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, 17 insertions, 9 deletions

diff --git a/cmd/evm/disasm.go b/cmd/evm/disasm.go
index 01a8c60ba..a78b2a8e1 100644
--- a/cmd/evm/disasm.go
+++ b/cmd/evm/disasm.go
@@ -20,10 +20,10 @@ import (
 	"errors"
 	"fmt"
 	"io/ioutil"
+	"strings"
 
 	"github.com/ethereum/go-ethereum/core/asm"
 	cli "gopkg.in/urfave/cli.v1"
-	"strings"
 )
 
 var disasmCommand = cli.Command{
diff --git a/cmd/geth/main.go b/cmd/geth/main.go
index cc6d3ac6a..e942d53c8 100644
--- a/cmd/geth/main.go
+++ b/cmd/geth/main.go
@@ -303,7 +303,15 @@ func startNode(ctx *cli.Context, stack *node.Node) {
 		if err := stack.Service(&ethereum); err != nil {
 			utils.Fatalf("ethereum service not running: %v", err)
 		}
-		if err := ethereum.StartMining(ctx.GlobalInt(utils.MinerThreadsFlag.Name)); err != nil {
+		if threads := ctx.GlobalInt(utils.MinerThreadsFlag.Name); threads > 0 {
+			type threaded interface {
+				SetThreads(threads int)
+			}
+			if th, ok := ethereum.Engine().(threaded); ok {
+				th.SetThreads(threads)
+			}
+		}
+		if err := ethereum.StartMining(); err != nil {
 			utils.Fatalf("Failed to start mining: %v", err)
 		}
 	}
diff --git a/cmd/geth/misccmd.go b/cmd/geth/misccmd.go
index 073c36beb..079f49310 100644
--- a/cmd/geth/misccmd.go
+++ b/cmd/geth/misccmd.go
@@ -26,9 +26,9 @@ import (
 	"strings"
 
 	"github.com/ethereum/go-ethereum/cmd/utils"
+	"github.com/ethereum/go-ethereum/consensus/ethash"
 	"github.com/ethereum/go-ethereum/eth"
 	"github.com/ethereum/go-ethereum/params"
-	"github.com/ethereum/go-ethereum/pow"
 	"gopkg.in/urfave/cli.v1"
 )
 
@@ -87,7 +87,7 @@ func makedag(ctx *cli.Context) error {
 				utils.Fatalf("Can't find dir")
 			}
 			fmt.Println("making DAG, this could take awhile...")
-			pow.MakeDataset(blockNum, dir)
+			ethash.MakeDataset(blockNum, dir)
 		}
 	default:
 		wrongArgs()
diff --git a/cmd/utils/flags.go b/cmd/utils/flags.go
index 478e08834..acdf5d5dc 100644
--- a/cmd/utils/flags.go
+++ b/cmd/utils/flags.go
@@ -32,6 +32,7 @@ import (
 	"github.com/ethereum/go-ethereum/accounts"
 	"github.com/ethereum/go-ethereum/accounts/keystore"
 	"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/vm"
@@ -49,7 +50,6 @@ import (
 	"github.com/ethereum/go-ethereum/p2p/nat"
 	"github.com/ethereum/go-ethereum/p2p/netutil"
 	"github.com/ethereum/go-ethereum/params"
-	"github.com/ethereum/go-ethereum/pow"
 	"github.com/ethereum/go-ethereum/rpc"
 	whisper "github.com/ethereum/go-ethereum/whisper/whisperv2"
 	"gopkg.in/urfave/cli.v1"
@@ -149,7 +149,7 @@ var (
 	}
 	TestNetFlag = cli.BoolFlag{
 		Name:  "testnet",
-		Usage: "Ropsten network: pre-configured test network",
+		Usage: "Ropsten network: pre-configured proof-of-work test network",
 	}
 	DevModeFlag = cli.BoolFlag{
 		Name:  "dev",
@@ -921,16 +921,16 @@ func MakeChain(ctx *cli.Context, stack *node.Node) (chain *core.BlockChain, chai
 	var err error
 	chainDb = MakeChainDatabase(ctx, stack)
 
-	seal := pow.PoW(pow.FakePow{})
+	engine := ethash.NewFaker()
 	if !ctx.GlobalBool(FakePoWFlag.Name) {
-		seal = pow.NewFullEthash("", 1, 0, "", 1, 0)
+		engine = ethash.New("", 1, 0, "", 1, 0)
 	}
 	config, _, err := core.SetupGenesisBlock(chainDb, MakeGenesis(ctx))
 	if err != nil {
 		Fatalf("%v", err)
 	}
 	vmcfg := vm.Config{EnablePreimageRecording: ctx.GlobalBool(VMEnableDebugFlag.Name)}
-	chain, err = core.NewBlockChain(chainDb, config, seal, new(event.TypeMux), vmcfg)
+	chain, err = core.NewBlockChain(chainDb, config, engine, new(event.TypeMux), vmcfg)
 	if err != nil {
 		Fatalf("Can't create BlockChain: %v", err)
 	}