AuthZ Service: Use singleflight group to fetch and build the folder tree (#98299)

* AuthZ Service: Use singleflight group to fetch and build the folder tree

* Change the sfgroup key

* Future proof

pkg/services/authz/rbac/service.go

@@ -8,6 +8,7 @@ import (
 
 	authzv1 "github.com/grafana/authlib/authz/proto/v1"
 	"github.com/grafana/authlib/claims"
+	"golang.org/x/sync/singleflight"
 	"google.golang.org/grpc/codes"
 	"google.golang.org/grpc/status"
 	"k8s.io/apiserver/pkg/endpoints/request"
@@ -49,6 +50,9 @@ type Service struct {
 	teamCache      *localcache.CacheService
 	basicRoleCache *localcache.CacheService
 	folderCache    *localcache.CacheService
+
+	// Deduplication of concurrent requests
+	sf *singleflight.Group
 }
 
 func NewService(sql legacysql.LegacyDatabaseProvider, identityStore legacy.LegacyIdentityStore, logger log.Logger, tracer tracing.Tracer) *Service {
@@ -63,6 +67,7 @@ func NewService(sql legacysql.LegacyDatabaseProvider, identityStore legacy.Legac
 		teamCache:      localcache.New(shortCacheTTL, shortCleanupInterval),
 		basicRoleCache: localcache.New(longCacheTTL, longCleanupInterval),
 		folderCache:    localcache.New(shortCacheTTL, shortCleanupInterval),
+		sf:             new(singleflight.Group),
 	}
 }
 
@@ -339,6 +344,7 @@ func (s *Service) buildFolderTree(ctx context.Context, ns claims.NamespaceInfo)
 		return cached.(map[string]FolderNode), nil
 	}
 
+	res, err, _ := s.sf.Do(ns.Value+"_buildFolderTree", func() (interface{}, error) {
 		folders, err := s.store.GetFolders(ctx, ns)
 		if err != nil {
 			return nil, fmt.Errorf("could not get folders: %w", err)
@@ -371,6 +377,12 @@ func (s *Service) buildFolderTree(ctx context.Context, ns claims.NamespaceInfo)
 		}
 
 		s.folderCache.Set(key, folderMap, 0)
-
 		return folderMap, nil
+	})
+
+	if err != nil {
+		return nil, err
+	}
+
+	return res.(map[string]FolderNode), nil
 }

pkg/services/authz/rbac/service_test.go

@@ -8,6 +8,7 @@ import (
 	"github.com/grafana/authlib/claims"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
+	"golang.org/x/sync/singleflight"
 
 	"github.com/grafana/grafana/pkg/infra/localcache"
 	"github.com/grafana/grafana/pkg/infra/log"
@@ -438,6 +439,7 @@ func TestService_buildFolderTree(t *testing.T) {
 				store:       store,
 				folderCache: cacheService,
 				logger:      log.New("test"),
+				sf:          new(singleflight.Group),
 			}
 
 			tree, err := s.buildFolderTree(ctx, ns)