multi: query chan update timestamps

channeldb/graph.go

@@ -314,7 +314,6 @@ func (c *ChannelGraph) getChannelMap(edges kvdb.RBucket) (
 var graphTopLevelBuckets = [][]byte{
 	nodeBucket,
 	edgeBucket,
-	edgeIndexBucket,
 	graphMetaBucket,
 }
 
@@ -2087,10 +2086,12 @@ func (c *ChannelGraph) NodeUpdatesInHorizon(startTime,
 // words, we perform a set difference of our set of chan ID's and the ones
 // passed in. This method can be used by callers to determine the set of
 // channels another peer knows of that we don't.
-func (c *ChannelGraph) FilterKnownChanIDs(chanIDs []uint64) ([]uint64, error) {
+func (c *ChannelGraph) FilterKnownChanIDs(chansInfo []ChannelUpdateInfo,
+	isZombieChan func(time.Time, time.Time) bool) ([]uint64, error) {
+
 	var newChanIDs []uint64
 
-	err := kvdb.View(c.db, func(tx kvdb.RTx) error {
+	err := kvdb.Update(c.db, func(tx kvdb.RwTx) error {
 		edges := tx.ReadBucket(edgeBucket)
 		if edges == nil {
 			return ErrGraphNoEdgesFound
@@ -2108,8 +2109,9 @@ func (c *ChannelGraph) FilterKnownChanIDs(chanIDs []uint64) ([]uint64, error) {
 		// We'll run through the set of chanIDs and collate only the
 		// set of channel that are unable to be found within our db.
 		var cidBytes [8]byte
-		for _, cid := range chanIDs {
-			byteOrder.PutUint64(cidBytes[:], cid)
+		for _, info := range chansInfo {
+			scid := info.ShortChannelID.ToUint64()
+			byteOrder.PutUint64(cidBytes[:], scid)
 
 			// If the edge is already known, skip it.
 			if v := edgeIndex.Get(cidBytes[:]); v != nil {
@@ -2118,13 +2120,37 @@ func (c *ChannelGraph) FilterKnownChanIDs(chanIDs []uint64) ([]uint64, error) {
 
 			// If the edge is a known zombie, skip it.
 			if zombieIndex != nil {
-				isZombie, _, _ := isZombieEdge(zombieIndex, cid)
-				if isZombie {
+				isZombie, _, _ := isZombieEdge(
+					zombieIndex, scid,
+				)
+
+				isStillZombie := isZombieChan(
+					info.Node1UpdateTimestamp,
+					info.Node2UpdateTimestamp,
+				)
+
+				switch {
+				// If the edge is a known zombie and if we
+				// would still consider it a zombie given the
+				// latest update timestamps, then we skip this
+				// channel.
+				case isZombie && isStillZombie:
 					continue
+
+				// Otherwise, if we have marked it as a zombie
+				// but the latest update timestamps could bring
+				// it back from the dead, then we mark it alive,
+				// and we let it be added to the set of IDs to
+				// query our peer for.
+				case isZombie && !isStillZombie:
+					err := c.markEdgeLive(tx, scid)
+					if err != nil {
+						return err
+					}
 				}
 			}
 
-			newChanIDs = append(newChanIDs, cid)
+			newChanIDs = append(newChanIDs, scid)
 		}
 
 		return nil
@@ -2135,7 +2161,12 @@ func (c *ChannelGraph) FilterKnownChanIDs(chanIDs []uint64) ([]uint64, error) {
 	// If we don't know of any edges yet, then we'll return the entire set
 	// of chan IDs specified.
 	case err == ErrGraphNoEdgesFound:
-		return chanIDs, nil
+		ogChanIDs := make([]uint64, len(chansInfo))
+		for i, info := range chansInfo {
+			ogChanIDs[i] = info.ShortChannelID.ToUint64()
+		}
+
+		return ogChanIDs, nil
 
 	case err != nil:
 		return nil, err
@@ -2144,6 +2175,23 @@ func (c *ChannelGraph) FilterKnownChanIDs(chanIDs []uint64) ([]uint64, error) {
 	return newChanIDs, nil
 }
 
