autopilot: trigger agent channel open on new scores

This commit adds a new signal to the autopilot agent, meant to signal
when any of the available heuristics has gotten an update.

We currently use this to trigger a new channel opening after the
external scores have been updated.

autopilot/agent.go

@@ -141,6 +141,10 @@ type Agent struct {
 	// time.
 	chanOpenFailures chan *chanOpenFailureUpdate
 
+	// heuristicUpdates is a channel where updates from active heurstics
+	// will be sent.
+	heuristicUpdates chan *heuristicUpdate
+
 	// totalBalance is the total number of satoshis the backing wallet is
 	// known to control at any given instance. This value will be updated
 	// when the agent receives external balance update signals.
@@ -179,6 +183,7 @@ func New(cfg Config, initialState []Channel) (*Agent, error) {
 		balanceUpdates:     make(chan *balanceUpdate, 1),
 		nodeUpdates:        make(chan *nodeUpdates, 1),
 		chanOpenFailures:   make(chan *chanOpenFailureUpdate, 1),
+		heuristicUpdates:   make(chan *heuristicUpdate, 1),
 		pendingOpenUpdates: make(chan *chanPendingOpenUpdate, 1),
 		failedNodes:        make(map[NodeID]struct{}),
 		pendingConns:       make(map[NodeID]struct{}),
@@ -256,6 +261,13 @@ type chanPendingOpenUpdate struct{}
 // a previous channel open failed, and that it might be possible to try again.
 type chanOpenFailureUpdate struct{}
 
+// heuristicUpdate is an update sent when one of the autopilot heuristics has
+// changed, and prompts the agent to make a new attempt at opening more
+// channels.
+type heuristicUpdate struct {
+	heuristic AttachmentHeuristic
+}
+
 // chanCloseUpdate is a type of external state update that indicates that the
 // backing Lightning Node has closed a previously open channel.
 type chanCloseUpdate struct {
@@ -329,6 +341,17 @@ func (a *Agent) OnChannelClose(closedChans ...lnwire.ShortChannelID) {
 	}()
 }
 
+// OnHeuristicUpdate is a method called when a heuristic has been updated, to
+// trigger the agent to do a new state assessment.
+func (a *Agent) OnHeuristicUpdate(h AttachmentHeuristic) {
+	select {
+	case a.heuristicUpdates <- &heuristicUpdate{
+		heuristic: h,
+	}:
+	default:
+	}
+}
+
 // mergeNodeMaps merges the Agent's set of nodes that it already has active
 // channels open to, with the other sets of nodes that should be removed from
 // consideration during heuristic selection. This ensures that the Agent doesn't
@@ -470,6 +493,12 @@ func (a *Agent) controller() {
 			log.Debugf("Node updates received, assessing " +
 				"need for more channels")
 
+		// Any of the deployed heuristics has been updated, check
+		// whether we have new channel candidates available.
+		case upd := <-a.heuristicUpdates:
+			log.Debugf("Heuristic %v updated, assessing need for "+
+				"more channels", upd.heuristic.Name())
+
 		// The agent has been signalled to exit, so we'll bail out
 		// immediately.
 		case <-a.quit:

autopilot/manager.go

@@ -358,6 +358,9 @@ func (m *Manager) queryHeuristics(nodes map[NodeID]struct{}, localState bool) (
 // SetNodeScores is used to set the scores of the given heuristic, if it is
 // active, and ScoreSettable.
 func (m *Manager) SetNodeScores(name string, scores map[NodeID]float64) error {
+	m.Lock()
+	defer m.Unlock()
+
 	// It must be ScoreSettable to be available for external
 	// scores.
 	s, ok := m.cfg.PilotCfg.Heuristic.(ScoreSettable)
@@ -376,5 +379,11 @@ func (m *Manager) SetNodeScores(name string, scores map[NodeID]float64) error {
 		return fmt.Errorf("heuristic with name %v not found", name)
 	}
 
+	// If the autopilot agent is active, notify about the updated
+	// heuristic.
+	if m.pilot != nil {
+		m.pilot.OnHeuristicUpdate(m.cfg.PilotCfg.Heuristic)
+	}
+
 	return nil
 }

pilot.go

@@ -31,7 +31,7 @@ func validateAtplCfg(cfg *autoPilotConfig) ([]*autopilot.WeightedHeuristic,
 	for _, a := range autopilot.AvailableHeuristics {
 		heuristicsStr += fmt.Sprintf(" '%v' ", a.Name())
 	}
-	availStr := fmt.Sprintf("Avaiblable heuristcs are: [%v]", heuristicsStr)
+	availStr := fmt.Sprintf("Available heuristics are: [%v]", heuristicsStr)
 
 	// We'll go through the config and make sure all the heuristics exists,
 	// and that the sum of their weights is 1.0.