[server] Cache count improvement (#2972)

## Description
This does not handle the case where the server might get multiple
request for same user to get the count, and the file count is not cached
yet.

## Tests

server/cmd/museum/main.go

@@ -188,7 +188,9 @@ func main() {
 	}
 
 	userCache := cache2.NewUserCache()
-	userCacheCtrl := &usercache.Controller{UserCache: userCache, FileRepo: fileRepo, StoreBonusRepo: storagBonusRepo}
+	userCacheCtrl := &usercache.Controller{UserCache: userCache, FileRepo: fileRepo,
+		UsageRepo: usageRepo, TrashRepo: trashRepo,
+		StoreBonusRepo: storagBonusRepo}
 	offerController := offer.NewOfferController(*userRepo, discordController, storagBonusRepo, userCacheCtrl)
 	plans := billing.GetPlans()
 	defaultPlan := billing.GetDefaultPlans(plans)

server/ente/cache/user_data_cache.go

@@ -10,20 +10,26 @@ import (
 // UserCache struct holds can be used to fileCount various entities for user.
 type UserCache struct {
 	mu         sync.Mutex
-	fileCache  map[string]int64
+	fileCache  map[string]*FileCountCache
 	bonusCache map[int64]*storagebonus.ActiveStorageBonus
 }
 
+type FileCountCache struct {
+	Count          int64
+	TrashUpdatedAt int64
+	Usage          int64
+}
+
 // NewUserCache creates a new instance of the UserCache struct.
 func NewUserCache() *UserCache {
 	return &UserCache{
-		fileCache:  make(map[string]int64),
+		fileCache:  make(map[string]*FileCountCache),
 		bonusCache: make(map[int64]*storagebonus.ActiveStorageBonus),
 	}
 }
 
 // SetFileCount updates the fileCount with the given userID and fileCount.
-func (c *UserCache) SetFileCount(userID, fileCount int64, app ente.App) {
+func (c *UserCache) SetFileCount(userID int64, fileCount *FileCountCache, app ente.App) {
 	c.mu.Lock()
 	defer c.mu.Unlock()
 	c.fileCache[cacheKey(userID, app)] = fileCount
@@ -44,7 +50,7 @@ func (c *UserCache) GetBonus(userID int64) (*storagebonus.ActiveStorageBonus, bo
 
 // GetFileCount retrieves the file count from the fileCount for the given userID.
 // It returns the file count and a boolean indicating if the value was found.
-func (c *UserCache) GetFileCount(userID int64, app ente.App) (int64, bool) {
+func (c *UserCache) GetFileCount(userID int64, app ente.App) (*FileCountCache, bool) {
 	c.mu.Lock()
 	defer c.mu.Unlock()
 	count, ok := c.fileCache[cacheKey(userID, app)]

server/pkg/controller/user/user_details.go

@@ -11,27 +11,6 @@ import (
 	"golang.org/x/sync/errgroup"
 )
 
-func (c *UserController) getUserFileCountWithCache(userID int64, app ente.App) (int64, error) {
-	// Check if the value is present in the cache
-	if count, ok := c.UserCache.GetFileCount(userID, app); ok {
-		// Cache hit, update the cache asynchronously
-		go func() {
-			_, _ = c.getUserCountAndUpdateCache(userID, app)
-		}()
-		return count, nil
-	}
-	return c.getUserCountAndUpdateCache(userID, app)
-}
-
-func (c *UserController) getUserCountAndUpdateCache(userID int64, app ente.App) (int64, error) {
-	count, err := c.FileRepo.GetFileCountForUser(userID, app)
-	if err != nil {
-		return 0, stacktrace.Propagate(err, "")
-	}
-	c.UserCache.SetFileCount(userID, count, app)
-	return count, nil
-}
-
 func (c *UserController) GetDetailsV2(ctx *gin.Context, userID int64, fetchMemoryCount bool, app ente.App) (details.UserDetailsResponse, error) {
 
 	g := new(errgroup.Group)
@@ -86,7 +65,7 @@ func (c *UserController) GetDetailsV2(ctx *gin.Context, userID int64, fetchMemor
 
