routing/router: move sending and receiving payment result into loop

routing/router.go

@@ -1513,6 +1513,7 @@ type LightningPayment struct {
 	// when we should should abandon the payment attempt after consecutive
 	// payment failure. This prevents us from attempting to send a payment
 	// indefinitely.
+	// TODO(halseth): make wallclock time to allow resume after startup.
 	PayAttemptTimeout time.Duration
 
 	// RouteHints represents the different routing hints that can be used to
@@ -1617,6 +1618,8 @@ func (r *ChannelRouter) sendPayment(payment *LightningPayment,
 
 	timeoutChan := time.After(payAttemptTimeout)
 
+	paymentHash := payment.PaymentHash
+
 	// We'll continue until either our payment succeeds, or we encounter a
 	// critical error during path finding.
 	var lastError error
@@ -1657,26 +1660,6 @@ func (r *ChannelRouter) sendPayment(payment *LightningPayment,
 			return [32]byte{}, nil, err
 		}
 
-		// Send payment attempt. It will return a final boolean
-		// indicating if more attempts are needed.
-		preimage, final, err := r.sendPaymentAttempt(
-			paySession, route, payment.PaymentHash,
-		)
-		if final {
-			return preimage, route, err
-		}
-
-		lastError = err
-	}
-}
-
-// sendPaymentAttempt tries to send the payment via the specified route. If
-// successful, it returns the obtained preimage. If an error occurs, the last
-// bool parameter indicates whether this is a final outcome or more attempts
-// should be made.
-func (r *ChannelRouter) sendPaymentAttempt(paySession *paymentSession,
-	route *route.Route, paymentHash [32]byte) ([32]byte, bool, error) {
-
 		log.Tracef("Attempting to send payment %x, using route: %v",
 			paymentHash, newLogClosure(func() string {
 				return spew.Sdump(route)
@@ -1686,8 +1669,9 @@ func (r *ChannelRouter) sendPaymentAttempt(paySession *paymentSession,
 		// Generate a new key to be used for this attempt.
 		sessionKey, err := generateNewSessionKey()
 		if err != nil {
-		return [32]byte{}, true, err
+			return [32]byte{}, nil, err
 		}
+
 		// Generate the raw encoded sphinx packet to be included along
 		// with the htlcAdd message that we send directly to the
 		// switch.
@@ -1695,7 +1679,7 @@ func (r *ChannelRouter) sendPaymentAttempt(paySession *paymentSession,
 			route, paymentHash[:], sessionKey,
 		)
 		if err != nil {
-		return [32]byte{}, true, err
+			return [32]byte{}, nil, err
 		}
 
 		// Craft an HTLC packet to send to the layer 2 switch. The
@@ -1719,23 +1703,28 @@ func (r *ChannelRouter) sendPaymentAttempt(paySession *paymentSession,
 		// this HTLC.
 		paymentID, err := r.cfg.NextPaymentID()
 		if err != nil {
-		return [32]byte{}, true, err
+			return [32]byte{}, nil, err
 		}
 
 		err = r.cfg.Payer.SendHTLC(
 			firstHop, paymentID, htlcAdd,
 		)
 		if err != nil {
-		log.Errorf("Failed sending attempt %d for payment %x to "+
+			log.Errorf("Failed sending attempt %d for payment "+
-			"switch: %v", paymentID, paymentHash, err)
+				"%x to switch: %v", paymentID, paymentHash, err)
 
-		// We must inspect the error to know whether it was critical or
+			// We must inspect the error to know whether it was
-		// not, to decide whether we should continue trying.
+			// critical or not, to decide whether we should
+			// continue trying.
 			finalOutcome := r.processSendError(
 				paySession, route, err,
 			)
+			if finalOutcome {
+				return [32]byte{}, nil, err
+			}
 
-		return [32]byte{}, finalOutcome, err
+			lastError = err
+			continue
 		}
 
 		// Using the created circuit, initialize the error decrypter so we can
@@ -1753,7 +1742,7 @@ func (r *ChannelRouter) sendPaymentAttempt(paySession *paymentSession,
 		if err != nil {
 			log.Errorf("Failed getting result for paymentID %d "+
 				"from switch: %v", paymentID, err)
-		return [32]byte{}, true, err
+			return [32]byte{}, nil, err
 		}
 
 		var (
@@ -1763,11 +1752,11 @@ func (r *ChannelRouter) sendPaymentAttempt(paySession *paymentSession,
 		select {
 		case result, ok = <-resultChan:
 			if !ok {
-			return [32]byte{}, true, htlcswitch.ErrSwitchExiting
+				return [32]byte{}, nil, htlcswitch.ErrSwitchExiting
 			}
 
 		case <-r.quit:
-		return [32]byte{}, true, ErrRouterShuttingDown
+			return [32]byte{}, nil, ErrRouterShuttingDown
 		}
 
 		if result.Error != nil {
@@ -1778,10 +1767,17 @@ func (r *ChannelRouter) sendPaymentAttempt(paySession *paymentSession,
 				paySession, route, result.Error,
 			)
 
-		return [32]byte{}, finalOutcome, result.Error
+			if finalOutcome {
+				return [32]byte{}, nil, result.Error
+			}
+
+			lastError = result.Error
+			continue
+		}
+
+		return result.Preimage, route, nil
 	}
 
-	return result.Preimage, true, nil
 }
 
 // processSendError analyzes the error for the payment attempt received from the