htlcswitch: hodl invoice

This commit modifies the invoice registry to handle invoices for which
the preimage is not known yet (hodl invoices). In that case, the
resolution channel passed in from links and resolvers is stored until we
either learn the preimage or want to cancel the htlc.

channeldb/invoice_test.go

@@ -99,7 +99,7 @@ func TestInvoiceWorkflow(t *testing.T) {
 	// now have the settled bit toggle to true and a non-default
 	// SettledDate
 	payAmt := fakeInvoice.Terms.Value * 2
-	if _, err := db.SettleInvoice(paymentHash, payAmt); err != nil {
+	if _, err := db.AcceptOrSettleInvoice(paymentHash, payAmt); err != nil {
 		t.Fatalf("unable to settle invoice: %v", err)
 	}
 	dbInvoice2, err := db.LookupInvoice(paymentHash)
@@ -261,7 +261,7 @@ func TestInvoiceAddTimeSeries(t *testing.T) {
 
 		paymentHash := invoice.Terms.PaymentPreimage.Hash()
 
-		_, err := db.SettleInvoice(paymentHash, 0)
+		_, err := db.AcceptOrSettleInvoice(paymentHash, 0)
 		if err != nil {
 			t.Fatalf("unable to settle invoice: %v", err)
 		}
@@ -342,7 +342,7 @@ func TestDuplicateSettleInvoice(t *testing.T) {
 	}
 
 	// With the invoice in the DB, we'll now attempt to settle the invoice.
-	dbInvoice, err := db.SettleInvoice(payHash, amt)
+	dbInvoice, err := db.AcceptOrSettleInvoice(payHash, amt)
 	if err != nil {
 		t.Fatalf("unable to settle invoice: %v", err)
 	}
@@ -362,7 +362,7 @@ func TestDuplicateSettleInvoice(t *testing.T) {
 
 	// If we try to settle the invoice again, then we should get the very
 	// same invoice back, but with an error this time.
-	dbInvoice, err = db.SettleInvoice(payHash, amt)
+	dbInvoice, err = db.AcceptOrSettleInvoice(payHash, amt)
 	if err != ErrInvoiceAlreadySettled {
 		t.Fatalf("expected ErrInvoiceAlreadySettled")
 	}
@@ -407,7 +407,7 @@ func TestQueryInvoices(t *testing.T) {
 
 		// We'll only settle half of all invoices created.
 		if i%2 == 0 {
-			if _, err := db.SettleInvoice(paymentHash, i); err != nil {
+			if _, err := db.AcceptOrSettleInvoice(paymentHash, i); err != nil {
 				t.Fatalf("unable to settle invoice: %v", err)
 			}
 		}