[#304] cmd/neofs-node: Catch closing channel of listener endpoint

As in #72 storage application should behave the same way at remote
RPC node failures. The simplest way is to restart application. Later
we can reinitialize it without downtime.

Signed-off-by: Alex Vanin <alexey@nspcc.ru>

cmd/neofs-node/config.go

@@ -142,6 +142,10 @@ const (
 type cfg struct {
 	ctx context.Context
 
+	ctxCancel func()
+
+	internalErr chan error // channel for internal application errors at runtime
+
 	viper *viper.Viper
 
 	log *zap.Logger
@@ -291,6 +295,7 @@ func initCfg(path string) *cfg {
 
 	c := &cfg{
 		ctx:         context.Background(),
+		internalErr: make(chan error),
 		viper:       viperCfg,
 		log:         log,
 		wg:          new(sync.WaitGroup),

cmd/neofs-node/main.go

@@ -1,10 +1,12 @@
 package main
 
 import (
+	"context"
 	"flag"
 	"log"
 
 	"github.com/nspcc-dev/neofs-node/pkg/util/grace"
+	"go.uber.org/zap"
 )
 
 func fatalOnErr(err error) {
@@ -29,7 +31,7 @@ func main() {
 }
 
 func initApp(c *cfg) {
-	c.ctx = grace.NewGracefulContext(nil)
+	c.ctx, c.ctxCancel = context.WithCancel(grace.NewGracefulContext(nil))
 
 	initGRPC(c)
 
@@ -56,7 +58,15 @@ func bootUp(c *cfg) {
 func wait(c *cfg) {
 	c.log.Info("application started")
 
-	<-c.ctx.Done()
+	select {
+	case <-c.ctx.Done(): // graceful shutdown
+	case err := <-c.internalErr: // internal application error
+		close(c.internalErr)
+		c.ctxCancel()
+
+		c.log.Warn("internal application error",
+			zap.String("message", err.Error()))
+	}
 }
 
 func shutdown(c *cfg) {

cmd/neofs-node/morph.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"context"
 	"fmt"
 
 	"github.com/nspcc-dev/neo-go/pkg/util"
@@ -51,7 +52,9 @@ func listenMorphNotifications(c *cfg) {
 	})
 	fatalOnErr(err)
 
-	c.workers = append(c.workers, newWorkerFromFunc(lis.Listen))
+	c.workers = append(c.workers, newWorkerFromFunc(func(ctx context.Context) {
+		lis.ListenWithError(ctx, c.internalErr)
+	}))
 
 	setNetmapNotificationParser(c, newEpochNotification, netmapEvent.ParseNewEpoch)
 	registerNotificationHandlers(c.cfgNetmap.scriptHash, lis, c.cfgNetmap.parsers, c.cfgNetmap.subscribers)