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.

4 files changed, 16 insertions, 18 deletions

diff --git a/les/backend.go b/les/backend.go
index d656cf41f..bb08efd91 100644
--- a/les/backend.go
+++ b/les/backend.go
@@ -25,6 +25,7 @@ import (
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/common/compiler"
 	"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/types"
 	"github.com/ethereum/go-ethereum/eth"
@@ -39,7 +40,6 @@ 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"
 	rpc "github.com/ethereum/go-ethereum/rpc"
 )
 
@@ -59,7 +59,7 @@ type LightEthereum struct {
 	ApiBackend *LesApiBackend
 
 	eventMux       *event.TypeMux
-	pow            pow.PoW
+	engine         consensus.Engine
 	accountManager *accounts.Manager
 	solcPath       string
 	solc           *compiler.Solidity
@@ -88,14 +88,12 @@ func New(ctx *node.ServiceContext, config *eth.Config) (*LightEthereum, error) {
 		chainConfig:    chainConfig,
 		eventMux:       ctx.EventMux,
 		accountManager: ctx.AccountManager,
-		pow:            eth.CreatePoW(ctx, config),
+		engine:         eth.CreateConsensusEngine(ctx, config, chainConfig, chainDb),
 		shutdownChan:   make(chan bool),
 		netVersionId:   config.NetworkId,
 		solcPath:       config.SolcPath,
 	}
-
-	eth.blockchain, err = light.NewLightChain(odr, eth.chainConfig, eth.pow, eth.eventMux)
-	if err != nil {
+	if eth.blockchain, err = light.NewLightChain(odr, eth.chainConfig, eth.engine, eth.eventMux); err != nil {
 		return nil, err
 	}
 	// Rewind the chain in case of an incompatible config upgrade.
@@ -106,7 +104,7 @@ func New(ctx *node.ServiceContext, config *eth.Config) (*LightEthereum, error) {
 	}
 
 	eth.txPool = light.NewTxPool(eth.chainConfig, eth.eventMux, eth.blockchain, eth.relay)
-	if eth.protocolManager, err = NewProtocolManager(eth.chainConfig, config.LightMode, config.NetworkId, eth.eventMux, eth.pow, eth.blockchain, nil, chainDb, odr, relay); err != nil {
+	if eth.protocolManager, err = NewProtocolManager(eth.chainConfig, config.LightMode, config.NetworkId, eth.eventMux, eth.engine, eth.blockchain, nil, chainDb, odr, relay); err != nil {
 		return nil, err
 	}
 	relay.ps = eth.protocolManager.peers
diff --git a/les/handler.go b/les/handler.go
index ece2060ee..fbb9e9906 100644
--- a/les/handler.go
+++ b/les/handler.go
@@ -27,6 +27,7 @@ import (
 	"time"
 
 	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/consensus"
 	"github.com/ethereum/go-ethereum/core"
 	"github.com/ethereum/go-ethereum/core/state"
 	"github.com/ethereum/go-ethereum/core/types"
@@ -39,7 +40,6 @@ import (
 	"github.com/ethereum/go-ethereum/p2p/discover"
 	"github.com/ethereum/go-ethereum/p2p/discv5"
 	"github.com/ethereum/go-ethereum/params"
-	"github.com/ethereum/go-ethereum/pow"
 	"github.com/ethereum/go-ethereum/rlp"
 	"github.com/ethereum/go-ethereum/trie"
 )
@@ -128,7 +128,7 @@ type ProtocolManager struct {
 
 // NewProtocolManager returns a new ethereum sub protocol manager. The Ethereum sub protocol manages peers capable
 // with the ethereum network.
-func NewProtocolManager(chainConfig *params.ChainConfig, lightSync bool, networkId int, mux *event.TypeMux, pow pow.PoW, blockchain BlockChain, txpool txPool, chainDb ethdb.Database, odr *LesOdr, txrelay *LesTxRelay) (*ProtocolManager, error) {
+func NewProtocolManager(chainConfig *params.ChainConfig, lightSync bool, networkId int, mux *event.TypeMux, engine consensus.Engine, blockchain BlockChain, txpool txPool, chainDb ethdb.Database, odr *LesOdr, txrelay *LesTxRelay) (*ProtocolManager, error) {
 	// Create the protocol manager with the base fields
 	manager := &ProtocolManager{
 		lightSync:   lightSync,
diff --git a/les/helper_test.go b/les/helper_test.go
index f37bec80e..7e442c131 100644
--- a/les/helper_test.go
+++ b/les/helper_test.go
@@ -28,6 +28,7 @@ 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/types"
 	"github.com/ethereum/go-ethereum/core/vm"
@@ -39,7 +40,6 @@ 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 (
@@ -134,10 +134,10 @@ func testRCL() RequestCostList {
 // channels for different events.
 func newTestProtocolManager(lightSync bool, blocks int, generator func(int, *core.BlockGen)) (*ProtocolManager, ethdb.Database, *LesOdr, 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{testBankAddress: {Balance: testBankFunds}},
 		}
@@ -148,9 +148,9 @@ func newTestProtocolManager(lightSync bool, blocks int, generator func(int, *cor
 
 	if lightSync {
 		odr = NewLesOdr(db)
-		chain, _ = light.NewLightChain(odr, gspec.Config, pow, evmux)
+		chain, _ = light.NewLightChain(odr, gspec.Config, engine, evmux)
 	} else {
-		blockchain, _ := core.NewBlockChain(db, gspec.Config, pow, evmux, vm.Config{})
+		blockchain, _ := core.NewBlockChain(db, gspec.Config, engine, evmux, vm.Config{})
 		gchain, _ := core.GenerateChain(gspec.Config, genesis, db, blocks, generator)
 		if _, err := blockchain.InsertChain(gchain); err != nil {
 			panic(err)
@@ -158,7 +158,7 @@ func newTestProtocolManager(lightSync bool, blocks int, generator func(int, *cor
 		chain = blockchain
 	}
 
-	pm, err := NewProtocolManager(gspec.Config, lightSync, NetworkId, evmux, pow, chain, nil, db, odr, nil)
+	pm, err := NewProtocolManager(gspec.Config, lightSync, NetworkId, evmux, engine, chain, nil, db, odr, nil)
 	if err != nil {
 		return nil, nil, nil, err
 	}
diff --git a/les/server.go b/les/server.go
index 5957add36..22fe59b7a 100644
--- a/les/server.go
+++ b/les/server.go
@@ -45,7 +45,7 @@ type LesServer struct {
 }
 
 func NewLesServer(eth *eth.Ethereum, config *eth.Config) (*LesServer, error) {
-	pm, err := NewProtocolManager(eth.BlockChain().Config(), false, config.NetworkId, eth.EventMux(), eth.Pow(), eth.BlockChain(), eth.TxPool(), eth.ChainDb(), nil, nil)
+	pm, err := NewProtocolManager(eth.BlockChain().Config(), false, config.NetworkId, eth.EventMux(), eth.Engine(), eth.BlockChain(), eth.TxPool(), eth.ChainDb(), nil, nil)
 	if err != nil {
 		return nil, err
 	}