Add heartbeat goroutine to write heartbeat data to redis for active

worker

processor.go

@@ -78,18 +78,37 @@ func (p *processor) exec() {
 		}
 	}
 
-	t := &Task{Type: msg.Type, Payload: msg.Payload}
+	task := &Task{Type: msg.Type, Payload: msg.Payload}
 	p.sema <- struct{}{} // acquire token
 	go func(task *Task) {
+		quit := make(chan struct{}) // channel to signal heartbeat goroutine
 		defer func() {
+			quit <- struct{}{}
 			if err := p.rdb.srem(inProgress, msg); err != nil {
 				log.Printf("[SERVER ERROR] SREM failed: %v\n", err)
 			}
+			if err := p.rdb.clearHeartbeat(msg.ID); err != nil {
+				log.Printf("[SERVER ERROR] DEL heartbeat failed: %v\n", err)
+			}
 			<-p.sema // release token
 		}()
-		err := p.handler(task)
+		// start "heartbeat" goroutine
+		go func() {
+			ticker := time.NewTicker(5 * time.Second)
+			for {
+				select {
+				case <-quit:
+					return
+				case t := <-ticker.C:
+					if err := p.rdb.heartbeat(msg.ID, t); err != nil {
+						log.Printf("[ERROR] heartbeat failed for %v at %v: %v", msg.ID, t, err)
+					}
+				}
+			}
+		}()
+		err := p.handler(task) // TODO(hibiken): maybe also handle panic?
 		if err != nil {
 			retryTask(p.rdb, msg, err)
 		}
-	}(t)
+	}(task)
 }

rdb.go

@@ -9,16 +9,18 @@ import (
 	"time"
 
 	"github.com/go-redis/redis/v7"
+	"github.com/google/uuid"
 )
 
 // Redis keys
 const (
-	queuePrefix = "asynq:queues:"     // LIST
+	queuePrefix     = "asynq:queues:"     // LIST - asynq:queues:<qname>
 	allQueues       = "asynq:queues"      // SET
 	scheduled       = "asynq:scheduled"   // ZSET
 	retry           = "asynq:retry"       // ZSET
 	dead            = "asynq:dead"        // ZSET
 	inProgress      = "asynq:in_progress" // SET
+	heartbeatPrefix = "asynq:heartbeat:"  // STRING - asynq:heartbeat:<taskID>
 )
 
 var (
@@ -145,6 +147,24 @@ func (r *rdb) move(from string, msg *taskMessage) error {
 	return nil
 }
 
+func (r *rdb) heartbeat(id uuid.UUID, timestamp time.Time) error {
+	key := heartbeatPrefix + id.String()
+	err := r.client.Set(key, timestamp, 0).Err() // zero expiration means no expiration
+	if err != nil {
+		return fmt.Errorf("command SET %s %v failed: %v", key, timestamp, err)
+	}
+	return nil
+}
+
+func (r *rdb) clearHeartbeat(id uuid.UUID) error {
+	key := heartbeatPrefix + id.String()
+	err := r.client.Del(key).Err()
+	if err != nil {
+		return fmt.Errorf("command DEL %s failed: %v", key, err)
+	}
+	return nil
+}
+
 const maxDeadTask = 100
 const deadExpirationInDays = 90