Add selected chain store and optimize block locator with it (#1394)

* Add selected chain store and optimize block locator with it

* Fix build error

* Fix comments

* Fix IsStaged

* Rename CalculateSelectedParentChainChanges to CalculateChainPath and SelectedParentChainChanges->SelectedChainPath

* Use binary.LittleEndian directly to allow compiler optimizations

* Remove boolean from HeadersSelectedChainStore interface

* Prevent endless loop in block locator

app/protocol/flows/blockrelay/ibd.go

@@ -131,7 +131,7 @@ func (flow *handleRelayInvsFlow) findHighestSharedBlockHash(targetHash *external
 
 	for !lowHash.Equal(highHash) {
 		log.Debugf("Sending a blockLocator to %s between %s and %s", flow.peer, lowHash, highHash)
-		blockLocator, err := flow.Domain().Consensus().CreateBlockLocator(lowHash, highHash, 0)
+		blockLocator, err := flow.Domain().Consensus().CreateHeadersSelectedChainBlockLocator(lowHash, highHash)
 		if err != nil {
 			return nil, err
 		}
@@ -169,6 +169,13 @@ func (flow *handleRelayInvsFlow) findHighestSharedBlockHash(targetHash *external
 		log.Debugf("The index of the highest hash in the original "+
 			"blockLocator sent to %s is %d", flow.peer, highestHashIndex)
 
+		// If the block locator contains only two adjacent chain blocks, the
+		// syncer will always find the same highest chain block, so to avoid
+		// an endless loop, we explicitly stop the loop in such situation.
+		if len(blockLocator) == 2 && highestHashIndex == 1 {
+			return highestHash, nil
+		}
+
 		locatorHashAboveHighestHash := highestHash
 		if highestHashIndex > 0 {
 			locatorHashAboveHighestHash = blockLocator[highestHashIndex-1]

app/rpc/rpccontext/chain_changed.go

@@ -9,7 +9,7 @@ import (
 // ConvertVirtualSelectedParentChainChangesToChainChangedNotificationMessage converts
 // VirtualSelectedParentChainChanges to VirtualSelectedParentChainChangedNotificationMessage
 func (ctx *Context) ConvertVirtualSelectedParentChainChangesToChainChangedNotificationMessage(
-	selectedParentChainChanges *externalapi.SelectedParentChainChanges) (*appmessage.VirtualSelectedParentChainChangedNotificationMessage, error) {
+	selectedParentChainChanges *externalapi.SelectedChainPath) (*appmessage.VirtualSelectedParentChainChangedNotificationMessage, error) {
 
 	removedChainBlockHashes := make([]string, len(selectedParentChainChanges.Removed))
 	for i, removed := range selectedParentChainChanges.Removed {

domain/consensus/consensus.go

@@ -32,19 +32,20 @@ type consensus struct {
 	reachabilityManager   model.ReachabilityManager
 	finalityManager       model.FinalityManager
 
-	acceptanceDataStore     model.AcceptanceDataStore
-	blockStore              model.BlockStore
-	blockHeaderStore        model.BlockHeaderStore
-	pruningStore            model.PruningStore
-	ghostdagDataStore       model.GHOSTDAGDataStore
-	blockRelationStore      model.BlockRelationStore
-	blockStatusStore        model.BlockStatusStore
-	consensusStateStore     model.ConsensusStateStore
-	headersSelectedTipStore model.HeaderSelectedTipStore
-	multisetStore           model.MultisetStore
-	reachabilityDataStore   model.ReachabilityDataStore
-	utxoDiffStore           model.UTXODiffStore
-	finalityStore           model.FinalityStore
+	acceptanceDataStore       model.AcceptanceDataStore
+	blockStore                model.BlockStore
+	blockHeaderStore          model.BlockHeaderStore
+	pruningStore              model.PruningStore
+	ghostdagDataStore         model.GHOSTDAGDataStore
+	blockRelationStore        model.BlockRelationStore
+	blockStatusStore          model.BlockStatusStore
+	consensusStateStore       model.ConsensusStateStore
+	headersSelectedTipStore   model.HeaderSelectedTipStore
+	multisetStore             model.MultisetStore
+	reachabilityDataStore     model.ReachabilityDataStore
+	utxoDiffStore             model.UTXODiffStore
+	finalityStore             model.FinalityStore
+	headersSelectedChainStore model.HeadersSelectedChainStore
 }
 
 // BuildBlock builds a block over the current state, with the transactions
@@ -297,6 +298,14 @@ func (s *consensus) CreateBlockLocator(lowHash, highHash *externalapi.DomainHash
 	return s.syncManager.CreateBlockLocator(lowHash, highHash, limit)
 }
 
+func (s *consensus) CreateHeadersSelectedChainBlockLocator(lowHash,
+	highHash *externalapi.DomainHash) (externalapi.BlockLocator, error) {
+	s.lock.Lock()
+	defer s.lock.Unlock()
+
+	return s.syncManager.CreateHeadersSelectedChainBlockLocator(lowHash, highHash)
+}
+
 func (s *consensus) FindNextBlockLocatorBoundaries(blockLocator externalapi.BlockLocator) (lowHash, highHash *externalapi.DomainHash, err error) {
 	s.lock.Lock()
 	defer s.lock.Unlock()
@@ -327,7 +336,7 @@ func (s *consensus) IsValidPruningPoint(blockHash *externalapi.DomainHash) (bool
 	return s.pruningManager.IsValidPruningPoint(blockHash)
 }
 
-func (s *consensus) GetVirtualSelectedParentChainFromBlock(blockHash *externalapi.DomainHash) (*externalapi.SelectedParentChainChanges, error) {
+func (s *consensus) GetVirtualSelectedParentChainFromBlock(blockHash *externalapi.DomainHash) (*externalapi.SelectedChainPath, error) {
 	s.lock.Lock()
 	defer s.lock.Unlock()
 

domain/consensus/database/binaryserialization/hash.go

@@ -0,0 +1,13 @@
+package binaryserialization
+
+import "github.com/kaspanet/kaspad/domain/consensus/model/externalapi"
+
+// SerializeHash serializes hash to a slice of bytes
+func SerializeHash(hash *externalapi.DomainHash) []byte {
+	return hash.ByteSlice()
+}
+
+// DeserializeHash a slice of bytes to a hash
+func DeserializeHash(hashBytes []byte) (*externalapi.DomainHash, error) {
+	return externalapi.NewDomainHashFromByteSlice(hashBytes)
+}

domain/consensus/database/binaryserialization/selected_chain.go

@@ -0,0 +1,15 @@
+package binaryserialization
+
+import "encoding/binary"
+
+// SerializeChainBlockIndex serializes chain block index
+func SerializeChainBlockIndex(index uint64) []byte {
+	var keyBytes [8]byte
+	binary.LittleEndian.PutUint64(keyBytes[:], index)
+	return keyBytes[:]
+}
+
+// DeserializeChainBlockIndex deserializes chain block index to uint64
+func DeserializeChainBlockIndex(indexBytes []byte) uint64 {
+	return binary.LittleEndian.Uint64(indexBytes)
+}

domain/consensus/datastructures/headersselectedchainstore/headersselectedchainstore.go

