[DEV-303] Implement block finality (#139)

* [DEV-303] Implement block finality

* [DEV-303] Add finality tests

* [DEV-303] Make finality tests use maybeAcceptBlock

* [DEV-303] Only check finality rules if we are fastAdd mode

* [DEV-303] replace hasBiggerFinalityScoreThan checks with .finalityScore()

blockdag/blocknode.go

@@ -244,6 +244,10 @@ func (node *blockNode) isGenesis() bool {
 	return len(node.parents) == 0
 }
 
+func (node *blockNode) finalityScore() uint64 {
+	return node.blueScore / finalityInterval
+}
+
 // String returns a string that contains the block hash and height.
 func (node blockNode) String() string {
 	return fmt.Sprintf("%s (%d)", node.hash, node.height)

blockdag/blocknode_test.go

@@ -6,24 +6,19 @@ import (
 
 func TestChainHeight(t *testing.T) {
 	phantomK := uint32(2)
-	buildNode := buildNodeGenerator(phantomK)
+	buildNode := buildNodeGenerator(phantomK, true)
-	buildWithChildren := func(parents blockSet) *blockNode {
-		node := buildNode(parents)
-		addNodeAsChildToParents(node)
-		return node
-	}
 
-	node0 := buildWithChildren(setFromSlice())
+	node0 := buildNode(setFromSlice())
-	node1 := buildWithChildren(setFromSlice(node0))
+	node1 := buildNode(setFromSlice(node0))
-	node2 := buildWithChildren(setFromSlice(node0))
+	node2 := buildNode(setFromSlice(node0))
-	node3 := buildWithChildren(setFromSlice(node0))
+	node3 := buildNode(setFromSlice(node0))
-	node4 := buildWithChildren(setFromSlice(node1, node2, node3))
+	node4 := buildNode(setFromSlice(node1, node2, node3))
-	node5 := buildWithChildren(setFromSlice(node1, node2, node3))
+	node5 := buildNode(setFromSlice(node1, node2, node3))
-	node6 := buildWithChildren(setFromSlice(node1, node2, node3))
+	node6 := buildNode(setFromSlice(node1, node2, node3))
-	node7 := buildWithChildren(setFromSlice(node0))
+	node7 := buildNode(setFromSlice(node0))
-	node8 := buildWithChildren(setFromSlice(node7))
+	node8 := buildNode(setFromSlice(node7))
-	node9 := buildWithChildren(setFromSlice(node8))
+	node9 := buildNode(setFromSlice(node8))
-	node10 := buildWithChildren(setFromSlice(node9, node6))
+	node10 := buildNode(setFromSlice(node9, node6))
 
 	// Because nodes 7 & 8 were mined secretly, node10's selected
 	// parent will be node6, although node9 is higher. So in this

blockdag/common_test.go

@@ -200,15 +200,23 @@ func addNodeAsChildToParents(node *blockNode) {
 	}
 }
 
-func buildNodeGenerator(phantomK uint32) func(parents blockSet) *blockNode {
+func buildNodeGenerator(phantomK uint32, withChildren bool) func(parents blockSet) *blockNode {
 	// For the purposes of these tests, we'll create blockNodes whose hashes are a
-	// series of numbers from 0 to n.
+	// series of numbers from 1 to 255.
-	hashCounter := byte(0)
+	hashCounter := byte(1)
-	return func(parents blockSet) *blockNode {
+	buildNode := func(parents blockSet) *blockNode {
 		block := newBlockNode(nil, parents, phantomK)
 		block.hash = daghash.Hash{hashCounter}
 		hashCounter++
 
 		return block
 	}
+	if withChildren {
+		return func(parents blockSet) *blockNode {
+			node := buildNode(parents)
+			addNodeAsChildToParents(node)
+			return node
+		}
+	}
+	return buildNode
 }

blockdag/dag.go

@@ -23,6 +23,8 @@ const (
 	// maxOrphanBlocks is the maximum number of orphan blocks that can be
 	// queued.
 	maxOrphanBlocks = 100
+
+	finalityInterval = 100
 )
 
