autopilot/agent: add queryHeuristics

This commit adds a method queryHeuristic that will query all simple
heuristics for node scores, in addition to the current active heuristic.

autopilot/agent.go

@@ -768,3 +768,55 @@ func (a *Agent) executeDirective(directive AttachmentDirective) {
 	// we'll trigger the autopilot agent to query for more peers.
 	a.OnChannelPendingOpen()
 }
+
+// HeuristicScores is an alias for a map that maps heuristic names to a map of
+// scores for pubkeys.
+type HeuristicScores map[string]map[NodeID]float64
+
+// queryHeuristics gets node scores from all available simple heuristics, and
+// the agent's current active heuristic.
+func (a *Agent) queryHeuristics(nodes map[NodeID]struct{}) (
+	HeuristicScores, error) {
+
+	// Get the agent's current channel state.
+	a.chanStateMtx.Lock()
+	a.pendingMtx.Lock()
+	totalChans := mergeChanState(a.pendingOpens, a.chanState)
+	a.pendingMtx.Unlock()
+	a.chanStateMtx.Unlock()
+
+	// As channel size we'll use the maximum size.
+	chanSize := a.cfg.Constraints.MaxChanSize()
+
+	// We'll start by getting the scores from each available sub-heuristic,
+	// in addition the active agent heuristic.
+	report := make(HeuristicScores)
+	for _, h := range append(availableHeuristics, a.cfg.Heuristic) {
+		name := h.Name()
+
+		// If the active agent heuristic is among the simple heuristics
+		// it might get queried more than once. As an optimization
+		// we'll just skip it the second time.
+		if _, ok := report[name]; ok {
+			continue
+		}
+
+		s, err := h.NodeScores(
+			a.cfg.Graph, totalChans, chanSize, nodes,
+		)
+		if err != nil {
+			return nil, fmt.Errorf("unable to get sub score: %v", err)
+		}
+
+		log.Debugf("Heuristic \"%v\" scored %d nodes", name, len(s))
+
+		scores := make(map[NodeID]float64)
+		for nID, score := range s {
+			scores[nID] = score.Score
+		}
+
+		report[name] = scores
+	}
+
+	return report, nil
+}