@@ -0,0 +1,230 @@
+package headersselectedchainstore
+
+import (
+	"encoding/binary"
+	"github.com/kaspanet/kaspad/domain/consensus/database/binaryserialization"
+	"github.com/kaspanet/kaspad/domain/consensus/model"
+	"github.com/kaspanet/kaspad/domain/consensus/model/externalapi"
+	"github.com/kaspanet/kaspad/domain/consensus/utils/dbkeys"
+	"github.com/kaspanet/kaspad/domain/consensus/utils/lrucache"
+	"github.com/kaspanet/kaspad/domain/consensus/utils/lrucacheuint64tohash"
+	"github.com/kaspanet/kaspad/infrastructure/db/database"
+	"github.com/pkg/errors"
+)
+
+var bucketChainBlockHashByIndex = dbkeys.MakeBucket([]byte("chain-block-hash-by-index"))
+var bucketChainBlockIndexByHash = dbkeys.MakeBucket([]byte("chain-block-index-by-hash"))
+var highestChainBlockIndexKey = dbkeys.MakeBucket().Key([]byte("highest-chain-block-index"))
+
+type headersSelectedChainStore struct {
+	stagingAddedByHash          map[externalapi.DomainHash]uint64
+	stagingRemovedByHash        map[externalapi.DomainHash]struct{}
+	stagingAddedByIndex         map[uint64]*externalapi.DomainHash
+	stagingRemovedByIndex       map[uint64]struct{}
+	cacheByIndex                *lrucacheuint64tohash.LRUCache
+	cacheByHash                 *lrucache.LRUCache
+	cacheHighestChainBlockIndex uint64
+}
+
+// New instantiates a new HeadersSelectedChainStore
+func New(cacheSize int) model.HeadersSelectedChainStore {
+	return &headersSelectedChainStore{
+		stagingAddedByHash:    make(map[externalapi.DomainHash]uint64),
+		stagingRemovedByHash:  make(map[externalapi.DomainHash]struct{}),
+		stagingAddedByIndex:   make(map[uint64]*externalapi.DomainHash),
+		stagingRemovedByIndex: make(map[uint64]struct{}),
+		cacheByIndex:          lrucacheuint64tohash.New(cacheSize),
+		cacheByHash:           lrucache.New(cacheSize),
+	}
+}
+
+// Stage stages the given chain changes
+func (hscs *headersSelectedChainStore) Stage(dbContext model.DBReader,
+	chainChanges *externalapi.SelectedChainPath) error {
+
+	if hscs.IsStaged() {
+		return errors.Errorf("can't stage when there's already staged data")
+	}
+
+	for _, blockHash := range chainChanges.Removed {
+		index, err := hscs.GetIndexByHash(dbContext, blockHash)
+		if err != nil {
+			return err
+		}
+
+		hscs.stagingRemovedByIndex[index] = struct{}{}
+		hscs.stagingRemovedByHash[*blockHash] = struct{}{}
+	}
+
+	currentIndex := uint64(0)
+	highestChainBlockIndex, exists, err := hscs.highestChainBlockIndex(dbContext)
+	if err != nil {
+		return err
+	}
+
+	if exists {
+		currentIndex = highestChainBlockIndex - uint64(len(chainChanges.Removed)) + 1
+	}
+
+	for _, blockHash := range chainChanges.Added {
+		hscs.stagingAddedByIndex[currentIndex] = blockHash
+		hscs.stagingAddedByHash[*blockHash] = currentIndex
+		currentIndex++
+	}
+
+	return nil
+}
+
+func (hscs *headersSelectedChainStore) IsStaged() bool {
+	return len(hscs.stagingAddedByHash) != 0 ||
+		len(hscs.stagingRemovedByHash) != 0 ||
+		len(hscs.stagingAddedByIndex) != 0 ||
+		len(hscs.stagingAddedByIndex) != 0
+}
+
+func (hscs *headersSelectedChainStore) Discard() {
+	hscs.stagingAddedByHash = make(map[externalapi.DomainHash]uint64)
+	hscs.stagingRemovedByHash = make(map[externalapi.DomainHash]struct{})
+	hscs.stagingAddedByIndex = make(map[uint64]*externalapi.DomainHash)
+	hscs.stagingRemovedByIndex = make(map[uint64]struct{})
+}
+
+func (hscs *headersSelectedChainStore) Commit(dbTx model.DBTransaction) error {
+	if !hscs.IsStaged() {
+		return nil
+	}
+
+	for hash := range hscs.stagingRemovedByHash {
+		hashCopy := hash
+		err := dbTx.Delete(hscs.hashAsKey(&hashCopy))
+		if err != nil {
+			return err
+		}
+		hscs.cacheByHash.Remove(&hashCopy)
+	}
+
+	for index := range hscs.stagingRemovedByIndex {
+		err := dbTx.Delete(hscs.indexAsKey(index))
+		if err != nil {
+			return err
+		}
+		hscs.cacheByIndex.Remove(index)
+	}
+
+	highestIndex := uint64(0)
+	for hash, index := range hscs.stagingAddedByHash {
+		hashCopy := hash
+		err := dbTx.Put(hscs.hashAsKey(&hashCopy), hscs.serializeIndex(index))
+		if err != nil {
+			return err
+		}
+
+		err = dbTx.Put(hscs.indexAsKey(index), binaryserialization.SerializeHash(&hashCopy))
+		if err != nil {
+			return err
+		}
+
+		hscs.cacheByHash.Add(&hashCopy, index)
+		hscs.cacheByIndex.Add(index, &hashCopy)
+
+		if index > highestIndex {
+			highestIndex = index
+		}
+	}
+
+	err := dbTx.Put(highestChainBlockIndexKey, hscs.serializeIndex(highestIndex))
+	if err != nil {
+		return err
+	}
+
+	hscs.cacheHighestChainBlockIndex = highestIndex
+
+	hscs.Discard()
+	return nil
+}
+
+// Get gets the chain block index for the given blockHash
+func (hscs *headersSelectedChainStore) GetIndexByHash(dbContext model.DBReader, blockHash *externalapi.DomainHash) (uint64, error) {
+	if index, ok := hscs.stagingAddedByHash[*blockHash]; ok {
+		return index, nil
+	}
+
+	if _, ok := hscs.stagingRemovedByHash[*blockHash]; ok {
+		return 0, errors.Wrapf(database.ErrNotFound, "couldn't find block %s", blockHash)
+	}
+
+	if index, ok := hscs.cacheByHash.Get(blockHash); ok {
+		return index.(uint64), nil
+	}
+
+	indexBytes, err := dbContext.Get(hscs.hashAsKey(blockHash))
+	if err != nil {
+		return 0, err
+	}
+
+	index := hscs.deserializeIndex(indexBytes)
+	hscs.cacheByHash.Add(blockHash, index)
+	return index, nil
+}
+
+func (hscs *headersSelectedChainStore) GetHashByIndex(dbContext model.DBReader, index uint64) (*externalapi.DomainHash, error) {
+	if blockHash, ok := hscs.stagingAddedByIndex[index]; ok {
+		return blockHash, nil
+	}
+
+	if _, ok := hscs.stagingRemovedByIndex[index]; ok {
+		return nil, errors.Wrapf(database.ErrNotFound, "couldn't find chain block with index %d", index)
+	}
+
+	if blockHash, ok := hscs.cacheByIndex.Get(index); ok {
+		return blockHash, nil
+	}
+
+	hashBytes, err := dbContext.Get(hscs.indexAsKey(index))
+	if err != nil {
+		return nil, err
+	}
+
+	blockHash, err := binaryserialization.DeserializeHash(hashBytes)
+	if err != nil {
+		return nil, err
+	}
+	hscs.cacheByIndex.Add(index, blockHash)
+	return blockHash, nil
+}
+
+func (hscs *headersSelectedChainStore) serializeIndex(index uint64) []byte {
+	return binaryserialization.SerializeChainBlockIndex(index)
+}
+
+func (hscs *headersSelectedChainStore) deserializeIndex(indexBytes []byte) uint64 {
+	return binaryserialization.DeserializeChainBlockIndex(indexBytes)
+}
+
+func (hscs *headersSelectedChainStore) hashAsKey(hash *externalapi.DomainHash) model.DBKey {
+	return bucketChainBlockIndexByHash.Key(hash.ByteSlice())
+}
+
+func (hscs *headersSelectedChainStore) indexAsKey(index uint64) model.DBKey {
+	var keyBytes [8]byte
+	binary.BigEndian.PutUint64(keyBytes[:], index)
+	return bucketChainBlockHashByIndex.Key(keyBytes[:])
+}
+
+func (hscs *headersSelectedChainStore) highestChainBlockIndex(dbContext model.DBReader) (uint64, bool, error) {
+	if hscs.cacheHighestChainBlockIndex != 0 {
+		return hscs.cacheHighestChainBlockIndex, true, nil
+	}
+
+	indexBytes, err := dbContext.Get(highestChainBlockIndexKey)
+	if err != nil {
+		if errors.Is(err, database.ErrNotFound) {
+			return 0, false, nil
+		}
+		return 0, false, err
+	}
+
+	index := hscs.deserializeIndex(indexBytes)
+	hscs.cacheHighestChainBlockIndex = index
+	return index, true, nil
+}