 // BlockLocator is used to help locate a specific block.  The algorithm for
@@ -138,6 +140,8 @@ type BlockDAG struct {
 	// certain blockchain events.
 	notificationsLock sync.RWMutex
 	notifications     []NotificationCallback
+
+	lastFinalityPoint *blockNode
 }
 
 // HaveBlock returns whether or not the DAG instance has the block represented
@@ -503,12 +507,26 @@ func (dag *BlockDAG) connectBlock(node *blockNode, block *util.Block, fastAdd bo
 		}
 	}
 
+	var finalityPointCandidate *blockNode
+
+	if !fastAdd {
+		var err error
+		finalityPointCandidate, err = dag.checkFinalityRulesAndGetFinalityPointCandidate(node)
+		if err != nil {
+			return err
+		}
+	}
+
 	// Add the node to the virtual and update the UTXO set of the DAG.
 	utxoDiff, acceptedTxsData, err := dag.applyUTXOChanges(node, block, fastAdd)
 	if err != nil {
 		return err
 	}
 
+	if finalityPointCandidate != nil {
+		dag.lastFinalityPoint = finalityPointCandidate
+	}
+
 	// Write any block status changes to DB before updating the DAG state.
 	err = dag.index.flushToDB()
 	if err != nil {
@@ -518,7 +536,11 @@ func (dag *BlockDAG) connectBlock(node *blockNode, block *util.Block, fastAdd bo
 	// Atomically insert info into the database.
 	err = dag.db.Update(func(dbTx database.Tx) error {
 		// Update best block state.
-		err := dbPutDAGTipHashes(dbTx, dag.TipHashes())
+		state := &dagState{
+			TipHashes:         dag.TipHashes(),
+			LastFinalityPoint: dag.lastFinalityPoint.hash,
+		}
+		err := dbPutDAGState(dbTx, state)
 		if err != nil {
 			return err
 		}
@@ -563,6 +585,27 @@ func (dag *BlockDAG) connectBlock(node *blockNode, block *util.Block, fastAdd bo
 	return nil
 }
 
+func (dag *BlockDAG) checkFinalityRulesAndGetFinalityPointCandidate(node *blockNode) (*blockNode, error) {
+	var finalityPointCandidate *blockNode
+	finalityErr := ruleError(ErrFinality, "The last finality point is not in the selected chain of this block")
+
+	if node.blueScore <= dag.lastFinalityPoint.blueScore {
+		return nil, finalityErr
+	}
+
+	shouldFindFinalityPointCandidate := node.finalityScore() > dag.lastFinalityPoint.finalityScore()
+
+	for currentNode := node.selectedParent; currentNode != dag.lastFinalityPoint; currentNode = currentNode.selectedParent {
+		if currentNode.blueScore <= dag.lastFinalityPoint.blueScore {
+			return nil, finalityErr
+		}
+		if shouldFindFinalityPointCandidate && currentNode.finalityScore() > currentNode.selectedParent.finalityScore() {
+			finalityPointCandidate = currentNode
+		}
+	}
+	return finalityPointCandidate, nil
+}
+
 // applyUTXOChanges does the following:
 // 1. Verifies that each transaction within the new block could spend an existing UTXO.
 // 2. Connects each of the new block's parents to the block.
@@ -1528,7 +1571,7 @@ func New(config *Config) (*BlockDAG, error) {
 	}
 
 	// Initialize the chain state from the passed database.  When the db
-	// does not yet contain any chain state, both it and the chain state
+	// does not yet contain any DAG state, both it and the DAG state
 	// will be initialized to contain only the genesis block.
 	if err := dag.initDAGState(); err != nil {
 		return nil, err

blockdag/dag_test.go

@@ -40,16 +40,16 @@ func TestBlockCount(t *testing.T) {
 		blocks = append(blocks, blockTmp...)
 	}
 
-	// Create a new database and chain instance to run tests against.
+	// Create a new database and DAG instance to run tests against.
 	dag, teardownFunc, err := DAGSetup("haveblock", Config{
 		DAGParams: &dagconfig.SimNetParams,
 	})
 	if err != nil {
-		t.Fatalf("Failed to setup chain instance: %v", err)
+		t.Fatalf("Failed to setup DAG instance: %v", err)
 	}
 	defer teardownFunc()
 
