From ddbc93d9934249b7c4f637a82bffc89edc7af620 Mon Sep 17 00:00:00 2001
From: William Banfield <4561443+williambanfield@users.noreply.github.com>
Date: Wed, 9 Mar 2022 14:33:57 -0500
Subject: [PATCH] service: add NopService and use for PexReactor (#8100)

---
 libs/service/service.go | 11 +++++++++++
 node/node.go            |  2 +-
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/libs/service/service.go b/libs/service/service.go
index f7701633a..6221c7d92 100644
--- a/libs/service/service.go
+++ b/libs/service/service.go
@@ -14,6 +14,11 @@ var (
 	errAlreadyStopped = errors.New("already stopped")
 )
 
+var (
+	_ Service = (*BaseService)(nil)
+	_ Service = (*NopService)(nil)
+)
+
 // Service defines a service that can be started, stopped, and reset.
 type Service interface {
 	// Start is called to start the service, which should run until
@@ -85,6 +90,12 @@ type BaseService struct {
 	impl Implementation
 }
 
+type NopService struct{}
+
+func (NopService) Start(_ context.Context) error { return nil }
+func (NopService) IsRunning() bool               { return true }
+func (NopService) Wait()                         {}
+
 // NewBaseService creates a new BaseService.
 func NewBaseService(logger log.Logger, name string, impl Implementation) *BaseService {
 	return &BaseService{
diff --git a/node/node.go b/node/node.go
index 4bb72f4f6..3329d9f9a 100644
--- a/node/node.go
+++ b/node/node.go
@@ -357,7 +357,7 @@ func makeNode(
 		return nil, combineCloseError(err, makeCloser(closers))
 	}
 
-	var pexReactor service.Service
+	var pexReactor service.Service = service.NopService{}
 	if cfg.P2P.PexReactor {
 		pexReactor, err = pex.NewReactor(ctx, logger, peerManager, router.OpenChannel, peerManager.Subscribe(ctx))
 		if err != nil {