Live: persisting last message in cache for broadcast scope (#32938)

pkg/services/live/database/storage.go

@@ -0,0 +1,66 @@
+package database
+
+import (
+	"fmt"
+	"time"
+
+	"github.com/grafana/grafana/pkg/infra/localcache"
+	"github.com/grafana/grafana/pkg/models"
+	"github.com/grafana/grafana/pkg/services/sqlstore"
+)
+
+type Storage struct {
+	store *sqlstore.SQLStore
+	cache *localcache.CacheService
+}
+
+func NewStorage(store *sqlstore.SQLStore, cache *localcache.CacheService) *Storage {
+	return &Storage{store: store, cache: cache}
+}
+
+func getLiveMessageCacheKey(orgID int64, channel string) string {
+	return fmt.Sprintf("live_message_%d_%s", orgID, channel)
+}
+
+func (s *Storage) SaveLiveMessage(query *models.SaveLiveMessageQuery) error {
+	// Come back to saving into database after evaluating database structure.
+	//err := s.store.WithDbSession(context.Background(), func(sess *sqlstore.DBSession) error {
+	//	params := []interface{}{query.OrgId, query.Channel, query.Data, time.Now()}
+	//	upsertSQL := s.store.Dialect.UpsertSQL(
+	//		"live_message",
+	//		[]string{"org_id", "channel"},
+	//		[]string{"org_id", "channel", "data", "published"})
+	//	_, err := sess.SQL(upsertSQL, params...).Query()
+	//	return err
+	//})
+	// return err
+	s.cache.Set(getLiveMessageCacheKey(query.OrgId, query.Channel), models.LiveMessage{
+		Id:        0, // Not used actually.
+		OrgId:     query.OrgId,
+		Channel:   query.Channel,
+		Data:      query.Data,
+		Published: time.Now(),
+	}, 0)
+	return nil
+}
+
+func (s *Storage) GetLiveMessage(query *models.GetLiveMessageQuery) (models.LiveMessage, bool, error) {
+	// Come back to saving into database after evaluating database structure.
+	//var msg models.LiveMessage
+	//var exists bool
+	//err := s.store.WithDbSession(context.Background(), func(sess *sqlstore.DBSession) error {
+	//	var err error
+	//	exists, err = sess.Where("org_id=? AND channel=?", query.OrgId, query.Channel).Get(&msg)
+	//	return err
+	//})
+	//return msg, exists, err
+	m, ok := s.cache.Get(getLiveMessageCacheKey(query.OrgId, query.Channel))
+	if !ok {
+		return models.LiveMessage{}, false, nil
+	}
+	msg, ok := m.(models.LiveMessage)
+	if !ok {
+		return models.LiveMessage{}, false, fmt.Errorf("unexpected live message type in cache: %T", m)
+	}
+	return msg, true, nil
+}