core, consensus: pluggable consensus engines (#3817)

This commit adds pluggable consensus engines to go-ethereum. In short, it
introduces a generic consensus interface, and refactors the entire codebase to
use this interface.

7 files changed, 100 insertions, 89 deletions

diff --git a/eth/api.go b/eth/api.go
index b64153fd7..58ae27df2 100644
--- a/eth/api.go
+++ b/eth/api.go
@@ -26,7 +26,6 @@ import (
 	"io/ioutil"
 	"math/big"
 	"os"
-	"runtime"
 	"strings"
 	"time"
 
@@ -37,6 +36,7 @@ import (
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/core/vm"
 	"github.com/ethereum/go-ethereum/internal/ethapi"
+	"github.com/ethereum/go-ethereum/log"
 	"github.com/ethereum/go-ethereum/miner"
 	"github.com/ethereum/go-ethereum/params"
 	"github.com/ethereum/go-ethereum/rlp"
@@ -56,18 +56,18 @@ func NewPublicEthereumAPI(e *Ethereum) *PublicEthereumAPI {
 }
 
 // Etherbase is the address that mining rewards will be send to
-func (s *PublicEthereumAPI) Etherbase() (common.Address, error) {
-	return s.e.Etherbase()
+func (api *PublicEthereumAPI) Etherbase() (common.Address, error) {
+	return api.e.Etherbase()
 }
 
 // Coinbase is the address that mining rewards will be send to (alias for Etherbase)
-func (s *PublicEthereumAPI) Coinbase() (common.Address, error) {
-	return s.Etherbase()
+func (api *PublicEthereumAPI) Coinbase() (common.Address, error) {
+	return api.Etherbase()
 }
 
 // Hashrate returns the POW hashrate
-func (s *PublicEthereumAPI) Hashrate() hexutil.Uint64 {
-	return hexutil.Uint64(s.e.Miner().HashRate())
+func (api *PublicEthereumAPI) Hashrate() hexutil.Uint64 {
+	return hexutil.Uint64(api.e.Miner().HashRate())
 }
 
 // PublicMinerAPI provides an API to control the miner.
@@ -79,34 +79,34 @@ type PublicMinerAPI struct {
 
 // NewPublicMinerAPI create a new PublicMinerAPI instance.
 func NewPublicMinerAPI(e *Ethereum) *PublicMinerAPI {
-	agent := miner.NewRemoteAgent(e.Pow())
+	agent := miner.NewRemoteAgent(e.BlockChain(), e.Engine())
 	e.Miner().Register(agent)
 
 	return &PublicMinerAPI{e, agent}
 }
 
 // Mining returns an indication if this node is currently mining.
-func (s *PublicMinerAPI) Mining() bool {
-	return s.e.IsMining()
+func (api *PublicMinerAPI) Mining() bool {
+	return api.e.IsMining()
 }
 
 // SubmitWork can be used by external miner to submit their POW solution. It returns an indication if the work was
 // accepted. Note, this is not an indication if the provided work was valid!
-func (s *PublicMinerAPI) SubmitWork(nonce types.BlockNonce, solution, digest common.Hash) bool {
-	return s.agent.SubmitWork(nonce, digest, solution)
+func (api *PublicMinerAPI) SubmitWork(nonce types.BlockNonce, solution, digest common.Hash) bool {
+	return api.agent.SubmitWork(nonce, digest, solution)
 }
 
