan)

	return nil
}