Add more comments to new code; make prevHash 32 byte array

aws-code/transaction_generator.go

@@ -24,8 +24,8 @@ import (
 // NOTE: the genesis block should contain 1000 coinbase transactions adding
 //       value to each address in [1 - 1000]. See node.AddMoreFakeTransactions()
 func getNewFakeTransactions(dataNode *node.Node, numTxs int) []*blockchain.Transaction {
-
 	/*
+	  UTXO map structure:
 	     address - [
 	                txId1 - [
 	                        outputIndex1 - value1
@@ -37,7 +37,6 @@ func getNewFakeTransactions(dataNode *node.Node, numTxs int) []*blockchain.Trans
 	                       ]
 	               ]
 	*/
-
 	var outputs []*blockchain.Transaction
 	count := 0
 	countAll := 0
@@ -119,15 +118,15 @@ func main() {
 	numTxsPerBatch := flag.Int("num_txs_per_batch", 1000, "number of transactions to send per message")
 	flag.Parse()
 	config := readConfigFile(*configFile)
+	leaders := getLeaders(&config)
 
-	// Testing node
+	// Testing node to mirror the node data in consensus
 	dataNode := node.NewNode(&consensus.Consensus{})
 	dataNode.AddMoreFakeTransactions()
 
 	start := time.Now()
 	totalTime := 60.0
-	leaders := getLeaders(&config)
-	time.Sleep(5 * time.Second) // wait for nodes to run
+	time.Sleep(3 * time.Second) // wait for nodes to be ready
 	for true {
 		t := time.Now()
 		if t.Sub(start).Seconds() >= totalTime {
@@ -139,9 +138,12 @@ func main() {
 		log.Debug("[Generator] Sending txs...", "numTxs", len(txsToSend))
 		p2p.BroadcastMessage(leaders, msg)
 
+		// Update local utxo pool to mirror the utxo pool of a real node
 		dataNode.UtxoPool.Update(txsToSend)
-		time.Sleep(1 * time.Second) // 10 transactions per second
+		time.Sleep(1 * time.Second) // Send a batch of transactions every second
 	}
+
+	// Send a stop message to stop the nodes at the end
 	msg := node.ConstructStopMessage()
 	peers := append(getValidators(*configFile), leaders...)
 	p2p.BroadcastMessage(peers, msg)

benchmark_main.go

@@ -76,6 +76,7 @@ func main() {
 	consensus := consensus.NewConsensus(*ip, *port, shardId, peers, leader)
 
 	node := node.NewNode(&consensus)
+	// Temporary testing code, to be removed.
 	node.AddMoreFakeTransactions()
 
 	if consensus.IsLeader {

blockchain/block.go

@@ -13,7 +13,7 @@ import (
 type Block struct {
 	Timestamp     int64
 	Transactions  []*Transaction
-	PrevBlockHash []byte
+	PrevBlockHash [32]byte
 	Hash          [32]byte
 }
 
@@ -63,7 +63,7 @@ func (b *Block) HashTransactions() []byte {
 }
 
 // NewBlock creates and returns a neew block.
-func NewBlock(transactions []*Transaction, prevBlockHash []byte) *Block {
+func NewBlock(transactions []*Transaction, prevBlockHash [32]byte) *Block {
 	block := &Block{time.Now().Unix(), transactions, prevBlockHash, [32]byte{}}
 	copy(block.Hash[:], block.HashTransactions()[:]) // TODO(Minh): the blockhash should be a hash of everything in the block
 
@@ -72,5 +72,5 @@ func NewBlock(transactions []*Transaction, prevBlockHash []byte) *Block {
 
 // NewGenesisBlock creates and returns genesis Block.
 func NewGenesisBlock(coinbase *Transaction) *Block {
-	return NewBlock([]*Transaction{coinbase}, []byte{})
+	return NewBlock([]*Transaction{coinbase}, [32]byte{})
 }

blockchain/block_test.go

@@ -19,7 +19,7 @@ func TestBlockSerialize(t *testing.T) {
 		t.Errorf("Serialize or Deserialize incorrect at TimeStamp.")
 	}
 