 // GetWork returns a work package for external miner. The work package consists of 3 strings
 // result[0], 32 bytes hex encoded current block header pow-hash
 // result[1], 32 bytes hex encoded seed hash used for DAG
 // result[2], 32 bytes hex encoded boundary condition ("target"), 2^256/difficulty
-func (s *PublicMinerAPI) GetWork() ([3]string, error) {
-	if !s.e.IsMining() {
-		if err := s.e.StartMining(0); err != nil {
+func (api *PublicMinerAPI) GetWork() ([3]string, error) {
+	if !api.e.IsMining() {
+		if err := api.e.StartMining(); err != nil {
 			return [3]string{}, err
 		}
 	}
-	work, err := s.agent.GetWork()
+	work, err := api.agent.GetWork()
 	if err != nil {
 		return work, fmt.Errorf("mining not ready: %v", err)
 	}
@@ -116,8 +116,8 @@ func (s *PublicMinerAPI) GetWork() ([3]string, error) {
 // SubmitHashrate can be used for remote miners to submit their hash rate. This enables the node to report the combined
 // hash rate of all miners which submit work through this node. It accepts the miner hash rate and an identifier which
 // must be unique between nodes.
-func (s *PublicMinerAPI) SubmitHashrate(hashrate hexutil.Uint64, id common.Hash) bool {
-	s.agent.SubmitHashrate(id, uint64(hashrate))
+func (api *PublicMinerAPI) SubmitHashrate(hashrate hexutil.Uint64, id common.Hash) bool {
+	api.agent.SubmitHashrate(id, uint64(hashrate))
 	return true
 }
 
@@ -132,47 +132,59 @@ func NewPrivateMinerAPI(e *Ethereum) *PrivateMinerAPI {
 	return &PrivateMinerAPI{e: e}
 }
 
-// Start the miner with the given number of threads. If threads is nil the number of
-// workers started is equal to the number of logical CPU's that are usable by this process.
-func (s *PrivateMinerAPI) Start(threads *int) (bool, error) {
-	var err error
-	if threads == nil {
-		err = s.e.StartMining(runtime.NumCPU())
-	} else {
-		err = s.e.StartMining(*threads)
+// Start the miner with the given number of threads. If threads is nil the number
+// of workers started is equal to the number of logical CPUs that are usable by
+// this process. If mining is already running, this method adjust the number of
+// threads allowed to use.
+func (api *PrivateMinerAPI) Start(threads *int) error {
+	// Set the number of threads if the seal engine supports it
+	if threads != nil {
+		type threaded interface {
+			SetThreads(threads int)
+		}
+		if th, ok := api.e.engine.(threaded); ok {
+			log.Info("Updated mining threads", "threads", *threads)
+			th.SetThreads(*threads)
+		} else {
+			log.Warn("Current seal engine isn't threaded")
+		}
 	}
-	return err == nil, err
+	// Start the miner and return
+	if !api.e.IsMining() {
+		return api.e.StartMining()
+	}
+	return nil
 }
 
 // Stop the miner
-func (s *PrivateMinerAPI) Stop() bool {
-	s.e.StopMining()
+func (api *PrivateMinerAPI) Stop() bool {
+	api.e.StopMining()
 	return true
 }
 
 // SetExtra sets the extra data string that is included when this miner mines a block.
-func (s *PrivateMinerAPI) SetExtra(extra string) (bool, error) {
-	if err := s.e.Miner().SetExtra([]byte(extra)); err != nil {
+func (api *PrivateMinerAPI) SetExtra(extra string) (bool, error) {
+	if err := api.e.Miner().SetExtra([]byte(extra)); err != nil {
 		return false, err
 	}
 	return true, nil
 }
 
 // SetGasPrice sets the minimum accepted gas price for the miner.
-func (s *PrivateMinerAPI) SetGasPrice(gasPrice hexutil.Big) bool {
-	s.e.Miner().SetGasPrice((*big.Int)(&gasPrice))
+func (api *PrivateMinerAPI) SetGasPrice(gasPrice hexutil.Big) bool {
+	api.e.Miner().SetGasPrice((*big.Int)(&gasPrice))
 	return true
 }
 
 // SetEtherbase sets the etherbase of the miner
-func (s *PrivateMinerAPI) SetEtherbase(etherbase common.Address) bool {
-	s.e.SetEtherbase(etherbase)
+func (api *PrivateMinerAPI) SetEtherbase(etherbase common.Address) bool {
+	api.e.SetEtherbase(etherbase)
 	return true
 }
 
 // GetHashrate returns the current hashrate of the miner.
-func (s *PrivateMinerAPI) GetHashrate() uint64 {
-	return uint64(s.e.miner.HashRate())
+func (api *PrivateMinerAPI) GetHashrate() uint64 {
+	return uint64(api.e.miner.HashRate())
 }
 
