Add TaskStateProber to get task state changed events

internal/rdb/rdb.go

@@ -7,6 +7,7 @@ package rdb
 
 import (
 	"context"
+	"encoding/json"
 	"fmt"
 	"math"
 	"time"
@@ -131,6 +132,7 @@ func (r *RDB) Enqueue(ctx context.Context, msg *base.TaskMessage) error {
 	if n == 0 {
 		return errors.E(op, errors.AlreadyExists, errors.ErrTaskIdConflict)
 	}
+	r.state(ctx, msg, base.TaskStatePending)
 	return nil
 }
 
@@ -198,6 +200,7 @@ func (r *RDB) EnqueueUnique(ctx context.Context, msg *base.TaskMessage, ttl time
 	if n == 0 {
 		return errors.E(op, errors.AlreadyExists, errors.ErrTaskIdConflict)
 	}
+	r.state(ctx, msg, base.TaskStatePending)
 	return nil
 }
 
@@ -464,9 +467,13 @@ func (r *RDB) MarkAsComplete(ctx context.Context, msg *base.TaskMessage) error {
 	// Note: We cannot pass empty unique key when running this script in redis-cluster.
 	if len(msg.UniqueKey) > 0 {
 		keys = append(keys, msg.UniqueKey)
-		return r.runScript(ctx, op, markAsCompleteUniqueCmd, keys, argv...)
+		err := r.runScript(ctx, op, markAsCompleteUniqueCmd, keys, argv...)
+		r.state(ctx, msg, base.TaskStateCompleted, err)
+		return err
 	}
-	return r.runScript(ctx, op, markAsCompleteCmd, keys, argv...)
+	err = r.runScript(ctx, op, markAsCompleteCmd, keys, argv...)
+	r.state(ctx, msg, base.TaskStateCompleted, err)
+	return err
 }
 
 // KEYS[1] -> asynq:{<qname>}:active
@@ -495,7 +502,9 @@ func (r *RDB) Requeue(ctx context.Context, msg *base.TaskMessage) error {
 		base.PendingKey(msg.Queue),
 		base.TaskKey(msg.Queue, msg.ID),
 	}
-	return r.runScript(ctx, op, requeueCmd, keys, msg.ID)
+	err := r.runScript(ctx, op, requeueCmd, keys, msg.ID)
+	r.state(ctx, msg, base.TaskStatePending, err)
+	return err
 }
 
 // KEYS[1] -> asynq:{<qname>}:t:<task_id>
@@ -550,6 +559,7 @@ func (r *RDB) AddToGroup(ctx context.Context, msg *base.TaskMessage, groupKey st
 	if n == 0 {
 		return errors.E(op, errors.AlreadyExists, errors.ErrTaskIdConflict)
 	}
+	r.state(ctx, msg, base.TaskStateAggregating)
 	return nil
 }
 
@@ -617,6 +627,7 @@ func (r *RDB) AddToGroupUnique(ctx context.Context, msg *base.TaskMessage, group
 	if n == 0 {
 		return errors.E(op, errors.AlreadyExists, errors.ErrTaskIdConflict)
 	}
+	r.state(ctx, msg, base.TaskStateAggregating)
 	return nil
 }
 
@@ -667,6 +678,7 @@ func (r *RDB) Schedule(ctx context.Context, msg *base.TaskMessage, processAt tim
 	if n == 0 {
 		return errors.E(op, errors.AlreadyExists, errors.ErrTaskIdConflict)
 	}
+	r.state(ctx, msg, base.TaskStateScheduled)
 	return nil
 }
 
@@ -731,6 +743,7 @@ func (r *RDB) ScheduleUnique(ctx context.Context, msg *base.TaskMessage, process
 	if n == 0 {
 		return errors.E(op, errors.AlreadyExists, errors.ErrTaskIdConflict)
 	}
+	r.state(ctx, msg, base.TaskStateScheduled)
 	return nil
 }
 
@@ -813,7 +826,9 @@ func (r *RDB) Retry(ctx context.Context, msg *base.TaskMessage, processAt time.T
 		isFailure,
 		int64(math.MaxInt64),
 	}
-	return r.runScript(ctx, op, retryCmd, keys, argv...)
+	err = r.runScript(ctx, op, retryCmd, keys, argv...)
+	r.state(ctx, msg, base.TaskStateRetry, err)
+	return err
 }
 
 const (
@@ -899,7 +914,9 @@ func (r *RDB) Archive(ctx context.Context, msg *base.TaskMessage, errMsg string)
 		expireAt.Unix(),
 		int64(math.MaxInt64),
 	}
-	return r.runScript(ctx, op, archiveCmd, keys, argv...)
+	err = r.runScript(ctx, op, archiveCmd, keys, argv...)
+	r.state(ctx, msg, base.TaskStateArchived, err)
+	return err
 }
 
 // ForwardIfReady checks scheduled and retry sets of the given queues
@@ -1444,6 +1461,79 @@ func (r *RDB) ClearSchedulerEntries(scheduelrID string) error {
 	return nil
 }
 
+func (r *RDB) state(ctx context.Context, msg *base.TaskMessage, state base.TaskState, errs ...error) {
+	var err error
+	if len(errs) > 0 {
+		if errs[0] != nil {
+			err = errs[0]
+		}
+	}
+	out := map[string]interface{}{
+		"queue": msg.Queue,
+		"id":    msg.ID,
+		"state": state,
+	}
+	if err != nil {
+		out["err"] = err.Error()
+	}
+	if len(msg.GroupKey) > 0 {
+		out["group"] = msg.GroupKey
+	}
+	if len(msg.UniqueKey) > 0 {
+		out["unique"] = msg.UniqueKey
+	}
+
+	payload, _ := json.Marshal(out)
+	r.client.Publish(ctx, "state-changed", payload)
+}
+
+// StateChanged watch state updates, with more customized detail
+func (r *RDB) SetTaskProber(prober base.TaskProber) {
+	ctx := context.Background()
+	pubsub := r.client.Subscribe(ctx, "state-changed")
+
+	changed := func(out map[string]interface{}, err error) {
+		if err != nil {
+			out["err"] = "prober: " + err.Error()
+		}
+		go prober.Changed(out)
+	}
+
+	handler := func(payload string) {
+		var out map[string]interface{}
+		err := json.Unmarshal([]byte(payload), &out)
+		if err != nil {
+			changed(out, err)
+			return
+		}
+		s, ok := out["state"].(float64)
+		if !ok {
+			changed(out, fmt.Errorf("invalid state %v", out["state"]))
+			return
+		}
+		state := base.TaskState(s)
+		out["state"] = state.String()
+		res, err := r.GetTaskInfo(out["queue"].(string), out["id"].(string))
+		if err != nil {
+			changed(out, err)
+			return
+		}
+		msg := res.Message
+		if state == base.TaskStateCompleted {
+			out["at"] = msg.CompletedAt
+		}
+		key, data := prober.Result(state, res)
+		if data != nil {
+			out[key] = data
+		}
+		changed(out, nil)
+	}
+
+	for m := range pubsub.Channel() {
+		handler(m.Payload)
+	}
+}
+
 // CancelationPubSub returns a pubsub for cancelation messages.
 func (r *RDB) CancelationPubSub() (*redis.PubSub, error) {
 	var op errors.Op = "rdb.CancelationPubSub"