-	if bytes.Compare(block.PrevBlockHash, deserializedBlock.PrevBlockHash) != 0 {
+	if bytes.Compare(block.PrevBlockHash[:], deserializedBlock.PrevBlockHash[:]) != 0 {
 		t.Errorf("Serialize or Deserialize incorrect at PrevBlockHash.")
 	}
 

blockchain/blockchain.go

@@ -12,6 +12,7 @@ type Blockchain struct {
 
 const genesisCoinbaseData = "The Times 03/Jan/2009 Chancellor on brink of second bailout for banks"
 
+// Get the latest block at the end of the chain
 func (bc *Blockchain) GetLatestBlock() *Block{
 	if len(bc.Blocks) == 0 {
 		return nil
@@ -142,7 +143,7 @@ func (bc *Blockchain) NewUTXOTransaction(from, to string, amount int) *Transacti
 func (bc *Blockchain) AddNewUserTransfer(utxoPool *UTXOPool, from, to string, amount int) bool {
 	tx := bc.NewUTXOTransaction(from, to, amount)
 	if tx != nil {
-		newBlock := NewBlock([]*Transaction{tx}, bc.Blocks[len(bc.Blocks)-1].Hash[:])
+		newBlock := NewBlock([]*Transaction{tx}, bc.Blocks[len(bc.Blocks)-1].Hash)
 		if bc.VerifyNewBlockAndUpdate(utxoPool, newBlock) {
 			return true
 		}
@@ -153,7 +154,7 @@ func (bc *Blockchain) AddNewUserTransfer(utxoPool *UTXOPool, from, to string, am
 // VerifyNewBlockAndUpdate verifies if the new coming block is valid for the current blockchain.
 func (bc *Blockchain) VerifyNewBlockAndUpdate(utxopool *UTXOPool, block *Block) bool {
 	length := len(bc.Blocks)
-	if bytes.Compare(block.PrevBlockHash, bc.Blocks[length-1].Hash[:]) != 0 {
+	if bytes.Compare(block.PrevBlockHash[:], bc.Blocks[length-1].Hash[:]) != 0 {
 		return false
 	}
 	if block.Timestamp < bc.Blocks[length-1].Timestamp {

blockchain/blockchain_test.go

@@ -68,7 +68,7 @@ func TestVerifyNewBlock(t *testing.T) {
 	if tx == nil {
 		t.Error("failed to create a new transaction.")
 	}
-	newBlock := NewBlock([]*Transaction{tx}, bc.Blocks[len(bc.Blocks)-1].Hash[:])
+	newBlock := NewBlock([]*Transaction{tx}, bc.Blocks[len(bc.Blocks)-1].Hash)
 
 	if !bc.VerifyNewBlockAndUpdate(utxoPool, newBlock) {
 		t.Error("failed to add a new valid block.")

consensus/consensus_leader.go

@@ -301,6 +301,8 @@ func (consensus *Consensus) processResponseMessage(payload []byte) {
 
 			consensus.ResetState()
 			consensus.consensusId++
+
+			// Send signal to Node so the new block can be added and new round of consensus can be triggered
 			consensus.ReadySignal <- 1
 		}
 		// TODO: composes new block and broadcast the new block to validators

node/node.go

@@ -14,21 +14,32 @@ var pendingTxMutex = &sync.Mutex{}
 
 // A node represents a program (machine) participating in the network
 type Node struct {
+	// Consensus object containing all consensus related data (e.g. committee members, signatures, commits)
 	consensus              *consensus.Consensus
+	// The channel to receive new blocks from Node
 	BlockChannel           chan blockchain.Block
+	// All the transactions received but not yet processed for consensus
 	pendingTransactions    []*blockchain.Transaction
+	// The transactions selected into the new block and under consensus process
 	transactionInConsensus []*blockchain.Transaction
+	// The blockchain for the shard where this node belongs
 	blockchain             *blockchain.Blockchain
+	// The corresponding UTXO pool of the current blockchain
 	UtxoPool               *blockchain.UTXOPool
+
+	// Log utility
 	log                    log.Logger
 }
 