 // PrivateAdminAPI is the collection of Etheruem full node-related APIs
@@ -321,7 +333,7 @@ type TraceArgs struct {
 	Timeout *string
 }
 
-// TraceBlock processes the given block's RLP but does not import the block in to
+// TraceBlock processes the given block'api RLP but does not import the block in to
 // the chain.
 func (api *PrivateDebugAPI) TraceBlock(blockRlp []byte, config *vm.LogConfig) BlockTraceResult {
 	var block types.Block
@@ -338,7 +350,7 @@ func (api *PrivateDebugAPI) TraceBlock(blockRlp []byte, config *vm.LogConfig) Bl
 	}
 }
 
-// TraceBlockFromFile loads the block's RLP from the given file name and attempts to
+// TraceBlockFromFile loads the block'api RLP from the given file name and attempts to
 // process it but does not import the block in to the chain.
 func (api *PrivateDebugAPI) TraceBlockFromFile(file string, config *vm.LogConfig) BlockTraceResult {
 	blockRlp, err := ioutil.ReadFile(file)
@@ -395,8 +407,7 @@ func (api *PrivateDebugAPI) traceBlock(block *types.Block, logConfig *vm.LogConf
 		Debug:  true,
 		Tracer: structLogger,
 	}
-
-	if err := core.ValidateHeader(api.config, blockchain.AuxValidator(), block.Header(), blockchain.GetHeader(block.ParentHash(), block.NumberU64()-1), true, false); err != nil {
+	if err := api.eth.engine.VerifyHeader(blockchain, block.Header(), true); err != nil {
 		return false, structLogger.StructLogs(), err
 	}
 	statedb, err := blockchain.StateAt(blockchain.GetBlock(block.ParentHash(), block.NumberU64()-1).Root())
diff --git a/eth/backend.go b/eth/backend.go
index b8df98976..af1d46a2c 100644
--- a/eth/backend.go
+++ b/eth/backend.go
@@ -22,10 +22,11 @@ import (
 	"math/big"
 	"regexp"
 	"sync"
-	"time"
 
 	"github.com/ethereum/go-ethereum/accounts"
 	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/consensus"
+	"github.com/ethereum/go-ethereum/consensus/ethash"
 	"github.com/ethereum/go-ethereum/core"
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/core/vm"
@@ -40,18 +41,9 @@ import (
 	"github.com/ethereum/go-ethereum/node"
 	"github.com/ethereum/go-ethereum/p2p"
 	"github.com/ethereum/go-ethereum/params"
-	"github.com/ethereum/go-ethereum/pow"
 	"github.com/ethereum/go-ethereum/rpc"
 )
 
-const (
-	epochLength    = 30000
-	ethashRevision = 23
-
-	autoDAGcheckInterval = 10 * time.Hour
-	autoDAGepochHeight   = epochLength / 2
-)
-
 var (
 	datadirInUseErrnos = map[uint]bool{11: true, 32: true, 35: true}
 	portInUseErrRE     = regexp.MustCompile("address already in use")
@@ -124,7 +116,7 @@ type Ethereum struct {
 	chainDb ethdb.Database // Block chain database
 
 	eventMux       *event.TypeMux
-	pow            pow.PoW
+	engine         consensus.Engine
 	accountManager *accounts.Manager
 
 	ApiBackend *EthApiBackend
@@ -163,7 +155,7 @@ func New(ctx *node.ServiceContext, config *Config) (*Ethereum, error) {
 		chainConfig:    chainConfig,
 		eventMux:       ctx.EventMux,
 		accountManager: ctx.AccountManager,
-		pow:            CreatePoW(ctx, config),
+		engine:         CreateConsensusEngine(ctx, config, chainConfig, chainDb),
 		shutdownChan:   make(chan bool),
 		stopDbUpgrade:  stopDbUpgrade,
 		netVersionId:   config.NetworkId,
@@ -186,7 +178,7 @@ func New(ctx *node.ServiceContext, config *Config) (*Ethereum, error) {
 	}
 
