[DEV-34] In blockNode, made parents a pointer slice, got rid of numPrevHashes, and extracted a lookupPreviousNodes function. Changed c-style loops to range loops.

blockdag/accept.go

@@ -24,32 +24,18 @@ import (
 func (b *BlockChain) maybeAcceptBlock(block *btcutil.Block, flags BehaviorFlags) (bool, error) {
 	// The height of this block is one more than the referenced previous
 	// block.
-	prevHeader := &block.MsgBlock().Header
+	nodes, err := lookupPreviousNodes(block, b)
-	numPrevHashes := prevHeader.NumPrevBlocks
+	if err != nil {
-	prevHashes := prevHeader.PrevBlocks
+		return false, err
-
-	nodes := make([]blockNode, numPrevHashes)
-	for i := byte(0); i < numPrevHashes; i++ {
-		prevHash := prevHashes[i]
-		node := b.index.LookupNode(&prevHash)
-		if node == nil {
-			str := fmt.Sprintf("previous block %s is unknown", prevHashes)
-			return false, ruleError(ErrPreviousBlockUnknown, str)
-		} else if b.index.NodeStatus(node).KnownInvalid() {
-			str := fmt.Sprintf("previous block %s is known to be invalid", prevHashes)
-			return false, ruleError(ErrInvalidAncestorBlock, str)
 	}
 
-		nodes = append(nodes, *node)
+	firstNode := nodes[0] // TODO: (Stas) This is wrong. Modified only to satisfy compilation.
-	}
-
-	firstNode := nodes[0]
 	blockHeight := firstNode.height + 1
 	block.SetHeight(blockHeight)
 
 	// The block must pass all of the validation rules which depend on the
 	// position of the block within the block chain.
-	err := b.checkBlockContext(block, &firstNode, flags)
+	err = b.checkBlockContext(block, firstNode, flags)
 	if err != nil {
 		return false, err
 	}
@@ -100,3 +86,24 @@ func (b *BlockChain) maybeAcceptBlock(block *btcutil.Block, flags BehaviorFlags)
 
 	return isMainChain, nil
 }
+
+func lookupPreviousNodes(block *btcutil.Block, blockChain *BlockChain) ([]*blockNode, error) {
+	header := block.MsgBlock().Header
+	prevHashes := header.PrevBlocks
+
+	nodes := make([]*blockNode, len(prevHashes))
+	for _, prevHash := range prevHashes {
+		node := blockChain.index.LookupNode(&prevHash)
+		if node == nil {
+			str := fmt.Sprintf("previous block %s is unknown", prevHashes)
+			return nil, ruleError(ErrPreviousBlockUnknown, str)
+		} else if blockChain.index.NodeStatus(node).KnownInvalid() {
+			str := fmt.Sprintf("previous block %s is known to be invalid", prevHashes)
+			return nil, ruleError(ErrInvalidAncestorBlock, str)
+		}
+
+		nodes = append(nodes, node)
+	}
+
+	return nodes, nil
+}

blockdag/blockindex.go

@@ -71,11 +71,8 @@ type blockNode struct {
 	// hundreds of thousands of these in memory, so a few extra bytes of
 	// padding adds up.
 
-	// numParents is the amount of parent blocks for this node.
-	numParents byte
-
 	// parents is the parent blocks for this node.
-	parents []blockNode
+	parents []*blockNode
 