+// Add new transactions to the pending transaction list
 func (node *Node) addPendingTransactions(newTxs []*blockchain.Transaction) {
 	pendingTxMutex.Lock()
 	node.pendingTransactions = append(node.pendingTransactions, newTxs...)
 	pendingTxMutex.Unlock()
 }
 
+// Take out a subset of valid transactions from the pending transaction list
+// Note the pending transaction list will then contain the rest of the txs
 func (node *Node) getTransactionsForNewBlock() []*blockchain.Transaction {
 	pendingTxMutex.Lock()
 	selected, unselected := node.UtxoPool.SelectTransactionsForNewBlock(node.pendingTransactions)
@@ -64,9 +75,8 @@ func (node *Node) String() string {
 	return node.consensus.String()
 }
 
-
-// Testing code. Should be deleted for production
-// Create in genesis block 1000 transactions assigning 1000 token to each address in [1 - 1000]
+// [Testing code] Should be deleted for production
+// Create in genesis block 1000 transactions which assign 1000 token to each address in [1 - 1000]
 func (node *Node) AddMoreFakeTransactions() {
 	txs := make([]*blockchain.Transaction, 1000)
 	for i := range txs {

node/node_handler.go

@@ -123,29 +123,34 @@ func (node *Node) WaitForConsensusReady(readySignal chan int) {
 		<-readySignal
 		//node.log.Debug("Adding new block", "currentChainSize", len(node.blockchain.Blocks), "numTxs", len(node.blockchain.GetLatestBlock().Transactions), "PrevHash", node.blockchain.GetLatestBlock().PrevBlockHash, "Hash", node.blockchain.GetLatestBlock().Hash)
 		if newBlock != nil {
-			// Consensus is done on the previous newBlock, add it to blockchain
+			// Consensus is done on the newBlock (in the previous round of consensus), add it to blockchain
 			node.blockchain.Blocks = append(node.blockchain.Blocks, newBlock)
 			// Update UTXO pool
 			node.UtxoPool.Update(node.transactionInConsensus)
-			// Clear transaction in consensus slice
+			// Clear transaction-in-consensus list
 			node.transactionInConsensus = []*blockchain.Transaction{}
 		}
 		for {
+			// Once we have more than 10 transactions pending we will try creating a new block
 			if len(node.pendingTransactions) >= 10 {
 				selectedTxs := node.getTransactionsForNewBlock()
 
 				if len(selectedTxs) == 0 {
-					node.log.Debug("No transactions is selected for consensus", "pendingTx", len(node.pendingTransactions))
+					node.log.Debug("No valid transactions exist", "pendingTx", len(node.pendingTransactions))
 				} else {
 					node.log.Debug("Creating new block", "numTxs", len(selectedTxs), "pendingTxs", len(node.pendingTransactions), "currentChainSize", len(node.blockchain.Blocks))
 
 					node.transactionInConsensus = selectedTxs
-					newBlock = blockchain.NewBlock(selectedTxs, node.blockchain.GetLatestBlock().Hash[:])
+					newBlock = blockchain.NewBlock(selectedTxs, node.blockchain.GetLatestBlock().Hash)
 					break
 				}
 			}
-			time.Sleep(1 * time.Second) // Periodically check whether we have enough transactions to package into block.
+			// If not enough transactions to run consensus,
+			// periodically check whether we have enough transactions to package into block.
+			time.Sleep(1 * time.Second)
 		}
+
+		// Send the new block to consensus so it can be confirmed.
 		node.BlockChannel <- *newBlock
 	}
 }