 	vmConfig := vm.Config{EnablePreimageRecording: config.EnablePreimageRecording}
-	eth.blockchain, err = core.NewBlockChain(chainDb, eth.chainConfig, eth.pow, eth.eventMux, vmConfig)
+	eth.blockchain, err = core.NewBlockChain(chainDb, eth.chainConfig, eth.engine, eth.eventMux, vmConfig)
 	if err != nil {
 		return nil, err
 	}
@@ -211,10 +203,11 @@ func New(ctx *node.ServiceContext, config *Config) (*Ethereum, error) {
 		}
 	}
 
-	if eth.protocolManager, err = NewProtocolManager(eth.chainConfig, config.FastSync, config.NetworkId, maxPeers, eth.eventMux, eth.txPool, eth.pow, eth.blockchain, chainDb); err != nil {
+	if eth.protocolManager, err = NewProtocolManager(eth.chainConfig, config.FastSync, config.NetworkId, maxPeers, eth.eventMux, eth.txPool, eth.engine, eth.blockchain, chainDb); err != nil {
 		return nil, err
 	}
-	eth.miner = miner.New(eth, eth.chainConfig, eth.EventMux(), eth.pow)
+
+	eth.miner = miner.New(eth, eth.chainConfig, eth.EventMux(), eth.engine)
 	eth.miner.SetGasPrice(config.GasPrice)
 	eth.miner.SetExtra(config.ExtraData)
 
@@ -241,20 +234,20 @@ func CreateDB(ctx *node.ServiceContext, config *Config, name string) (ethdb.Data
 	return db, err
 }
 
-// CreatePoW creates the required type of PoW instance for an Ethereum service
-func CreatePoW(ctx *node.ServiceContext, config *Config) pow.PoW {
+// CreateConsensusEngine creates the required type of consensus engine instance for an Ethereum service
+func CreateConsensusEngine(ctx *node.ServiceContext, config *Config, chainConfig *params.ChainConfig, db ethdb.Database) consensus.Engine {
 	switch {
 	case config.PowFake:
 		log.Warn("Ethash used in fake mode")
-		return pow.FakePow{}
+		return ethash.NewFaker()
 	case config.PowTest:
 		log.Warn("Ethash used in test mode")
-		return pow.NewTestEthash()
+		return ethash.NewTester()
 	case config.PowShared:
 		log.Warn("Ethash used in shared mode")
-		return pow.NewSharedEthash()
+		return ethash.NewShared()
 	default:
-		return pow.NewFullEthash(ctx.ResolvePath(config.EthashCacheDir), config.EthashCachesInMem, config.EthashCachesOnDisk,
+		return ethash.New(ctx.ResolvePath(config.EthashCacheDir), config.EthashCachesInMem, config.EthashCachesOnDisk,
 			config.EthashDatasetDir, config.EthashDatasetsInMem, config.EthashDatasetsOnDisk)
 	}
 }
@@ -262,7 +255,13 @@ func CreatePoW(ctx *node.ServiceContext, config *Config) pow.PoW {
 // APIs returns the collection of RPC services the ethereum package offers.
 // NOTE, some of these services probably need to be moved to somewhere else.
 func (s *Ethereum) APIs() []rpc.API {
-	return append(ethapi.GetAPIs(s.ApiBackend, s.solcPath), []rpc.API{
+	apis := ethapi.GetAPIs(s.ApiBackend, s.solcPath)
+
+	// Append any APIs exposed explicitly by the consensus engine
+	apis = append(apis, s.engine.APIs(s.BlockChain())...)
+
+	// Append all the local APIs and return
+	return append(apis, []rpc.API{
 		{
 			Namespace: "eth",
 			Version:   "1.0",
@@ -332,13 +331,13 @@ func (self *Ethereum) SetEtherbase(etherbase common.Address) {
 	self.miner.SetEtherbase(etherbase)
 }
 
