Add filesystem based blob storage (#3187)

* Refactor transaction hooks. Add preCommit
* Add BlobStore
* Use blobStore for tag images
* Use blobStore for studio images
* Use blobStore for performer images
* Use blobStore for scene covers
* Don't generate screenshots in legacy directory
* Run post-hooks outside original transaction
* Use blobStore for movie images
* Remove unnecessary DestroyImage methods
* Add missing filter for scene cover
* Add covers to generate options
* Add generate cover option to UI
* Add screenshot migration
* Delete thumb files as part of screenshot migration

pkg/sqlite/blob/fs.go

@@ -0,0 +1,108 @@
+package blob
+
+import (
+	"bytes"
+	"context"
+	"fmt"
+	"io"
+	"io/fs"
+	"os"
+	"path/filepath"
+
+	"github.com/stashapp/stash/pkg/file"
+	"github.com/stashapp/stash/pkg/fsutil"
+)
+
+const (
+	blobsDirDepth  int = 2
+	blobsDirLength int = 2 // thumbDirDepth * thumbDirLength must be smaller than the length of checksum
+)
+
+type FS interface {
+	Create(name string) (*os.File, error)
+	MkdirAll(path string, perm fs.FileMode) error
+	Open(name string) (fs.ReadDirFile, error)
+	Remove(name string) error
+
+	file.RenamerRemover
+}
+
+type FilesystemStore struct {
+	deleter *file.Deleter
+	path    string
+	fs      FS
+}
+
+func NewFilesystemStore(path string, fs FS) *FilesystemStore {
+	deleter := &file.Deleter{
+		RenamerRemover: fs,
+	}
+
+	return &FilesystemStore{
+		deleter: deleter,
+		path:    path,
+		fs:      fs,
+	}
+}
+
+func (s *FilesystemStore) checksumToPath(checksum string) string {
+	return filepath.Join(s.path, fsutil.GetIntraDir(checksum, blobsDirDepth, blobsDirLength), checksum)
+}
+
+func (s *FilesystemStore) Write(ctx context.Context, checksum string, data []byte) error {
+	if s.path == "" {
+		return fmt.Errorf("no path set")
+	}
+
+	fn := s.checksumToPath(checksum)
+
+	// create the directory if it doesn't exist
+	if err := s.fs.MkdirAll(filepath.Dir(fn), 0755); err != nil {
+		return fmt.Errorf("creating directory %q: %w", filepath.Dir(fn), err)
+	}
+
+	out, err := s.fs.Create(fn)
+	if err != nil {
+		return fmt.Errorf("creating file %q: %w", fn, err)
+	}
+
+	r := bytes.NewReader(data)
+
+	if _, err = io.Copy(out, r); err != nil {
+		return fmt.Errorf("writing file %q: %w", fn, err)
+	}
+
+	return nil
+}
+
+func (s *FilesystemStore) Read(ctx context.Context, checksum string) ([]byte, error) {
+	if s.path == "" {
+		return nil, fmt.Errorf("no path set")
+	}
+
+	fn := s.checksumToPath(checksum)
+	f, err := s.fs.Open(fn)
+	if err != nil {
+		return nil, fmt.Errorf("opening file %q: %w", fn, err)
+	}
+
+	defer f.Close()
+
+	return io.ReadAll(f)
+}
+
+func (s *FilesystemStore) Delete(ctx context.Context, checksum string) error {
+	if s.path == "" {
+		return fmt.Errorf("no path set")
+	}
+
+	s.deleter.RegisterHooks(ctx)
+
+	fn := s.checksumToPath(checksum)
+
+	if err := s.deleter.Files([]string{fn}); err != nil {
+		return fmt.Errorf("deleting file %q: %w", fn, err)
+	}
+
+	return nil
+}