Refactor NewBlockchain

blockchain.go

@@ -1,9 +1,7 @@
 package main
 
 import (
-	"fmt"
 	"log"
-	"os"
 
 	"github.com/boltdb/bolt"
 )
@@ -13,8 +11,7 @@ const blocksBucket = "blocks"
 
 // Blockchain keeps a sequence of Blocks
 type Blockchain struct {
-	blocks []*Block
+	tip []byte
-	tip    []byte
 }
 
 // BlockchainIterator is used to iterate over blockchain blocks
@@ -91,18 +88,18 @@ func (i *BlockchainIterator) Next() *Block {
 // NewBlockchain creates a new Blockchain with genesis Block
 func NewBlockchain() *Blockchain {
 	bc := Blockchain{}
+	db, err := bolt.Open(dbFile, 0600, nil)
+	if err != nil {
+		log.Panic(err)
+	}
+	defer db.Close()
 
-	if _, err := os.Stat(dbFile); os.IsNotExist(err) {
+	err = db.Update(func(tx *bolt.Tx) error {
-		fmt.Println("Creating a new blockchain...")
+		b := tx.Bucket([]byte(blocksBucket))
-		db, err := bolt.Open(dbFile, 0600, nil)
-		if err != nil {
-			log.Panic(err)
-		}
-		defer db.Close()
 
-		genesis := NewGenesisBlock()
+		if b == nil {
+			genesis := NewGenesisBlock()
 
-		err = db.Update(func(tx *bolt.Tx) error {
 			b, err := tx.CreateBucket([]byte(blocksBucket))
 			if err != nil {
 				log.Panic(err)
@@ -117,26 +114,16 @@ func NewBlockchain() *Blockchain {
 			if err != nil {
 				log.Panic(err)
 			}
-
+			bc.tip = genesis.Hash
-			return nil
+		} else {
-		})
-
-		bc.tip = genesis.Hash
-	} else {
-		// TODO: remove the duplication, check for the "l" key
-		db, err := bolt.Open(dbFile, 0600, nil)
-		if err != nil {
-			log.Panic(err)
-		}
-		defer db.Close()
-
-		err = db.View(func(tx *bolt.Tx) error {
-			b := tx.Bucket([]byte(blocksBucket))
 			tip := b.Get([]byte("l"))
 			bc.tip = tip
+		}
 
-			return nil
+		return nil
-		})
+	})
+	if err != nil {
+		log.Panic(err)
 	}
 
 	return &bc

main.go

@@ -8,8 +8,8 @@ import (
 func main() {
 	bc := NewBlockchain()
 
-	// bc.AddBlock("Send 1 BTC to Ivan")
+	bc.AddBlock("Send 1 BTC to Ivan")
-	// bc.AddBlock("Send 2 more BTC to Ivan")
+	bc.AddBlock("Send 2 more BTC to Ivan")
 
 	bci := bc.Iterator()