-func (s *Ethereum) StartMining(threads int) error {
+func (s *Ethereum) StartMining() error {
 	eb, err := s.Etherbase()
 	if err != nil {
 		log.Error("Cannot start mining without etherbase", "err", err)
 		return fmt.Errorf("etherbase missing: %v", err)
 	}
-	go s.miner.Start(eb, threads)
+	go s.miner.Start(eb)
 	return nil
 }
 
@@ -350,7 +349,7 @@ func (s *Ethereum) AccountManager() *accounts.Manager  { return s.accountManager
 func (s *Ethereum) BlockChain() *core.BlockChain       { return s.blockchain }
 func (s *Ethereum) TxPool() *core.TxPool               { return s.txPool }
 func (s *Ethereum) EventMux() *event.TypeMux           { return s.eventMux }
-func (s *Ethereum) Pow() pow.PoW                       { return s.pow }
+func (s *Ethereum) Engine() consensus.Engine           { return s.engine }
 func (s *Ethereum) ChainDb() ethdb.Database            { return s.chainDb }
 func (s *Ethereum) IsListening() bool                  { return true } // Always listening
 func (s *Ethereum) EthVersion() int                    { return int(s.protocolManager.SubProtocols[0].Version) }
diff --git a/eth/fetcher/fetcher.go b/eth/fetcher/fetcher.go
index d82f4f3e6..64a991069 100644
--- a/eth/fetcher/fetcher.go
+++ b/eth/fetcher/fetcher.go
@@ -52,8 +52,8 @@ type headerRequesterFn func(common.Hash) error
 // bodyRequesterFn is a callback type for sending a body retrieval request.
 type bodyRequesterFn func([]common.Hash) error
 
-// blockValidatorFn is a callback type to verify a block's header for fast propagation.
-type blockValidatorFn func(block *types.Block, parent *types.Block) error
+// headerVerifierFn is a callback type to verify a block's header for fast propagation.
+type headerVerifierFn func(header *types.Header) error
 
 // blockBroadcasterFn is a callback type for broadcasting a block to connected peers.
 type blockBroadcasterFn func(block *types.Block, propagate bool)
@@ -129,7 +129,7 @@ type Fetcher struct {
 
 	// Callbacks
 	getBlock       blockRetrievalFn   // Retrieves a block from the local chain
-	validateBlock  blockValidatorFn   // Checks if a block's headers have a valid proof of work
+	verifyHeader   headerVerifierFn   // Checks if a block's headers have a valid proof of work
 	broadcastBlock blockBroadcasterFn // Broadcasts a block to connected peers
 	chainHeight    chainHeightFn      // Retrieves the current chain's height
 	insertChain    chainInsertFn      // Injects a batch of blocks into the chain
@@ -144,7 +144,7 @@ type Fetcher struct {
 }
 
 // New creates a block fetcher to retrieve blocks based on hash announcements.
-func New(getBlock blockRetrievalFn, validateBlock blockValidatorFn, broadcastBlock blockBroadcasterFn, chainHeight chainHeightFn, insertChain chainInsertFn, dropPeer peerDropFn) *Fetcher {
+func New(getBlock blockRetrievalFn, verifyHeader headerVerifierFn, broadcastBlock blockBroadcasterFn, chainHeight chainHeightFn, insertChain chainInsertFn, dropPeer peerDropFn) *Fetcher {
 	return &Fetcher{
 		notify:         make(chan *announce),
 		inject:         make(chan *inject),
@@ -162,7 +162,7 @@ func New(getBlock blockRetrievalFn, validateBlock blockValidatorFn, broadcastBlo
 		queues:         make(map[string]int),
 		queued:         make(map[common.Hash]*inject),
 		getBlock:       getBlock,
-		validateBlock:  validateBlock,
+		verifyHeader:   verifyHeader,
 		broadcastBlock: broadcastBlock,
 		chainHeight:    chainHeight,
 		insertChain:    insertChain,
@@ -648,7 +648,7 @@ func (f *Fetcher) insert(peer string, block *types.Block) {
 			return
 		}
 		// Quickly validate the header and propagate the block if it passes
-		switch err := f.validateBlock(block, parent); err {
+		switch err := f.verifyHeader(block.Header()); err {
 		case nil:
 			// All ok, quickly propagate to our peers
 			propBroadcastOutTimer.UpdateSince(block.ReceivedAt)
diff --git a/eth/fetcher/fetcher_test.go b/eth/fetcher/fetcher_test.go
index 7a94241c6..85d2f8645 100644
--- a/eth/fetcher/fetcher_test.go
+++ b/eth/fetcher/fetcher_test.go
@@ -91,7 +91,7 @@ func newTester() *fetcherTester {
 		blocks: map[common.Hash]*types.Block{genesis.Hash(): genesis},
 		drops:  make(map[string]bool),
 	}
-	tester.fetcher = New(tester.getBlock, tester.verifyBlock, tester.broadcastBlock, tester.chainHeight, tester.insertChain, tester.dropPeer)
+	tester.fetcher = New(tester.getBlock, tester.verifyHeader, tester.broadcastBlock, tester.chainHeight, tester.insertChain, tester.dropPeer)
 	tester.fetcher.Start()
 