-	// Since we're not dealing with the real block chain, set the coinbase
+	// Since we're not dealing with the real block DAG, set the coinbase
 	// maturity to 1.
 	dag.TstSetCoinbaseMaturity(1)
 
@@ -849,3 +849,132 @@ func testErrorThroughPatching(t *testing.T, expectedErrorMessage string, targetF
 			"Want: %s, got: %s", expectedErrorMessage, err)
 	}
 }
+
+// TestFinality checks that the finality mechanism works as expected.
+// This is how the flow goes:
+// 1) We build a chain of finalityInterval blocks and call its tip altChainTip.
+// 2) We build another chain (let's call it mainChain) of 2 * finalityInterval
+// blocks, which points to genesis, and then we check that the block in that
+// chain with height of finalityInterval is marked as finality point (This is
+// very predictable, because the blue score of each new block in a chain is the
+// parents plus one).
+// 3) We make a new child to block with height (2 * finalityInterval - 1)
+// in mainChain, and we check that connecting it to the DAG
+// doesn't affect the last finality point.
+// 4) We make a block that points to genesis, and check that it
+// gets rejected because its blue score is lower then the last finality
+// point.
+// 5) We make a block that points to altChainTip, and check that it
+// gets rejected because it doesn't have the last finality point in
+// its selected parent chain.
+func TestFinality(t *testing.T) {
+	params := dagconfig.SimNetParams
+	params.K = 1
+	dag, teardownFunc, err := DAGSetup("TestFinality", Config{
+		DAGParams: &params,
+	})
+	if err != nil {
+		t.Fatalf("Failed to setup DAG instance: %v", err)
+	}
+	defer teardownFunc()
+	blockTime := time.Unix(dag.genesis.timestamp, 0)
+	extraNonce := int64(0)
+	buildNodeToDag := func(parents blockSet) (*blockNode, error) {
+		// We need to change the blockTime to keep all block hashes unique
+		blockTime = blockTime.Add(time.Second)
+
+		// We need to change the extraNonce to keep coinbase hashes unique
+		extraNonce++
+
+		bh := &wire.BlockHeader{
+			Version:      1,
+			Bits:         dag.genesis.bits,
+			ParentHashes: parents.hashes(),
+			Timestamp:    blockTime,
+		}
+		msgBlock := wire.NewMsgBlock(bh)
+		blockHeight := parents.maxHeight() + 1
+		coinbaseTx, err := createCoinbaseTx(blockHeight, 1, extraNonce, dag.dagParams)
+		if err != nil {
+			return nil, err
+		}
+		msgBlock.AddTransaction(coinbaseTx)
+		block := util.NewBlock(msgBlock)
+
+		dag.dagLock.Lock()
+		defer dag.dagLock.Unlock()
+
+		err = dag.maybeAcceptBlock(block, BFNone)
+		if err != nil {
+			return nil, err
+		}
+
+		return dag.index.LookupNode(block.Hash()), nil
+	}
+
+	currentNode := dag.genesis
+
+	// First we build a chain of finalityInterval blocks for future use
+	for currentNode.blueScore < finalityInterval {
+		currentNode, err = buildNodeToDag(setFromSlice(currentNode))
+		if err != nil {
+			t.Fatalf("TestFinality: buildNodeToDag unexpectedly returned an error: %v", err)
+		}
+	}
+
+	altChainTip := currentNode
+
+	// Now we build a new chain of 2 * finalityInterval blocks, pointed to genesis, and
+	// we expect the block with height 1 * finalityInterval to be the last finality point
+	currentNode = dag.genesis
+	for currentNode.blueScore < finalityInterval {
+		currentNode, err = buildNodeToDag(setFromSlice(currentNode))
+		if err != nil {
+			t.Fatalf("TestFinality: buildNodeToDag unexpectedly returned an error: %v", err)
+		}
+	}
+
+	expectedFinalityPoint := currentNode
+
+	for currentNode.blueScore < 2*finalityInterval {
+		currentNode, err = buildNodeToDag(setFromSlice(currentNode))
+		if err != nil {
+			t.Fatalf("TestFinality: buildNodeToDag unexpectedly returned an error: %v", err)
+		}
+	}
+
+	if dag.lastFinalityPoint != expectedFinalityPoint {
+		t.Errorf("TestFinality: dag.lastFinalityPoint expected to be %v but got %v", expectedFinalityPoint, dag.lastFinalityPoint)
+	}
+
+	// Here we check that even if we create a parallel tip (a new tip with
+	// the same parents as the current one) with the same blue score as the
+	// current tip, it still won't affect the last finality point.
+	_, err = buildNodeToDag(setFromSlice(currentNode.selectedParent))
+	if err != nil {
+		t.Fatalf("TestFinality: buildNodeToDag unexpectedly returned an error: %v", err)
+	}
+	if dag.lastFinalityPoint != expectedFinalityPoint {
+		t.Errorf("TestFinality: dag.lastFinalityPoint was unexpectly changed")
+	}
+
+	// Here we check that a block with lower blue score than the last finality
+	// point will get rejected
+	nodeWithLowBlueScore, err := buildNodeToDag(setFromSlice(dag.genesis))
+	if err != nil {
+		t.Fatalf("TestFinality: buildNodeToDag unexpectedly returned an error: %v", err)
+	}
+	if !dag.index.NodeStatus(nodeWithLowBlueScore).KnownInvalid() {
+		t.Errorf("TestFinality: nodeWithLowBlueScore was expected to be invalid, but got valid instead")
+	}
+
+	// Here we check that a block that doesn't have the last finality point in
+	// its selected parent chain will get rejected
+	nodeWithFinalityPointInAnticone, err := buildNodeToDag(setFromSlice(altChainTip))
+	if err != nil {
+		t.Fatalf("TestFinality: buildNodeToDag unexpectedly returned an error: %v", err)
+	}
+	if !dag.index.NodeStatus(nodeWithFinalityPointInAnticone).KnownInvalid() {
+		t.Errorf("TestFinality: invalidNode was expected to be invalid, but got valid instead")
+	}
+}