 	// hash is the double sha 256 of the block.
 	hash daghash.Hash
@@ -108,12 +105,11 @@ type blockNode struct {
 // calculating the height and workSum from the respective fields on the first parent.
 // This function is NOT safe for concurrent access.  It must only be called when
 // initially creating a node.
-func initBlockNode(node *blockNode, blockHeader *wire.BlockHeader, parents []blockNode) {
+func initBlockNode(node *blockNode, blockHeader *wire.BlockHeader, parents []*blockNode) {
 	numParents := byte(len(parents))
 	*node = blockNode{
 		hash:       blockHeader.BlockHash(),
 		parents:    parents,
-		numParents: numParents,
 		workSum:    CalcWork(blockHeader.Bits),
 		version:    blockHeader.Version,
 		bits:       blockHeader.Bits,
@@ -131,7 +127,7 @@ func initBlockNode(node *blockNode, blockHeader *wire.BlockHeader, parents []blo
 // newBlockNode returns a new block node for the given block header and parent
 // nodes, calculating the height and workSum from the respective fields on the
 // parent. This function is NOT safe for concurrent access.
-func newBlockNode(blockHeader *wire.BlockHeader, parents []blockNode) *blockNode {
+func newBlockNode(blockHeader *wire.BlockHeader, parents []*blockNode) *blockNode {
 	var node blockNode
 	initBlockNode(&node, blockHeader, parents)
 	return &node
@@ -142,14 +138,11 @@ func newBlockNode(blockHeader *wire.BlockHeader, parents []blockNode) *blockNode
 // This function is safe for concurrent access.
 func (node *blockNode) Header() wire.BlockHeader {
 	// No lock is needed because all accessed fields are immutable.
-	prevHashes := make([]daghash.Hash, node.numParents)
+	prevHashes := node.prevHashes()
-	for _, parent := range node.parents {
-		prevHashes = append(prevHashes, parent.hash)
-	}
 
 	return wire.BlockHeader{
 		Version:       node.version,
-		NumPrevBlocks: node.numParents,
+		NumPrevBlocks: byte(len(node.parents)),
 		PrevBlocks:    prevHashes,
 		MerkleRoot:    node.merkleRoot,
 		Timestamp:     time.Unix(node.timestamp, 0),
@@ -170,7 +163,7 @@ func (node *blockNode) Ancestor(height int32) *blockNode {
 	}
 
 	n := node
-	for ; n != nil && n.height != height; n = &n.parents[0] {
+	for ; n != nil && n.height != height; n = n.parents[0] {
 		// Intentionally left blank
 	}
 
@@ -200,7 +193,7 @@ func (node *blockNode) CalcPastMedianTime() time.Time {
 		timestamps[i] = iterNode.timestamp
 		numNodes++
 
-		iterNode = &iterNode.parents[0]
+		iterNode = iterNode.parents[0]
 	}
 
 	// Prune the slice to the actual number of available timestamps which
@@ -225,6 +218,15 @@ func (node *blockNode) CalcPastMedianTime() time.Time {
 	return time.Unix(medianTimestamp, 0)
 }
 
+func (node *blockNode) prevHashes() []daghash.Hash {
+	prevHashes := make([]daghash.Hash, len(node.parents))
+	for _, parent := range node.parents {
+		prevHashes = append(prevHashes, parent.hash)
+	}
+
+	return prevHashes
+}
+
 // blockIndex provides facilities for keeping track of an in-memory index of the
 // block chain.  Although the name block chain suggests a single chain of
 // blocks, it is actually a tree-shaped structure where any node can have

