refactor(handler): delay `store.UserByID` as much as possible

In internal/reader/handler/handler.go:RefreshFeed, there is a call to
store.UserByID pretty early, which is only used for
originalFeed.WithTranslatedErrorMessage(localizedError.Translate(user.Language)
Its only other usage is in processor.ProcessFeedEntries(store, originalFeed,
user, forceRefresh), which is pretty late in RefreshFeed, and only called if
there are new items in the feed. It makes sense to only fetch the user's
language if the error localization function is used.

Calls to `store.UserByID` take around 10% of the CPU time of RefreshFeed in my
profiling.

This commit also makes `processor.ProcessFeedEntries` take a `userID` instead
of a `user`, to make the code a bit more concise.

This should close #2984

internal/reader/handler/handler.go

@@ -31,11 +31,6 @@ func CreateFeedFromSubscriptionDiscovery(store *storage.Storage, userID int64, f
 		slog.String("feed_url", feedCreationRequest.FeedURL),
 	)
 
-	user, storeErr := store.UserByID(userID)
-	if storeErr != nil {
-		return nil, locale.NewLocalizedErrorWrapper(storeErr, "error.database_error", storeErr)
-	}
-
 	if !store.CategoryIDExists(userID, feedCreationRequest.CategoryID) {
 		return nil, locale.NewLocalizedErrorWrapper(ErrCategoryNotFound, "error.category_not_found")
 	}
@@ -71,7 +66,7 @@ func CreateFeedFromSubscriptionDiscovery(store *storage.Storage, userID int64, f
 	subscription.WithCategoryID(feedCreationRequest.CategoryID)
 	subscription.CheckedNow()
 
-	processor.ProcessFeedEntries(store, subscription, user, true)
+	processor.ProcessFeedEntries(store, subscription, userID, true)
 
 	if storeErr := store.CreateFeed(subscription); storeErr != nil {
 		return nil, locale.NewLocalizedErrorWrapper(storeErr, "error.database_error", storeErr)
@@ -105,11 +100,6 @@ func CreateFeed(store *storage.Storage, userID int64, feedCreationRequest *model
 		slog.String("feed_url", feedCreationRequest.FeedURL),
 	)
 
-	user, storeErr := store.UserByID(userID)
-	if storeErr != nil {
-		return nil, locale.NewLocalizedErrorWrapper(storeErr, "error.database_error", storeErr)
-	}
-
 	if !store.CategoryIDExists(userID, feedCreationRequest.CategoryID) {
 		return nil, locale.NewLocalizedErrorWrapper(ErrCategoryNotFound, "error.category_not_found")
 	}
@@ -170,7 +160,7 @@ func CreateFeed(store *storage.Storage, userID int64, feedCreationRequest *model
 	subscription.WithCategoryID(feedCreationRequest.CategoryID)
 	subscription.CheckedNow()
 
-	processor.ProcessFeedEntries(store, subscription, user, true)
+	processor.ProcessFeedEntries(store, subscription, userID, true)
 
 	if storeErr := store.CreateFeed(subscription); storeErr != nil {
 		return nil, locale.NewLocalizedErrorWrapper(storeErr, "error.database_error", storeErr)
@@ -195,11 +185,6 @@ func RefreshFeed(store *storage.Storage, userID, feedID int64, forceRefresh bool
 		slog.Bool("force_refresh", forceRefresh),
 	)
 
-	user, storeErr := store.UserByID(userID)
-	if storeErr != nil {
-		return locale.NewLocalizedErrorWrapper(storeErr, "error.database_error", storeErr)
-	}
-
 	originalFeed, storeErr := store.FeedByID(userID, feedID)
 	if storeErr != nil {
 		return locale.NewLocalizedErrorWrapper(storeErr, "error.database_error", storeErr)
@@ -256,6 +241,10 @@ func RefreshFeed(store *storage.Storage, userID, feedID int64, forceRefresh bool
 
 	if localizedError := responseHandler.LocalizedError(); localizedError != nil {
 		slog.Warn("Unable to fetch feed", slog.String("feed_url", originalFeed.FeedURL), slog.Any("error", localizedError.Error()))
+		user, storeErr := store.UserByID(userID)
+		if storeErr != nil {
+			return locale.NewLocalizedErrorWrapper(storeErr, "error.database_error", storeErr)
+		}
 		originalFeed.WithTranslatedErrorMessage(localizedError.Translate(user.Language))
 		store.UpdateFeedError(originalFeed)
 		return localizedError
@@ -263,6 +252,10 @@ func RefreshFeed(store *storage.Storage, userID, feedID int64, forceRefresh bool
 
