blockchain: Accept parent in blockNode constructor.

This modifies the newBlockNode function to accept the parent as an
argument to automatically connect the newly created node.  When it is
not nil, the work sum will automatically be summed and the parent of the
new node will be set accordingly.

This simplifies the block node construction a bit and allows some
redundant code to be removed.  It also paves the way for easier simpler
full block index construction in the future.

blockchain/accept.go

@@ -126,8 +126,6 @@ func (b *BlockChain) maybeAcceptBlock(block *dcrutil.Block, flags BehaviorFlags)
 		return false, ruleError(ErrMissingParent, str)
 	}
 
-	blockHeight := block.Height()
-
 	// 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, prevNode, flags)
@@ -160,11 +158,8 @@ func (b *BlockChain) maybeAcceptBlock(block *dcrutil.Block, flags BehaviorFlags)
 	// Create a new block node for the block and add it to the in-memory
 	// block chain (could be either a side chain or the main chain).
 	blockHeader := &block.MsgBlock().Header
-	newNode := newBlockNode(blockHeader)
+	newNode := newBlockNode(blockHeader, prevNode)
 	newNode.populateTicketInfo(stake.FindSpentTicketsInBlock(block.MsgBlock()))
-	newNode.parent = prevNode
-	newNode.height = blockHeight
-	newNode.workSum.Add(prevNode.workSum, newNode.workSum)
 
 	// Fetching a stake node could enable a new DoS vector, so restrict
 	// this only to blocks that are recent in history.

blockchain/blockindex.go

@@ -91,11 +91,10 @@ type blockNode struct {
 	votes []stake.VoteVersionTuple
 }
 
-// newBlockNode returns a new block node for the given block header.  It is
-// completely disconnected from the chain and the workSum value is just the work
-// for the passed block.  The work sum is updated accordingly when the node is
-// inserted into a chain.
-func newBlockNode(blockHeader *wire.BlockHeader) *blockNode {
+// newBlockNode returns a new block node for the given block header and parent
+// node.  The workSum is calculated based on the parent, or, in the case no
+// parent is provided, it will just be the work for the passed block.
+func newBlockNode(blockHeader *wire.BlockHeader, parent *blockNode) *blockNode {
 	// Serialize the block header for use in calculating the initialization
 	// vector for the ticket lottery.  The only way this can fail is if the
 	// process is out of memory in which case it would panic anyways, so
@@ -132,6 +131,10 @@ func newBlockNode(blockHeader *wire.BlockHeader) *blockNode {
 		stakeVersion: blockHeader.StakeVersion,
 		lotteryIV:    stake.CalcHash256PRNGIV(hB),
 	}
+	if parent != nil {
+		node.parent = parent
+		node.workSum = node.workSum.Add(parent.workSum, node.workSum)
+	}
 
 	return &node
 }
@@ -253,7 +256,7 @@ func (bi *blockIndex) loadBlockNode(dbTx database.Tx, hash *chainhash.Hash) (*bl
 
 	// Create the new block node for the block.
 	blockHeader := block.MsgBlock().Header
-	node := newBlockNode(&blockHeader)
+	node := newBlockNode(&blockHeader, nil)
 	node.populateTicketInfo(stake.FindSpentTicketsInBlock(block.MsgBlock()))
 	node.inMainChain = true
 

blockchain/blockindex_test.go

@@ -54,9 +54,8 @@ func TestBlockNodeHeader(t *testing.T) {
 		ExtraData:    [32]byte{0xbb},
 		StakeVersion: 5,
 	}
-	node := newBlockNode(&testHeader)
+	node := newBlockNode(&testHeader, bc.bestNode)
 	bc.index.AddNode(node)
-	node.parent = bc.bestNode
 
 	// Ensure reconstructing the header for the node produces the same header
 	// used to create the node.

blockchain/chainio.go

@@ -1268,7 +1268,7 @@ func (b *BlockChain) createChainState() error {
 	// Create a new node from the genesis block and set it as the best node.
 	genesisBlock := dcrutil.NewBlock(b.chainParams.GenesisBlock)
 	header := &genesisBlock.MsgBlock().Header
-	node := newBlockNode(header)
+	node := newBlockNode(header, nil)
 	node.inMainChain = true
 
 	// Initialize the state related to the best block.  Since it is the
@@ -1476,7 +1476,7 @@ func (b *BlockChain) initChainState(interrupt <-chan struct{}) error {
 		// Create a new node and set it as the best node.  The preceding
 		// nodes will be loaded on demand as needed.
 		header := &block.Header
-		node := newBlockNode(header)
+		node := newBlockNode(header, nil)
 		node.populateTicketInfo(stake.FindSpentTicketsInBlock(&block))
 		node.inMainChain = true
 		node.workSum = state.workSum

blockchain/difficulty.go

@@ -1087,8 +1087,7 @@ func (b *BlockChain) estimateNextStakeDifficultyV1(curNode *blockNode, ticketsIn
 			// Connect the header.
 			emptyHeader.PrevBlock = topNode.hash
 
