fix(redis,scanner): atomic IncrWindow Lua, lock rand/ctx fixes, ScanLock renewal, single-flight, error logging (B1,B2,B3,B9,B10,B11)

backend/internal/scanner/scanner.go

@@ -10,6 +10,7 @@ import (
 	"os"
 	"path/filepath"
 	"strings"
+	"sync"
 	"time"
 
 	"booklib/internal/bookfile"
@@ -22,6 +23,9 @@ type Scanner struct {
 	st  *store.Store
 	cfg *config.Config
 	rdb *redispkg.R
+	// B9-②: per-library single-flight — concurrent scan triggers for the same
+	// library are merged into one execution, even without redis.
+	flights sync.Map // map[int64]*sync.WaitGroup
 }
 
 func New(st *store.Store, cfg *config.Config, rdb *redispkg.R) *Scanner {
@@ -42,7 +46,7 @@ func (s *Scanner) Run(ctx context.Context) {
 				continue
 			}
 			for _, l := range libs {
-				s.ScanLibrary(ctx, l)
+				s.scanOnce(ctx, l)
 			}
 		}
 	}
@@ -54,12 +58,28 @@ func (s *Scanner) ScanLibraryByID(ctx context.Context, id int64) {
 		log.Printf("scan: library %d: %v", id, err)
 		return
 	}
+	s.scanOnce(ctx, lib)
+}
+
+// scanOnce ensures only one scan per library runs concurrently in this process.
+// Concurrent callers block until the in-flight scan completes (B9-②).
+func (s *Scanner) scanOnce(ctx context.Context, lib store.Library) {
+	wg := &sync.WaitGroup{}
+	wg.Add(1)
+	if existing, loaded := s.flights.LoadOrStore(lib.ID, wg); loaded {
+		existing.(*sync.WaitGroup).Wait()
+		return
+	}
+	defer func() {
+		s.flights.Delete(lib.ID)
+		wg.Done()
+	}()
 	s.ScanLibrary(ctx, lib)
 }
 
 func (s *Scanner) ScanLibrary(ctx context.Context, lib store.Library) {
-	// ponytail: 5min lock TTL; a scan longer than this lets another replica join — refresh mid-walk if libs ever outgrow it
-	unlock, ok := s.rdb.Lock(ctx, fmt.Sprintf("scan:%d", lib.ID), 5*time.Minute)
+	// B9-①: ScanLock auto-renews every TTL/2 during long scans.
+	unlock, ok := s.rdb.ScanLock(ctx, fmt.Sprintf("scan:%d", lib.ID), 5*time.Minute)
 	if !ok {
 		return // 别的副本在扫
 	}
@@ -137,8 +157,6 @@ func titleOf(rel string) string {
 	return strings.TrimSpace(strings.ReplaceAll(strings.TrimSuffix(base, filepath.Ext(base)), "_", " "))
 }
 
-// cbz 完整性判定集中在 add/update:PageIndex 失败 → state=error。
-// InsertBook/UpdateBookFile 的 SQL 已把 state 重置为 ready(Task 2),无需显式清 error。
 func (s *Scanner) add(ctx context.Context, libID int64, root, rel string, ds diskStat) {
 	format := bookfile.FormatFromExt(filepath.Base(rel))
 	pageCount := 0
@@ -147,7 +165,7 @@ func (s *Scanner) add(ctx context.Context, libID int64, root, rel string, ds dis
 		idx, err := s.zipIndex(root, rel)
 		pageCount = len(idx)
 		idxErr = err
-		if idxErr == nil && pageCount == 0 { // 视频/文档 zip 不是漫画,空白 reader 没有意义
+		if idxErr == nil && pageCount == 0 {
 			idxErr = errors.New("no images in archive")
 		}
 	}
@@ -157,7 +175,10 @@ func (s *Scanner) add(ctx context.Context, libID int64, root, rel string, ds dis
 		return
 	}
 	if idxErr != nil {
-		s.st.SetBookState(ctx, id, "error", idxErr.Error())
+		// B10: log SetBookState errors instead of discarding.
+		if e := s.st.SetBookState(ctx, id, "error", idxErr.Error()); e != nil {
+			log.Printf("scan: SetBookState error for %s: %v", rel, e)
+		}
 		return
 	}
 	s.cover(ctx, id, root, rel, format, ds)
@@ -171,7 +192,7 @@ func (s *Scanner) update(ctx context.Context, libID, bookID int64, root, rel str
 		idx, err := s.zipIndex(root, rel)
 		pageCount = len(idx)
 		idxErr = err
-		if idxErr == nil && pageCount == 0 { // 视频/文档 zip 不是漫画,空白 reader 没有意义
+		if idxErr == nil && pageCount == 0 {
 			idxErr = errors.New("no images in archive")
 		}
 	}
@@ -180,7 +201,9 @@ func (s *Scanner) update(ctx context.Context, libID, bookID int64, root, rel str
 		return
 	}
 	if idxErr != nil {
-		s.st.SetBookState(ctx, bookID, "error", idxErr.Error())
+		if e := s.st.SetBookState(ctx, bookID, "error", idxErr.Error()); e != nil {
+			log.Printf("scan: SetBookState error for %s: %v", rel, e)
+		}
 		return
 	}
 	s.cover(ctx, bookID, root, rel, format, ds)
@@ -199,7 +222,8 @@ func (s *Scanner) zipIndex(root, rel string) ([]string, error) {
 	return bookfile.PageIndex(f, st.Size())
 }
 
-// cover 失败(坏 epub、无图等)只 log — 书的 state 由 PageIndex 判定,封面缺了有占位 SVG 兜底
+// cover writes the cover image to the cache dir. B11: all write errors are
+// checked and logged; orphan .tmp files are cleaned only on failure path.
 func (s *Scanner) cover(ctx context.Context, id int64, root, rel, format string, ds diskStat) {
 	var img []byte
 	var ext string
@@ -223,8 +247,15 @@ func (s *Scanner) cover(ctx context.Context, id int64, root, rel, format string,
 	}
 	tmp := filepath.Join(dir, "cover"+ext+".tmp")
 	dst := filepath.Join(dir, "cover"+ext)
-	if e := os.WriteFile(tmp, img, 0o644); e == nil {
-		os.Rename(tmp, dst)
+	if e := os.WriteFile(tmp, img, 0o644); e != nil {
+		log.Printf("scan: write cover tmp %s: %v", rel, e)
+		os.Remove(tmp)
+		return
+	}
+	if e := os.Rename(tmp, dst); e != nil {
+		log.Printf("scan: rename cover %s: %v", rel, e)
+		os.Remove(tmp)
+		return
 	}
 }