blockdag/dagio.go

@@ -41,9 +41,9 @@ var (
 	// the block height -> block hash index.
 	heightIndexBucketName = []byte("heightidx")
 
-	// dagTipHashesKeyName is the name of the db key used to store the DAG
+	// dagStateKeyName is the name of the db key used to store the DAG
 	// tip hashes.
-	dagTipHashesKeyName = []byte("dagtiphashes")
+	dagStateKeyName = []byte("dagstate")
 
 	// utxoSetVersionKeyName is the name of the db key used to store the
 	// version of the utxo set currently in the database.
@@ -697,38 +697,43 @@ func dbFetchHeightByHash(dbTx database.Tx, hash *daghash.Hash) (int32, error) {
 	return int32(byteOrder.Uint32(serializedHeight)), nil
 }
 
-// serializeDAGTipHashes returns the serialization of the DAG tip hashes.
+type dagState struct {
-// This is data to be stored in the DAG tip hashes bucket.
+	TipHashes         []daghash.Hash
-func serializeDAGTipHashes(tipHashes []daghash.Hash) ([]byte, error) {
+	LastFinalityPoint daghash.Hash
-	return json.Marshal(tipHashes)
 }
 
-// deserializeDAGTipHashes deserializes the passed serialized DAG tip hashes.
+// serializeDAGState returns the serialization of the DAG state.
-// This is data stored in the DAG tip hashes bucket and is updated after
+// This is data to be stored in the DAG state bucket.
+func serializeDAGState(state *dagState) ([]byte, error) {
+	return json.Marshal(state)
+}
+
+// deserializeDAGState deserializes the passed serialized DAG state.
+// This is data stored in the DAG state bucket and is updated after
 // every block is connected to the DAG.
-func deserializeDAGTipHashes(serializedData []byte) ([]daghash.Hash, error) {
+func deserializeDAGState(serializedData []byte) (*dagState, error) {
-	var tipHashes []daghash.Hash
+	var state *dagState
-	err := json.Unmarshal(serializedData, &tipHashes)
+	err := json.Unmarshal(serializedData, &state)
 	if err != nil {
 		return nil, database.Error{
 			ErrorCode:   database.ErrCorruption,
-			Description: "corrupt DAG tip hashes",
+			Description: "corrupt DAG state",
 		}
 	}
 