 	if fetchMemoryCount {
 		g.Go(func() error {
-			fCount, err := c.getUserFileCountWithCache(userID, app)
+			fCount, err := c.UserCacheController.GetUserFileCountWithCache(userID, app)
 			if err == nil {
 				fileCount = fCount
 			}

server/pkg/controller/usercache/controller.go

@@ -14,6 +14,8 @@ import (
 // Avoid adding any direct dependencies to the other controller.
 type Controller struct {
 	FileRepo       *repo.FileRepository
+	UsageRepo      *repo.UsageRepository
+	TrashRepo      *repo.TrashRepository
 	StoreBonusRepo *storagebonus.Repository
 	UserCache      *cache.UserCache
 }

server/pkg/controller/usercache/count.go

@@ -2,7 +2,9 @@ package usercache
 
 import (
 	"github.com/ente-io/museum/ente"
+	"github.com/ente-io/museum/ente/cache"
 	"github.com/ente-io/stacktrace"
+	"github.com/sirupsen/logrus"
 )
 
 func (c *Controller) GetUserFileCountWithCache(userID int64, app ente.App) (int64, error) {
@@ -10,18 +12,35 @@ func (c *Controller) GetUserFileCountWithCache(userID int64, app ente.App) (int6
 	if count, ok := c.UserCache.GetFileCount(userID, app); ok {
 		// Cache hit, update the cache asynchronously
 		go func() {
-			_, _ = c.getUserCountAndUpdateCache(userID, app)
+			_, _ = c.getUserCountAndUpdateCache(userID, app, count)
 		}()
-		return count, nil
+		return count.Count, nil
 	}
-	return c.getUserCountAndUpdateCache(userID, app)
+	return c.getUserCountAndUpdateCache(userID, app, nil)
 }
 
-func (c *Controller) getUserCountAndUpdateCache(userID int64, app ente.App) (int64, error) {
+func (c *Controller) getUserCountAndUpdateCache(userID int64, app ente.App, oldCache *cache.FileCountCache) (int64, error) {
+	usage, err := c.UsageRepo.GetUsage(userID)
+	if err != nil {
+		return 0, stacktrace.Propagate(err, "")
+	}
+	trashUpdatedAt, err := c.TrashRepo.GetTrashUpdatedAt(userID)
+	if err != nil {
+		return 0, stacktrace.Propagate(err, "")
+	}
+	if oldCache != nil && oldCache.Usage == usage && oldCache.TrashUpdatedAt == trashUpdatedAt {
+		logrus.Debugf("Cache hit for user %d", userID)
+		return oldCache.Count, nil
+	}
 	count, err := c.FileRepo.GetFileCountForUser(userID, app)
 	if err != nil {
 		return 0, stacktrace.Propagate(err, "")
 	}
-	c.UserCache.SetFileCount(userID, count, app)
+	cntCache := &cache.FileCountCache{
+		Count:          count,
+		Usage:          usage,
+		TrashUpdatedAt: trashUpdatedAt,
+	}
+	c.UserCache.SetFileCount(userID, cntCache, app)
 	return count, nil
 }

server/pkg/repo/trash.go

@@ -422,6 +422,16 @@ func (t *TrashRepository) EmptyTrash(ctx context.Context, userID int64, lastUpda
 	return t.QueueRepo.InsertItem(ctx, TrashEmptyQueue, itemID)
 }
 
+func (t *TrashRepository) GetTrashUpdatedAt(userID int64) (int64, error) {
+	row := t.DB.QueryRow(`SELECT max(updated_at) FROM trash WHERE user_id = $1`, userID)
+	var updatedAt int64
+	err := row.Scan(&updatedAt)
+	if errors.Is(err, sql.ErrNoRows) {
+		return 0, nil
+	}
+	return updatedAt, stacktrace.Propagate(err, "")
+}
+
 func convertRowsToTrash(rows *sql.Rows) ([]ente.Trash, error) {
 	defer rows.Close()
 	trashFiles := make([]ente.Trash, 0)