domain/consensus/factory.go

@@ -1,6 +1,7 @@
 package consensus
 
 import (
+	"github.com/kaspanet/kaspad/domain/consensus/datastructures/headersselectedchainstore"
 	"io/ioutil"
 	"os"
 	"sync"
@@ -89,6 +90,7 @@ func (f *factory) NewConsensus(dagParams *dagconfig.Params, db infrastructuredat
 	ghostdagDataStore := ghostdagdatastore.New(pruningWindowSizeForCaches)
 	headersSelectedTipStore := headersselectedtipstore.New()
 	finalityStore := finalitystore.New(200)
+	headersSelectedChainStore := headersselectedchainstore.New(pruningWindowSizeForCaches)
 
 	// Processes
 	reachabilityManager := reachabilitymanager.New(
@@ -148,7 +150,8 @@ func (f *factory) NewConsensus(dagParams *dagconfig.Params, db infrastructuredat
 		dagParams.CoinbasePayloadScriptPublicKeyMaxLength,
 		ghostdagDataStore,
 		acceptanceDataStore)
-	headerTipsManager := headersselectedtipmanager.New(dbManager, dagTopologyManager, ghostdagManager, headersSelectedTipStore)
+	headerTipsManager := headersselectedtipmanager.New(dbManager, dagTopologyManager, dagTraversalManager,
+		ghostdagManager, headersSelectedTipStore, headersSelectedChainStore)
 	genesisHash := dagParams.GenesisHash
 	finalityManager := finalitymanager.New(
 		dbManager,
@@ -258,7 +261,8 @@ func (f *factory) NewConsensus(dagParams *dagconfig.Params, db infrastructuredat
 		blockStatusStore,
 		blockHeaderStore,
 		blockStore,
-		pruningStore)
+		pruningStore,
+		headersSelectedChainStore)
 
 	blockBuilder := blockbuilder.New(
 		dbManager,
@@ -300,7 +304,8 @@ func (f *factory) NewConsensus(dagParams *dagconfig.Params, db infrastructuredat
 		utxoDiffStore,
 		blockHeaderStore,
 		headersSelectedTipStore,
-		finalityStore)
+		finalityStore,
+		headersSelectedChainStore)
 
 	c := &consensus{
 		lock:            &sync.Mutex{},
@@ -324,19 +329,20 @@ func (f *factory) NewConsensus(dagParams *dagconfig.Params, db infrastructuredat
 		reachabilityManager:   reachabilityManager,
 		finalityManager:       finalityManager,
 
-		acceptanceDataStore:     acceptanceDataStore,
-		blockStore:              blockStore,
-		blockHeaderStore:        blockHeaderStore,
-		pruningStore:            pruningStore,
-		ghostdagDataStore:       ghostdagDataStore,
-		blockStatusStore:        blockStatusStore,
-		blockRelationStore:      blockRelationStore,
-		consensusStateStore:     consensusStateStore,
-		headersSelectedTipStore: headersSelectedTipStore,
-		multisetStore:           multisetStore,
-		reachabilityDataStore:   reachabilityDataStore,
-		utxoDiffStore:           utxoDiffStore,
-		finalityStore:           finalityStore,
+		acceptanceDataStore:       acceptanceDataStore,
+		blockStore:                blockStore,
+		blockHeaderStore:          blockHeaderStore,
+		pruningStore:              pruningStore,
+		ghostdagDataStore:         ghostdagDataStore,
+		blockStatusStore:          blockStatusStore,
+		blockRelationStore:        blockRelationStore,
+		consensusStateStore:       consensusStateStore,
+		headersSelectedTipStore:   headersSelectedTipStore,
+		multisetStore:             multisetStore,
+		reachabilityDataStore:     reachabilityDataStore,
+		utxoDiffStore:             utxoDiffStore,
+		finalityStore:             finalityStore,
+		headersSelectedChainStore: headersSelectedChainStore,
 	}
 
 	genesisInfo, err := c.GetBlockInfo(genesisHash)

domain/consensus/model/externalapi/consensus.go

@@ -18,12 +18,13 @@ type Consensus interface {
 	ValidateAndInsertPruningPoint(newPruningPoint *DomainBlock, serializedUTXOSet []byte) error
 	GetVirtualSelectedParent() (*DomainHash, error)
 	CreateBlockLocator(lowHash, highHash *DomainHash, limit uint32) (BlockLocator, error)
+	CreateHeadersSelectedChainBlockLocator(lowHash, highHash *DomainHash) (BlockLocator, error)
 	FindNextBlockLocatorBoundaries(blockLocator BlockLocator) (lowHash, highHash *DomainHash, err error)
 	GetSyncInfo() (*SyncInfo, error)
 	Tips() ([]*DomainHash, error)
 	GetVirtualInfo() (*VirtualInfo, error)
 	IsValidPruningPoint(blockHash *DomainHash) (bool, error)
-	GetVirtualSelectedParentChainFromBlock(blockHash *DomainHash) (*SelectedParentChainChanges, error)
+	GetVirtualSelectedParentChainFromBlock(blockHash *DomainHash) (*SelectedChainPath, error)
 	IsInSelectedParentChainOf(blockHashA *DomainHash, blockHashB *DomainHash) (bool, error)
 	GetHeadersSelectedTip() (*DomainHash, error)
 }

domain/consensus/model/externalapi/insertblockresult.go

@@ -2,11 +2,11 @@ package externalapi
 
 // BlockInsertionResult is auxiliary data returned from ValidateAndInsertBlock
 type BlockInsertionResult struct {
-	VirtualSelectedParentChainChanges *SelectedParentChainChanges
+	VirtualSelectedParentChainChanges *SelectedChainPath
 }
 
