multi: add loop out routing hints config parameter for opt-in

client.go

@@ -107,6 +107,10 @@ type ClientConfig struct {
 	// for a loop out swap. When greater than one, a multi-part payment may
 	// be attempted.
 	LoopOutMaxParts uint32
+
+	// LoopOutRoutingHints indicates whether to use server-provided routing
+	// hints to improve off-chain routing.
+	LoopOutRoutingHints bool
 }
 
 // NewClient returns a new instance to initiate swaps with.
@@ -146,6 +150,7 @@ func NewClient(dbDir string, cfg *ClientConfig) (*Client, func(), error) {
 		sweeper:           sweeper,
 		createExpiryTimer: config.CreateExpiryTimer,
 		loopOutMaxParts:   cfg.LoopOutMaxParts,
+		routingHints:      cfg.LoopOutRoutingHints,
 		cancelSwap:        swapServerClient.CancelLoopOutSwap,
 	})
 

executor.go

@@ -25,6 +25,7 @@ type executorConfig struct {
 	createExpiryTimer func(expiry time.Duration) <-chan time.Time
 
 	loopOutMaxParts uint32
+	routingHints    bool
 
 	cancelSwap func(ctx context.Context, details *outCancelDetails) error
 }
@@ -146,6 +147,7 @@ func (s *executor) run(mainCtx context.Context,
 					blockEpochChan:  queue.ChanOut(),
 					timerFactory:    s.executorConfig.createExpiryTimer,
 					loopOutMaxParts: s.executorConfig.loopOutMaxParts,
+					routingHints:    s.executorConfig.routingHints,
 					cancelSwap:      s.executorConfig.cancelSwap,
 				}, height)
 				if err != nil && err != context.Canceled {

loopd/config.go

@@ -129,7 +129,8 @@ type Config struct {
 	MaxLSATCost uint32 `long:"maxlsatcost" description:"Maximum cost in satoshis that loopd is going to pay for an LSAT token automatically. Does not include routing fees."`
 	MaxLSATFee  uint32 `long:"maxlsatfee" description:"Maximum routing fee in satoshis that we are willing to pay while paying for an LSAT token."`
 
-	LoopOutMaxParts uint32 `long:"loopoutmaxparts" description:"The maximum number of payment parts that may be used for a loop out swap."`
+	LoopOutMaxParts     uint32 `long:"loopoutmaxparts" description:"The maximum number of payment parts that may be used for a loop out swap."`
+	LoopOutRoutingHints bool   `long:"loopouthints" description:"Whether to use server-provided hints to improve the success rate of off-chain routing. Note that enabling this setting will apply updates to lnd's mission control state."`
 
 	Lnd *lndConfig `group:"lnd" namespace:"lnd"`
 

loopd/utils.go

@@ -17,14 +17,15 @@ func getClient(config *Config, lnd *lndclient.LndServices) (*loop.Client,
 	func(), error) {
 
 	clientConfig := &loop.ClientConfig{
-		ServerAddress:   config.Server.Host,
-		ProxyAddress:    config.Server.Proxy,
-		SwapServerNoTLS: config.Server.NoTLS,
-		TLSPathServer:   config.Server.TLSPath,
-		Lnd:             lnd,
-		MaxLsatCost:     btcutil.Amount(config.MaxLSATCost),
-		MaxLsatFee:      btcutil.Amount(config.MaxLSATFee),
-		LoopOutMaxParts: config.LoopOutMaxParts,
+		ServerAddress:       config.Server.Host,
+		ProxyAddress:        config.Server.Proxy,
+		SwapServerNoTLS:     config.Server.NoTLS,
+		TLSPathServer:       config.Server.TLSPath,
+		Lnd:                 lnd,
+		MaxLsatCost:         btcutil.Amount(config.MaxLSATCost),
+		MaxLsatFee:          btcutil.Amount(config.MaxLSATFee),
+		LoopOutMaxParts:     config.LoopOutMaxParts,
+		LoopOutRoutingHints: config.LoopOutRoutingHints,
 	}
 
 	swapClient, cleanUp, err := loop.NewClient(config.DataDir, clientConfig)

loopout.go

@@ -85,6 +85,7 @@ type executeConfig struct {
 	blockEpochChan  <-chan interface{}
 	timerFactory    func(d time.Duration) <-chan time.Time
 	loopOutMaxParts uint32
+	routingHints    bool
 	cancelSwap      func(context.Context, *outCancelDetails) error
 }