Refactor forwarding of scheduled tasks

background.go

@@ -24,7 +24,7 @@ type Background struct {
 // NewBackground returns a new Background instance.
 func NewBackground(numWorkers int, config *RedisConfig) *Background {
 	r := rdb.NewRDB(newRedisClient(config))
-	poller := newPoller(r, 5*time.Second, []string{rdb.Scheduled, rdb.Retry})
+	poller := newPoller(r, 5*time.Second)
 	processor := newProcessor(r, numWorkers, nil)
 	return &Background{
 		rdb:       r,

internal/rdb/rdb.go

@@ -229,10 +229,21 @@ func (r *RDB) RestoreUnfinished() error {
 	return err
 }
 
+// CheckScheduled checks for all scheduled tasks and moves any tasks that
+// have to be processed to the queue.
+func (r *RDB) CheckScheduled() error {
+	delayed := []string{Scheduled, Retry}
+	for _, zset := range delayed {
+		if err := r.forward(zset); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
 // Forward moves all tasks with a score less than the current unix time
 // from the given zset to the default queue.
-// TODO(hibiken): Find a better method name that reflects what this does.
-func (r *RDB) Forward(from string) error {
+func (r *RDB) forward(from string) error {
 	script := redis.NewScript(`
 	local msgs = redis.call("ZRANGEBYSCORE", KEYS[1], "-inf", ARGV[1])
 	for _, msg in ipairs(msgs) do

internal/rdb/rdb_test.go

@@ -323,38 +323,50 @@ func TestRestoreUnfinished(t *testing.T) {
 	}
 }
 
-func TestForward(t *testing.T) {
+func TestCheckScheduled(t *testing.T) {
 	r := setup(t)
 	t1 := randomTask("send_email", "default", nil)
 	t2 := randomTask("generate_csv", "default", nil)
+	t3 := randomTask("gen_thumbnail", "default", nil)
 	secondAgo := time.Now().Add(-time.Second)
 	hourFromNow := time.Now().Add(time.Hour)
 
 	tests := []struct {
-		tasks         []*redis.Z     // scheduled tasks with timestamp as a score
+		initScheduled []*redis.Z     // tasks to be processed later
+		initRetry     []*redis.Z     // tasks to be retired later
 		wantQueued    []*TaskMessage // queue after calling forward
-		wantScheduled []*TaskMessage // scheduled queue after calling forward
+		wantScheduled []*TaskMessage // tasks in scheduled queue after calling CheckScheduled
+		wantRetry     []*TaskMessage // tasks in retry queue after calling CheckScheduled
 	}{
 		{
-			tasks: []*redis.Z{
+			initScheduled: []*redis.Z{
 				&redis.Z{Member: mustMarshal(t, t1), Score: float64(secondAgo.Unix())},
 				&redis.Z{Member: mustMarshal(t, t2), Score: float64(secondAgo.Unix())}},
-			wantQueued:    []*TaskMessage{t1, t2},
+			initRetry: []*redis.Z{
+				&redis.Z{Member: mustMarshal(t, t3), Score: float64(secondAgo.Unix())}},
+			wantQueued:    []*TaskMessage{t1, t2, t3},
 			wantScheduled: []*TaskMessage{},
+			wantRetry:     []*TaskMessage{},
 		},
 		{
-			tasks: []*redis.Z{
+			initScheduled: []*redis.Z{
 				&redis.Z{Member: mustMarshal(t, t1), Score: float64(hourFromNow.Unix())},
 				&redis.Z{Member: mustMarshal(t, t2), Score: float64(secondAgo.Unix())}},
-			wantQueued:    []*TaskMessage{t2},
+			initRetry: []*redis.Z{
+				&redis.Z{Member: mustMarshal(t, t3), Score: float64(secondAgo.Unix())}},
+			wantQueued:    []*TaskMessage{t2, t3},
 			wantScheduled: []*TaskMessage{t1},
+			wantRetry:     []*TaskMessage{},
 		},
 		{
-			tasks: []*redis.Z{
+			initScheduled: []*redis.Z{
 				&redis.Z{Member: mustMarshal(t, t1), Score: float64(hourFromNow.Unix())},
 				&redis.Z{Member: mustMarshal(t, t2), Score: float64(hourFromNow.Unix())}},
+			initRetry: []*redis.Z{
+				&redis.Z{Member: mustMarshal(t, t3), Score: float64(hourFromNow.Unix())}},
 			wantQueued:    []*TaskMessage{},
 			wantScheduled: []*TaskMessage{t1, t2},
+			wantRetry:     []*TaskMessage{t3},
 		},
 	}
 
@@ -363,14 +375,18 @@ func TestForward(t *testing.T) {
 		if err := r.client.FlushDB().Err(); err != nil {
 			t.Fatal(err)
 		}
-		if err := r.client.ZAdd(Scheduled, tc.tasks...).Err(); err != nil {
+		if err := r.client.ZAdd(Scheduled, tc.initScheduled...).Err(); err != nil {
+			t.Error(err)
+			continue
+		}
+		if err := r.client.ZAdd(Retry, tc.initRetry...).Err(); err != nil {
 			t.Error(err)
 			continue
 		}
 
-		err := r.Forward(Scheduled)
+		err := r.CheckScheduled()
 		if err != nil {
-			t.Errorf("(*RDB).Forward(%q) = %v, want nil", Scheduled, err)
+			t.Errorf("(*RDB).CheckScheduled() = %v, want nil", err)
 			continue
 		}
 		queued := r.client.LRange(DefaultQueue, 0, -1).Val()

poller.go

@@ -15,17 +15,13 @@ type poller struct {
 
 	// poll interval on average
 	avgInterval time.Duration
-
-	// redis ZSETs to poll
-	zsets []string
 }
 
-func newPoller(r *rdb.RDB, avgInterval time.Duration, zsets []string) *poller {
+func newPoller(r *rdb.RDB, avgInterval time.Duration) *poller {
 	return &poller{
 		rdb:         r,
 		done:        make(chan struct{}),
 		avgInterval: avgInterval,
-		zsets:       zsets,
 	}
 }
 
@@ -52,9 +48,7 @@ func (p *poller) start() {
 }
 
 func (p *poller) exec() {
-	for _, zset := range p.zsets {
-		if err := p.rdb.Forward(zset); err != nil {
-			log.Printf("[ERROR] could not forward scheduled tasks from %q: %v\n", zset, err)
-		}
+	if err := p.rdb.CheckScheduled(); err != nil {
+		log.Printf("[ERROR] could not forward scheduled tasks: %v\n", err)
 	}
 }

poller_test.go

@@ -16,7 +16,7 @@ func TestPoller(t *testing.T) {
 	r := setup(t)
 	rdbClient := rdb.NewRDB(r)
 	const pollInterval = time.Second
-	p := newPoller(rdbClient, pollInterval, []string{rdb.Scheduled, rdb.Retry})
+	p := newPoller(rdbClient, pollInterval)
 	t1 := randomTask("gen_thumbnail", "default", nil)
 	t2 := randomTask("send_email", "default", nil)
 	t3 := randomTask("reindex", "default", nil)