Explicit type check for backend (ethereum#27)

cmd/geth/main.go

@@ -19,6 +19,7 @@ package main
 
 import (
 	"fmt"
+	"github.com/ethereum/go-ethereum/eth"
 	"math"
 	"os"
 	godebug "runtime/debug"
@@ -376,7 +377,6 @@ func startNode(ctx *cli.Context, stack *node.Node, backend ethapi.Backend) {
 	if err != nil {
 		utils.Fatalf("Failed to attach to self: %v", err)
 	}
-
 	ethClient := ethclient.NewClient(rpcClient)
 
 	go func() {
@@ -442,23 +442,24 @@ func startNode(ctx *cli.Context, stack *node.Node, backend ethapi.Backend) {
 		if ctx.GlobalString(utils.SyncModeFlag.Name) == "light" {
 			utils.Fatalf("Light clients do not support mining")
 		}
+		ethBackend, ok := backend.(*eth.EthAPIBackend)
+		if !ok {
+			utils.Fatalf("Ethereum service not running: %v", err)
+		}
+
 		// Set the gas price to the limits from the CLI and start mining
 		gasprice := utils.GlobalBig(ctx, utils.MinerGasPriceFlag.Name)
 		if ctx.GlobalIsSet(utils.LegacyMinerGasPriceFlag.Name) && !ctx.GlobalIsSet(utils.MinerGasPriceFlag.Name) {
 			gasprice = utils.GlobalBig(ctx, utils.LegacyMinerGasPriceFlag.Name)
 		}
-		txpool := backend.TxPool()
-		if txpool == nil {
-			utils.Fatalf("Ethereum service not running: %v", err)
-		}
-		txpool.SetGasPrice(gasprice)
-
+		ethBackend.TxPool().SetGasPrice(gasprice)
+		// start mining
 		threads := ctx.GlobalInt(utils.MinerThreadsFlag.Name)
 		if ctx.GlobalIsSet(utils.LegacyMinerThreadsFlag.Name) && !ctx.GlobalIsSet(utils.MinerThreadsFlag.Name) {
 			threads = ctx.GlobalInt(utils.LegacyMinerThreadsFlag.Name)
 			log.Warn("The flag --minerthreads is deprecated and will be removed in the future, please use --miner.threads")
 		}
-		if err := backend.StartMining(threads); err != nil {
+		if err := ethBackend.StartMining(threads); err != nil {
 			utils.Fatalf("Failed to start mining: %v", err)
 		}
 	}

eth/api_backend.go

@@ -318,10 +318,6 @@ func (b *EthAPIBackend) Engine() consensus.Engine {
 	return b.eth.engine
 }
 
-func (b *EthAPIBackend) GetBlockByNumber(ctx context.Context, number uint64) (*types.Block, error) {
-	return b.eth.blockchain.GetBlockByNumber(number), nil
-}
-
 func (b *EthAPIBackend) CurrentHeader() *types.Header {
 	return b.eth.blockchain.CurrentHeader()
 }

ethstats/ethstats.go

@@ -22,6 +22,10 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
+	"github.com/ethereum/go-ethereum/eth/downloader"
+	"github.com/ethereum/go-ethereum/event"
+	"github.com/ethereum/go-ethereum/miner"
+	"github.com/ethereum/go-ethereum/rpc"
 	"math/big"
 	"net/http"
 	"regexp"
@@ -36,7 +40,6 @@ import (
 	"github.com/ethereum/go-ethereum/core"
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/eth"
-	"github.com/ethereum/go-ethereum/internal/ethapi"
 	"github.com/ethereum/go-ethereum/les"
 	"github.com/ethereum/go-ethereum/log"
 	"github.com/ethereum/go-ethereum/node"
@@ -56,14 +59,29 @@ const (
 	chainHeadChanSize = 10
 )
 