-			thisNode := newBlockNode(&emptyHeader)
-			thisNode.parent = topNode
+			thisNode := newBlockNode(&emptyHeader, topNode)
 			topNode = thisNode
 		}
 	}

blockchain/difficulty_test.go

@@ -428,8 +428,7 @@ nextTest:
 					FreshStake: ticketInfo.newTickets,
 					PoolSize:   poolSize,
 				}
-				node := newBlockNode(header)
-				node.parent = bc.bestNode
+				node := newBlockNode(header, bc.bestNode)
 
 				// Update the pool size for the next header.
 				// Notice how tickets that mature for this block
@@ -729,8 +728,7 @@ nextTest:
 					FreshStake: ticketInfo.newTickets,
 					PoolSize:   poolSize,
 				}
-				node := newBlockNode(header)
-				node.parent = bc.bestNode
+				node := newBlockNode(header, bc.bestNode)
 
 				// Update the pool size for the next header.
 				// Notice how tickets that mature for this block

blockchain/internal_test.go

@@ -39,6 +39,6 @@ func (b *BlockChain) TstCheckBlockHeaderContext(header *wire.BlockHeader, prevNo
 
 // TstNewBlockNode makes the internal newBlockNode function available to the
 // test package.
-func TstNewBlockNode(blockHeader *wire.BlockHeader) *blockNode {
-	return newBlockNode(blockHeader)
+func TstNewBlockNode(blockHeader *wire.BlockHeader, parent *blockNode) *blockNode {
+	return newBlockNode(blockHeader, parent)
 }

blockchain/stakeversion_test.go

@@ -22,7 +22,7 @@ import (
 func newFakeChain(params *chaincfg.Params) *BlockChain {
 	// Create a genesis block node and block index populated with it for use
 	// when creating the fake chain below.
-	node := newBlockNode(&params.GenesisBlock.Header)
+	node := newBlockNode(&params.GenesisBlock.Header, nil)
 	node.inMainChain = true
 	index := newBlockIndex(nil, params)
 	index.AddNode(node)
@@ -53,10 +53,7 @@ func newFakeNode(parent *blockNode, blockVersion int32, stakeVersion uint32, bit
 		Timestamp:    timestamp,
 		StakeVersion: stakeVersion,
 	}
-	node := newBlockNode(header)
-	node.parent = parent
-	node.workSum.Add(parent.workSum, node.workSum)
-	return node
+	return newBlockNode(header, parent)
 }
 
 // appendFakeVotes appends the passed number of votes to the node with the

blockchain/validate.go

@@ -2601,10 +2601,8 @@ func (b *BlockChain) CheckConnectBlock(block *dcrutil.Block, flags BehaviorFlags
 		return err
 	}
 
-	newNode := newBlockNode(&block.MsgBlock().Header)
+	newNode := newBlockNode(&block.MsgBlock().Header, prevNode)
 	newNode.populateTicketInfo(stake.FindSpentTicketsInBlock(block.MsgBlock()))
-	newNode.parent = prevNode
-	newNode.workSum.Add(prevNode.workSum, newNode.workSum)
 
 	// If we are extending the main (best) chain with a new block, just use
 	// the ticket database we already have.

blockchain/validate_test.go

@@ -2110,7 +2110,7 @@ func TestCheckWorklessBlockSanity(t *testing.T) {
 }
 
 // TestCheckBlockHeaderContext tests that genesis block passes context headers
-// because it's previousNode is nil.
+// because its parent is nil.
 func TestCheckBlockHeaderContext(t *testing.T) {
 	// Create a new database for the blocks.
 	params := &chaincfg.SimNetParams
@@ -2145,7 +2145,7 @@ func TestCheckBlockHeaderContext(t *testing.T) {
 	// Test failing checkBlockHeaderContext when calcNextRequiredDifficulty
 	// fails.
 	block := dcrutil.NewBlock(&badBlock)
-	newNode := blockchain.TstNewBlockNode(&block.MsgBlock().Header)
+	newNode := blockchain.TstNewBlockNode(&block.MsgBlock().Header, nil)
 	err = chain.TstCheckBlockHeaderContext(&block.MsgBlock().Header, newNode, blockchain.BFNone)
 	if err == nil {
 		t.Fatalf("Should fail due to bad diff in newNode\n")