 	if store.AnotherFeedURLExists(userID, originalFeed.ID, responseHandler.EffectiveURL()) {
 		localizedError := locale.NewLocalizedErrorWrapper(ErrDuplicatedFeed, "error.duplicated_feed")
+		user, storeErr := store.UserByID(userID)
+		if storeErr != nil {
+			return locale.NewLocalizedErrorWrapper(storeErr, "error.database_error", storeErr)
+		}
 		originalFeed.WithTranslatedErrorMessage(localizedError.Translate(user.Language))
 		store.UpdateFeedError(originalFeed)
 		return localizedError
@@ -289,6 +282,10 @@ func RefreshFeed(store *storage.Storage, userID, feedID int64, forceRefresh bool
 			if errors.Is(parseErr, parser.ErrFeedFormatNotDetected) {
 				localizedError = locale.NewLocalizedErrorWrapper(parseErr, "error.feed_format_not_detected", parseErr)
 			}
+			user, storeErr := store.UserByID(userID)
+			if storeErr != nil {
+				return locale.NewLocalizedErrorWrapper(storeErr, "error.database_error", storeErr)
+			}
 
 			originalFeed.WithTranslatedErrorMessage(localizedError.Translate(user.Language))
 			store.UpdateFeedError(originalFeed)
@@ -309,13 +306,17 @@ func RefreshFeed(store *storage.Storage, userID, feedID int64, forceRefresh bool
 		)
 
 		originalFeed.Entries = updatedFeed.Entries
-		processor.ProcessFeedEntries(store, originalFeed, user, forceRefresh)
+		processor.ProcessFeedEntries(store, originalFeed, userID, forceRefresh)
 
 		// We don't update existing entries when the crawler is enabled (we crawl only inexisting entries). Unless it is forced to refresh
 		updateExistingEntries := forceRefresh || !originalFeed.Crawler
 		newEntries, storeErr := store.RefreshFeedEntries(originalFeed.UserID, originalFeed.ID, originalFeed.Entries, updateExistingEntries)
 		if storeErr != nil {
 			localizedError := locale.NewLocalizedErrorWrapper(storeErr, "error.database_error", storeErr)
+			user, storeErr := store.UserByID(userID)
+			if storeErr != nil {
+				return locale.NewLocalizedErrorWrapper(storeErr, "error.database_error", storeErr)
+			}
 			originalFeed.WithTranslatedErrorMessage(localizedError.Translate(user.Language))
 			store.UpdateFeedError(originalFeed)
 			return localizedError
@@ -359,6 +360,10 @@ func RefreshFeed(store *storage.Storage, userID, feedID int64, forceRefresh bool
 
 	if storeErr := store.UpdateFeed(originalFeed); storeErr != nil {
 		localizedError := locale.NewLocalizedErrorWrapper(storeErr, "error.database_error", storeErr)
+		user, storeErr := store.UserByID(userID)
+		if storeErr != nil {
+			return locale.NewLocalizedErrorWrapper(storeErr, "error.database_error", storeErr)
+		}
 		originalFeed.WithTranslatedErrorMessage(localizedError.Translate(user.Language))
 		store.UpdateFeedError(originalFeed)
 		return localizedError

internal/reader/processor/processor.go

@@ -28,9 +28,15 @@ import (
 var customReplaceRuleRegex = regexp.MustCompile(`rewrite\("([^"]+)"\|"([^"]+)"\)`)
 
 // ProcessFeedEntries downloads original web page for entries and apply filters.
-func ProcessFeedEntries(store *storage.Storage, feed *model.Feed, user *model.User, forceRefresh bool) {
+func ProcessFeedEntries(store *storage.Storage, feed *model.Feed, userID int64, forceRefresh bool) {
 	var filteredEntries model.Entries
 
+	user, storeErr := store.UserByID(userID)
+	if storeErr != nil {
+		slog.Error("Database error", slog.Any("error", storeErr))
+		return
+	}
+
 	// Process older entries first
 	for i := len(feed.Entries) - 1; i >= 0; i-- {
 		entry := feed.Entries[i]