修复 Emby 大海报在剧集图缓存被淘汰后显示占位图

Co-authored-by: Cursor <cursoragent@cursor.com>

internal/service/emby_series_cache.go

@@ -1,6 +1,7 @@
 package service
 
 import (
+	"sort"
 	"strings"
 	"time"
 )
@@ -37,11 +38,7 @@ func (e *EmbyService) rememberSeriesGroup(group embySeriesGroup) {
 	if e.virtualArtwork == nil {
 		e.virtualArtwork = make(map[string]embyArtworkCacheEntry)
 	}
-	if len(e.virtualSeries) > 2000 || len(e.virtualSeasons) > 5000 || len(e.virtualArtwork) > 7000 {
-		e.virtualSeries = make(map[string]embySeriesCacheEntry)
-		e.virtualSeasons = make(map[string]embySeasonCacheEntry)
-		e.virtualArtwork = make(map[string]embyArtworkCacheEntry)
-	}
+	e.trimVirtualCachesLocked(time.Now())
 	e.virtualSeries[group.ID] = embySeriesCacheEntry{group: group, expiresAt: expiresAt}
 	e.virtualArtwork[group.ID] = embyArtworkCacheEntry{primary: group.PosterURL, backdrop: group.BackdropURL, expiresAt: expiresAt}
 	e.virtualArtwork[group.ID+"-bd"] = embyArtworkCacheEntry{primary: group.PosterURL, backdrop: group.BackdropURL, expiresAt: expiresAt}
@@ -65,6 +62,7 @@ func (e *EmbyService) rememberSeasonGroup(season embySeasonGroup) {
 	if e.virtualArtwork == nil {
 		e.virtualArtwork = make(map[string]embyArtworkCacheEntry)
 	}
+	e.trimVirtualCachesLocked(time.Now())
 	e.virtualSeasons[season.ID] = embySeasonCacheEntry{season: season, expiresAt: expiresAt}
 	e.virtualArtwork[season.ID] = embyArtworkCacheEntry{primary: season.Series.PosterURL, backdrop: season.Series.BackdropURL, expiresAt: expiresAt}
 	e.virtualArtwork[season.ID+"-bd"] = embyArtworkCacheEntry{primary: season.Series.PosterURL, backdrop: season.Series.BackdropURL, expiresAt: expiresAt}
@@ -135,3 +133,123 @@ func (e *EmbyService) cachedArtworkURL(id, imageType string) (string, bool) {
 	}
 	return entry.backdrop, entry.backdrop != ""
 }
+
+// embyArtworkRef is the poster/backdrop pair stored next to a Latest payload
+// so a JSON-cache hit can refill the in-memory artwork map before the client
+// asks for the image.
+type embyArtworkRef struct {
+	Primary  string `json:"primary,omitempty"`
+	Backdrop string `json:"backdrop,omitempty"`
+}
+
+func (e *EmbyService) artworkRefsForSeriesGroups(groups []embySeriesGroup) map[string]embyArtworkRef {
+	if e == nil || len(groups) == 0 {
+		return nil
+	}
+	refs := make(map[string]embyArtworkRef, len(groups)*2)
+	for _, group := range groups {
+		if group.PosterURL == "" && group.BackdropURL == "" {
+			continue
+		}
+		ref := embyArtworkRef{Primary: group.PosterURL, Backdrop: group.BackdropURL}
+		refs[group.ID] = ref
+		for _, season := range e.seasonsForSeries(group) {
+			refs[season.ID] = ref
+		}
+	}
+	if len(refs) == 0 {
+		return nil
+	}
+	return refs
+}
+
+func (e *EmbyService) rememberArtworkRefs(refs map[string]embyArtworkRef) {
+	if e == nil || len(refs) == 0 {
+		return
+	}
+	expiresAt := time.Now().Add(embyVirtualCacheTTL)
+	e.virtualMu.Lock()
+	defer e.virtualMu.Unlock()
+	if e.virtualArtwork == nil {
+		e.virtualArtwork = make(map[string]embyArtworkCacheEntry, len(refs))
+	}
+	e.trimVirtualArtworkLocked(time.Now())
+	for id, ref := range refs {
+		if strings.TrimSpace(id) == "" || (ref.Primary == "" && ref.Backdrop == "") {
+			continue
+		}
+		e.virtualArtwork[id] = embyArtworkCacheEntry{primary: ref.Primary, backdrop: ref.Backdrop, expiresAt: expiresAt}
+	}
+}
+
+func (e *EmbyService) trimVirtualCachesLocked(now time.Time) {
+	e.trimVirtualSeriesLocked(now)
+	e.trimVirtualSeasonsLocked(now)
+	e.trimVirtualArtworkLocked(now)
+}
+
+func (e *EmbyService) trimVirtualSeriesLocked(now time.Time) {
+	for id, entry := range e.virtualSeries {
+		if now.After(entry.expiresAt) {
+			delete(e.virtualSeries, id)
+		}
+	}
+	evictOldest(e.virtualSeries, embyVirtualSeriesCap, func(entry embySeriesCacheEntry) time.Time {
+		return entry.expiresAt
+	})
+}
+
+func (e *EmbyService) trimVirtualSeasonsLocked(now time.Time) {
+	for id, entry := range e.virtualSeasons {
+		if now.After(entry.expiresAt) {
+			delete(e.virtualSeasons, id)
+		}
+	}
+	evictOldest(e.virtualSeasons, embyVirtualSeasonCap, func(entry embySeasonCacheEntry) time.Time {
+		return entry.expiresAt
+	})
+}
+
+func (e *EmbyService) trimVirtualArtworkLocked(now time.Time) {
+	for id, entry := range e.virtualArtwork {
+		if now.After(entry.expiresAt) {
+			delete(e.virtualArtwork, id)
+		}
+	}
+	evictOldest(e.virtualArtwork, embyVirtualArtworkCap, func(entry embyArtworkCacheEntry) time.Time {
+		return entry.expiresAt
+	})
+}
+
+// evictOldest drops the soonest-expiring entries until the map is under cap.
+// It must not replace the map: a homepage refresh remembers many series at
+// once, and wiping the whole cache made the just-advertised backdrops 404
+// into a 1x1 placeholder.
+func evictOldest[T any](items map[string]T, cap int, expiresAt func(T) time.Time) {
+	excess := len(items) - cap
+	if cap <= 0 || excess <= 0 {
+		return
+	}
+	type pair struct {
+		id string
+		at time.Time
+	}
+	ordered := make([]pair, 0, len(items))
+	for id, entry := range items {
+		ordered = append(ordered, pair{id: id, at: expiresAt(entry)})
+	}
+	sort.Slice(ordered, func(i, j int) bool { return ordered[i].at.Before(ordered[j].at) })
+	if excess > len(ordered) {
+		excess = len(ordered)
+	}
+	for i := 0; i < excess; i++ {
+		delete(items, ordered[i].id)
+	}
+}
+
+func embyVirtualImageTag(id, suffix string) string {
+	if strings.HasPrefix(id, embyVirtualSeriesPrefix) || strings.HasPrefix(id, embyVirtualSeasonPrefix) {
+		return id + suffix
+	}
+	return id
+}