-// Backend encompasses the backend behaviors needed for the ethstats service.
-type Backend ethapi.Backend
+type backend interface{
+	SubscribeChainHeadEvent(ch chan<- core.ChainHeadEvent) event.Subscription
+	SubscribeNewTxsEvent(ch chan<- core.NewTxsEvent) event.Subscription
+	CurrentHeader() *types.Header
+	HeaderByNumber(ctx context.Context, number rpc.BlockNumber) (*types.Header, error)
+	GetTd(blockHash common.Hash) *big.Int
+	Stats() (pending int, queued int)
+	Downloader() *downloader.Downloader
+}
+
+type fullNodeBackend interface{
+	backend
+	Miner() *miner.Miner
+	BlockByNumber(ctx context.Context, number rpc.BlockNumber) (*types.Block, error)
+	CurrentBlock() *types.Block
+	SuggestPrice(ctx context.Context) (*big.Int, error)
+}
 
 // Service implements an Ethereum netstats reporting daemon that pushes local
 // chain statistics up to a monitoring server.
 type Service struct {
 	server  *p2p.Server // Peer-to-peer server to retrieve networking infos
-	backend Backend
+	backend backend
 	engine  consensus.Engine // Consensus engine to retrieve variadic block fields
 
 	node string // Name of the node to display on the monitoring page
@@ -75,7 +93,7 @@ type Service struct {
 }
 
 // New returns a monitoring service ready for stats reporting.
-func New(node *node.Node, backend Backend, engine consensus.Engine, url string) error {
+func New(node *node.Node, backend backend, engine consensus.Engine, url string) error {
 	// Parse the netstats connection url
 	re := regexp.MustCompile("([^:@]*)(:([^@]*))?@(.+)")
 	parts := re.FindStringSubmatch(url)
@@ -530,18 +548,30 @@ func (s *Service) assembleBlockStats(block *types.Block) *blockStats {
 		uncles []*types.Header
 	)
 
-	// Full nodes have all needed information available
-	if block == nil {
-		block = s.backend.CurrentBlock()
-	}
-	header = block.Header()
-	td = s.backend.GetTd(header.Hash()) // TODO is it okay to just call `GetTD` with just the hash and not number?
+	// check if backend is a full node
+	fullBackend, ok := s.backend.(fullNodeBackend)
+	if ok {
+		if block == nil {
+			block = fullBackend.CurrentBlock()
+		}
+		header = block.Header()
+		td = fullBackend.GetTd(header.Hash())
 
-	txs = make([]txStats, len(block.Transactions()))
-	for i, tx := range block.Transactions() {
-		txs[i].Hash = tx.Hash()
+		txs = make([]txStats, len(block.Transactions()))
+		for i, tx := range block.Transactions() {
+			txs[i].Hash = tx.Hash()
+		}
+		uncles = block.Uncles()
+	} else {
+		// Light nodes would need on-demand lookups for transactions/uncles, skip
+		if block != nil {
+			header = block.Header()
+		} else {
+			header = s.backend.CurrentHeader()
+		}
+		td = s.backend.GetTd(header.Hash())
+		txs = []txStats{}
 	}
-	uncles = block.Uncles()
 
 	// Assemble and return the block stats
 	author, _ := s.engine.Author(header)
@@ -585,12 +615,16 @@ func (s *Service) reportHistory(conn *websocket.Conn, list []uint64) error {
 	// Gather the batch of blocks to report
 	history := make([]*blockStats, len(indexes))
 	for i, number := range indexes {
+		fullBackend, ok := s.backend.(fullNodeBackend)
 		// Retrieve the next block if it's known to us
-		block, err := s.backend.GetBlockByNumber(context.Background(), number)
-		if err != nil {
-			return err
+		var block *types.Block
+		if ok {
+			block, _ = fullBackend.BlockByNumber(context.Background(), rpc.BlockNumber(number)) // TODO ignore error here ?
+		} else {
+			if header, _ := s.backend.HeaderByNumber(context.Background(), rpc.BlockNumber(number)); header != nil {
+				block = types.NewBlockWithHeader(header)
+			}
 		}
-
 		// If we do have the block, add to the history and continue
 		if block != nil {
 			history[len(history)-1-i] = s.assembleBlockStats(block)
@@ -652,27 +686,31 @@ type nodeStats struct {
 	Uptime   int  `json:"uptime"`
 }
 
-// reportPending retrieves various stats about the node at the networking and
+// reportStats retrieves various stats about the node at the networking and
 // mining layer and reports it to the stats server.
 func (s *Service) reportStats(conn *websocket.Conn) error {
 	// Gather the syncing and mining infos from the local miner instance
 	var (
 		mining   bool
 		hashrate int
+		syncing bool
+		gasprice int
 	)
+	// check if backend is a full node
+	fullBackend, ok := s.backend.(fullNodeBackend)
+	if ok {
+		mining = fullBackend.Miner().Mining()
+		hashrate = int(fullBackend.Miner().HashRate())
 
