feat: use recent chain points as intersect for chainsync client (#86)

Fixes #84

chainsync.go

@@ -25,6 +25,10 @@ import (
 	ocommon "github.com/blinklabs-io/gouroboros/protocol/common"
 )
 
+const (
+	chainsyncIntersectPointCount = 100
+)
+
 func (n *Node) chainsyncServerConnOpts() []ochainsync.ChainSyncOptionFunc {
 	return []ochainsync.ChainSyncOptionFunc{
 		ochainsync.WithFindIntersectFunc(n.chainsyncServerFindIntersect),
@@ -45,12 +49,22 @@ func (n *Node) chainsyncClientStart(connId ouroboros.ConnectionId) error {
 		return fmt.Errorf("failed to lookup connection ID: %s", connId.String())
 	}
 	oConn := conn.Conn
-	// TODO: use our recent blocks to build intersect points
-	tip, err := oConn.ChainSync().Client.GetCurrentTip()
+	intersectPoints, err := n.ledgerState.RecentChainPoints(chainsyncIntersectPointCount)
 	if err != nil {
 		return err
 	}
-	intersectPoints := []ocommon.Point{tip.Point}
+	// Empty intersect point means initial sync
+	if len(intersectPoints) == 0 {
+		// TODO: make this behavior configurable (genesis, tip, or specific point)
+		tip, err := oConn.ChainSync().Client.GetCurrentTip()
+		if err != nil {
+			return err
+		}
+		intersectPoints = append(
+			intersectPoints,
+			tip.Point,
+		)
+	}
 	if err := oConn.ChainSync().Client.Sync(intersectPoints); err != nil {
 		return err
 	}

internal/node/node.go

@@ -32,6 +32,8 @@ func Run(logger *slog.Logger) error {
 	n, err := node.New(
 		node.NewConfig(
 			node.WithLogger(logger),
+			// TODO: uncomment and make this configurable
+			//node.WithDataDir(".data"),
 			// TODO: make this configurable
 			node.WithNetwork("preview"),
 			node.WithListeners(

state/state.go

@@ -27,7 +27,6 @@ import (
 	"gorm.io/gorm"
 
 	ochainsync "github.com/blinklabs-io/gouroboros/protocol/chainsync"
-	"github.com/blinklabs-io/gouroboros/protocol/common"
 	ocommon "github.com/blinklabs-io/gouroboros/protocol/common"
 	badger "github.com/dgraph-io/badger/v4"
 )
@@ -155,8 +154,28 @@ func (ls *LedgerState) GetBlock(point ocommon.Point) (*models.Block, error) {
 	return &ret, nil
 }
 
-func (ls *LedgerState) GetIntersectPoint(points []common.Point) (*common.Point, error) {
-	var ret common.Point
+// RecentChainPoints returns the requested count of recent chain points in descending order. This is used mostly
+// for building a set of intersect points when acting as a chainsync client
+func (ls *LedgerState) RecentChainPoints(count int) ([]ocommon.Point, error) {
+	ls.RLock()
+	defer ls.RUnlock()
+	var tmpBlocks []models.Block
+	result := ls.db.Metadata().Order("number DESC").Limit(count).Find(&tmpBlocks)
+	if result.Error != nil {
+		return nil, result.Error
+	}
+	var ret []ocommon.Point
+	for _, tmpBlock := range tmpBlocks {
+		ret = append(
+			ret,
+			ocommon.NewPoint(tmpBlock.Slot, tmpBlock.Hash),
+		)
+	}
+	return ret, nil
+}
+
+func (ls *LedgerState) GetIntersectPoint(points []ocommon.Point) (*ocommon.Point, error) {
+	var ret ocommon.Point
 	for _, point := range points {
 		// Ignore points with a slot earlier than an existing match
 		if point.Slot < ret.Slot {
@@ -180,7 +199,7 @@ func (ls *LedgerState) GetIntersectPoint(points []common.Point) (*common.Point,
 	return nil, nil
 }
 
-func (ls *LedgerState) GetChainFromPoint(point common.Point) (*ChainIterator, error) {
+func (ls *LedgerState) GetChainFromPoint(point ocommon.Point) (*ChainIterator, error) {
 	return newChainIterator(ls, point)
 }