fix: NewScheduler incorrectly creates underlying Client, closing broker properly (#977)

* fix: NewScheduler wrongly creates a client whose sharedConnection value is always true

* This is affecting the PeriodicManager as well as the Scheduler

* fix: closing the Client also closes the broker

* The error was also previously unhandled. For shared connections an error will be returned by the broker itself because the sharedConnection bool is also set on the client. This also means we can get rid of the sharedConnection flag on the Scheduler itself and let it work internally.

Author: kamikazechaser

scheduler.go

@@ -44,29 +44,41 @@ type Scheduler struct {
 	// to avoid using cron.EntryID as the public API of
 	// the Scheduler.
 	idmap map[string]cron.EntryID
-	// When a Scheduler has been created with an existing Redis connection, we do
-	// not want to close it.
-	sharedConnection bool
 }
 
 const defaultHeartbeatInterval = 10 * time.Second
 
 // NewScheduler returns a new Scheduler instance given the redis connection option.
 // The parameter opts is optional, defaults will be used if opts is set to nil
 func NewScheduler(r RedisConnOpt, opts *SchedulerOpts) *Scheduler {
+	scheduler := newScheduler(opts)
+
 	redisClient, ok := r.MakeRedisClient().(redis.UniversalClient)
 	if !ok {
 		panic(fmt.Sprintf("asynq: unsupported RedisConnOpt type %T", r))
 	}
-	scheduler := NewSchedulerFromRedisClient(redisClient, opts)
-	scheduler.sharedConnection = false
+
+	rdb := rdb.NewRDB(redisClient)
+
+	scheduler.rdb = rdb
+	scheduler.client = &Client{broker: rdb, sharedConnection: false}
+
 	return scheduler
 }
 
 // NewSchedulerFromRedisClient returns a new instance of Scheduler given a redis.UniversalClient
 // The parameter opts is optional, defaults will be used if opts is set to nil.
 // Warning: The underlying redis connection pool will not be closed by Asynq, you are responsible for closing it.
 func NewSchedulerFromRedisClient(c redis.UniversalClient, opts *SchedulerOpts) *Scheduler {
+	scheduler := newScheduler(opts)
+
+	scheduler.rdb = rdb.NewRDB(c)
+	scheduler.client = NewClientFromRedisClient(c)
+
+	return scheduler
+}
+
+func newScheduler(opts *SchedulerOpts) *Scheduler {
 	if opts == nil {
 		opts = &SchedulerOpts{}
 	}
@@ -93,8 +105,6 @@ func NewSchedulerFromRedisClient(c redis.UniversalClient, opts *SchedulerOpts) *
 		state:             &serverState{value: srvStateNew},
 		heartbeatInterval: heartbeatInterval,
 		logger:            logger,
-		client:            NewClientFromRedisClient(c),
-		rdb:               rdb.NewRDB(c),
 		cron:              cron.New(cron.WithLocation(loc)),
 		location:          loc,
 		done:              make(chan struct{}),
@@ -294,9 +304,6 @@ func (s *Scheduler) Shutdown() {
 	if err := s.client.Close(); err != nil {
 		s.logger.Errorf("Failed to close redis client connection: %v", err)
 	}
-	if !s.sharedConnection {
-		s.rdb.Close()
-	}
 	s.logger.Info("Scheduler stopped")
 }