+// ChannelUpdateInfo couples the SCID of a channel with the timestamps of the
+// latest received channel updates for the channel.
+type ChannelUpdateInfo struct {
+	// ShortChannelID is the SCID identifier of the channel.
+	ShortChannelID lnwire.ShortChannelID
+
+	// Node1UpdateTimestamp is the timestamp of the latest received update
+	// from the node 1 channel peer. This will be set to zero time if no
+	// update has yet been received from this node.
+	Node1UpdateTimestamp time.Time
+
+	// Node2UpdateTimestamp is the timestamp of the latest received update
+	// from the node 2 channel peer. This will be set to zero time if no
+	// update has yet been received from this node.
+	Node2UpdateTimestamp time.Time
+}
+
 // BlockChannelRange represents a range of channels for a given block height.
 type BlockChannelRange struct {
 	// Height is the height of the block all of the channels below were
@@ -2152,17 +2200,20 @@ type BlockChannelRange struct {
 
 	// Channels is the list of channels identified by their short ID
 	// representation known to us that were included in the block height
-	// above.
-	Channels []lnwire.ShortChannelID
+	// above. The list may include channel update timestamp information if
+	// requested.
+	Channels []ChannelUpdateInfo
 }
 
 // FilterChannelRange returns the channel ID's of all known channels which were
 // mined in a block height within the passed range. The channel IDs are grouped
 // by their common block height. This method can be used to quickly share with a
 // peer the set of channels we know of within a particular range to catch them
-// up after a period of time offline.
+// up after a period of time offline. If withTimestamps is true then the
+// timestamp info of the latest received channel update messages of the channel
+// will be included in the response.
 func (c *ChannelGraph) FilterChannelRange(startHeight,
-	endHeight uint32) ([]BlockChannelRange, error) {
+	endHeight uint32, withTimestamps bool) ([]BlockChannelRange, error) {
 
 	startChanID := &lnwire.ShortChannelID{
 		BlockHeight: startHeight,
@@ -2181,7 +2232,7 @@ func (c *ChannelGraph) FilterChannelRange(startHeight,
 	byteOrder.PutUint64(chanIDStart[:], startChanID.ToUint64())
 	byteOrder.PutUint64(chanIDEnd[:], endChanID.ToUint64())
 
-	var channelsPerBlock map[uint32][]lnwire.ShortChannelID
+	var channelsPerBlock map[uint32][]ChannelUpdateInfo
 	err := kvdb.View(c.db, func(tx kvdb.RTx) error {
 		edges := tx.ReadBucket(edgeBucket)
 		if edges == nil {
@@ -2213,14 +2264,60 @@ func (c *ChannelGraph) FilterChannelRange(startHeight,
 			// we'll add it to our returned set.
 			rawCid := byteOrder.Uint64(k)
 			cid := lnwire.NewShortChanIDFromInt(rawCid)
+
+			chanInfo := ChannelUpdateInfo{
+				ShortChannelID: cid,
+			}
+
+			if !withTimestamps {
+				channelsPerBlock[cid.BlockHeight] = append(
+					channelsPerBlock[cid.BlockHeight],
+					chanInfo,
+				)
+
+				continue
+			}
+
+			node1Key, node2Key := computeEdgePolicyKeys(&edgeInfo)
+
+			rawPolicy := edges.Get(node1Key)
+			if len(rawPolicy) != 0 {
+				r := bytes.NewReader(rawPolicy)
+
+				edge, err := deserializeChanEdgePolicyRaw(r)
+				if err != nil && !errors.Is(
+					err, ErrEdgePolicyOptionalFieldNotFound,
+				) {
+
+					return err
+				}
+
+				chanInfo.Node1UpdateTimestamp = edge.LastUpdate
+			}
+
+			rawPolicy = edges.Get(node2Key)
+			if len(rawPolicy) != 0 {
+				r := bytes.NewReader(rawPolicy)
+
+				edge, err := deserializeChanEdgePolicyRaw(r)
+				if err != nil && !errors.Is(
+					err, ErrEdgePolicyOptionalFieldNotFound,
+				) {
+
+					return err
+				}
+
+				chanInfo.Node2UpdateTimestamp = edge.LastUpdate
+			}
+
 			channelsPerBlock[cid.BlockHeight] = append(
-				channelsPerBlock[cid.BlockHeight], cid,
+				channelsPerBlock[cid.BlockHeight], chanInfo,
 			)
 		}
 
