multi: terminate SubscribeSingleInvoice once completed

channeldb/invoices.go

@@ -362,6 +362,11 @@ func (c ContractState) String() string {
 	return "Unknown"
 }
 
+// IsFinal returns a boolean indicating whether an invoice state is final
+func (c ContractState) IsFinal() bool {
+	return c == ContractSettled || c == ContractCanceled
+}
+
 // ContractTerm is a companion struct to the Invoice struct. This struct houses
 // the necessary conditions required before the invoice can be considered fully
 // settled by the payee.

lnrpc/invoicesrpc/invoices_server.go

@@ -247,6 +247,12 @@ func (s *Server) SubscribeSingleInvoice(req *SubscribeSingleInvoiceRequest,
 				return err
 			}
 
+			// If we have reached a terminal state, close the
+			// stream with no error.
+			if newInvoice.State.IsFinal() {
+				return nil
+			}
+
 		case <-s.quit:
 			return nil
 		}

lntest/itest/lnd_hold_persistence_test.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"crypto/rand"
 	"fmt"
+	"io"
 	"sync"
 	"time"
 
@@ -403,4 +404,11 @@ func testHoldInvoicePersistence(net *lntest.NetworkHarness, t *harnessTest) {
 			}
 		}
 	}
+
+	// Check that all of our invoice streams are terminated by the server
+	// since the invoices have completed.
+	for _, stream := range invoiceStreams {
+		_, err = stream.Recv()
+		require.Equal(t.t, io.EOF, err)
+	}
 }