-// SelectedParentChainChanges is the set of changes made to the selected parent chain
-type SelectedParentChainChanges struct {
+// SelectedChainPath is a path the of the selected chains between two blocks.
+type SelectedChainPath struct {
 	Added   []*DomainHash
 	Removed []*DomainHash
 }

domain/consensus/model/interface_datastructures_headersselectedchainstore.go

@@ -0,0 +1,13 @@
+package model
+
+import "github.com/kaspanet/kaspad/domain/consensus/model/externalapi"
+
+// HeadersSelectedChainStore represents a store of the headers selected chain
+type HeadersSelectedChainStore interface {
+	Store
+	Stage(dbContext DBReader,
+		chainChanges *externalapi.SelectedChainPath) error
+	IsStaged() bool
+	GetIndexByHash(dbContext DBReader, blockHash *externalapi.DomainHash) (uint64, error)
+	GetHashByIndex(dbContext DBReader, index uint64) (*externalapi.DomainHash, error)
+}

domain/consensus/model/interface_processes_consensusstatemanager.go

@@ -4,10 +4,10 @@ import "github.com/kaspanet/kaspad/domain/consensus/model/externalapi"
 
 // ConsensusStateManager manages the node's consensus state
 type ConsensusStateManager interface {
-	AddBlock(blockHash *externalapi.DomainHash) (*externalapi.SelectedParentChainChanges, error)
+	AddBlock(blockHash *externalapi.DomainHash) (*externalapi.SelectedChainPath, error)
 	PopulateTransactionWithUTXOEntries(transaction *externalapi.DomainTransaction) error
 	UpdatePruningPoint(newPruningPoint *externalapi.DomainBlock, serializedUTXOSet []byte) error
 	RestorePastUTXOSetIterator(blockHash *externalapi.DomainHash) (ReadOnlyUTXOSetIterator, error)
 	CalculatePastUTXOAndAcceptanceData(blockHash *externalapi.DomainHash) (UTXODiff, externalapi.AcceptanceData, Multiset, error)
-	GetVirtualSelectedParentChainFromBlock(blockHash *externalapi.DomainHash) (*externalapi.SelectedParentChainChanges, error)
+	GetVirtualSelectedParentChainFromBlock(blockHash *externalapi.DomainHash) (*externalapi.SelectedChainPath, error)
 }

domain/consensus/model/interface_processes_dagtraversalmanager.go

@@ -13,4 +13,6 @@ type DAGTraversalManager interface {
 	BlueWindow(highHash *externalapi.DomainHash, windowSize int) ([]*externalapi.DomainHash, error)
 	NewDownHeap() BlockHeap
 	NewUpHeap() BlockHeap
+	CalculateChainPath(
+		fromBlockHash, toBlockHash *externalapi.DomainHash) (*externalapi.SelectedChainPath, error)
 }

domain/consensus/model/interface_processes_syncmanager.go

@@ -7,6 +7,7 @@ type SyncManager interface {
 	GetHashesBetween(lowHash, highHash *externalapi.DomainHash, maxBlueScoreDifference uint64) ([]*externalapi.DomainHash, error)
 	GetMissingBlockBodyHashes(highHash *externalapi.DomainHash) ([]*externalapi.DomainHash, error)
 	CreateBlockLocator(lowHash, highHash *externalapi.DomainHash, limit uint32) (externalapi.BlockLocator, error)
+	CreateHeadersSelectedChainBlockLocator(lowHash, highHash *externalapi.DomainHash) (externalapi.BlockLocator, error)
 	FindNextBlockLocatorBoundaries(blockLocator externalapi.BlockLocator) (lowHash, highHash *externalapi.DomainHash, err error)
 	GetSyncInfo() (*externalapi.SyncInfo, error)
 }

domain/consensus/model/testapi/test_consensus.go

@@ -40,6 +40,7 @@ type TestConsensus interface {
 	PruningStore() model.PruningStore
 	ReachabilityDataStore() model.ReachabilityDataStore
 	UTXODiffStore() model.UTXODiffStore
+	HeadersSelectedChainStore() model.HeadersSelectedChainStore
 
 	BlockBuilder() TestBlockBuilder
 	BlockProcessor() model.BlockProcessor

domain/consensus/processes/blockprocessor/blockprocessor.go

@@ -24,19 +24,20 @@ type blockProcessor struct {
 	headerTipsManager     model.HeadersSelectedTipManager
 	syncManager           model.SyncManager
 
-	acceptanceDataStore     model.AcceptanceDataStore
-	blockStore              model.BlockStore
-	blockStatusStore        model.BlockStatusStore
-	blockRelationStore      model.BlockRelationStore
-	multisetStore           model.MultisetStore
-	ghostdagDataStore       model.GHOSTDAGDataStore
-	consensusStateStore     model.ConsensusStateStore
-	pruningStore            model.PruningStore
-	reachabilityDataStore   model.ReachabilityDataStore
-	utxoDiffStore           model.UTXODiffStore
-	blockHeaderStore        model.BlockHeaderStore
-	headersSelectedTipStore model.HeaderSelectedTipStore
-	finalityStore           model.FinalityStore
+	acceptanceDataStore       model.AcceptanceDataStore
+	blockStore                model.BlockStore
+	blockStatusStore          model.BlockStatusStore
+	blockRelationStore        model.BlockRelationStore
+	multisetStore             model.MultisetStore
+	ghostdagDataStore         model.GHOSTDAGDataStore
+	consensusStateStore       model.ConsensusStateStore
+	pruningStore              model.PruningStore
+	reachabilityDataStore     model.ReachabilityDataStore
+	utxoDiffStore             model.UTXODiffStore
+	blockHeaderStore          model.BlockHeaderStore
+	headersSelectedTipStore   model.HeaderSelectedTipStore
+	finalityStore             model.FinalityStore
+	headersSelectedChainStore model.HeadersSelectedChainStore
 
 	stores []model.Store
 }
@@ -70,6 +71,7 @@ func New(
 	blockHeaderStore model.BlockHeaderStore,
 	headersSelectedTipStore model.HeaderSelectedTipStore,
 	finalityStore model.FinalityStore,
+	headersSelectedChainStore model.HeadersSelectedChainStore,
 ) model.BlockProcessor {
 
 	return &blockProcessor{
@@ -86,20 +88,21 @@ func New(
 		headerTipsManager:     headerTipsManager,
 		syncManager:           syncManager,
 
