config+pilot: define autopilot.heuristic

And validate the config set by the user.

autopilot/interface.go

@@ -142,6 +142,27 @@ type AttachmentHeuristic interface {
 		map[NodeID]*NodeScore, error)
 }
 
+var (
+	// availableHeuristics holds all heuristics possible to combine for use
+	// with the autopilot agent.
+	availableHeuristics = []AttachmentHeuristic{
+		NewPrefAttachment(),
+	}
+
+	// AvailableHeuristics is a map that holds the name of available
+	// heuristics to the actual heuristic for easy lookup. It will be
+	// filled during init().
+	AvailableHeuristics = make(map[string]AttachmentHeuristic)
+)
+
+func init() {
+	// Fill the map from heuristic names to available heuristics for easy
+	// lookup.
+	for _, h := range availableHeuristics {
+		AvailableHeuristics[h.Name()] = h
+	}
+}
+
 // ChannelController is a simple interface that allows an auto-pilot agent to
 // open a channel within the graph to a target peer, close targeted channels,
 // or add/remove funds from existing channels via a splice in/out mechanisms.

config.go

@@ -142,13 +142,14 @@ type bitcoindConfig struct {
 }
 
 type autoPilotConfig struct {
-	Active         bool    `long:"active" description:"If the autopilot agent should be active or not."`
-	MaxChannels    int     `long:"maxchannels" description:"The maximum number of channels that should be created"`
-	Allocation     float64 `long:"allocation" description:"The percentage of total funds that should be committed to automatic channel establishment"`
-	MinChannelSize int64   `long:"minchansize" description:"The smallest channel that the autopilot agent should create"`
-	MaxChannelSize int64   `long:"maxchansize" description:"The largest channel that the autopilot agent should create"`
-	Private        bool    `long:"private" description:"Whether the channels created by the autopilot agent should be private or not. Private channels won't be announced to the network."`
-	MinConfs       int32   `long:"minconfs" description:"The minimum number of confirmations each of your inputs in funding transactions created by the autopilot agent must have."`
+	Active         bool               `long:"active" description:"If the autopilot agent should be active or not."`
+	Heuristic      map[string]float64 `long:"heuristic" description:"Heuristic to activate, and the weight to give it during scoring."`
+	MaxChannels    int                `long:"maxchannels" description:"The maximum number of channels that should be created"`
+	Allocation     float64            `long:"allocation" description:"The percentage of total funds that should be committed to automatic channel establishment"`
+	MinChannelSize int64              `long:"minchansize" description:"The smallest channel that the autopilot agent should create"`
+	MaxChannelSize int64              `long:"maxchansize" description:"The largest channel that the autopilot agent should create"`
+	Private        bool               `long:"private" description:"Whether the channels created by the autopilot agent should be private or not. Private channels won't be announced to the network."`
+	MinConfs       int32              `long:"minconfs" description:"The minimum number of confirmations each of your inputs in funding transactions created by the autopilot agent must have."`
 }
 
 type torConfig struct {
@@ -312,6 +313,9 @@ func loadConfig() (*config, error) {
 			Allocation:     0.6,
 			MinChannelSize: int64(minChanFundingSize),
 			MaxChannelSize: int64(maxFundingAmount),
+			Heuristic: map[string]float64{
+				"preferential": 1.0,
+			},
 		},
 		TrickleDelay:        defaultTrickleDelay,
 		InactiveChanTimeout: defaultInactiveChanTimeout,
@@ -463,6 +467,10 @@ func loadConfig() (*config, error) {
 		cfg.Autopilot.MaxChannelSize = int64(maxFundingAmount)
 	}
 
+	if _, err := validateAtplCfg(cfg.Autopilot); err != nil {
+		return nil, err
+	}
+
 	// Validate the Tor config parameters.
 	socks, err := lncfg.ParseAddressString(
 		cfg.Tor.SOCKS, strconv.Itoa(defaultTorSOCKSPort),

pilot.go

@@ -14,6 +14,60 @@ import (
 	"github.com/lightningnetwork/lnd/tor"
 )
 
+// validateAtplConfig is a helper method that makes sure the passed
+// configuration is sane. Currently it checks that the heuristic configuration
+// makes sense. In case the config is valid, it will return a list of
+// WeightedHeuristics that can be combined for use with the autopilot agent.
+func validateAtplCfg(cfg *autoPilotConfig) ([]*autopilot.WeightedHeuristic,
+	error) {
+
+	var (
+		heuristicsStr string
+		sum           float64
+		heuristics    []*autopilot.WeightedHeuristic
+	)
+
+	// Create a help text that we can return in case the config is not
+	// correct.
+	for _, a := range autopilot.AvailableHeuristics {
+		heuristicsStr += fmt.Sprintf(" '%v' ", a.Name())
+	}
+	availStr := fmt.Sprintf("Avaiblable heuristcs 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.
+	for name, weight := range cfg.Heuristic {
+		a, ok := autopilot.AvailableHeuristics[name]
+		if !ok {
+			// No heuristic matching this config option was found.
+			return nil, fmt.Errorf("Heuristic %v not available. %v",
+				name, availStr)
+		}
+
+		// If this heuristic was among the registered ones, we add it
+		// to the list we'll give to the agent, and keep track of the
+		// sum of weights.
+		heuristics = append(
+			heuristics,
+			&autopilot.WeightedHeuristic{
+				Weight:              weight,
+				AttachmentHeuristic: a,
+			},
+		)
+		sum += weight
+	}
+
+	// Check found heuristics. We must have at least one to operate.
+	if len(heuristics) == 0 {
+		return nil, fmt.Errorf("No active heuristics. %v", availStr)
+	}
+
+	if sum != 1.0 {
+		return nil, fmt.Errorf("Heuristic weights must sum to 1.0")
+	}
+	return heuristics, nil
+}
+
 // chanController is an implementation of the autopilot.ChannelController
 // interface that's backed by a running lnd instance.
 type chanController struct {