优化

internal/service/scraper_lookup_cache.go

@@ -0,0 +1,126 @@
+package service
+
+import (
+	"strconv"
+	"strings"
+	"sync"
+	"time"
+)
+
+// A TV library scrapes one media row per episode, and every row in the same
+// show computes the same query candidate (the series folder title). Without a
+// cache each episode re-issues the identical TMDb/Douban/Bangumi/TheTVDB
+// search, so a 100-episode season costs 100x the network calls it needs.
+//
+// The cache lives on the ScraperService instance (not a package global) so that
+// two services with different provider configuration never share results. TTL
+// bounds staleness for out-of-band edits; explicit invalidation is unnecessary
+// because the key includes the effective media kind, theatrical flag, query
+// and year. Negative entries use a shorter TTL so a failed query is retried
+// sooner without manual intervention.
+const (
+	scrapeLookupCacheTTL         = 10 * time.Minute
+	scrapeLookupNegativeCacheTTL = 2 * time.Minute
+	scrapeLookupCacheMaxItems    = 1024
+)
+
+type scrapeLookupCache struct {
+	mu      sync.Mutex
+	entries map[string]scrapeLookupCacheEntry
+}
+
+type scrapeLookupCacheEntry struct {
+	match     *Match
+	expiresAt time.Time
+}
+
+func newScrapeLookupCache() *scrapeLookupCache {
+	return &scrapeLookupCache{entries: map[string]scrapeLookupCacheEntry{}}
+}
+
+func scrapeLookupCacheKey(kind, query string, year int, isTheatrical bool) string {
+	theatrical := "0"
+	if isTheatrical {
+		theatrical = "1"
+	}
+	return strings.ToLower(strings.TrimSpace(kind)) + "|" +
+		theatrical + "|" +
+		strconv.Itoa(year) + "|" +
+		strings.ToLower(strings.TrimSpace(query))
+}
+
+// get reports whether the key is cached. A hit may carry a nil match, which
+// means the provider chain already ran and found nothing (negative cache).
+// Use clearNegative before a user-triggered retry so stale negative entries
+// do not suppress the fresh provider round-trip.
+func (c *scrapeLookupCache) get(key string) (*Match, bool) {
+	if c == nil || key == "" {
+		return nil, false
+	}
+	now := time.Now()
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	item, ok := c.entries[key]
+	if !ok {
+		return nil, false
+	}
+	if now.After(item.expiresAt) {
+		delete(c.entries, key)
+		return nil, false
+	}
+	return cloneMatch(item.match), true
+}
+
+func (c *scrapeLookupCache) set(key string, match *Match) {
+	if c == nil || key == "" {
+		return
+	}
+	now := time.Now()
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	if len(c.entries) >= scrapeLookupCacheMaxItems {
+		for k, item := range c.entries {
+			if now.After(item.expiresAt) || len(c.entries) >= scrapeLookupCacheMaxItems {
+				delete(c.entries, k)
+			}
+			if len(c.entries) < scrapeLookupCacheMaxItems {
+				break
+			}
+		}
+	}
+	ttl := scrapeLookupCacheTTL
+	if match == nil {
+		ttl = scrapeLookupNegativeCacheTTL
+	}
+	c.entries[key] = scrapeLookupCacheEntry{match: cloneMatch(match), expiresAt: now.Add(ttl)}
+}
+
+// clearNegatives drops cached misses so a user-triggered retry gets a fresh
+// provider round-trip instead of reusing a stale negative entry.
+func (c *scrapeLookupCache) clearNegatives() {
+	if c == nil {
+		return
+	}
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	for k, item := range c.entries {
+		if item.match == nil {
+			delete(c.entries, k)
+		}
+	}
+}
+
+// cloneMatch returns an independent copy so callers that mutate the result
+// (localized title preference, local metadata merge, fanart artwork) cannot
+// corrupt the cached entry or leak state between media rows.
+func cloneMatch(m *Match) *Match {
+	if m == nil {
+		return nil
+	}
+	out := *m
+	out.Languages = append([]string(nil), m.Languages...)
+	out.Countries = append([]string(nil), m.Countries...)
+	out.Genres = append([]string(nil), m.Genres...)
+	out.Aliases = append([]string(nil), m.Aliases...)
+	return &out
+}