-		consensusStateManager:   consensusStateManager,
-		acceptanceDataStore:     acceptanceDataStore,
-		blockStore:              blockStore,
-		blockStatusStore:        blockStatusStore,
-		blockRelationStore:      blockRelationStore,
-		multisetStore:           multisetStore,
-		ghostdagDataStore:       ghostdagDataStore,
-		consensusStateStore:     consensusStateStore,
-		pruningStore:            pruningStore,
-		reachabilityDataStore:   reachabilityDataStore,
-		utxoDiffStore:           utxoDiffStore,
-		blockHeaderStore:        blockHeaderStore,
-		headersSelectedTipStore: headersSelectedTipStore,
-		finalityStore:           finalityStore,
+		consensusStateManager:     consensusStateManager,
+		acceptanceDataStore:       acceptanceDataStore,
+		blockStore:                blockStore,
+		blockStatusStore:          blockStatusStore,
+		blockRelationStore:        blockRelationStore,
+		multisetStore:             multisetStore,
+		ghostdagDataStore:         ghostdagDataStore,
+		consensusStateStore:       consensusStateStore,
+		pruningStore:              pruningStore,
+		reachabilityDataStore:     reachabilityDataStore,
+		utxoDiffStore:             utxoDiffStore,
+		blockHeaderStore:          blockHeaderStore,
+		headersSelectedTipStore:   headersSelectedTipStore,
+		finalityStore:             finalityStore,
+		headersSelectedChainStore: headersSelectedChainStore,
 
 		stores: []model.Store{
 			consensusStateStore,
@@ -116,6 +119,7 @@ func New(
 			blockHeaderStore,
 			headersSelectedTipStore,
 			finalityStore,
+			headersSelectedChainStore,
 		},
 	}
 }

domain/consensus/processes/blockprocessor/validateandinsertblock.go

@@ -81,7 +81,7 @@ func (bp *blockProcessor) validateAndInsertBlock(block *externalapi.DomainBlock,
 		return nil, err
 	}
 
-	var selectedParentChainChanges *externalapi.SelectedParentChainChanges
+	var selectedParentChainChanges *externalapi.SelectedChainPath
 	isHeaderOnlyBlock := isHeaderOnlyBlock(block)
 	if !isHeaderOnlyBlock {
 		// There's no need to update the consensus state manager when

domain/consensus/processes/coinbasemanager/payload.go

@@ -9,8 +9,6 @@ import (
 	"github.com/pkg/errors"
 )
 
-var byteOrder = binary.LittleEndian
-
 const uint64Len = 8
 const uint16Len = 2
 const lengthOfscriptPubKeyLength = 1
@@ -25,7 +23,7 @@ func (c *coinbaseManager) serializeCoinbasePayload(blueScore uint64, coinbaseDat
 	}
 
 	payload := make([]byte, uint64Len+lengthOfVersionScriptPubKey+lengthOfscriptPubKeyLength+scriptLengthOfScriptPubKey+len(coinbaseData.ExtraData))
-	byteOrder.PutUint64(payload[:uint64Len], blueScore)
+	binary.LittleEndian.PutUint64(payload[:uint64Len], blueScore)
 	if len(coinbaseData.ScriptPublicKey.Script) > math.MaxUint8 {
 		return nil, errors.Errorf("script public key is bigger than %d", math.MaxUint8)
 	}
@@ -47,7 +45,7 @@ func (c *coinbaseManager) ExtractCoinbaseDataAndBlueScore(coinbaseTx *externalap
 			"coinbase payload is less than the minimum length of %d", minLength)
 	}
 
-	blueScore = byteOrder.Uint64(coinbaseTx.Payload[:uint64Len])
+	blueScore = binary.LittleEndian.Uint64(coinbaseTx.Payload[:uint64Len])
 	scriptPubKeyVersion := uint16(coinbaseTx.Payload[uint64Len])
 	scriptPubKeyScriptLength := coinbaseTx.Payload[uint64Len+lengthOfVersionScriptPubKey]
 

domain/consensus/processes/consensusstatemanager/add_block_to_virtual.go

@@ -9,7 +9,7 @@ import (
 // AddBlock submits the given block to be added to the
 // current virtual. This process may result in a new virtual block
 // getting created
-func (csm *consensusStateManager) AddBlock(blockHash *externalapi.DomainHash) (*externalapi.SelectedParentChainChanges, error) {
+func (csm *consensusStateManager) AddBlock(blockHash *externalapi.DomainHash) (*externalapi.SelectedChainPath, error) {
 	logger.LogAndMeasureExecutionTime(log, "csm.AddBlock")
 
 	log.Debugf("Resolving whether the block %s is the next virtual selected parent", blockHash)

domain/consensus/processes/consensusstatemanager/find_selected_parent_chain_changes.go

@@ -6,7 +6,7 @@ import (
 )
 
 func (csm *consensusStateManager) GetVirtualSelectedParentChainFromBlock(
-	blockHash *externalapi.DomainHash) (*externalapi.SelectedParentChainChanges, error) {
+	blockHash *externalapi.DomainHash) (*externalapi.SelectedChainPath, error) {
 
 	// Calculate chain changes between the given blockHash and the
 	// virtual's selected parent. Note that we explicitly don't
@@ -18,55 +18,5 @@ func (csm *consensusStateManager) GetVirtualSelectedParentChainFromBlock(
 	}
 	virtualSelectedParent := virtualGHOSTDAGData.SelectedParent()
 
-	return csm.calculateSelectedParentChainChanges(blockHash, virtualSelectedParent)
-}
-
-func (csm *consensusStateManager) calculateSelectedParentChainChanges(
-	fromBlockHash, toBlockHash *externalapi.DomainHash) (*externalapi.SelectedParentChainChanges, error) {
-
-	// Walk down from fromBlockHash until we reach the common selected
-	// parent chain ancestor of fromBlockHash and toBlockHash. Note
-	// that this slice will be empty if fromBlockHash is the selected
-	// parent of toBlockHash
-	var removed []*externalapi.DomainHash
-	current := fromBlockHash
-	for {
-		isCurrentInTheSelectedParentChainOfNewVirtualSelectedParent, err := csm.dagTopologyManager.IsInSelectedParentChainOf(current, toBlockHash)
-		if err != nil {
-			return nil, err
-		}
-		if isCurrentInTheSelectedParentChainOfNewVirtualSelectedParent {
-			break
-		}
-		removed = append(removed, current)
-
-		currentGHOSTDAGData, err := csm.ghostdagDataStore.Get(csm.databaseContext, current)
-		if err != nil {
-			return nil, err
-		}
-		current = currentGHOSTDAGData.SelectedParent()
-	}
-	commonAncestor := current
-
-	// Walk down from the toBlockHash to the common ancestor
-	var added []*externalapi.DomainHash
-	current = toBlockHash
-	for !current.Equal(commonAncestor) {
-		added = append(added, current)
-		currentGHOSTDAGData, err := csm.ghostdagDataStore.Get(csm.databaseContext, current)
-		if err != nil {
-			return nil, err
-		}
-		current = currentGHOSTDAGData.SelectedParent()
-	}
-
-	// Reverse the order of `added` so that it's sorted from low hash to high hash
-	for i, j := 0, len(added)-1; i < j; i, j = i+1, j-1 {
-		added[i], added[j] = added[j], added[i]
-	}
-
-	return &externalapi.SelectedParentChainChanges{
-		Added:   added,
-		Removed: removed,
-	}, nil
+	return csm.dagTraversalManager.CalculateChainPath(blockHash, virtualSelectedParent)
 }

domain/consensus/processes/consensusstatemanager/find_selected_parent_chain_changes_test.go