blockdag/chain.go

@@ -373,7 +373,7 @@ func (b *BlockChain) calcSequenceLock(node *blockNode, tx *btcutil.Tx, utxoView
 		// Obtain the latest BIP9 version bits state for the
 		// CSV-package soft-fork deployment. The adherence of sequence
 		// locks depends on the current soft-fork state.
-		csvState, err := b.deploymentState(&node.parents[0], dagconfig.DeploymentCSV) // TODO: (Stas) This is wrong. Modified only to satisfy compilation.
+		csvState, err := b.deploymentState(node.parents[0], dagconfig.DeploymentCSV) // TODO: (Stas) This is wrong. Modified only to satisfy compilation.
 		if err != nil {
 			return nil, err
 		}
@@ -502,7 +502,7 @@ func (b *BlockChain) getReorganizeNodes(node *blockNode) (*list.List, *list.List
 	// Do not reorganize to a known invalid chain. Ancestors deeper than the
 	// direct parent are checked below but this is a quick check before doing
 	// more unnecessary work.
-	if b.index.NodeStatus(&node.parents[0]).KnownInvalid() { // TODO: (Stas) This is wrong. Modified only to satisfy compilation.
+	if b.index.NodeStatus(node.parents[0]).KnownInvalid() { // TODO: (Stas) This is wrong. Modified only to satisfy compilation.
 		b.index.SetStatusFlags(node, statusInvalidAncestor)
 		return detachNodes, attachNodes
 	}
@@ -513,7 +513,7 @@ func (b *BlockChain) getReorganizeNodes(node *blockNode) (*list.List, *list.List
 	// later.
 	forkNode := b.bestChain.FindFork(node)
 	invalidChain := false
-	for n := node; n != nil && n != forkNode; n = &n.parents[0] { // TODO: (Stas) This is wrong. Modified only to satisfy compilation.
+	for n := node; n != nil && n != forkNode; n = n.parents[0] { // TODO: (Stas) This is wrong. Modified only to satisfy compilation.
 		if b.index.NodeStatus(n).KnownInvalid() {
 			invalidChain = true
 			break
@@ -536,7 +536,7 @@ func (b *BlockChain) getReorganizeNodes(node *blockNode) (*list.List, *list.List
 	// Start from the end of the main chain and work backwards until the
 	// common ancestor adding each block to the list of nodes to detach from
 	// the main chain.
-	for n := b.bestChain.Tip(); n != nil && n != forkNode; n = &n.parents[0] { // TODO: (Stas) This is wrong. Modified only to satisfy compilation.
+	for n := b.bestChain.Tip(); n != nil && n != forkNode; n = n.parents[0] { // TODO: (Stas) This is wrong. Modified only to satisfy compilation.
 		detachNodes.PushBack(n)
 	}
 
@@ -684,7 +684,7 @@ func (b *BlockChain) disconnectBlock(node *blockNode, block *btcutil.Block, view
 	}
 
 	// Load the previous block since some details for it are needed below.
-	prevNode := &node.parents[0] // TODO: (Stas) This is wrong. Modified only to satisfy compilation.
+	prevNode := node.parents[0] // TODO: (Stas) This is wrong. Modified only to satisfy compilation.
 	var prevBlock *btcutil.Block
 	err := b.db.View(func(dbTx database.Tx) error {
 		var err error
@@ -762,7 +762,7 @@ func (b *BlockChain) disconnectBlock(node *blockNode, block *btcutil.Block, view
 	view.commit()
 
 	// This node's parent is now the end of the best chain.
-	b.bestChain.SetTip(&node.parents[0]) // TODO: (Stas) This is wrong. Modified only to satisfy compilation.
+	b.bestChain.SetTip(node.parents[0]) // TODO: (Stas) This is wrong. Modified only to satisfy compilation.
 
 	// Update the state for the best block.  Notice how this replaces the
 	// entire struct instead of updating the existing one.  This effectively
@@ -1355,7 +1355,7 @@ func (b *BlockChain) HeightToHashRange(startHeight int32,
 	hashes := make([]daghash.Hash, resultsLength)
 	for i := resultsLength - 1; i >= 0; i-- {
 		hashes[i] = node.hash
-		node = &node.parents[0] // TODO: (Stas) This is wrong. Modified only to satisfy compilation.
+		node = node.parents[0] // TODO: (Stas) This is wrong. Modified only to satisfy compilation.
 	}
 	return hashes, nil
 }

blockdag/chainio.go

@@ -1162,7 +1162,7 @@ func (b *BlockChain) initChainState() error {
 			// Initialize the block node for the block, connect it,
 			// and add it to the block index.
 			node := &blockNodes[i]
-			initBlockNode(node, header, []blockNode{*parent}) // TODO: (Stas) This is wrong. Modified only to satisfy compilation.
+			initBlockNode(node, header, []*blockNode{parent}) // TODO: (Stas) This is wrong. Modified only to satisfy compilation.
 			node.status = status
 			b.index.addNode(node)
 

blockdag/chainview.go

@@ -141,7 +141,7 @@ func (c *chainView) setTip(node *blockNode) {
 
 	for node != nil && c.nodes[node.height] != node {
 		c.nodes[node.height] = node
-		node = &node.parents[0] // TODO: (Stas) This is wrong. Modified only to satisfy compilation.
+		node = node.parents[0] // TODO: (Stas) This is wrong. Modified only to satisfy compilation.
 	}
 }
 
