graph: move topology subscription to `ChannelGraph` by ellemouton · Pull Request #9577 · lightningnetwork/lnd

ellemouton · 2025-03-05T06:04:46Z

We plan to later on add an option for a remote graph source which will
be managed from the ChannelGraph. In such a set-up, a node would rely on
the remote graph source for graph updates instead of from gossip sync.
In this scenario, however, our topology subscription logic should still
notify clients of all updates and so it makes more sense to have the
logic as part of the ChannelGraph so that we can send updates we receive
from the remote graph.

Part of #9494

coderabbitai · 2025-03-05T06:04:53Z

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yyforyongyu

Beautiful - the overall arch finally starts to look cool now😎

yyforyongyu · 2025-03-06T04:02:18Z

 		)
 	}

+	// No need to send topology updates for shell nodes.


q: what is a shell node?

it's a node that we only know about via a channel announcement that we have not received a channel update for yet

i'll add this comment

wait im also just gonna double check that this is actually needed. Now thinking about it, shell node anns should not come through here. but I remember i had to add this since they were coming through here.

Gimme a min

ok yeah we defs dont need this check.

itests all fine as this is only ever called from the gossiper which does a conversion from lnwire msg to model message and explicitly sets HaveNodeAnnouncement to true.

The issue was coming from unit tests in this package. So im removing this check and ensuring the unit tests pass by setting all expected fields for the models.LightningNode type.

ok adding some detailed info here just to make the changes im going to push here very clear:

So the failing test is TestPartialNode which currently tests that we can add a "Shell node" via the ChannelGraphs AddLightningNode method. It does an assertNodeInCache check too to ensure that this node is seen in the cache. However, as of today in master: this does not actually test what happens in reality. Today, we never add partial nodes (shell nodes) via this method. In reality, we only ever add these nodes (persist and add to cache) at the CRUD level via AddChannelEdge.

lnd/graph/db/graph.go

Lines 1143 to 1162 in 9feb761

if c.graphCache != nil {

c.graphCache.AddChannel(edge, nil, nil)

}

// Before we insert the channel into the database, we'll ensure that

// both nodes already exist in the channel graph. If either node

// doesn't, then we'll insert a "shell" node that just includes its

// public key, so subsequent validation and queries can work properly.

_, node1Err := fetchLightningNode(nodes, edge.NodeKey1Bytes[:])

switch {

case node1Err == ErrGraphNodeNotFound:

node1Shell := models.LightningNode{

PubKeyBytes: edge.NodeKey1Bytes,

HaveNodeAnnouncement: false,

}

err := addLightningNode(tx, &node1Shell)

if err != nil {

return fmt.Errorf("unable to create shell node "+

"for: %x: %w", edge.NodeKey1Bytes, err)

}

So, I've added an initial commit to fix the test so that it tests the correct flow.

bhandras

Awesomeness! LGTM ✨

The test as it stands today does not make sense as it adds a Partial/Shell node to the graph via AddLightningNode which will never happen since this is only ever triggered by the gossiper which only calls the method with a full node announcement. Shell/Partial nodes are only ever added via AddChannelEdge which will insert a partial node if we are adding a channel edge which has node pub keys that we dont have a node entry for. So we adjust the test to use this more accurate flow.

We plan to later on add an option for a remote graph source which will be managed from the ChannelGraph. In such a set-up, a node would rely on the remote graph source for graph updates instead of from gossip sync. In this scenario, however, our topology subscription logic should still notify clients of all updates and so it makes more sense to have the logic as part of the ChannelGraph so that we can send updates we receive from the remote graph.

A clean-up commit just to separate out all topology related fields in ChannelGraph into a dedicated struct that then gets mounted to the ChannelGraph.

ellemouton · 2025-03-06T10:32:41Z

soz for the re-request review yall, just wanna make sure you guys are ok with the final update here 🙏 see this thread for more flavour: #9577 (comment)

bhandras

LGTM 👏

yyforyongyu

🌹

ellemouton added graph refactoring labels Mar 5, 2025

ellemouton self-assigned this Mar 5, 2025

ellemouton force-pushed the graph19 branch from 00c8572 to dbb316f Compare March 5, 2025 06:05

ellemouton requested review from bhandras and yyforyongyu March 5, 2025 07:10

yyforyongyu approved these changes Mar 6, 2025

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bhandras approved these changes Mar 6, 2025

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Comment thread graph/db/graph.go

Comment thread graph/db/notifications.go

ellemouton added 4 commits March 6, 2025 12:23

graph/db: refactor to group all topology notification fields

2614110

A clean-up commit just to separate out all topology related fields in ChannelGraph into a dedicated struct that then gets mounted to the ChannelGraph.

docs: update release notes

220eac2

ellemouton force-pushed the graph19 branch from dbb316f to 220eac2 Compare March 6, 2025 10:27

ellemouton requested review from bhandras and yyforyongyu March 6, 2025 10:31

bhandras approved these changes Mar 6, 2025

View reviewed changes

yyforyongyu approved these changes Mar 6, 2025

View reviewed changes

ellemouton merged commit bb4d964 into lightningnetwork:elle-graphCacheBase Mar 6, 2025

ellemouton deleted the graph19 branch March 6, 2025 13:41

ellemouton mentioned this pull request Mar 6, 2025

graph: move graph cache out of CRUD layer #9544

Merged

	if c.graphCache != nil {
	c.graphCache.AddChannel(edge, nil, nil)
	}

	// Before we insert the channel into the database, we'll ensure that
	// both nodes already exist in the channel graph. If either node
	// doesn't, then we'll insert a "shell" node that just includes its
	// public key, so subsequent validation and queries can work properly.
	_, node1Err := fetchLightningNode(nodes, edge.NodeKey1Bytes[:])
	switch {
	case node1Err == ErrGraphNodeNotFound:
	node1Shell := models.LightningNode{
	PubKeyBytes: edge.NodeKey1Bytes,
	HaveNodeAnnouncement: false,
	}
	err := addLightningNode(tx, &node1Shell)
	if err != nil {
	return fmt.Errorf("unable to create shell node "+
	"for: %x: %w", edge.NodeKey1Bytes, err)
	}

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