@@ -10,10 +10,10 @@ import (
 	"github.com/kaspanet/kaspad/domain/dagconfig"
 )
 
-func TestCalculateSelectedParentChainChanges(t *testing.T) {
+func TestCalculateChainPath(t *testing.T) {
 	testutils.ForAllNets(t, true, func(t *testing.T, params *dagconfig.Params) {
 		factory := consensus.NewFactory()
-		consensus, teardown, err := factory.NewTestConsensus(params, false, "TestCalculateSelectedParentChainChanges")
+		consensus, teardown, err := factory.NewTestConsensus(params, false, "TestCalculateChainPath")
 		if err != nil {
 			t.Fatalf("Error setting up consensus: %+v", err)
 		}

domain/consensus/processes/consensusstatemanager/update_virtual.go

@@ -6,7 +6,7 @@ import (
 )
 
 func (csm *consensusStateManager) updateVirtual(newBlockHash *externalapi.DomainHash,
-	tips []*externalapi.DomainHash) (*externalapi.SelectedParentChainChanges, error) {
+	tips []*externalapi.DomainHash) (*externalapi.SelectedChainPath, error) {
 
 	log.Debugf("updateVirtual start for block %s", newBlockHash)
 	defer log.Debugf("updateVirtual end for block %s", newBlockHash)
@@ -64,14 +64,15 @@ func (csm *consensusStateManager) updateVirtual(newBlockHash *externalapi.Domain
 	}
 
 	log.Debugf("Calculating selected parent chain changes")
-	var selectedParentChainChanges *externalapi.SelectedParentChainChanges
+	var selectedParentChainChanges *externalapi.SelectedChainPath
 	if !newBlockHash.Equal(csm.genesisHash) {
 		newVirtualGHOSTDAGData, err := csm.ghostdagDataStore.Get(csm.databaseContext, model.VirtualBlockHash)
 		if err != nil {
 			return nil, err
 		}
 		newVirtualSelectedParent := newVirtualGHOSTDAGData.SelectedParent()
-		selectedParentChainChanges, err = csm.calculateSelectedParentChainChanges(oldVirtualSelectedParent, newVirtualSelectedParent)
+		selectedParentChainChanges, err = csm.dagTraversalManager.
+			CalculateChainPath(oldVirtualSelectedParent, newVirtualSelectedParent)
 		if err != nil {
 			return nil, err
 		}

domain/consensus/processes/dagtraversalmanager/dagtraversalmanager.go

@@ -145,3 +145,53 @@ func (dtm *dagTraversalManager) LowestChainBlockAboveOrEqualToBlueScore(highHash
 
 	return currentHash, nil
 }
+
+func (dtm *dagTraversalManager) CalculateChainPath(
+	fromBlockHash, toBlockHash *externalapi.DomainHash) (*externalapi.SelectedChainPath, error) {
+
+	// Walk down from fromBlockHash until we reach the common selected
+	// parent chain ancestor of fromBlockHash and toBlockHash. Note
+	// that this slice will be empty if fromBlockHash is the selected
+	// parent of toBlockHash
+	var removed []*externalapi.DomainHash
+	current := fromBlockHash
+	for {
+		isCurrentInTheSelectedParentChainOfNewVirtualSelectedParent, err := dtm.dagTopologyManager.IsInSelectedParentChainOf(current, toBlockHash)
+		if err != nil {
+			return nil, err
+		}
+		if isCurrentInTheSelectedParentChainOfNewVirtualSelectedParent {
+			break
+		}
+		removed = append(removed, current)
+
+		currentGHOSTDAGData, err := dtm.ghostdagDataStore.Get(dtm.databaseContext, current)
+		if err != nil {
+			return nil, err
+		}
+		current = currentGHOSTDAGData.SelectedParent()
+	}
+	commonAncestor := current
+
+	// Walk down from the toBlockHash to the common ancestor
+	var added []*externalapi.DomainHash
+	current = toBlockHash
+	for !current.Equal(commonAncestor) {
+		added = append(added, current)
+		currentGHOSTDAGData, err := dtm.ghostdagDataStore.Get(dtm.databaseContext, current)
+		if err != nil {
+			return nil, err
+		}
+		current = currentGHOSTDAGData.SelectedParent()
+	}
+
+	// Reverse the order of `added` so that it's sorted from low hash to high hash
+	for i, j := 0, len(added)-1; i < j; i, j = i+1, j-1 {
+		added[i], added[j] = added[j], added[i]
+	}
+
+	return &externalapi.SelectedChainPath{
+		Added:   added,
+		Removed: removed,
+	}, nil
+}

domain/consensus/processes/headersselectedtipmanager/headersselectedtipmanager.go

@@ -0,0 +1,79 @@
+package headersselectedtipmanager
+
+import (
+	"github.com/kaspanet/kaspad/domain/consensus/model"
+	"github.com/kaspanet/kaspad/domain/consensus/model/externalapi"
+)
+
+type headerTipsManager struct {
+	databaseContext model.DBReader
+
+	dagTopologyManager        model.DAGTopologyManager
+	dagTraversalManager       model.DAGTraversalManager
+	ghostdagManager           model.GHOSTDAGManager
+	headersSelectedTipStore   model.HeaderSelectedTipStore
+	headersSelectedChainStore model.HeadersSelectedChainStore
+}
+
+// New instantiates a new HeadersSelectedTipManager
+func New(databaseContext model.DBReader,
+	dagTopologyManager model.DAGTopologyManager,
+	dagTraversalManager model.DAGTraversalManager,
+	ghostdagManager model.GHOSTDAGManager,
+	headersSelectedTipStore model.HeaderSelectedTipStore,
+	headersSelectedChainStore model.HeadersSelectedChainStore) model.HeadersSelectedTipManager {
+
+	return &headerTipsManager{
+		databaseContext:           databaseContext,
+		dagTopologyManager:        dagTopologyManager,
+		dagTraversalManager:       dagTraversalManager,
+		ghostdagManager:           ghostdagManager,
+		headersSelectedTipStore:   headersSelectedTipStore,
+		headersSelectedChainStore: headersSelectedChainStore,
+	}
+}
+
+func (h *headerTipsManager) AddHeaderTip(hash *externalapi.DomainHash) error {
+	hasSelectedTip, err := h.headersSelectedTipStore.Has(h.databaseContext)
+	if err != nil {
+		return err
+	}
+
+	if !hasSelectedTip {
+		h.headersSelectedTipStore.Stage(hash)
+
+		err := h.headersSelectedChainStore.Stage(h.databaseContext, &externalapi.SelectedChainPath{
+			Added:   []*externalapi.DomainHash{hash},
+			Removed: nil,
+		})
+		if err != nil {
+			return err
+		}
+	} else {
+		headersSelectedTip, err := h.headersSelectedTipStore.HeadersSelectedTip(h.databaseContext)
+		if err != nil {
+			return err
+		}
+
+		newHeadersSelectedTip, err := h.ghostdagManager.ChooseSelectedParent(headersSelectedTip, hash)
+		if err != nil {
+			return err
+		}
+
+		if !newHeadersSelectedTip.Equal(headersSelectedTip) {
+			h.headersSelectedTipStore.Stage(newHeadersSelectedTip)
+
+			chainChanges, err := h.dagTraversalManager.CalculateChainPath(headersSelectedTip, newHeadersSelectedTip)
+			if err != nil {
+				return err
+			}
+
+			err = h.headersSelectedChainStore.Stage(h.databaseContext, chainChanges)
+			if err != nil {
+				return err
+			}
+		}
+	}
+
+	return nil
+}

domain/consensus/processes/headersselectedtipmanager/headersselectedtipmanager_test.go