 		return nil
 	}, func() {
-		channelsPerBlock = make(map[uint32][]lnwire.ShortChannelID)
+		channelsPerBlock = make(map[uint32][]ChannelUpdateInfo)
 	})
 
 	switch {
@@ -3119,6 +3216,24 @@ func (c *ChannelGraph) FetchOtherNode(tx kvdb.RTx,
 	return targetNode, err
 }
 
+// computeEdgePolicyKeys is a helper function that can be used to compute the
+// keys used to index the channel edge policy info for the two nodes of the
+// edge. The keys for node 1 and node 2 are returned respectively.
+func computeEdgePolicyKeys(info *models.ChannelEdgeInfo) ([]byte, []byte) {
+	var (
+		node1Key [33 + 8]byte
+		node2Key [33 + 8]byte
+	)
+
+	copy(node1Key[:], info.NodeKey1Bytes[:])
+	copy(node2Key[:], info.NodeKey2Bytes[:])
+
+	byteOrder.PutUint64(node1Key[33:], info.ChannelID)
+	byteOrder.PutUint64(node2Key[33:], info.ChannelID)
+
+	return node1Key[:], node2Key[:]
+}
+
 // FetchChannelEdgesByOutpoint attempts to lookup the two directed edges for
 // the channel identified by the funding outpoint. If the channel can't be
 // found, then ErrEdgeNotFound is returned. A struct which houses the general
@@ -3497,10 +3612,17 @@ func markEdgeZombie(zombieIndex kvdb.RwBucket, chanID uint64, pubKey1,
 
 // MarkEdgeLive clears an edge from our zombie index, deeming it as live.
 func (c *ChannelGraph) MarkEdgeLive(chanID uint64) error {
+	return c.markEdgeLive(nil, chanID)
+}
+
+// markEdgeLive clears an edge from the zombie index. This method can be called
+// with an existing kvdb.RwTx or the argument can be set to nil in which case a
+// new transaction will be created.
+func (c *ChannelGraph) markEdgeLive(tx kvdb.RwTx, chanID uint64) error {
 	c.cacheMu.Lock()
 	defer c.cacheMu.Unlock()
 
-	err := kvdb.Update(c.db, func(tx kvdb.RwTx) error {
+	dbFn := func(tx kvdb.RwTx) error {
 		edges := tx.ReadWriteBucket(edgeBucket)
 		if edges == nil {
 			return ErrGraphNoEdgesFound
@@ -3518,7 +3640,16 @@ func (c *ChannelGraph) MarkEdgeLive(chanID uint64) error {
 		}
 
 		return zombieIndex.Delete(k[:])
-	}, func() {})
+	}
+
+	// If the transaction is nil, we'll create a new one. Otherwise, we use
+	// the existing transaction
+	var err error
+	if tx == nil {
+		err = kvdb.Update(c.db, dbFn, func() {})
+	} else {
+		err = dbFn(tx)
+	}
 	if err != nil {
 		return err
 	}
@@ -3528,11 +3659,12 @@ func (c *ChannelGraph) MarkEdgeLive(chanID uint64) error {
 
 	// We need to add the channel back into our graph cache, otherwise we
 	// won't use it for path finding.
-	edgeInfos, err := c.FetchChanInfos([]uint64{chanID})
-	if err != nil {
-		return err
-	}
 	if c.graphCache != nil {
+		edgeInfos, err := c.FetchChanInfos([]uint64{chanID})
+		if err != nil {
+			return err
+		}
+
 		for _, edgeInfo := range edgeInfos {
 			c.graphCache.AddChannel(
 				edgeInfo.Info, edgeInfo.Policy1,