container, genesis: add functional options for genesis creation

container/blockchain.go

@@ -278,7 +278,11 @@ func (bc *blockchain) setupGenesis(addrs []common.Address) {
 		if err != nil {
 			log.Fatal("Failed to create setup dir", err)
 		}
-		err = genesis.Save(setupDir, genesis.New(addrs))
+		err = genesis.Save(setupDir,
+			genesis.New(
+				genesis.Validators(addrs...),
+			),
+		)
 		if err != nil {
 			log.Fatal("Failed to save genesis", err)
 		}

genesis/genesis.go

@@ -19,19 +19,14 @@ package genesis
 import (
 	"encoding/json"
 	"io/ioutil"
-	"log"
 	"math/big"
 	"path/filepath"
 	"time"
 
-	"github.com/ethereum/go-ethereum/common"
-	"github.com/ethereum/go-ethereum/common/hexutil"
 	"github.com/ethereum/go-ethereum/consensus/istanbul"
 	"github.com/ethereum/go-ethereum/core"
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/params"
-
-	"github.com/getamis/istanbul-tools/cmd/istanbul/extradata"
 )
 
 const (
@@ -40,13 +35,8 @@ const (
 	InitDifficulty = 1
 )
 
-func New(addrs []common.Address) *core.Genesis {
-	extraData, err := extradata.Encode("0x00", addrs)
-	if err != nil {
-		log.Fatalf("Failed to generate genesis, err:%s", err)
-	}
-
-	return &core.Genesis{
+func New(options ...Option) *core.Genesis {
+	genesis := &core.Genesis{
 		Timestamp:  uint64(time.Now().Unix()),
 		GasLimit:   InitGasLimit,
 		Difficulty: big.NewInt(InitDifficulty),
@@ -61,9 +51,14 @@ func New(addrs []common.Address) *core.Genesis {
 				Epoch:          istanbul.DefaultConfig.Epoch,
 			},
 		},
-		Mixhash:   types.IstanbulDigest,
-		ExtraData: hexutil.MustDecode(extraData),
+		Mixhash: types.IstanbulDigest,
 	}
+
+	for _, opt := range options {
+		opt(genesis)
+	}
+
+	return genesis
 }
 
 func Save(dataDir string, genesis *core.Genesis) error {

genesis/options.go

@@ -0,0 +1,45 @@
+// Copyright 2017 AMIS Technologies
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package genesis
+
+import (
+	"log"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/common/hexutil"
+	"github.com/ethereum/go-ethereum/core"
+
+	"github.com/getamis/istanbul-tools/cmd/istanbul/extradata"
+)
+
+type Option func(*core.Genesis)
+
+func Validators(addrs ...common.Address) Option {
+	return func(genesis *core.Genesis) {
+		extraData, err := extradata.Encode("0x00", addrs[:])
+		if err != nil {
+			log.Fatalf("Failed to generate genesis, err:%s", err)
+		}
+		genesis.ExtraData = hexutil.MustDecode(extraData)
+	}
+}
+
+func GasLimit(limit uint64) Option {
+	return func(genesis *core.Genesis) {
+		genesis.GasLimit = limit
+	}
+}