sqldb+graph/db: source nodes table, queries and CRUD

In this commit, we add the `source_nodes` table. It points to entries in
the `nodes` table. This table will store one entry per protocol version
that we are announcing a node_announcement on.

With this commit, we can run the TestSourceNode unit test against our
SQL backends.

graph/db/graph_test.go

@@ -355,10 +355,11 @@ func TestAliasLookup(t *testing.T) {
 	require.ErrorIs(t, err, ErrNodeAliasNotFound)
 }
 
+// TestSourceNode tests the source node functionality of the graph store.
 func TestSourceNode(t *testing.T) {
 	t.Parallel()
 
-	graph := MakeTestGraph(t)
+	graph := MakeTestGraphNew(t)
 
 	// We'd like to test the setting/getting of the source node, so we
 	// first create a fake node to use within the test.
@@ -369,11 +370,9 @@ func TestSourceNode(t *testing.T) {
 	_, err := graph.SourceNode()
 	require.ErrorIs(t, err, ErrSourceNodeNotSet)
 
-	// Set the source the source node, this should insert the node into the
+	// Set the source node, this should insert the node into the
 	// database in a special way indicating it's the source node.
-	if err := graph.SetSourceNode(testNode); err != nil {
-		t.Fatalf("unable to set source node: %v", err)
-	}
+	require.NoError(t, graph.SetSourceNode(testNode))
 
 	// Retrieve the source node from the database, it should exactly match
 	// the one we set above.

graph/db/sql_store.go

@@ -63,6 +63,12 @@ type SQLQueries interface {
 	GetNodeFeatures(ctx context.Context, nodeID int64) ([]sqlc.NodeFeature, error)
 	GetNodeFeaturesByPubKey(ctx context.Context, arg sqlc.GetNodeFeaturesByPubKeyParams) ([]int32, error)
 	DeleteNodeFeature(ctx context.Context, arg sqlc.DeleteNodeFeatureParams) error
+
+	/*
+		Source node queries.
+	*/
+	AddSourceNode(ctx context.Context, nodeID int64) error
+	GetSourceNodesByVersion(ctx context.Context, version int16) ([]sqlc.GetSourceNodesByVersionRow, error)
 }
 
 // BatchedSQLQueries is a version of SQLQueries that's capable of batched
@@ -372,6 +378,73 @@ func (s *SQLStore) LookupAlias(pub *btcec.PublicKey) (string, error) {
 	return alias, nil
 }
 
+// SourceNode returns the source node of the graph. The source node is treated
+// as the center node within a star-graph. This method may be used to kick off
+// a path finding algorithm in order to explore the reachability of another
+// node based off the source node.
+//
+// NOTE: part of the V1Store interface.
+func (s *SQLStore) SourceNode() (*models.LightningNode, error) {
+	ctx := context.TODO()
+
+	var (
+		readTx = NewReadTx()
+		node   *models.LightningNode
+	)
+	err := s.db.ExecTx(ctx, readTx, func(db SQLQueries) error {
+		_, nodePub, err := getSourceNode(ctx, db, ProtocolV1)
+		if err != nil {
+			return fmt.Errorf("unable to fetch V1 source node: %w",
+				err)
+		}
+
+		_, node, err = getNodeByPubKey(ctx, db, nodePub)
+
+		return err
+	}, func() {})
+	if err != nil {
+		return nil, fmt.Errorf("unable to fetch source node: %w", err)
+	}
+
+	return node, nil
+}
+
+// SetSourceNode sets the source node within the graph database. The source
+// node is to be used as the center of a star-graph within path finding
+// algorithms.
+//
+// NOTE: part of the V1Store interface.
+func (s *SQLStore) SetSourceNode(node *models.LightningNode) error {
+	ctx := context.TODO()
+	var writeTxOpts TxOptions
+
+	return s.db.ExecTx(ctx, &writeTxOpts, func(db SQLQueries) error {
+		id, err := upsertNode(ctx, db, node)
+		if err != nil {
+			return fmt.Errorf("unable to upsert source node: %w",
+				err)
+		}
+
+		// Make sure that if a source node for this version is already
+		// set, then the ID is the same as the one we are about to set.
+		dbSourceNodeID, _, err := getSourceNode(ctx, db, ProtocolV1)
+		if err != nil && !errors.Is(err, ErrSourceNodeNotSet) {
+			return fmt.Errorf("unable to fetch source node: %w",
+				err)
+		} else if err == nil {
+			if dbSourceNodeID != id {
+				return fmt.Errorf("v1 source node already "+
+					"set to a different node: %d vs %d",
+					dbSourceNodeID, id)
+			}
+
+			return nil
+		}
+
+		return db.AddSourceNode(ctx, id)
+	}, func() {})
+}
+
 // NodeUpdatesInHorizon returns all the known lightning node which have an
 // update timestamp within the passed range. This method can be used by two
 // nodes to quickly determine if they have the same set of up to date node
@@ -932,6 +1005,31 @@ func upsertNodeExtraSignedFields(ctx context.Context, db SQLQueries,
 	return nil
 }
 
