autopilot: for ConstrainedPrefAttachment.Select factor in skipNodes

This commit modifies the Select method for the
ConstrainedPrefAttachment attachment heuristic slightly. Previously, it
was possible for an autopilot.Agent to go over the allotted number of
channels as it would unconditionally attempt to establish channel with
all returned Attachment Directives. To remedy this, we now assume that
we already have active, or pending channels to each of the nodes in the
set of skipNodes. Therefore, we now use the size of the skipNodes map
as an  upper limit within the primary selection loop.
This commit is contained in:
Olaoluwa Osuntokun 2017-08-21 22:24:35 -07:00
parent a8576eaa69
commit 77e3e74ea2
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GPG Key ID: 9CC5B105D03521A2
2 changed files with 6 additions and 2 deletions

@ -112,6 +112,8 @@ type AttachmentHeuristic interface {
// indeed need more channels, then the second argument returned will // indeed need more channels, then the second argument returned will
// represent the amount of additional funds to be used towards creating // represent the amount of additional funds to be used towards creating
// channels. // channels.
//
// TODO(roasbeef): return number of chans? ensure doesn't go over
NeedMoreChans(chans []Channel, balance btcutil.Amount) (btcutil.Amount, bool) NeedMoreChans(chans []Channel, balance btcutil.Amount) (btcutil.Amount, bool)
// Select is a method that given the current state of the channel // Select is a method that given the current state of the channel

@ -122,7 +122,8 @@ func NewNodeID(pub *btcec.PublicKey) NodeID {
// //
// NOTE: This is a part of the AttachmentHeuristic interface. // NOTE: This is a part of the AttachmentHeuristic interface.
func (p *ConstrainedPrefAttachment) Select(self *btcec.PublicKey, g ChannelGraph, func (p *ConstrainedPrefAttachment) Select(self *btcec.PublicKey, g ChannelGraph,
fundsAvailable btcutil.Amount, skipNodes map[NodeID]struct{}) ([]AttachmentDirective, error) { fundsAvailable btcutil.Amount,
skipNodes map[NodeID]struct{}) ([]AttachmentDirective, error) {
// TODO(roasbeef): rename? // TODO(roasbeef): rename?
@ -135,7 +136,8 @@ func (p *ConstrainedPrefAttachment) Select(self *btcec.PublicKey, g ChannelGraph
// We'll continue our attachment loop until we've exhausted the current // We'll continue our attachment loop until we've exhausted the current
// amount of available funds. // amount of available funds.
visited := make(map[NodeID]struct{}) visited := make(map[NodeID]struct{})
for i := uint16(0); i < p.chanLimit; i++ { chanLimit := p.chanLimit - uint16(len(skipNodes))
for i := uint16(0); i < chanLimit; i++ {
// selectionSlice will be used to randomly select a node // selectionSlice will be used to randomly select a node
// according to a power law distribution. For each connected // according to a power law distribution. For each connected
// edge, we'll add an instance of the node to this slice. Thus, // edge, we'll add an instance of the node to this slice. Thus,