@@ -311,7 +311,7 @@ func (c *chainView) findFork(node *blockNode) *blockNode {
 	// contain the node or there are no more nodes in which case there is no
 	// common node between the two.
 	for node != nil && !c.contains(node) {
-		node = &node.parents[0] // TODO: (Stas) This is wrong. Modified only to satisfy compilation.
+		node = node.parents[0] // TODO: (Stas) This is wrong. Modified only to satisfy compilation.
 	}
 
 	return node

blockdag/chainview_test.go

@@ -31,7 +31,7 @@ func chainedNodes(parent *blockNode, numNodes int) []*blockNode {
 		if tip != nil {
 			header.PrevBlocks = []daghash.Hash{tip.hash} // TODO: (Stas) This is wrong. Modified only to satisfy compilation.
 		}
-		nodes[i] = newBlockNode(&header, []blockNode{*tip}) // TODO: (Stas) This is wrong. Modified only to satisfy compilation.
+		nodes[i] = newBlockNode(&header, []*blockNode{tip}) // TODO: (Stas) This is wrong. Modified only to satisfy compilation.
 		tip = nodes[i]
 	}
 	return nodes

blockdag/common_test.go

@@ -380,5 +380,5 @@ func newFakeNode(parent *blockNode, blockVersion int32, bits uint32, timestamp t
 		Bits:       bits,
 		Timestamp:  timestamp,
 	}
-	return newBlockNode(header, []blockNode{*parent}) // TODO: (Stas) This is wrong. Modified only to satisfy compilation.
+	return newBlockNode(header, []*blockNode{parent}) // TODO: (Stas) This is wrong. Modified only to satisfy compilation.
 }

blockdag/difficulty.go

@@ -201,7 +201,7 @@ func (b *BlockChain) findPrevTestNetDifficulty(startNode *blockNode) uint32 {
 	for iterNode != nil && iterNode.height%b.blocksPerRetarget != 0 &&
 		iterNode.bits == b.chainParams.PowLimitBits {
 
-		iterNode = &iterNode.parents[0] // TODO: (Stas) This is wrong. Modified only to satisfy compilation.
+		iterNode = iterNode.parents[0] // TODO: (Stas) This is wrong. Modified only to satisfy compilation.
 	}
 
 	// Return the found difficulty or the minimum difficulty if no

blockdag/process.go

@@ -211,11 +211,8 @@ func (b *BlockChain) ProcessBlock(block *btcutil.Block, flags BehaviorFlags) (bo
 	}
 
 	// Handle orphan blocks.
-	numPrevHashes := blockHeader.NumPrevBlocks
-	prevHashes := blockHeader.PrevBlocks
 	allPrevHashesExist := true
-	for i := byte(0); i < numPrevHashes; i++ {
+	for _, prevHash := range blockHeader.PrevBlocks {
-		prevHash := prevHashes[i]
 		prevHashExists, err := b.blockExists(&prevHash)
 		if err != nil {
 			return false, false, err

blockdag/thresholdstate.go

@@ -230,7 +230,7 @@ func (b *BlockChain) thresholdState(prevNode *blockNode, checker thresholdCondit
 				}
 
 				// Get the previous block node.
-				countNode = &countNode.parents[0] // TODO: (Stas) This is wrong. Modified only to satisfy compilation.
+				countNode = countNode.parents[0] // TODO: (Stas) This is wrong. Modified only to satisfy compilation.
 			}
 
