This commit is a large refactor that moves over various responsibilities
from the ChannelRouter to the graph.Builder. These include all graph
related tasks such as:
- graph pruning
- validation of new network updates & persisting new updates
- notifying topology update clients of any changes.
This is a large commit but:
- many of the files are purely moved from `routing` to `graph`
- the business logic put in the graph Builder is copied exactly as is
from the ChannelRouter with one exception:
- The ChannelRouter just needs to be able to call the Builder's
`ApplyChannelUpdate` method. So this is now exported and provided to
the ChannelRouter as a config option.
- The trickiest part was just moving over the test code since quite a
bit had to be duplicated.
In preparation for adding a clean Graph DB interface, we create a
version of FetchLightningNode that doesnt allow a caller to provide in a
transaction.
Finally, The LightningNode object is removed from ChannelEdgePolicy.
This is a step towards letting ChannelEdgePolicy reflect exactly the
schema that is on disk.
This is also nice because the `Node` object is not necessarily always
required when the ChannelEdgePolicy is loaded from the DB, so now it
only get's loaded when needed.
In preparation for the next commit which will remove the
`*LightningNode` from the `ChannelEdgePolicy` struct,
`FetchLightningNode` is modified to take in an optional transaction so
that it can be utilised in places where a transaction exists.
Having a `ForEachChannel` method on the `LightningNode` struct itself
results in a `kvdb.Backend` object needing to be stored within the
LightningNode struct. In this commit, this method is replaced with a
`ForEachNodeChannel` method on the `ChannelGraph` struct will perform
the same function without needing the db pointer to be stored within the
LightningNode. This change, the LightningNode struct more closely
represents the schema on disk.
The existing `ForEachNodeChannel` method on `ChannelGraph` is renamed to
`ForEachNodeDirectedChannel`. It performs a slightly different function
since it's call-back operates on Cached policies.
With this commit we fix a few occurrences of loop variables being
accessed in closures.
While we touch the code, we also migrate it to using the require
library.
This commit was previously split into the following parts to ease
review:
- 2d746f68: replace imports
- 4008f0fd: use ecdsa.Signature
- 849e33d1: remove btcec.S256()
- b8f6ebbd: use v2 library correctly
- fa80bca9: bump go modules
To further separate the channel graph from the channel state, we
refactor the AddrsForNode method to use the graphs's public methods
instead of directly accessing any buckets. This makes sure that we can
have the channel state cached with just its buckets while not using a
kvdb level cache for the graph.
At the same time we refactor the graph's test to also be less dependent
upon the channel state DB.
We rename the field Capacity on local channels to Balance, define a new
method ChannelInfo on the manager config that let us query the database
for our latest channels state. Using this we will use the current local
balance instead of the channel capacity when doing allocation
calculations.
This commit creates a new autopilot heuristic which simply returns
normalized betweenness centrality values for the current graph. This
new heuristic will make it possible to prefer nodes with large
centrality when we're trying to open channels. The heuristic is also
somewhat dumb as it doesn't try to figure out the best nodes, as that'd
require adding ghost edges to the graph recalculating the centrality as
many times as many nodes there are (minus the one we already have
channels with).
This commit removes an extra filter on address availability which is not
needed as the scored nodes are a already prefiltered subset of the whole
graph where address availability has already been checked.
This commit adds betweenness centrality to the available node metrics.
Betweenness centrality is a per node centrality measure which for an
arbitrary node v equals to the sum of shortest paths going trough v
divided by the number of all shortest paths for for each vertex pair
k, s where k != s != v.
This commit adds the NodeMetric interface which will be used for all
graph metrics not directly part of the autopilot but are useful in
composite heuristics to drive autopilot decisions and improve node
scores.