@@ -0,0 +1,77 @@
+package headersselectedtipmanager_test
+
+import (
+	"github.com/kaspanet/kaspad/domain/consensus"
+	"github.com/kaspanet/kaspad/domain/consensus/model/externalapi"
+	"github.com/kaspanet/kaspad/domain/consensus/utils/testutils"
+	"github.com/kaspanet/kaspad/domain/dagconfig"
+	"github.com/kaspanet/kaspad/infrastructure/db/database"
+	"github.com/pkg/errors"
+	"testing"
+)
+
+func TestAddHeaderTip(t *testing.T) {
+	testutils.ForAllNets(t, true, func(t *testing.T, params *dagconfig.Params) {
+		factory := consensus.NewFactory()
+		tc, tearDown, err := factory.NewTestConsensus(params, false, "TestAddHeaderTip")
+		if err != nil {
+			t.Fatalf("NewTestConsensus: %s", err)
+		}
+		defer tearDown(false)
+
+		checkExpectedSelectedChain := func(expectedSelectedChain []*externalapi.DomainHash) {
+			for i, blockHash := range expectedSelectedChain {
+				chainBlockHash, err := tc.HeadersSelectedChainStore().GetHashByIndex(tc.DatabaseContext(), uint64(i))
+				if err != nil {
+					t.Fatalf("GetHashByIndex: %+v", err)
+				}
+
+				if !blockHash.Equal(chainBlockHash) {
+					t.Fatalf("chain block %d is expected to be %s but got %s", i, blockHash, chainBlockHash)
+				}
+
+				index, err := tc.HeadersSelectedChainStore().GetIndexByHash(tc.DatabaseContext(), blockHash)
+				if err != nil {
+					t.Fatalf("GetIndexByHash: %+v", err)
+				}
+
+				if uint64(i) != index {
+					t.Fatalf("chain block %s is expected to be %d but got %d", blockHash, i, index)
+				}
+			}
+
+			_, err := tc.HeadersSelectedChainStore().GetHashByIndex(tc.DatabaseContext(),
+				uint64(len(expectedSelectedChain)+1))
+			if !errors.Is(err, database.ErrNotFound) {
+				t.Fatalf("index %d is not expected to exist, but instead got error: %+v",
+					uint64(len(expectedSelectedChain)+1), err)
+			}
+		}
+
+		expectedSelectedChain := []*externalapi.DomainHash{params.GenesisHash}
+		tipHash := params.GenesisHash
+		for i := 0; i < 10; i++ {
+			var err error
+			tipHash, _, err = tc.AddBlock([]*externalapi.DomainHash{tipHash}, nil, nil)
+			if err != nil {
+				t.Fatalf("AddBlock: %+v", err)
+			}
+
+			expectedSelectedChain = append(expectedSelectedChain, tipHash)
+			checkExpectedSelectedChain(expectedSelectedChain)
+		}
+
+		expectedSelectedChain = []*externalapi.DomainHash{params.GenesisHash}
+		tipHash = params.GenesisHash
+		for i := 0; i < 11; i++ {
+			var err error
+			tipHash, _, err = tc.AddBlock([]*externalapi.DomainHash{tipHash}, nil, nil)
+			if err != nil {
+				t.Fatalf("AddBlock: %+v", err)
+			}
+
+			expectedSelectedChain = append(expectedSelectedChain, tipHash)
+		}
+		checkExpectedSelectedChain(expectedSelectedChain)
+	})
+}

domain/consensus/processes/headersselectedtipmanager/headertipsmanager.go

@@ -1,55 +0,0 @@
-package headersselectedtipmanager
-
-import (
-	"github.com/kaspanet/kaspad/domain/consensus/model"
-	"github.com/kaspanet/kaspad/domain/consensus/model/externalapi"
-)
-
-type headerTipsManager struct {
-	databaseContext model.DBReader
-
-	dagTopologyManager      model.DAGTopologyManager
-	ghostdagManager         model.GHOSTDAGManager
-	headersSelectedTipStore model.HeaderSelectedTipStore
-}
-
-// New instantiates a new HeadersSelectedTipManager
-func New(databaseContext model.DBReader,
-	dagTopologyManager model.DAGTopologyManager,
-	ghostdagManager model.GHOSTDAGManager,
-	headersSelectedTipStore model.HeaderSelectedTipStore) model.HeadersSelectedTipManager {
-
-	return &headerTipsManager{
-		databaseContext:         databaseContext,
-		dagTopologyManager:      dagTopologyManager,
-		ghostdagManager:         ghostdagManager,
-		headersSelectedTipStore: headersSelectedTipStore,
-	}
-}
-
-func (h *headerTipsManager) AddHeaderTip(hash *externalapi.DomainHash) error {
-	hasSelectedTip, err := h.headersSelectedTipStore.Has(h.databaseContext)
-	if err != nil {
-		return err
-	}
-
-	if !hasSelectedTip {
-		h.headersSelectedTipStore.Stage(hash)
-	} else {
-		headersSelectedTip, err := h.headersSelectedTipStore.HeadersSelectedTip(h.databaseContext)
-		if err != nil {
-			return err
-		}
-
-		newHeadersSelectedTip, err := h.ghostdagManager.ChooseSelectedParent(headersSelectedTip, hash)
-		if err != nil {
-			return err
-		}
-
-		if !newHeadersSelectedTip.Equal(headersSelectedTip) {
-			h.headersSelectedTipStore.Stage(newHeadersSelectedTip)
-		}
-	}
-
-	return nil
-}

