feat: cache top-picks with stale-while-refresh

2026-06-27 15:43:48 +02:00
parent cbf084e935
commit e502056f2f
3 changed files with 261 additions and 7 deletions
--- a/internal/anime/recommendations_cache_test.go
+++ b/internal/anime/recommendations_cache_test.go
@@ -0,0 +1,123 @@
+package anime
+
+import (
+	"context"
+	"errors"
+	"testing"
+	"time"
+
+	"mal/integrations/jikan"
+	"mal/internal/domain"
+)
+
+func TestGetTopPicksForYouReturnsEmptyOnCacheMissAndRefreshesInBackground(t *testing.T) {
+	refreshed := make(chan struct{}, 1)
+	svc := NewAnimeService(nil, nil)
+	svc.computeTopPicks = func(context.Context, string, int) (domain.CatalogSectionData, error) {
+		refreshed <- struct{}{}
+		return domain.CatalogSectionData{Animes: []domain.Anime{{Anime: jikan.Anime{MalID: 7}}}}, nil
+	}
+
+	got, err := svc.GetTopPicksForYou(context.Background(), "user-1")
+	if err != nil {
+		t.Fatalf("GetTopPicksForYou cache miss: %v", err)
+	}
+	if len(got.Animes) != 0 {
+		t.Fatalf("cache miss animes = %+v, want empty while refresh runs", got.Animes)
+	}
+
+	waitForRefresh(t, refreshed)
+
+	got, err = svc.GetTopPicksForYou(context.Background(), "user-1")
+	if err != nil {
+		t.Fatalf("GetTopPicksForYou cache hit: %v", err)
+	}
+	if len(got.Animes) != 1 || got.Animes[0].MalID != 7 {
+		t.Fatalf("cache hit animes = %+v, want anime 7", got.Animes)
+	}
+}
+
+func TestGetTopPicksForYouReturnsStaleDataWhenRefreshFails(t *testing.T) {
+	svc := NewAnimeService(nil, nil)
+	svc.topPicksCacheTTL = time.Nanosecond
+	refreshed := make(chan struct{}, 2)
+	svc.computeTopPicks = func(context.Context, string, int) (domain.CatalogSectionData, error) {
+		refreshed <- struct{}{}
+		return domain.CatalogSectionData{Animes: []domain.Anime{{Anime: jikan.Anime{MalID: 11}}}}, nil
+	}
+
+	if _, err := svc.GetTopPicksForYou(context.Background(), "user-1"); err != nil {
+		t.Fatalf("prime cache: %v", err)
+	}
+	waitForRefresh(t, refreshed)
+
+	svc.computeTopPicks = func(context.Context, string, int) (domain.CatalogSectionData, error) {
+		refreshed <- struct{}{}
+		return domain.CatalogSectionData{}, errors.New("provider unavailable")
+	}
+	time.Sleep(time.Nanosecond)
+
+	got, err := svc.GetTopPicksForYou(context.Background(), "user-1")
+	if err != nil {
+		t.Fatalf("stale GetTopPicksForYou: %v", err)
+	}
+	if len(got.Animes) != 1 || got.Animes[0].MalID != 11 {
+		t.Fatalf("stale animes = %+v, want anime 11", got.Animes)
+	}
+}
+
+func TestInvalidateTopPicksForUserRefreshesNextRequest(t *testing.T) {
+	refreshed := make(chan struct{}, 2)
+	results := []int{3, 4}
+
+	svc := newPickSvc(refreshed, &results)
+
+	primePickCache(t, svc, refreshed)
+
+	svc.InvalidateTopPicksForUser("user-1")
+
+	got, err := svc.GetTopPicksForYou(context.Background(), "user-1")
+	if err != nil {
+		t.Fatalf("GetTopPicksForYou after invalidation: %v", err)
+	}
+	if len(got.Animes) != 0 {
+		t.Fatalf("invalidated cache animes = %+v, want empty while refresh runs", got.Animes)
+	}
+	waitForRefresh(t, refreshed)
+
+	got, err = svc.GetTopPicksForYou(context.Background(), "user-1")
+	if err != nil {
+		t.Fatalf("GetTopPicksForYou refreshed cache: %v", err)
+	}
+	if len(got.Animes) != 1 || got.Animes[0].MalID != 4 {
+		t.Fatalf("refreshed animes = %+v, want anime 4", got.Animes)
+	}
+}
+
+func newPickSvc(refreshed chan struct{}, results *[]int) *animeService {
+	svc := NewAnimeService(nil, nil)
+	svc.computeTopPicks = func(context.Context, string, int) (domain.CatalogSectionData, error) {
+		id := (*results)[0]
+		*results = (*results)[1:]
+		refreshed <- struct{}{}
+		return domain.CatalogSectionData{Animes: []domain.Anime{{Anime: jikan.Anime{MalID: id}}}}, nil
+	}
+	return svc
+}
+
+func primePickCache(t *testing.T, svc *animeService, refreshed chan struct{}) {
+	t.Helper()
+	if _, err := svc.GetTopPicksForYou(context.Background(), "user-1"); err != nil {
+		t.Fatalf("prime cache: %v", err)
+	}
+	waitForRefresh(t, refreshed)
+}
+
+func waitForRefresh(t *testing.T, refreshed chan struct{}) {
+	t.Helper()
+	select {
+	case <-refreshed:
+	case <-time.After(time.Second):
+		t.Fatal("background refresh did not run")
+	}
+}