Merge pull request #4804 from wpaulino/proper-gossip-query-reply-chunk-splitting

discovery: adhere to proper channel chunk splitting for ReplyChannelRange

channeldb/graph.go

@@ -10,6 +10,7 @@ import (
 	"io"
 	"math"
 	"net"
+	"sort"
 	"sync"
 	"time"
 
@@ -1704,12 +1705,25 @@ func (c *ChannelGraph) FilterKnownChanIDs(chanIDs []uint64) ([]uint64, error) {
 	return newChanIDs, nil
 }
 
+// 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
+	// included in.
+	Height uint32
+
+	// 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
+}
+
 // FilterChannelRange returns the channel ID's of all known channels which were
-// mined in a block height within the passed range. 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.
-func (c *ChannelGraph) FilterChannelRange(startHeight, endHeight uint32) ([]uint64, error) {
-	var chanIDs []uint64
+// 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.
+func (c *ChannelGraph) FilterChannelRange(startHeight,
+	endHeight uint32) ([]BlockChannelRange, error) {
 
 	startChanID := &lnwire.ShortChannelID{
 		BlockHeight: startHeight,
@@ -1728,6 +1742,7 @@ func (c *ChannelGraph) FilterChannelRange(startHeight, endHeight uint32) ([]uint
 	byteOrder.PutUint64(chanIDStart[:], startChanID.ToUint64())
 	byteOrder.PutUint64(chanIDEnd[:], endChanID.ToUint64())
 
+	var channelsPerBlock map[uint32][]lnwire.ShortChannelID
 	err := kvdb.View(c.db, func(tx kvdb.RTx) error {
 		edges := tx.ReadBucket(edgeBucket)
 		if edges == nil {
@@ -1742,33 +1757,51 @@ func (c *ChannelGraph) FilterChannelRange(startHeight, endHeight uint32) ([]uint
 
 		// We'll now iterate through the database, and find each
 		// channel ID that resides within the specified range.
-		var cid uint64
 		for k, _ := cursor.Seek(chanIDStart[:]); k != nil &&
 			bytes.Compare(k, chanIDEnd[:]) <= 0; k, _ = cursor.Next() {
 
 			// This channel ID rests within the target range, so
-			// we'll convert it into an integer and add it to our
-			// returned set.
-			cid = byteOrder.Uint64(k)
-			chanIDs = append(chanIDs, cid)
+			// we'll add it to our returned set.
+			rawCid := byteOrder.Uint64(k)
+			cid := lnwire.NewShortChanIDFromInt(rawCid)
+			channelsPerBlock[cid.BlockHeight] = append(
+				channelsPerBlock[cid.BlockHeight], cid,
+			)
 		}
 
 		return nil
 	}, func() {
-		chanIDs = nil
+		channelsPerBlock = make(map[uint32][]lnwire.ShortChannelID)
 	})
 
 	switch {
 	// If we don't know of any channels yet, then there's nothing to
 	// filter, so we'll return an empty slice.
-	case err == ErrGraphNoEdgesFound:
-		return chanIDs, nil
+	case err == ErrGraphNoEdgesFound || len(channelsPerBlock) == 0:
+		return nil, nil
 
 	case err != nil:
 		return nil, err
 	}
 
-	return chanIDs, nil
+	// Return the channel ranges in ascending block height order.
+	blocks := make([]uint32, 0, len(channelsPerBlock))
+	for block := range channelsPerBlock {
+		blocks = append(blocks, block)
+	}
+	sort.Slice(blocks, func(i, j int) bool {
+		return blocks[i] < blocks[j]
+	})
+
+	channelRanges := make([]BlockChannelRange, 0, len(channelsPerBlock))
+	for _, block := range blocks {
+		channelRanges = append(channelRanges, BlockChannelRange{
+			Height:   block,
+			Channels: channelsPerBlock[block],
+		})
+	}
+
+	return channelRanges, nil
 }
 
 // FetchChanInfos returns the set of channel edges that correspond to the passed

channeldb/graph_test.go

@@ -1848,24 +1848,32 @@ func TestFilterChannelRange(t *testing.T) {
 		t.Fatalf("expected zero chans, instead got %v", len(resp))
 	}
 
-	// To start, we'll create a set of channels, each mined in a block 10
+	// To start, we'll create a set of channels, two mined in a block 10
 	// blocks after the prior one.
 	startHeight := uint32(100)
 	endHeight := startHeight
 	const numChans = 10
-	chanIDs := make([]uint64, 0, numChans)
-	for i := 0; i < numChans; i++ {
+	channelRanges := make([]BlockChannelRange, 0, numChans/2)
+	for i := 0; i < numChans/2; i++ {
 		chanHeight := endHeight
-		channel, chanID := createEdge(
-			uint32(chanHeight), uint32(i+1), 0, 0, node1, node2,
+		channel1, chanID1 := createEdge(
+			chanHeight, uint32(i+1), 0, 0, node1, node2,
 		)
-
-		if err := graph.AddChannelEdge(&channel); err != nil {
+		if err := graph.AddChannelEdge(&channel1); err != nil {
 			t.Fatalf("unable to create channel edge: %v", err)
 		}
 
-		chanIDs = append(chanIDs, chanID.ToUint64())
+		channel2, chanID2 := createEdge(
+			chanHeight, uint32(i+2), 0, 0, node1, node2,
+		)
+		if err := graph.AddChannelEdge(&channel2); err != nil {
+			t.Fatalf("unable to create channel edge: %v", err)
+		}
 
+		channelRanges = append(channelRanges, BlockChannelRange{
+			Height:   chanHeight,
+			Channels: []lnwire.ShortChannelID{chanID1, chanID2},
+		})
 		endHeight += 10
 	}
 
@@ -1876,7 +1884,7 @@ func TestFilterChannelRange(t *testing.T) {
 		startHeight uint32
 		endHeight   uint32
 
-		resp []uint64
+		resp []BlockChannelRange
 	}{
 		// If we query for the entire range, then we should get the same
 		// set of short channel IDs back.
@@ -1884,7 +1892,7 @@ func TestFilterChannelRange(t *testing.T) {
 			startHeight: startHeight,
 			endHeight:   endHeight,
 
-			resp: chanIDs,
+			resp: channelRanges,
 		},
 
 		// If we query for a range of channels right before our range, we
@@ -1900,7 +1908,7 @@ func TestFilterChannelRange(t *testing.T) {
 			startHeight: endHeight - 10,
 			endHeight:   endHeight - 10,
 
-			resp: chanIDs[9:],
+			resp: channelRanges[4:],
 		},
 
 		// If we query for just the first height, we should only get a
@@ -1909,7 +1917,14 @@ func TestFilterChannelRange(t *testing.T) {
 			startHeight: startHeight,
 			endHeight:   startHeight,
 
-			resp: chanIDs[:1],
+			resp: channelRanges[:1],
+		},
+
+		{
+			startHeight: startHeight + 10,
+			endHeight:   endHeight - 10,
+
+			resp: channelRanges[1:5],
 		},
 	}
 	for i, queryCase := range queryCases {