domain/consensus/processes/syncmanager/blocklocator.go

@@ -98,3 +98,46 @@ func (sm *syncManager) findNextBlockLocatorBoundaries(blockLocator externalapi.B
 	}
 	return highestKnownHash, lowestUnknownHash, nil
 }
+
+func (sm *syncManager) createHeadersSelectedChainBlockLocator(lowHash,
+	highHash *externalapi.DomainHash) (externalapi.BlockLocator, error) {
+
+	if highHash.Equal(sm.genesisBlockHash) && lowHash.Equal(sm.genesisBlockHash) {
+		return externalapi.BlockLocator{sm.genesisBlockHash}, nil
+	}
+
+	lowHashIndex, err := sm.headersSelectedChainStore.GetIndexByHash(sm.databaseContext, lowHash)
+	if err != nil {
+		return nil, err
+	}
+
+	highHashIndex, err := sm.headersSelectedChainStore.GetIndexByHash(sm.databaseContext, highHash)
+	if err != nil {
+		return nil, err
+	}
+
+	if highHashIndex < lowHashIndex {
+		return nil, errors.Errorf("cannot build block locator while highHash is lower than lowHash")
+	}
+
+	locator := externalapi.BlockLocator{}
+	currentIndex := highHashIndex
+	step := uint64(1)
+	for currentIndex > lowHashIndex {
+		blockHash, err := sm.headersSelectedChainStore.GetHashByIndex(sm.databaseContext, currentIndex)
+		if err != nil {
+			return nil, err
+		}
+
+		locator = append(locator, blockHash)
+		if currentIndex < step {
+			break
+		}
+
+		currentIndex -= step
+		step *= 2
+	}
+
+	locator = append(locator, lowHash)
+	return locator, nil
+}

domain/consensus/processes/syncmanager/syncmanager.go

@@ -15,11 +15,12 @@ type syncManager struct {
 	ghostdagManager     model.GHOSTDAGManager
 	pruningManager      model.PruningManager
 
-	ghostdagDataStore model.GHOSTDAGDataStore
-	blockStatusStore  model.BlockStatusStore
-	blockHeaderStore  model.BlockHeaderStore
-	blockStore        model.BlockStore
-	pruningStore      model.PruningStore
+	ghostdagDataStore         model.GHOSTDAGDataStore
+	blockStatusStore          model.BlockStatusStore
+	blockHeaderStore          model.BlockHeaderStore
+	blockStore                model.BlockStore
+	pruningStore              model.PruningStore
+	headersSelectedChainStore model.HeadersSelectedChainStore
 }
 
 // New instantiates a new SyncManager
@@ -35,16 +36,18 @@ func New(
 	blockStatusStore model.BlockStatusStore,
 	blockHeaderStore model.BlockHeaderStore,
 	blockStore model.BlockStore,
-	pruningStore model.PruningStore) model.SyncManager {
+	pruningStore model.PruningStore,
+	headersSelectedChainStore model.HeadersSelectedChainStore) model.SyncManager {
 
 	return &syncManager{
 		databaseContext:  databaseContext,
 		genesisBlockHash: genesisBlockHash,
 
-		dagTraversalManager: dagTraversalManager,
-		dagTopologyManager:  dagTopologyManager,
-		ghostdagManager:     ghostdagManager,
-		pruningManager:      pruningManager,
+		dagTraversalManager:       dagTraversalManager,
+		dagTopologyManager:        dagTopologyManager,
+		ghostdagManager:           ghostdagManager,
+		pruningManager:            pruningManager,
+		headersSelectedChainStore: headersSelectedChainStore,
 
 		ghostdagDataStore: ghostdagDataStore,
 		blockStatusStore:  blockStatusStore,
@@ -77,6 +80,15 @@ func (sm *syncManager) CreateBlockLocator(lowHash, highHash *externalapi.DomainH
 	return sm.createBlockLocator(lowHash, highHash, limit)
 }
 
+func (sm *syncManager) CreateHeadersSelectedChainBlockLocator(lowHash,
+	highHash *externalapi.DomainHash) (externalapi.BlockLocator, error) {
+
+	onEnd := logger.LogAndMeasureExecutionTime(log, "CreateHeadersSelectedChainBlockLocator")
+	defer onEnd()
+
+	return sm.createHeadersSelectedChainBlockLocator(lowHash, highHash)
+}
+
 func (sm *syncManager) FindNextBlockLocatorBoundaries(blockLocator externalapi.BlockLocator) (lowHash, highHash *externalapi.DomainHash, err error) {
 	onEnd := logger.LogAndMeasureExecutionTime(log, "FindNextBlockLocatorBoundaries")
 	defer onEnd()

domain/consensus/test_consensus.go

@@ -95,4 +95,5 @@ func (tc *testConsensus) DiscardAllStores() {
 	tc.PruningStore().Discard()
 	tc.ReachabilityDataStore().Discard()
 	tc.UTXODiffStore().Discard()
+	tc.HeadersSelectedChainStore().Discard()
 }

domain/consensus/test_consensus_getters.go

@@ -133,3 +133,7 @@ func (tc *testConsensus) FinalityManager() model.FinalityManager {
 func (tc *testConsensus) FinalityStore() model.FinalityStore {
 	return tc.finalityStore
 }
+
+func (tc *testConsensus) HeadersSelectedChainStore() model.HeadersSelectedChainStore {
+	return tc.headersSelectedChainStore
+}

domain/consensus/utils/lrucacheuint64tohash/lrucacheuint64tohash.go

@@ -0,0 +1,57 @@
+package lrucacheuint64tohash
+
+import "github.com/kaspanet/kaspad/domain/consensus/model/externalapi"
+
+// LRUCache is a least-recently-used cache from
+// uint64 to DomainHash
+type LRUCache struct {
+	cache    map[uint64]*externalapi.DomainHash
+	capacity int
+}
+
+// New creates a new LRUCache
+func New(capacity int) *LRUCache {
+	return &LRUCache{
+		cache:    make(map[uint64]*externalapi.DomainHash, capacity+1),
+		capacity: capacity,
+	}
+}
+
+// Add adds an entry to the LRUCache
+func (c *LRUCache) Add(key uint64, value *externalapi.DomainHash) {
+	c.cache[key] = value
+
+	if len(c.cache) > c.capacity {
+		c.evictRandom()
+	}
+}
+
+// Get returns the entry for the given key, or (nil, false) otherwise
+func (c *LRUCache) Get(key uint64) (*externalapi.DomainHash, bool) {
+	value, ok := c.cache[key]
+	if !ok {
+		return nil, false
+	}
+	return value, true
+}
+
+// Has returns whether the LRUCache contains the given key
+func (c *LRUCache) Has(key uint64) bool {
+	_, ok := c.cache[key]
+	return ok
+}
+
+// Remove removes the entry for the the given key. Does nothing if
+// the entry does not exist
+func (c *LRUCache) Remove(key uint64) {
+	delete(c.cache, key)
+}
+
+func (c *LRUCache) evictRandom() {
+	var keyToEvict uint64
+	for key := range c.cache {
+		keyToEvict = key
+		break
+	}
+	c.Remove(keyToEvict)
+}

domain/utxoindex/utxoindex.go

@@ -29,7 +29,7 @@ func New(consensus externalapi.Consensus, database database.Database) *UTXOIndex
 }
 
 // Update updates the UTXO index with the given DAG selected parent chain changes
-func (ui *UTXOIndex) Update(chainChanges *externalapi.SelectedParentChainChanges) (*UTXOChanges, error) {
+func (ui *UTXOIndex) Update(chainChanges *externalapi.SelectedChainPath) (*UTXOChanges, error) {
 	onEnd := logger.LogAndMeasureExecutionTime(log, "UTXOIndex.Update")
 	defer onEnd()