-	return tipHashes, nil
+	return state, nil
 }
 
-// dbPutDAGTipHashes uses an existing database transaction to store the latest
+// dbPutDAGState uses an existing database transaction to store the latest
 // tip hashes of the DAG.
-func dbPutDAGTipHashes(dbTx database.Tx, tipHashes []daghash.Hash) error {
+func dbPutDAGState(dbTx database.Tx, state *dagState) error {
-	serializedData, err := serializeDAGTipHashes(tipHashes)
+	serializedData, err := serializeDAGState(state)
 
 	if err != nil {
 		return err
 	}
 
-	return dbTx.Metadata().Put(dagTipHashesKeyName, serializedData)
+	return dbTx.Metadata().Put(dagStateKeyName, serializedData)
 }
 
 // createDAGState initializes both the database and the DAG state to the
@@ -758,6 +763,9 @@ func (dag *BlockDAG) createDAGState() error {
 	// Add the new node to the index which is used for faster lookups.
 	dag.index.addNode(node)
 
+	// Initiate the last finality point to the genesis block
+	dag.lastFinalityPoint = node
+
 	// Create the initial the database chain state including creating the
 	// necessary index buckets and inserting the genesis block.
 	err := dag.db.Update(func(dbTx database.Tx) error {
@@ -810,8 +818,12 @@ func (dag *BlockDAG) createDAGState() error {
 			return err
 		}
 
-		// Store the current DAG tip hashes into the database.
+		// Store the current DAG state into the database.
-		err = dbPutDAGTipHashes(dbTx, dag.TipHashes())
+		state := &dagState{
+			TipHashes:         dag.TipHashes(),
+			LastFinalityPoint: *genesisBlock.Hash(),
+		}
+		err = dbPutDAGState(dbTx, state)
 		if err != nil {
 			return err
 		}
@@ -830,7 +842,7 @@ func (dag *BlockDAG) initDAGState() error {
 	// everything from scratch or upgrade certain buckets.
 	var initialized bool
 	err := dag.db.View(func(dbTx database.Tx) error {
-		initialized = dbTx.Metadata().Get(dagTipHashesKeyName) != nil
+		initialized = dbTx.Metadata().Get(dagStateKeyName) != nil
 		return nil
 	})
 	if err != nil {
@@ -849,9 +861,9 @@ func (dag *BlockDAG) initDAGState() error {
 		// When it doesn't exist, it means the database hasn't been
 		// initialized for use with the DAG yet, so break out now to allow
 		// that to happen under a writable database transaction.
-		serializedData := dbTx.Metadata().Get(dagTipHashesKeyName)
+		serializedData := dbTx.Metadata().Get(dagStateKeyName)
 		log.Tracef("Serialized DAG tip hashes: %x", serializedData)
-		tipHashes, err := deserializeDAGTipHashes(serializedData)
+		state, err := deserializeDAGState(serializedData)
 		if err != nil {
 			return err
 		}
@@ -977,16 +989,19 @@ func (dag *BlockDAG) initDAGState() error {
 
 		// Apply the stored tips to the virtual block.
 		tips := newSet()
-		for _, tipHash := range tipHashes {
+		for _, tipHash := range state.TipHashes {
 			tip := dag.index.LookupNode(&tipHash)
 			if tip == nil {
 				return AssertError(fmt.Sprintf("initDAGState: cannot find "+
-					"DAG tip %s in block index", tipHashes))
+					"DAG tip %s in block index", state.TipHashes))
 			}
 			tips.add(tip)
 		}
 		dag.virtual.SetTips(tips)
 