+// getSourceNode returns the DB node ID and pub key of the source node for the
+// specified protocol version.
+func getSourceNode(ctx context.Context, db SQLQueries,
+	version ProtocolVersion) (int64, route.Vertex, error) {
+
+	var pubKey route.Vertex
+
+	nodes, err := db.GetSourceNodesByVersion(ctx, int16(version))
+	if err != nil {
+		return 0, pubKey, fmt.Errorf("unable to fetch source node: %w",
+			err)
+	}
+
+	if len(nodes) == 0 {
+		return 0, pubKey, ErrSourceNodeNotSet
+	} else if len(nodes) > 1 {
+		return 0, pubKey, fmt.Errorf("multiple source nodes for "+
+			"protocol %s found", version)
+	}
+
+	copy(pubKey[:], nodes[0].PubKey)
+
+	return nodes[0].NodeID, pubKey, nil
+}
+
 // marshalExtraOpaqueData takes a flat byte slice parses it as a TLV stream.
 // This then produces a map from TLV type to value. If the input is not a
 // valid TLV stream, then an error is returned.

sqldb/sqlc/graph.sql.go

@@ -10,6 +10,22 @@ import (
 	"database/sql"
 )
 
+const addSourceNode = `-- name: AddSourceNode :exec
+/* ─────────────────────────────────────────────
+   source_nodes table queries
+   ─────────────────────────────────────────────
+*/
+
+INSERT INTO source_nodes (node_id)
+VALUES ($1)
+ON CONFLICT (node_id) DO NOTHING
+`
+
+func (q *Queries) AddSourceNode(ctx context.Context, nodeID int64) error {
+	_, err := q.db.ExecContext(ctx, addSourceNode, nodeID)
+	return err
+}
+
 const deleteExtraNodeType = `-- name: DeleteExtraNodeType :exec
 DELETE FROM node_extra_types
 WHERE node_id = $1
@@ -272,6 +288,41 @@ func (q *Queries) GetNodesByLastUpdateRange(ctx context.Context, arg GetNodesByL
 	return items, nil
 }
 
+const getSourceNodesByVersion = `-- name: GetSourceNodesByVersion :many
+SELECT sn.node_id, n.pub_key
+FROM source_nodes sn
+    JOIN nodes n ON sn.node_id = n.id
+WHERE n.version = $1
+`
+
+type GetSourceNodesByVersionRow struct {
+	NodeID int64
+	PubKey []byte
+}
+
+func (q *Queries) GetSourceNodesByVersion(ctx context.Context, version int16) ([]GetSourceNodesByVersionRow, error) {
+	rows, err := q.db.QueryContext(ctx, getSourceNodesByVersion, version)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	var items []GetSourceNodesByVersionRow
+	for rows.Next() {
+		var i GetSourceNodesByVersionRow
+		if err := rows.Scan(&i.NodeID, &i.PubKey); err != nil {
+			return nil, err
+		}
+		items = append(items, i)
+	}
+	if err := rows.Close(); err != nil {
+		return nil, err
+	}
+	if err := rows.Err(); err != nil {
+		return nil, err
+	}
+	return items, nil
+}
+
 const insertNodeAddress = `-- name: InsertNodeAddress :exec
 /* ─────────────────────────────────────────────
    node_addresses table queries

