Add wait logic directly in the janitor.

The janitor already maintains the channel used for service termination
notifications. Exposing a wait() function simplifies the waiting without
having to let the caller worry about handling channels correctly.

janitor.go

@@ -19,7 +19,7 @@ type serviceJanitor struct {
 	// True if shutting down, false otherwise.
 	shuttingDown bool
 	// Service termination notification channel.
-	termNotificationCh chan<- *terminatedService
+	termNotificationCh chan *terminatedService
 }
 
 // janitorRepo is the repository interface used by the janitor to remove
@@ -36,15 +36,13 @@ type terminatedService struct {
 }
 
 // newServiceJanitor instantiates a new janitor.
-func newServiceJanitor(log zzzlogi.Logger, repo janitorRepo, multiServiceMode bool) (*serviceJanitor, <-chan *terminatedService) {
-	sj := &serviceJanitor{
-		log:              log,
-		repo:             repo,
-		multiServiceMode: multiServiceMode,
+func newServiceJanitor(log zzzlogi.Logger, repo janitorRepo, multiServiceMode bool) *serviceJanitor {
+	return &serviceJanitor{
+		log:                log,
+		repo:               repo,
+		multiServiceMode:   multiServiceMode,
+		termNotificationCh: make(chan *terminatedService, 1),
 	}
-	ch := make(chan *terminatedService, 1)
-	sj.termNotificationCh = ch
-	return sj, ch
 }
 
 // handleProcTermination handles the termination of the specified processes.
@@ -61,6 +59,13 @@ func (s *serviceJanitor) handleProcTermination(procs []*reapedProcInfo) {
 	}
 }
 
+// wait waits till the first service terminates and returns the terminated
+// service information along with its exit status.
+func (s *serviceJanitor) wait() (*launchedService, int) {
+	t := <-s.termNotificationCh
+	return t.service, t.exitStatus
+}
+
 // handleServiceTermination handles the termination of the specified service.
 func (s *serviceJanitor) handleServiceTermination(serv *launchedService, exitStatus int) {
 	s.log.Infof("Service: %v exited, exit status: %d", serv, exitStatus)

service_manager.go

@@ -13,11 +13,6 @@ import (
 type serviceManagerImpl struct {
 	// Logger used by the service manager.
 	log zzzlogi.Logger
-
-	// The channel used to receive notification about the first service
-	// that gets terminated.
-	serviceTermNotificationCh <-chan *terminatedService
-
 	// Service repository.
 	repo *serviceRepo
 	// Service janitor.
@@ -39,7 +34,7 @@ func NewServiceManager(log zzzlogi.Logger, services ...*ServiceInfo) (InitServic
 		log: log,
 	}
 	sm.repo = newServiceRepo(log)
-	sm.janitor, sm.serviceTermNotificationCh = newServiceJanitor(log, sm.repo, multiServiceMode)
+	sm.janitor = newServiceJanitor(log, sm.repo, multiServiceMode)
 	sm.signals = newSignalManager(log, sm.repo, newZombieReaper(log), sm.janitor)
 
 	err := launchServices(log, sm.repo, services...)
@@ -60,13 +55,11 @@ func NewServiceManager(log zzzlogi.Logger, services ...*ServiceInfo) (InitServic
 // service which exited. In multi service mode, the exit status is the
 // same as the first service which exited if non-zero, 77 otherwise.
 func (s *serviceManagerImpl) Wait() int {
-	// Wait for the first service termination.
-	t := <-s.serviceTermNotificationCh
-
-	s.log.Infof("Shutting down since service: %v terminated", t.service)
+	serv, exitStatus := s.janitor.wait()
+	s.log.Infof("Shutting down since service: %v terminated", serv)
 
 	s.shutDown()
-	return t.exitStatus
+	return exitStatus
 }
 
 // shutDown terminates any running services launched by InitServiceManager,