+		// Set the last finality point
+		dag.lastFinalityPoint = dag.index.LookupNode(&state.LastFinalityPoint)
+
 		return nil
 	})
 }

blockdag/dagio_test.go

@@ -532,64 +532,70 @@ func TestUtxoEntryDeserializeErrors(t *testing.T) {
 	}
 }
 
-// TestDAGTipHashesSerialization ensures serializing and deserializing the
+// TestDAGStateSerialization ensures serializing and deserializing the
-// DAG tip hashes works as expected.
+// DAG state works as expected.
-func TestDAGTipHashesSerialization(t *testing.T) {
+func TestDAGStateSerialization(t *testing.T) {
 	t.Parallel()
 
 	tests := []struct {
 		name       string
-		tipHashes  []daghash.Hash
+		state      *dagState
 		serialized []byte
 	}{
 		{
 			name: "genesis",
-			tipHashes:  []daghash.Hash{*newHashFromStr("000000000019d6689c085ae165831e934ff763ae46a2a6c172b3f1b60a8ce26f")},
+			state: &dagState{
-			serialized: []byte("[[111,226,140,10,182,241,179,114,193,166,162,70,174,99,247,79,147,30,131,101,225,90,8,156,104,214,25,0,0,0,0,0]]"),
+				LastFinalityPoint: *newHashFromStr("000000000019d6689c085ae165831e934ff763ae46a2a6c172b3f1b60a8ce26f"),
+				TipHashes:         []daghash.Hash{*newHashFromStr("000000000019d6689c085ae165831e934ff763ae46a2a6c172b3f1b60a8ce26f")},
+			},
+			serialized: []byte("{\"TipHashes\":[[111,226,140,10,182,241,179,114,193,166,162,70,174,99,247,79,147,30,131,101,225,90,8,156,104,214,25,0,0,0,0,0]],\"LastFinalityPoint\":[111,226,140,10,182,241,179,114,193,166,162,70,174,99,247,79,147,30,131,101,225,90,8,156,104,214,25,0,0,0,0,0]}"),
 		},
 		{
 			name: "block 1",
-			tipHashes:  []daghash.Hash{*newHashFromStr("00000000839a8e6886ab5951d76f411475428afc90947ee320161bbf18eb6048")},
+			state: &dagState{
-			serialized: []byte("[[72,96,235,24,191,27,22,32,227,126,148,144,252,138,66,117,20,65,111,215,81,89,171,134,104,142,154,131,0,0,0,0]]"),
+				LastFinalityPoint: *newHashFromStr("000000000019d6689c085ae165831e934ff763ae46a2a6c172b3f1b60a8ce26f"),
+				TipHashes:         []daghash.Hash{*newHashFromStr("00000000839a8e6886ab5951d76f411475428afc90947ee320161bbf18eb6048")},
+			},
+			serialized: []byte("{\"TipHashes\":[[72,96,235,24,191,27,22,32,227,126,148,144,252,138,66,117,20,65,111,215,81,89,171,134,104,142,154,131,0,0,0,0]],\"LastFinalityPoint\":[111,226,140,10,182,241,179,114,193,166,162,70,174,99,247,79,147,30,131,101,225,90,8,156,104,214,25,0,0,0,0,0]}"),
 		},
 	}
 
 	for i, test := range tests {
-		gotBytes, err := serializeDAGTipHashes(test.tipHashes)
+		gotBytes, err := serializeDAGState(test.state)
 		if err != nil {
-			t.Errorf("serializeDAGTipHashes #%d (%s) "+
+			t.Errorf("serializeDAGState #%d (%s) "+
 				"unexpected error: %v", i, test.name, err)
 			continue
 		}
 
-		// Ensure the tipHashes serializes to the expected value.
+		// Ensure the dagState serializes to the expected value.
 		if !bytes.Equal(gotBytes, test.serialized) {
-			t.Errorf("serializeDAGTipHashes #%d (%s): mismatched "+
+			t.Errorf("serializeDAGState #%d (%s): mismatched "+
 				"bytes - got %s, want %s", i, test.name,
 				string(gotBytes), string(test.serialized))
 			continue
 		}
 
