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routing: modify findPaths to take an upper limit on the number of routes

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In this commit, we modify the findPaths method to take the max number
of routes to return. With this change, FindRoutes can eventually itself
also take a max number of routes in order to make the function useable
again.
This commit is contained in:
Olaoluwa Osuntokun 2018-02-12 16:18:44 -08:00
parent 3e422fedd3
commit 33ba60ce66
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GPG Key ID: 964EA263DD637C21
1 changed files with 13 additions and 10 deletions
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23
routing/pathfind.go
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@ -612,9 +612,7 @@ func findPath(tx *bolt.Tx, graph *channeldb.ChannelGraph,
// algorithm in a block box manner. // algorithm in a block box manner.
func findPaths(tx *bolt.Tx, graph *channeldb.ChannelGraph, func findPaths(tx *bolt.Tx, graph *channeldb.ChannelGraph,
source *channeldb.LightningNode, target *btcec.PublicKey, source *channeldb.LightningNode, target *btcec.PublicKey,
amt lnwire.MilliSatoshi) ([][]*ChannelHop, error) { amt lnwire.MilliSatoshi, numPaths uint32) ([][]*ChannelHop, error) {
// TODO(roasbeef): take in db tx
ignoredEdges := make(map[uint64]struct{}) ignoredEdges := make(map[uint64]struct{})
ignoredVertexes := make(map[Vertex]struct{}) ignoredVertexes := make(map[Vertex]struct{})
@ -629,8 +627,9 @@ func findPaths(tx *bolt.Tx, graph *channeldb.ChannelGraph,
// First we'll find a single shortest path from the source (our // First we'll find a single shortest path from the source (our
// selfNode) to the target destination that's capable of carrying amt // selfNode) to the target destination that's capable of carrying amt
// satoshis along the path before fees are calculated. // satoshis along the path before fees are calculated.
startingPath, err := findPath(tx, graph, source, target, startingPath, err := findPath(
ignoredVertexes, ignoredEdges, amt) tx, graph, source, target, ignoredVertexes, ignoredEdges, amt,
)
if err != nil { if err != nil {
log.Errorf("Unable to find path: %v", err) log.Errorf("Unable to find path: %v", err)
return nil, err return nil, err
@ -651,7 +650,7 @@ func findPaths(tx *bolt.Tx, graph *channeldb.ChannelGraph,
// While we still have candidate paths to explore we'll keep exploring // While we still have candidate paths to explore we'll keep exploring
// the sub-graphs created to find the next k-th shortest path. // the sub-graphs created to find the next k-th shortest path.
for k := 1; k < 100; k++ { for k := uint32(1); k < numPaths; k++ {
prevShortest := shortestPaths[k-1] prevShortest := shortestPaths[k-1]
// We'll examine each edge in the previous iteration's shortest // We'll examine each edge in the previous iteration's shortest
@ -673,7 +672,8 @@ func findPaths(tx *bolt.Tx, graph *channeldb.ChannelGraph,
// Before we kickoff our next path finding iteration, // Before we kickoff our next path finding iteration,
// we'll find all the edges we need to ignore in this // we'll find all the edges we need to ignore in this
// next round. // next round. This ensures that we create a new unique
// path.
for _, path := range shortestPaths { for _, path := range shortestPaths {
// If our current rootPath is a prefix of this // If our current rootPath is a prefix of this
// shortest path, then we'll remove the edge // shortest path, then we'll remove the edge
@ -685,7 +685,8 @@ func findPaths(tx *bolt.Tx, graph *channeldb.ChannelGraph,
} }
// Next we'll remove all entries in the root path that // Next we'll remove all entries in the root path that
// aren't the current spur node from the graph. // aren't the current spur node from the graph. This
// ensures we don't create a path with loops.
for _, hop := range rootPath { for _, hop := range rootPath {
node := hop.Node.PubKeyBytes node := hop.Node.PubKeyBytes
if node == spurNode.PubKeyBytes { if node == spurNode.PubKeyBytes {
@ -699,8 +700,10 @@ func findPaths(tx *bolt.Tx, graph *channeldb.ChannelGraph,
// the Vertexes (other than the spur path) within the // the Vertexes (other than the spur path) within the
// root path removed, we'll attempt to find another // root path removed, we'll attempt to find another
// shortest path from the spur node to the destination. // shortest path from the spur node to the destination.
spurPath, err := findPath(tx, graph, spurNode, target, spurPath, err := findPath(
ignoredVertexes, ignoredEdges, amt) tx, graph, spurNode, target, ignoredVertexes,
ignoredEdges, amt,
)
// If we weren't able to find a path, we'll continue to // If we weren't able to find a path, we'll continue to
// the next round. // the next round.