graph/db: let IsZombieEdge return an error

graph/db/errors.go

@@ -66,6 +66,11 @@ var (
 	// ErrUnknownAddressType is returned when a node's addressType is not
 	// an expected value.
 	ErrUnknownAddressType = fmt.Errorf("address type cannot be resolved")
+
+	// ErrCantCheckIfZombieEdgeStr is an error returned when we
+	// attempt to check if an edge is a zombie but encounter an error.
+	ErrCantCheckIfZombieEdgeStr = fmt.Errorf("unable to check if edge " +
+		"is a zombie")
 )
 
 // ErrTooManyExtraOpaqueBytes creates an error which should be returned if the

graph/db/graph_test.go

@@ -453,7 +453,8 @@ func TestEdgeInsertionDeletion(t *testing.T) {
 	require.ErrorIs(t, err, ErrEdgeNotFound)
 	_, _, _, err = graph.FetchChannelEdgesByID(chanID)
 	require.ErrorIs(t, err, ErrZombieEdge)
-	isZombie, _, _ := graph.IsZombieEdge(chanID)
+	isZombie, _, _, err := graph.IsZombieEdge(chanID)
+	require.NoError(t, err)
 	require.True(t, isZombie)
 
 	// Finally, attempt to delete a (now) non-existent edge within the
@@ -2205,7 +2206,9 @@ func TestFilterKnownChanIDsZombieRevival(t *testing.T) {
 	)
 
 	isZombie := func(scid lnwire.ShortChannelID) bool {
-		zombie, _, _ := graph.IsZombieEdge(scid.ToUint64())
+		zombie, _, _, err := graph.IsZombieEdge(scid.ToUint64())
+		require.NoError(t, err)
+
 		return zombie
 	}
 
@@ -3844,15 +3847,17 @@ func TestGraphZombieIndex(t *testing.T) {
 
 	// Since the edge is known the graph and it isn't a zombie, IsZombieEdge
 	// should not report the channel as a zombie.
-	isZombie, _, _ := graph.IsZombieEdge(edge.ChannelID)
+	isZombie, _, _, err := graph.IsZombieEdge(edge.ChannelID)
+	require.NoError(t, err)
 	require.False(t, isZombie)
 	assertNumZombies(t, graph, 0)
 
 	// If we delete the edge and mark it as a zombie, then we should expect
 	// to see it within the index.
-	err := graph.DeleteChannelEdges(false, true, edge.ChannelID)
+	err = graph.DeleteChannelEdges(false, true, edge.ChannelID)
 	require.NoError(t, err, "unable to mark edge as zombie")
-	isZombie, pubKey1, pubKey2 := graph.IsZombieEdge(edge.ChannelID)
+	isZombie, pubKey1, pubKey2, err := graph.IsZombieEdge(edge.ChannelID)
+	require.NoError(t, err)
 	require.True(t, isZombie)
 	require.Equal(t, node1.PubKeyBytes, pubKey1)
 	require.Equal(t, node2.PubKeyBytes, pubKey2)
@@ -3868,7 +3873,8 @@ func TestGraphZombieIndex(t *testing.T) {
 		t, graph.MarkEdgeLive(edge.ChannelID), ErrZombieEdgeNotFound,
 	)
 
-	isZombie, _, _ = graph.IsZombieEdge(edge.ChannelID)
+	isZombie, _, _, err = graph.IsZombieEdge(edge.ChannelID)
+	require.NoError(t, err)
 	require.False(t, isZombie)
 
 	assertNumZombies(t, graph, 0)
@@ -3880,7 +3886,8 @@ func TestGraphZombieIndex(t *testing.T) {
 	)
 	require.NoError(t, err, "unable to mark edge as zombie")
 
-	isZombie, _, _ = graph.IsZombieEdge(edge.ChannelID)
+	isZombie, _, _, err = graph.IsZombieEdge(edge.ChannelID)
+	require.NoError(t, err)
 	require.True(t, isZombie)
 	assertNumZombies(t, graph, 1)
 }

graph/db/interfaces.go

@@ -308,7 +308,7 @@ type V1Store interface { //nolint:interfacebloat
 	// IsZombieEdge returns whether the edge is considered zombie. If it is
 	// a zombie, then the two node public keys corresponding to this edge
 	// are also returned.
-	IsZombieEdge(chanID uint64) (bool, [33]byte, [33]byte)
+	IsZombieEdge(chanID uint64) (bool, [33]byte, [33]byte, error)
 
 	// NumZombies returns the current number of zombie channels in the
 	// graph.

graph/db/kv_store.go

@@ -3792,7 +3792,9 @@ func (c *KVStore) markEdgeLiveUnsafe(tx kvdb.RwTx, chanID uint64) error {
 // IsZombieEdge returns whether the edge is considered zombie. If it is a
 // zombie, then the two node public keys corresponding to this edge are also
 // returned.
-func (c *KVStore) IsZombieEdge(chanID uint64) (bool, [33]byte, [33]byte) {
+func (c *KVStore) IsZombieEdge(chanID uint64) (bool, [33]byte, [33]byte,
+	error) {
+
 	var (
 		isZombie         bool
 		pubKey1, pubKey2 [33]byte
@@ -3817,10 +3819,11 @@ func (c *KVStore) IsZombieEdge(chanID uint64) (bool, [33]byte, [33]byte) {
 		pubKey2 = [33]byte{}
 	})
 	if err != nil {
-		return false, [33]byte{}, [33]byte{}
+		return false, [33]byte{}, [33]byte{}, fmt.Errorf("%w: %w "+
+			"(chanID=%d)", ErrCantCheckIfZombieEdgeStr, err, chanID)
 	}
 
-	return isZombie, pubKey1, pubKey2
+	return isZombie, pubKey1, pubKey2, nil
 }
 
 // isZombieEdge returns whether an entry exists for the given channel in the

graph/db/sql_store.go

@@ -1636,7 +1636,9 @@ func (s *SQLStore) MarkEdgeLive(chanID uint64) error {
 // returned.
 //
 // NOTE: part of the V1Store interface.
-func (s *SQLStore) IsZombieEdge(chanID uint64) (bool, [33]byte, [33]byte) {
+func (s *SQLStore) IsZombieEdge(chanID uint64) (bool, [33]byte, [33]byte,
+	error) {
+
 	var (
 		ctx              = context.TODO()
 		isZombie         bool
@@ -1666,12 +1668,12 @@ func (s *SQLStore) IsZombieEdge(chanID uint64) (bool, [33]byte, [33]byte) {
 		return nil
 	}, sqldb.NoOpReset)
 	if err != nil {
-		// TODO(elle): update the IsZombieEdge method to return an
-		// error.
-		return false, route.Vertex{}, route.Vertex{}
+		return false, route.Vertex{}, route.Vertex{},
+			fmt.Errorf("%w: %w (chanID=%d)",
+				ErrCantCheckIfZombieEdgeStr, err, chanID)
 	}
 
-	return isZombie, pubKey1, pubKey2
+	return isZombie, pubKey1, pubKey2, nil
 }
 
 // NumZombies returns the current number of zombie channels in the graph.