 		// Ensure the serialized bytes are decoded back to the expected
-		// tipHashes.
+		// dagState.
-		tipHashes, err := deserializeDAGTipHashes(test.serialized)
+		state, err := deserializeDAGState(test.serialized)
 		if err != nil {
-			t.Errorf("deserializeDAGTipHashes #%d (%s) "+
+			t.Errorf("deserializeDAGState #%d (%s) "+
 				"unexpected error: %v", i, test.name, err)
 			continue
 		}
-		if !reflect.DeepEqual(tipHashes, test.tipHashes) {
+		if !reflect.DeepEqual(state, test.state) {
-			t.Errorf("deserializeDAGTipHashes #%d (%s) "+
+			t.Errorf("deserializeDAGState #%d (%s) "+
-				"mismatched tipHashes - got %v, want %v", i,
+				"mismatched state - got %v, want %v", i,
-				test.name, tipHashes, test.tipHashes)
+				test.name, state, test.state)
 			continue
 		}
 	}
 }
 
-// TestDAGTipHashesDeserializeErrors performs negative tests against
+// TestDAGStateDeserializeErrors performs negative tests against
-// deserializing the DAG tip hashes to ensure error paths work as expected.
+// deserializing the DAG state to ensure error paths work as expected.
-func TestDAGTipHashesDeserializeErrors(t *testing.T) {
+func TestDAGStateDeserializeErrors(t *testing.T) {
 	t.Parallel()
 
 	tests := []struct {
@@ -611,9 +617,9 @@ func TestDAGTipHashesDeserializeErrors(t *testing.T) {
 
 	for _, test := range tests {
 		// Ensure the expected error type and code is returned.
-		_, err := deserializeDAGTipHashes(test.serialized)
+		_, err := deserializeDAGState(test.serialized)
 		if reflect.TypeOf(err) != reflect.TypeOf(test.errType) {
-			t.Errorf("deserializeDAGTipHashes (%s): expected "+
+			t.Errorf("deserializeDAGState (%s): expected "+
 				"error type does not match - got %T, want %T",
 				test.name, err, test.errType)
 			continue
@@ -621,7 +627,7 @@ func TestDAGTipHashesDeserializeErrors(t *testing.T) {
 		if derr, ok := err.(database.Error); ok {
 			tderr := test.errType.(database.Error)
 			if derr.ErrorCode != tderr.ErrorCode {
-				t.Errorf("deserializeDAGTipHashes (%s): "+
+				t.Errorf("deserializeDAGState (%s): "+
 					"wrong error code got: %v, want: %v",
 					test.name, derr.ErrorCode,
 					tderr.ErrorCode)

blockdag/error.go

@@ -209,6 +209,8 @@ const (
 	// ErrWithDiff indicates that there was an error with UTXOSet.WithDiff
 	ErrWithDiff
 
+	// ErrFinality indicates that a block doesn't adhere to the finality rules
+	ErrFinality
 	// ErrTransactionsNotSorted indicates that transactions in block are not
 	// sorted by subnetwork
 	ErrTransactionsNotSorted
@@ -256,6 +258,7 @@ var errorCodeStrings = map[ErrorCode]string{
 	ErrInvalidAncestorBlock:      "ErrInvalidAncestorBlock",
 	ErrParentBlockNotCurrentTips: "ErrParentBlockNotCurrentTips",
 	ErrWithDiff:                  "ErrWithDiff",
+	ErrFinality:                  "ErrFinality",
 	ErrTransactionsNotSorted:     "ErrTransactionsNotSorted",
 }
 

blockdag/error_test.go

@@ -55,6 +55,7 @@ func TestErrorCodeStringer(t *testing.T) {
 		{ErrInvalidAncestorBlock, "ErrInvalidAncestorBlock"},
 		{ErrParentBlockNotCurrentTips, "ErrParentBlockNotCurrentTips"},
 		{ErrWithDiff, "ErrWithDiff"},
+		{ErrFinality, "ErrFinality"},
 		{ErrTransactionsNotSorted, "ErrTransactionsNotSorted"},
 		{0xffff, "Unknown ErrorCode (65535)"},
 	}

blockdag/phantom.go

@@ -84,10 +84,24 @@ func traverseCandidates(newBlock *blockNode, candidates blockSet, selectedParent
 		queue.Push(parent)
 	}
 