 	return tester
@@ -105,8 +105,8 @@ func (f *fetcherTester) getBlock(hash common.Hash) *types.Block {
 	return f.blocks[hash]
 }
 
-// verifyBlock is a nop placeholder for the block header verification.
-func (f *fetcherTester) verifyBlock(block *types.Block, parent *types.Block) error {
+// verifyHeader is a nop placeholder for the block header verification.
+func (f *fetcherTester) verifyHeader(header *types.Header) error {
 	return nil
 }
 
diff --git a/eth/handler.go b/eth/handler.go
index ade8f7719..445272060 100644
--- a/eth/handler.go
+++ b/eth/handler.go
@@ -27,6 +27,8 @@ import (
 	"time"
 
 	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/consensus"
+	"github.com/ethereum/go-ethereum/consensus/misc"
 	"github.com/ethereum/go-ethereum/core"
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/eth/downloader"
@@ -37,7 +39,6 @@ import (
 	"github.com/ethereum/go-ethereum/p2p"
 	"github.com/ethereum/go-ethereum/p2p/discover"
 	"github.com/ethereum/go-ethereum/params"
-	"github.com/ethereum/go-ethereum/pow"
 	"github.com/ethereum/go-ethereum/rlp"
 )
 
@@ -97,7 +98,7 @@ type ProtocolManager struct {
 
 // NewProtocolManager returns a new ethereum sub protocol manager. The Ethereum sub protocol manages peers capable
 // with the ethereum network.
-func NewProtocolManager(config *params.ChainConfig, fastSync bool, networkId int, maxPeers int, mux *event.TypeMux, txpool txPool, pow pow.PoW, blockchain *core.BlockChain, chaindb ethdb.Database) (*ProtocolManager, error) {
+func NewProtocolManager(config *params.ChainConfig, fastSync bool, networkId int, maxPeers int, mux *event.TypeMux, txpool txPool, engine consensus.Engine, blockchain *core.BlockChain, chaindb ethdb.Database) (*ProtocolManager, error) {
 	// Create the protocol manager with the base fields
 	manager := &ProtocolManager{
 		networkId:   networkId,
@@ -165,8 +166,8 @@ func NewProtocolManager(config *params.ChainConfig, fastSync bool, networkId int
 		blockchain.GetTdByHash, blockchain.InsertHeaderChain, manager.insertChain, blockchain.InsertReceiptChain, blockchain.Rollback,
 		manager.removePeer)
 
-	validator := func(block *types.Block, parent *types.Block) error {
-		return core.ValidateHeader(config, pow, block.Header(), parent.Header(), true, false)
+	validator := func(header *types.Header) error {
+		return engine.VerifyHeader(blockchain, header, true)
 	}
 	heighter := func() uint64 {
 		return blockchain.CurrentBlock().NumberU64()
@@ -448,7 +449,7 @@ func (pm *ProtocolManager) handleMsg(p *peer) error {
 				p.forkDrop = nil
 
