perf(storage): minor optimization for `FetchJobs`

- Replace a call to fmt.Sprintf with a concatenation
- Explicit declaration of return values in FetchJobs
- Initialize the size of FetchJobs return value to b.limit: when b.limit is
  used, which is most of the time, this avoid resizing the slice, and when it
  isn't, the size of the map is set to 0, which is equivalent to the previous
  situation anyway.
- Move a call to `request.UserID(r)` to a lower scope.

internal/storage/batch.go

@@ -55,15 +55,15 @@ func (b *BatchBuilder) WithNextCheckExpired() *BatchBuilder {
 }
 
 func (b *BatchBuilder) WithoutDisabledFeeds() *BatchBuilder {
-	b.conditions = append(b.conditions, "disabled is false")
+	b.conditions = append(b.conditions, "disabled IS false")
 	return b
 }
 
-func (b *BatchBuilder) FetchJobs() (jobs model.JobList, err error) {
+func (b *BatchBuilder) FetchJobs() (model.JobList, error) {
 	query := `SELECT id, user_id FROM feeds`
 
 	if len(b.conditions) > 0 {
-		query += fmt.Sprintf(" WHERE %s", strings.Join(b.conditions, " AND "))
+		query += " WHERE " + strings.Join(b.conditions, " AND ")
 	}
 
 	if b.limit > 0 {
@@ -76,6 +76,8 @@ func (b *BatchBuilder) FetchJobs() (jobs model.JobList, err error) {
 	}
 	defer rows.Close()
 
+	jobs := make(model.JobList, 0, b.limit)
+
 	for rows.Next() {
 		var job model.Job
 		if err := rows.Scan(&job.FeedID, &job.UserID); err != nil {

internal/ui/feed_refresh.go

@@ -33,7 +33,6 @@ func (h *handler) refreshFeed(w http.ResponseWriter, r *http.Request) {
 }
 
 func (h *handler) refreshAllFeeds(w http.ResponseWriter, r *http.Request) {
-	userID := request.UserID(r)
 	printer := locale.NewPrinter(request.UserLanguage(r))
 	sess := session.New(h.store, request.SessionID(r))
 
@@ -42,6 +41,7 @@ func (h *handler) refreshAllFeeds(w http.ResponseWriter, r *http.Request) {
 		time := config.Opts.ForceRefreshInterval()
 		sess.NewFlashErrorMessage(printer.Plural("alert.too_many_feeds_refresh", time, time))
 	} else {
+		userID := request.UserID(r)
 		// We allow the end-user to force refresh all its feeds
 		// without taking into consideration the number of errors.
 		batchBuilder := h.store.NewBatchBuilder()