-	mine := s.backend.Miner()
-	if mine != nil {
-		mining = mine.Mining()
-		hashrate = int(s.backend.Miner().HashRate())
-	}
-
-	sync := s.backend.Downloader().Progress()
-	syncing := s.backend.CurrentHeader().Number.Uint64() >= sync.HighestBlock
-
-	price, _ := s.backend.SuggestPrice(context.Background())
-	gasprice := int(price.Uint64())
+		sync := fullBackend.Downloader().Progress()
+		syncing = fullBackend.CurrentHeader().Number.Uint64() >= sync.HighestBlock
 
+		price, _ := fullBackend.SuggestPrice(context.Background())
+		gasprice = int(price.Uint64())
+	} else {
+		sync := s.backend.Downloader().Progress()
+		syncing = s.backend.CurrentHeader().Number.Uint64() >= sync.HighestBlock
+	}
 	// Assemble the node stats and send it to the server
 	log.Trace("Sending node details to ethstats")
 

go.sum

@@ -218,20 +218,15 @@ golang.org/x/time v0.0.0-20190308202827-9d24e82272b4/go.mod h1:tRJNPiyCQ0inRvYxb
 golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
 gopkg.in/alecthomas/kingpin.v2 v2.2.6/go.mod h1:FMv+mEhP44yOT+4EoQTLFTRgOQ1FBLkstjWtayDeSgw=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
-gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127 h1:qIbj1fsPNlZgppZ+VLlY7N33q108Sa+fhmuc+sWQYwY=
 gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
-gopkg.in/fsnotify.v1 v1.4.7 h1:xOHLXZwVvI9hhs+cLKq5+I5onOuwQLhQwiu63xxlHs4=
 gopkg.in/fsnotify.v1 v1.4.7/go.mod h1:Tz8NjZHkW78fSQdbUxIjBTcgA1z1m8ZHf0WmKUhAMys=
-gopkg.in/natefinch/npipe.v2 v2.0.0-20160621034901-c1b8fa8bdcce h1:+JknDZhAj8YMt7GC73Ei8pv4MzjDUNPHgQWJdtMAaDU=
 gopkg.in/natefinch/npipe.v2 v2.0.0-20160621034901-c1b8fa8bdcce/go.mod h1:5AcXVHNjg+BDxry382+8OKon8SEWiKktQR07RKPsv1c=
 gopkg.in/olebedev/go-duktape.v3 v3.0.0-20200619000410-60c24ae608a6 h1:a6cXbcDDUkSBlpnkWV1bJ+vv3mOgQEltEJ2rPxroVu0=
 gopkg.in/olebedev/go-duktape.v3 v3.0.0-20200619000410-60c24ae608a6/go.mod h1:uAJfkITjFhyEEuUfm7bsmCZRbW5WRq8s9EY8HZ6hCns=
-gopkg.in/tomb.v1 v1.0.0-20141024135613-dd632973f1e7 h1:uRGJdciOHaEIrze2W8Q3AKkepLTh2hOroT7a+7czfdQ=
 gopkg.in/tomb.v1 v1.0.0-20141024135613-dd632973f1e7/go.mod h1:dt/ZhP58zS4L8KSrWDmTeBkI65Dw0HsyUHuEVlX15mw=
 gopkg.in/urfave/cli.v1 v1.20.0 h1:NdAVW6RYxDif9DhDHaAortIu956m2c0v+09AZBPTbE0=
 gopkg.in/urfave/cli.v1 v1.20.0/go.mod h1:vuBzUtMdQeixQj8LVd+/98pzhxNGQoyuPBlsXHOQNO0=
 gopkg.in/yaml.v2 v2.2.1/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
 gopkg.in/yaml.v2 v2.2.2 h1:ZCJp+EgiOT7lHqUV2J862kp8Qj64Jo6az82+3Td9dZw=
 gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
-gotest.tools v2.2.0+incompatible h1:VsBPFP1AI068pPrMxtb/S8Zkgf9xEmTLJjfM+P5UIEo=
 gotest.tools v2.2.0+incompatible/go.mod h1:DsYFclhRJ6vuDpmuTbkuFWG+y2sxOXAzmJt81HFBacw=

