lnd: add interrupt handler to handle shutdown requests while syncing chain backend

lnd.go

@@ -570,7 +570,20 @@ func lndMain() error {
 		ltndLog.Infof("Waiting for chain backend to finish sync, "+
 			"start_height=%v", bestHeight)
 
+		// We'll add an interrupt handler in order to process shutdown
+		// requests while the chain backend syncs.
+		addInterruptHandler(func() {
+			rpcServer.Stop()
+			fundingMgr.Stop()
+		})
+
 		for {
+			select {
+			case <-shutdownChannel:
+				return nil
+			default:
+			}
+
 			synced, _, err := activeChainControl.wallet.IsSynced()
 			if err != nil {
 				return err
@@ -617,16 +630,12 @@ func lndMain() error {
 	}
 
 	addInterruptHandler(func() {
-		ltndLog.Infof("Gracefully shutting down the server...")
 		rpcServer.Stop()
 		fundingMgr.Stop()
-		server.Stop()
-
 		if pilot != nil {
 			pilot.Stop()
 		}
-
-		server.WaitForShutdown()
+		server.Stop()
 	})
 
 	// Wait for shutdown signal from either a graceful server stop or from

server.go

@@ -663,11 +663,6 @@ func (s *server) Stopped() bool {
 	return atomic.LoadInt32(&s.shutdown) != 0
 }
 
-// WaitForShutdown blocks until all goroutines have been stopped.
-func (s *server) WaitForShutdown() {
-	s.wg.Wait()
-}
-
 // initNetworkBootstrappers initializes a set of network peer bootstrappers
 // based on the server, and currently active bootstrap mechanisms as defined
 // within the current configuration.

signal.go

@@ -48,10 +48,8 @@ func mainInterruptHandler() {
 		isShutdown = true
 		ltndLog.Infof("Shutting down...")
 
-		// Run handlers in LIFO order.
-		for i := range interruptCallbacks {
-			idx := len(interruptCallbacks) - 1 - i
-			callback := interruptCallbacks[idx]
+		// Execute the interrupt callbacks in FIFO order.
+		for _, callback := range interruptCallbacks {
 			callback()
 		}