sqldb/sqlc/migrations/000007_graph.down.sql

@@ -3,8 +3,10 @@ DROP INDEX IF EXISTS nodes_unique;
 DROP INDEX IF EXISTS node_extra_types_unique;
 DROP INDEX IF EXISTS node_features_unique;
 DROP INDEX IF EXISTS node_addresses_unique;
+DROP INDEX IF EXISTS source_nodes_unique;
 
 -- Drop tables in order of reverse dependencies.
+DROP TABLE IF EXISTS source_nodes;
 DROP TABLE IF EXISTS node_addresses;
 DROP TABLE IF EXISTS node_features;
 DROP TABLE IF EXISTS node_extra_types;

sqldb/sqlc/migrations/000007_graph.up.sql

@@ -88,3 +88,10 @@ CREATE TABLE IF NOT EXISTS node_addresses (
 CREATE UNIQUE INDEX IF NOT EXISTS node_addresses_unique ON node_addresses (
     node_id, type, position
 );
+
+CREATE TABLE IF NOT EXISTS source_nodes (
+    node_id BIGINT NOT NULL REFERENCES nodes (id) ON DELETE CASCADE
+);
+CREATE UNIQUE INDEX IF NOT EXISTS source_nodes_unique ON source_nodes (
+    node_id
+);

sqldb/sqlc/models.go

@@ -130,3 +130,7 @@ type NodeFeature struct {
 	NodeID     int64
 	FeatureBit int32
 }
+
+type SourceNode struct {
+	NodeID int64
+}

sqldb/sqlc/querier.go

@@ -11,6 +11,7 @@ import (
 )
 
 type Querier interface {
+	AddSourceNode(ctx context.Context, nodeID int64) error
 	ClearKVInvoiceHashIndex(ctx context.Context) error
 	DeleteCanceledInvoices(ctx context.Context) (sql.Result, error)
 	DeleteExtraNodeType(ctx context.Context, arg DeleteExtraNodeTypeParams) error
@@ -41,6 +42,7 @@ type Querier interface {
 	GetNodeFeatures(ctx context.Context, nodeID int64) ([]NodeFeature, error)
 	GetNodeFeaturesByPubKey(ctx context.Context, arg GetNodeFeaturesByPubKeyParams) ([]int32, error)
 	GetNodesByLastUpdateRange(ctx context.Context, arg GetNodesByLastUpdateRangeParams) ([]Node, error)
+	GetSourceNodesByVersion(ctx context.Context, version int16) ([]GetSourceNodesByVersionRow, error)
 	InsertAMPSubInvoice(ctx context.Context, arg InsertAMPSubInvoiceParams) error
 	InsertAMPSubInvoiceHTLC(ctx context.Context, arg InsertAMPSubInvoiceHTLCParams) error
 	InsertInvoice(ctx context.Context, arg InsertInvoiceParams) (int64, error)

sqldb/sqlc/queries/graph.sql

@@ -116,3 +116,19 @@ WHERE node_id = $1;
 DELETE FROM node_extra_types
 WHERE node_id = $1
   AND type = $2;
+
+/* ─────────────────────────────────────────────
+   source_nodes table queries
+   ─────────────────────────────────────────────
+*/
+
+-- name: AddSourceNode :exec
+INSERT INTO source_nodes (node_id)
+VALUES ($1)
+ON CONFLICT (node_id) DO NOTHING;
+
+-- name: GetSourceNodesByVersion :many
+SELECT sn.node_id, n.pub_key
+FROM source_nodes sn
+    JOIN nodes n ON sn.node_id = n.id
+WHERE n.version = $1;