 			// The state is locked in if the number of blocks in the
@@ -316,7 +316,7 @@ func (b *BlockChain) initThresholdCaches() error {
 	// threshold state for each of them.  This will ensure the caches are
 	// populated and any states that needed to be recalculated due to
 	// definition changes is done now.
-	prevNode := &b.bestChain.Tip().parents[0] // TODO: (Stas) This is wrong. Modified only to satisfy compilation.
+	prevNode := b.bestChain.Tip().parents[0] // TODO: (Stas) This is wrong. Modified only to satisfy compilation.
 	for bit := uint32(0); bit < vbNumBits; bit++ {
 		checker := bitConditionChecker{bit: bit, chain: b}
 		cache := &b.warningCaches[bit]

blockdag/validate.go

@@ -1141,7 +1141,7 @@ func (b *BlockChain) checkConnectBlock(node *blockNode, block *btcutil.Block, vi
 
 	// Enforce CHECKSEQUENCEVERIFY during all block validation checks once
 	// the soft-fork deployment is fully active.
-	csvState, err := b.deploymentState(&node.parents[0], dagconfig.DeploymentCSV) // TODO: (Stas) This is wrong. Modified only to satisfy compilation.
+	csvState, err := b.deploymentState(node.parents[0], dagconfig.DeploymentCSV) // TODO: (Stas) This is wrong. Modified only to satisfy compilation.
 	if err != nil {
 		return err
 	}
@@ -1232,6 +1232,6 @@ func (b *BlockChain) CheckConnectBlockTemplate(block *btcutil.Block) error {
 	// is not needed and thus extra work can be avoided.
 	view := NewUtxoViewpoint()
 	view.SetBestHash(&tip.hash)
-	newNode := newBlockNode(&header, []blockNode{*tip}) // TODO: (Stas) This is wrong. Modified only to satisfy compilation.
+	newNode := newBlockNode(&header, []*blockNode{tip}) // TODO: (Stas) This is wrong. Modified only to satisfy compilation.
 	return b.checkConnectBlock(newNode, block, view, nil)
 }

blockdag/versionbits.go

@@ -113,7 +113,7 @@ func (c bitConditionChecker) Condition(node *blockNode) (bool, error) {
 		return false, nil
 	}
 
-	expectedVersion, err := c.chain.calcNextBlockVersion(&node.parents[0]) // TODO: (Stas) This is wrong. Modified only to satisfy compilation.
+	expectedVersion, err := c.chain.calcNextBlockVersion(node.parents[0]) // TODO: (Stas) This is wrong. Modified only to satisfy compilation.
 	if err != nil {
 		return false, err
 	}
@@ -241,7 +241,7 @@ func (b *BlockChain) warnUnknownRuleActivations(node *blockNode) error {
 	for bit := uint32(0); bit < vbNumBits; bit++ {
 		checker := bitConditionChecker{bit: bit, chain: b}
 		cache := &b.warningCaches[bit]
-		state, err := b.thresholdState(&node.parents[0], checker, cache) // TODO: (Stas) This is wrong. Modified only to satisfy compilation.
+		state, err := b.thresholdState(node.parents[0], checker, cache) // TODO: (Stas) This is wrong. Modified only to satisfy compilation.
 		if err != nil {
 			return err
 		}
@@ -278,7 +278,7 @@ func (b *BlockChain) warnUnknownVersions(node *blockNode) error {
 	// Warn if enough previous blocks have unexpected versions.
 	numUpgraded := uint32(0)
 	for i := uint32(0); i < unknownVerNumToCheck && node != nil; i++ {
-		expectedVersion, err := b.calcNextBlockVersion(&node.parents[0]) // TODO: (Stas) This is wrong. Modified only to satisfy compilation.
+		expectedVersion, err := b.calcNextBlockVersion(node.parents[0]) // TODO: (Stas) This is wrong. Modified only to satisfy compilation.
 		if err != nil {
 			return err
 		}
@@ -288,7 +288,7 @@ func (b *BlockChain) warnUnknownVersions(node *blockNode) error {
 			numUpgraded++
 		}
 
-		node = &node.parents[0] // TODO: (Stas) This is wrong. Modified only to satisfy compilation.
+		node = node.parents[0] // TODO: (Stas) This is wrong. Modified only to satisfy compilation.
 	}
 	if numUpgraded > unknownVerWarnNum {
 		log.Warn("Unknown block versions are being mined, so new " +