+	// TODO (Ori): This is temporary until children bug is fixed. After it we should return it to `selectedParentPast.anyChildInSet(current)`
+	isInSelectedParentPast := func(block *blockNode) bool {
+		if selectedParent.parents.contains(block) {
+			return true
+		}
+		for _, child := range block.children {
+			if selectedParentPast.contains(child) {
+				return true
+			}
+		}
+
+		return false
+	}
+
 	for queue.Len() > 0 {
 		current := queue.pop()
 		if candidates.contains(current) {
-			if current == selectedParent || selectedParentPast.anyChildInSet(current) {
+			if current == selectedParent || isInSelectedParentPast(current) {
 				selectedParentPast.add(current)
 			} else {
 				blues = append(blues, current)

blockdag/utxoset.go

@@ -184,7 +184,7 @@ func (d *UTXODiff) diffFrom(other *UTXODiff) (*UTXODiff, error) {
 			result.toRemove.add(outPoint, utxoEntry)
 		}
 		if other.toRemove.contains(outPoint) {
-			return nil, errors.New("diffFrom: transaction both in d.toAdd and in other.toRemove")
+			return nil, fmt.Errorf("diffFrom: outpoint %v both in d.toAdd and in other.toRemove", outPoint)
 		}
 	}
 

blockdag/utxoset_test.go

@@ -803,9 +803,8 @@ func TestDiffUTXOSet_addTx(t *testing.T) {
 // outputs paying an appropriate subsidy based on the passed block height to the
 // address associated with the harness.  It automatically uses a standard
 // signature script that starts with the block height
-func createCoinbaseTx(blockHeight int32, numOutputs uint32) (*wire.MsgTx, error) {
+func createCoinbaseTx(blockHeight int32, numOutputs uint32, extraNonce int64, params *dagconfig.Params) (*wire.MsgTx, error) {
 	// Create standard coinbase script.
-	extraNonce := int64(0)
 	coinbaseScript, err := txscript.NewScriptBuilder().
 		AddInt64(int64(blockHeight)).AddInt64(extraNonce).Script()
 	if err != nil {
@@ -821,7 +820,7 @@ func createCoinbaseTx(blockHeight int32, numOutputs uint32) (*wire.MsgTx, error)
 		SignatureScript: coinbaseScript,
 		Sequence:        wire.MaxTxInSequenceNum,
 	})
-	totalInput := CalcBlockSubsidy(blockHeight, &dagconfig.MainNetParams)
+	totalInput := CalcBlockSubsidy(blockHeight, params)
 	amountPerOutput := totalInput / uint64(numOutputs)
 	remainder := totalInput - amountPerOutput*uint64(numOutputs)
 	for i := uint32(0); i < numOutputs; i++ {
@@ -858,7 +857,7 @@ func TestApplyUTXOChanges(t *testing.T) {
 		},
 	}
 
-	cbTx, err := createCoinbaseTx(1, 1)
+	cbTx, err := createCoinbaseTx(1, 1, 0, dag.dagParams)
 	if err != nil {
 		t.Errorf("createCoinbaseTx: %v", err)
 	}
@@ -925,7 +924,7 @@ func TestDiffFromTx(t *testing.T) {
 	fus := &FullUTXOSet{
 		utxoCollection: utxoCollection{},
 	}
-	cbTx, err := createCoinbaseTx(1, 1)
+	cbTx, err := createCoinbaseTx(1, 1, 0, &dagconfig.SimNetParams)
 	if err != nil {
 		t.Errorf("createCoinbaseTx: %v", err)
 	}

blockdag/virtualblock_test.go

@@ -12,7 +12,7 @@ import (
 // TestVirtualBlock ensures that VirtualBlock works as expected.
 func TestVirtualBlock(t *testing.T) {
 	phantomK := uint32(1)
-	buildNode := buildNodeGenerator(phantomK)
+	buildNode := buildNodeGenerator(phantomK, false)
 
 	// Create a DAG as follows:
 	// 0 <- 1 <- 2
@@ -101,7 +101,7 @@ func TestVirtualBlock(t *testing.T) {
 
 func TestSelectedPath(t *testing.T) {
 	phantomK := uint32(1)
-	buildNode := buildNodeGenerator(phantomK)
+	buildNode := buildNodeGenerator(phantomK, false)
 
 	// Create an empty VirtualBlock
 	virtual := newVirtualBlock(nil, phantomK)