[DEV-34] Added selectedParent to blockNode.

blockdag/blockindex.go

@@ -74,6 +74,9 @@ type blockNode struct {
 	// parents is the parent blocks for this node.
 	parents []*blockNode
 
+	// selectedParent is the selected parent for this node.
+	selectedParent *blockNode
+
 	// hash is the double sha 256 of the block.
 	hash daghash.Hash
 
@@ -117,9 +120,9 @@ func initBlockNode(node *blockNode, blockHeader *wire.BlockHeader, parents []*bl
 		merkleRoot: blockHeader.MerkleRoot,
 	}
 	if len(parents) > 0 {
-		parent := parents[0] // TODO: (Stas) This is wrong. Modified only to satisfy compilation.
+		node.selectedParent = parents[0]
-		node.height = parent.height + 1
+		node.height = node.selectedParent.height + 1
-		node.workSum = node.workSum.Add(parent.workSum, node.workSum)
+		node.workSum = node.workSum.Add(node.selectedParent.workSum, node.workSum)
 	}
 }
 
@@ -160,7 +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.selectedParent {
 		// Intentionally left blank
 	}
 
@@ -190,7 +193,7 @@ func (node *blockNode) CalcPastMedianTime() time.Time {
 		timestamps[i] = iterNode.timestamp
 		numNodes++
 
-		iterNode = iterNode.parents[0]
+		iterNode = iterNode.selectedParent
 	}
 
 	// Prune the slice to the actual number of available timestamps which

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.selectedParent, dagconfig.DeploymentCSV)
 		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.selectedParent).KnownInvalid() {
 		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.selectedParent {
 		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.Tips()[0]; n != nil && n != forkNode; n = n.parents[0] { // TODO: (Stas) This is wrong. Modified only to satisfy compilation.
+	for n := b.bestChain.Tips()[0]; n != nil && n != forkNode; n = n.selectedParent {
 		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.selectedParent
 	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.selectedParent)
 
 	// Update the state for the best block.  Notice how this replaces the
 	// entire struct instead of updating the existing one.  This effectively
@@ -1003,7 +1003,7 @@ func (b *BlockChain) reorganizeChain(detachNodes, attachNodes *list.List) error
 	firstAttachNode := attachNodes.Front().Value.(*blockNode)
 	firstDetachNode := detachNodes.Front().Value.(*blockNode)
 	lastAttachNode := attachNodes.Back().Value.(*blockNode)
-	log.Infof("REORGANIZE: Chain forks at %v", firstAttachNode.parents[0].hash) // TODO: (Stas) This is wrong. Modified only to satisfy compilation.
+	log.Infof("REORGANIZE: Chain forks at %v", firstAttachNode.selectedParent.hash)
 	log.Infof("REORGANIZE: Old best chain head was %v", firstDetachNode.hash)
 	log.Infof("REORGANIZE: New best chain head is %v", lastAttachNode.hash)
 
@@ -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.selectedParent
 	}
 	return hashes, nil
 }

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.selectedParent
 	}
 }
 
@@ -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.selectedParent
 	}
 
 	return node

blockdag/checkpoints.go

@@ -234,14 +234,14 @@ func (b *BlockChain) IsCheckpointCandidate(block *btcutil.Block) (bool, error) {
 	}
 
 	// A checkpoint must be have at least one block before it.
-	if &node.parents[0] == nil { // TODO: (Stas) This is wrong. Modified only to satisfy compilation.
+	if &node.selectedParent == nil {
 		return false, nil
 	}
 
 	// A checkpoint must have timestamps for the block and the blocks on
 	// either side of it in order (due to the median time allowance this is
 	// not always the case).
-	prevTime := time.Unix(node.parents[0].timestamp, 0) // TODO: (Stas) This is wrong. Modified only to satisfy compilation.
+	prevTime := time.Unix(node.selectedParent.timestamp, 0)
 	curTime := block.MsgBlock().Header.Timestamp
 	nextTime := time.Unix(nextNode.timestamp, 0)
 	if prevTime.After(curTime) || nextTime.Before(curTime) {

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.selectedParent
 	}
 
 	// Return the found difficulty or the minimum difficulty if no

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.selectedParent
 			}
 
 			// 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.Tips()[0].parents[0] // TODO: (Stas) This is wrong. Modified only to satisfy compilation.
+	prevNode := b.bestChain.Tips()[0].selectedParent // 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.selectedParent, dagconfig.DeploymentCSV)
 	if err != nil {
 		return err
 	}
@@ -1153,7 +1153,7 @@ func (b *BlockChain) checkConnectBlock(node *blockNode, block *btcutil.Block, vi
 
 		// We obtain the MTP of the *previous* block in order to
 		// determine if transactions in the current block are final.
-		medianTime := node.parents[0].CalcPastMedianTime() // TODO: (Stas) This is wrong. Modified only to satisfy compilation.
+		medianTime := node.selectedParent.CalcPastMedianTime()
 
 		// Additionally, if the CSV soft-fork package is now active,
 		// then we also enforce the relative sequence number based

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.selectedParent)
 	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.selectedParent, checker, cache)
 		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.selectedParent)
 		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.selectedParent
 	}
 	if numUpgraded > unknownVerWarnNum {
 		log.Warn("Unknown block versions are being mined, so new " +