routing: add newPaymentLifecycle to properly init lifecycle

This commit adds a new method to properly init a payment lifecycle so we
can easily see the default values used here.

routing/payment_lifecycle.go

@@ -31,6 +31,31 @@ type paymentLifecycle struct {
 	currentHeight int32
 }
 
+// newPaymentLifecycle initiates a new payment lifecycle and returns it.
+func newPaymentLifecycle(r *ChannelRouter, feeLimit lnwire.MilliSatoshi,
+	identifier lntypes.Hash, paySession PaymentSession,
+	shardTracker shards.ShardTracker, timeout time.Duration,
+	currentHeight int32) *paymentLifecycle {
+
+	p := &paymentLifecycle{
+		router:        r,
+		feeLimit:      feeLimit,
+		identifier:    identifier,
+		paySession:    paySession,
+		shardTracker:  shardTracker,
+		currentHeight: currentHeight,
+	}
+
+	// If a timeout is specified, create a timeout channel. If no timeout is
+	// specified, the channel is left nil and will never abort the payment
+	// loop.
+	if timeout != 0 {
+		p.timeoutChan = time.After(timeout)
+	}
+
+	return p
+}
+
 // calcFeeBudget returns the available fee to be used for sending HTLC
 // attempts.
 func (p *paymentLifecycle) calcFeeBudget(

routing/router.go

@@ -2415,21 +2415,10 @@ func (r *ChannelRouter) sendPayment(feeLimit lnwire.MilliSatoshi,
 
 	// Now set up a paymentLifecycle struct with these params, such that we
 	// can resume the payment from the current state.
-	p := &paymentLifecycle{
-		router:        r,
-		feeLimit:      feeLimit,
-		identifier:    identifier,
-		paySession:    paySession,
-		shardTracker:  shardTracker,
-		currentHeight: currentHeight,
-	}
-
-	// If a timeout is specified, create a timeout channel. If no timeout is
-	// specified, the channel is left nil and will never abort the payment
-	// loop.
-	if timeout != 0 {
-		p.timeoutChan = time.After(timeout)
-	}
+	p := newPaymentLifecycle(
+		r, feeLimit, identifier, paySession,
+		shardTracker, timeout, currentHeight,
+	)
 
 	return p.resumePayment()
 }