Implement state block verification

blockchain/block.go

@@ -128,14 +128,21 @@ func NewGenesisBlock(coinbase *Transaction, shardId uint32) *Block {
 }
 
 // NewStateBlock creates and returns a state Block based on utxo pool.
+// TODO(RJ): take care of dangling cross shard transaction
 func NewStateBlock(utxoPool *UTXOPool, numBlocks, numTxs int32) *Block {
 	stateTransactions := []*Transaction{}
 	stateTransactionIds := [][32]byte{}
 	for address, txHash2Vout2AmountMap := range utxoPool.UtxoMap {
 		stateTransaction := Transaction{}
-		for _, vout2AmountMap := range txHash2Vout2AmountMap {
+		for txHash, vout2AmountMap := range txHash2Vout2AmountMap {
-			for _, amount := range vout2AmountMap {
+			for index, amount := range vout2AmountMap {
+				txHashBytes, err := utils.Get32BytesFromString(txHash)
+				if err == nil {
+					stateTransaction.TxInput = append(stateTransaction.TxInput, *NewTXInput(NewOutPoint(&txHashBytes, index), address, utxoPool.ShardID))
 					stateTransaction.TxOutput = append(stateTransaction.TxOutput, TXOutput{Amount: amount, Address: address, ShardID: utxoPool.ShardID})
+				} else {
+					return nil
+				}
 			}
 		}
 		if len(stateTransaction.TxOutput) != 0 {

blockchain/transaction.go

@@ -33,7 +33,7 @@ type Transaction struct {
 
 // TXOutput is the struct of transaction output in a transaction.
 type TXOutput struct {
-	Amount  int
+	Amount  int      // TODO: Switch to big int or uint32
 	Address [20]byte // last 20 bytes of the hash of public key
 	ShardID uint32   // The Id of the shard where this UTXO belongs
 }

blockchain/utxopool.go

@@ -87,7 +87,29 @@ func (utxoPool *UTXOPool) VerifyTransactions(transactions []*Transaction) bool {
 
 // VerifyStateBlock verifies if the given state block matches the current utxo pool.
 func (utxoPool *UTXOPool) VerifyStateBlock(stateBlock *Block) bool {
-	// TODO: implement this
+	accountBalanceInUtxoPool := make(map[[20]byte]int)
+
+	for address, txHash2Vout2AmountMap := range utxoPool.UtxoMap {
+		for _, vout2AmountMap := range txHash2Vout2AmountMap {
+			for _, amount := range vout2AmountMap {
+				accountBalanceInUtxoPool[address] = accountBalanceInUtxoPool[address] + amount
+			}
+		}
+	}
+	for _, transaction := range stateBlock.Transactions {
+		for _, txOutput := range transaction.TxOutput {
+			if txOutput.ShardID != utxoPool.ShardID {
+				return false
+			}
+			accountBalanceInUtxoPool[txOutput.Address] = accountBalanceInUtxoPool[txOutput.Address] - txOutput.Amount
+		}
+	}
+
+	for _, amount := range accountBalanceInUtxoPool {
+		if amount != 0 {
+			return false
+		}
+	}
 	return true
 }
 

node/node_handler.go

@@ -21,7 +21,7 @@ const (
 	// The max number of transaction per a block.
 	MaxNumberOfTransactionsPerBlock = 3000
 	// The number of blocks allowed before generating state block
-	NumBlocksBeforeStateBlock = 100
+	NumBlocksBeforeStateBlock = 10
 )
 
 // NodeHandler handles a new incoming connection.