internal/ethapi/backend.go

@@ -32,7 +32,6 @@ import (
 	"github.com/ethereum/go-ethereum/eth/downloader"
 	"github.com/ethereum/go-ethereum/ethdb"
 	"github.com/ethereum/go-ethereum/event"
-	"github.com/ethereum/go-ethereum/miner"
 	"github.com/ethereum/go-ethereum/params"
 	"github.com/ethereum/go-ethereum/rpc"
 )
@@ -47,8 +46,8 @@ type Backend interface {
 	ChainDb() ethdb.Database
 	AccountManager() *accounts.Manager
 	ExtRPCEnabled() bool
+	RPCGasCap() uint64  // global gas cap for eth_call over rpc: DoS protection
 	RPCTxFeeCap() float64 // global tx fee cap for all transaction related APIs
-	RPCGasCap() uint64    // global gas cap for eth_call over rpc: DoS protection
 
 	// Blockchain API
 	SetHead(number uint64)
@@ -60,7 +59,6 @@ type Backend interface {
 	BlockByNumber(ctx context.Context, number rpc.BlockNumber) (*types.Block, error)
 	BlockByHash(ctx context.Context, hash common.Hash) (*types.Block, error)
 	BlockByNumberOrHash(ctx context.Context, blockNrOrHash rpc.BlockNumberOrHash) (*types.Block, error)
-	GetBlockByNumber(ctx context.Context, number uint64) (*types.Block, error)
 	StateAndHeaderByNumber(ctx context.Context, number rpc.BlockNumber) (*state.StateDB, *types.Header, error)
 	StateAndHeaderByNumberOrHash(ctx context.Context, blockNrOrHash rpc.BlockNumberOrHash) (*state.StateDB, *types.Header, error)
 	GetReceipts(ctx context.Context, hash common.Hash) (types.Receipts, error)
@@ -78,13 +76,8 @@ type Backend interface {
 	GetPoolNonce(ctx context.Context, addr common.Address) (uint64, error)
 	Stats() (pending int, queued int)
 	TxPoolContent() (map[common.Address]types.Transactions, map[common.Address]types.Transactions)
-	TxPool() *core.TxPool
 	SubscribeNewTxsEvent(chan<- core.NewTxsEvent) event.Subscription
 
-	// Mining API
-	Miner() *miner.Miner
-	StartMining(threads int) error
-
 	// Filter API
 	BloomStatus() (uint64, uint64)
 	GetLogs(ctx context.Context, blockHash common.Hash) ([][]*types.Log, error)

les/api_backend.go

@@ -19,7 +19,6 @@ package les
 import (
 	"context"
 	"errors"
-	"fmt"
 	"math/big"
 
 	"github.com/ethereum/go-ethereum/accounts"
@@ -36,7 +35,6 @@ import (
 	"github.com/ethereum/go-ethereum/ethdb"
 	"github.com/ethereum/go-ethereum/event"
 	"github.com/ethereum/go-ethereum/light"
-	"github.com/ethereum/go-ethereum/miner"
 	"github.com/ethereum/go-ethereum/params"
 	"github.com/ethereum/go-ethereum/rpc"
 )
@@ -290,23 +288,6 @@ func (b *LesApiBackend) Engine() consensus.Engine {
 	return b.eth.engine
 }
 
-func (b *LesApiBackend) GetBlockByNumber(ctx context.Context, number uint64) (*types.Block, error) {
-	header := b.eth.blockchain.GetHeaderByNumber(number)
-	return types.NewBlockWithHeader(header), nil // TODO is this okay?
-}
-
 func (b *LesApiBackend) CurrentHeader() *types.Header {
 	return b.eth.blockchain.CurrentHeader()
 }
-
-func (b *LesApiBackend) Miner() *miner.Miner {
-	return nil
-}
-
-func (b *LesApiBackend) StartMining(threads int) error {
-	return fmt.Errorf("Light clients do not support mining") // TODO is this okay?
-}
-
-func (b *LesApiBackend) TxPool() *core.TxPool {
-	return nil // TODO is this okay?
-}