 				// Validate the header and either drop the peer or continue
-				if err := core.ValidateDAOHeaderExtraData(pm.chainconfig, headers[0]); err != nil {
+				if err := misc.VerifyDAOHeaderExtraData(pm.chainconfig, headers[0]); err != nil {
 					p.Log().Debug("Verified to be on the other side of the DAO fork, dropping")
 					return err
 				}
diff --git a/eth/handler_test.go b/eth/handler_test.go
index 31435b331..f85d730b6 100644
--- a/eth/handler_test.go
+++ b/eth/handler_test.go
@@ -24,6 +24,7 @@ import (
 	"time"
 
 	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/consensus/ethash"
 	"github.com/ethereum/go-ethereum/core"
 	"github.com/ethereum/go-ethereum/core/state"
 	"github.com/ethereum/go-ethereum/core/types"
@@ -34,7 +35,6 @@ import (
 	"github.com/ethereum/go-ethereum/event"
 	"github.com/ethereum/go-ethereum/p2p"
 	"github.com/ethereum/go-ethereum/params"
-	"github.com/ethereum/go-ethereum/pow"
 )
 
 var bigTxGas = new(big.Int).SetUint64(params.TxGas)
@@ -469,7 +469,7 @@ func testDAOChallenge(t *testing.T, localForked, remoteForked bool, timeout bool
 	// Create a DAO aware protocol manager
 	var (
 		evmux         = new(event.TypeMux)
-		pow           = new(pow.FakePow)
+		pow           = ethash.NewFaker()
 		db, _         = ethdb.NewMemDatabase()
 		config        = &params.ChainConfig{DAOForkBlock: big.NewInt(1), DAOForkSupport: localForked}
 		gspec         = &core.Genesis{Config: config}
diff --git a/eth/helper_test.go b/eth/helper_test.go
index e67b49691..a8c538e6c 100644
--- a/eth/helper_test.go
+++ b/eth/helper_test.go
@@ -28,6 +28,7 @@ import (
 	"testing"
 
 	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/consensus/ethash"
 	"github.com/ethereum/go-ethereum/core"
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/core/vm"
@@ -37,7 +38,6 @@ import (
 	"github.com/ethereum/go-ethereum/p2p"
 	"github.com/ethereum/go-ethereum/p2p/discover"
 	"github.com/ethereum/go-ethereum/params"
-	"github.com/ethereum/go-ethereum/pow"
 )
 
 var (
@@ -50,22 +50,22 @@ var (
 // channels for different events.
 func newTestProtocolManager(fastSync bool, blocks int, generator func(int, *core.BlockGen), newtx chan<- []*types.Transaction) (*ProtocolManager, error) {
 	var (
-		evmux = new(event.TypeMux)
-		pow   = new(pow.FakePow)
-		db, _ = ethdb.NewMemDatabase()
-		gspec = &core.Genesis{
+		evmux  = new(event.TypeMux)
+		engine = ethash.NewFaker()
+		db, _  = ethdb.NewMemDatabase()
+		gspec  = &core.Genesis{
 			Config: params.TestChainConfig,
 			Alloc:  core.GenesisAlloc{testBank: {Balance: big.NewInt(1000000)}},
 		}
 		genesis       = gspec.MustCommit(db)
-		blockchain, _ = core.NewBlockChain(db, gspec.Config, pow, evmux, vm.Config{})
+		blockchain, _ = core.NewBlockChain(db, gspec.Config, engine, evmux, vm.Config{})
 	)
 	chain, _ := core.GenerateChain(gspec.Config, genesis, db, blocks, generator)
 	if _, err := blockchain.InsertChain(chain); err != nil {
 		panic(err)
 	}
 
-	pm, err := NewProtocolManager(gspec.Config, fastSync, NetworkId, 1000, evmux, &testTxPool{added: newtx}, pow, blockchain, db)
+	pm, err := NewProtocolManager(gspec.Config, fastSync, NetworkId, 1000, evmux, &testTxPool{added: newtx}, engine, blockchain, db)
 	if err != nil {
 		return nil, err
 	}