thumbnails: need to check fileHash, not fileId

storage.go

@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"io"
 	"log"
+	"math/rand"
 	"os"
 	"path/filepath"
 	"time"
@@ -13,9 +14,16 @@ import (
 	"github.com/minio/minio-go/v7/pkg/credentials"
 )
 
+type cleanupFunc func() error
+
 type Storage interface {
 	ReadFile(ctx context.Context, fileHash string) (io.ReadSeekCloser, error)
 	SaveFile(ctx context.Context, fileHash string, srcLen int64, src io.Reader) error
+
+	// TempLocalFilepath returns a local file path and a cleanup function that
+	// can be used to access the file through the filesystem.
+	// It's an alternative to ReadFile.
+	TempLocalFilepath(ctx context.Context, fileHash string) (string, cleanupFunc, error)
 }
 
 //
@@ -63,6 +71,19 @@ func (ls *localStorage) SaveFile(ctx context.Context, fileHash string, srcLen in
 	return nil
 }
 
+func (ls *localStorage) TempLocalFilepath(ctx context.Context, fileHash string) (string, cleanupFunc, error) {
+	path := filepath.Join(ls.dataDir, fileHash)
+	cleanup := func() error { return nil }
+
+	if _, err := os.Stat(path); err != nil {
+		return "", nil, err // e.g. not exists
+	}
+
+	// Exists (but may be TOCTTOU)
+
+	return path, cleanup, nil
+}
+
 var _ Storage = &localStorage{} // interface assertion
 
 //
@@ -100,7 +121,36 @@ func (ss *s3Storage) ReadFile(ctx context.Context, fileHash string) (io.ReadSeek
 func (ss *s3Storage) SaveFile(ctx context.Context, fileHash string, srcLen int64, src io.Reader) error {
 	_, err := ss.s3client.PutObject(ctx, ss.Bucket, ss.Prefix+fileHash, src, srcLen, minio.PutObjectOptions{})
 	return err
+}
 
+func (ss *s3Storage) TempLocalFilepath(ctx context.Context, fileHash string) (string, cleanupFunc, error) {
+
+	// Download to temporary file
+	fh, err := os.CreateTemp("", "contented-temp-*")
+	if err != nil {
+		return "", nil, err
+	}
+
+	name := fh.Name() // n.b. This is the absolute path to the file
+
+	r, err := ss.ReadFile(ctx, fileHash)
+	if err != nil {
+		return "", nil, err
+	}
+
+	_, err = io.Copy(fh, r)
+	if err != nil {
+		return "", nil, err
+	}
+
+	_ = r.Close()
+	_ = fh.Close()
+
+	cleanup := func() error {
+		return os.Remove(name)
+	}
+
+	return name, cleanup, nil
 }
 
 var _ Storage = &s3Storage{} // interface assertion
@@ -155,20 +205,39 @@ func (ts *tieredStorage) migrateNow() error {
 		return fmt.Errorf("Reading hot storage files: %w", err)
 	}
 
+	if len(dirents) == 0 {
+		return nil // Directory empty, nothing to do
+	}
+
 	cutOff := time.Now().Add(-TierMigrationAfter)
 
+	// Shuffle files to avoid getting stuck
+	rand.Shuffle(len(dirents), func(i, j int) {
+		dirents[i], dirents[j] = dirents[j], dirents[i]
+	})
+
+	log.Printf("tier-migration: Scanning %d items...", len(dirents))
+
+	var countMigrated int64 = 0
+
 	for _, dirent := range dirents {
 		fi, err := dirent.Info()
 		if err != nil {
 			return fmt.Errorf("Reading hot storage files: %w", err) // local files can't be stat'd = important error
 		}
 
-		if !fi.ModTime().After(cutOff) {
+		if fi.IsDir() {
+			continue // probably . or ..
+		}
+
+		if fi.ModTime().After(cutOff) {
 			continue // not eligible
 		}
 
 		fileHash := dirent.Name()
 
+		log.Printf("tier-migration: Migrating %q...", fileHash)
+
 		// Copy to cold storage
 		// Any concurrent reads will be serviced from the hot storage, so this
 		// is a safe operation
@@ -186,11 +255,15 @@ func (ts *tieredStorage) migrateNow() error {
 		// Copy was successful. Delete local file
 		err = os.Remove(filepath.Join(ts.hot.dataDir, fileHash))
 		if err != nil {
-			return fmt.Errorf("Remove %q from hot storage: %w", err) // can't rm local file
+			return fmt.Errorf("Remove %q from hot storage: %w", fileHash, err) // can't rm local file
 		}
+
+		countMigrated++
 	}
 
 	// Migrated everything we can for now
+	log.Printf("tier-migration: Sleeping (migrated %d/%d items)", countMigrated, len(dirents))
+
 	return nil
 }
 
@@ -206,4 +279,19 @@ func (ts *tieredStorage) SaveFile(ctx context.Context, fileHash string, srcLen i
 	return ts.hot.SaveFile(ctx, fileHash, srcLen, src)
 }
 
+func (ts *tieredStorage) TempLocalFilepath(ctx context.Context, fileHash string) (string, cleanupFunc, error) {
+	path, cleanup, err_hot := ts.hot.TempLocalFilepath(ctx, fileHash)
+	if err_hot == nil {
+		return path, cleanup, nil
+	}
+
+	path, cleanup, err_cold := ts.cold.TempLocalFilepath(ctx, fileHash)
+	if err_cold == nil {
+		return path, cleanup, nil
+	}
+
+	// Neither err_hot nor err_cold worked
+	return "", nil, fmt.Errorf("TempLocalFilepath: failed to allocate local path for %q (hot error: %q, cold error: %q)", fileHash, err_hot.Error(), err_cold.Error())
+}
+
 var _ Storage = &tieredStorage{} // interface assertion

thumb.go

@@ -4,11 +4,8 @@ import (
 	"context"
 	"errors"
 	"fmt"
-	"io"
 	"log"
 	"net/http"
-	"os"
-	"path/filepath"
 
 	"code.ivysaur.me/thumbnail"
 )
@@ -93,45 +90,30 @@ func (this *Server) handleThumbInternal(ctx context.Context, w http.ResponseWrit
 	// Load metadata
 	m, err := this.Metadata(fileId)
 	if err != nil {
-		return err
+		return fmt.Errorf("Metadata: %w", err)
 	}
 
 	if m.FileSize > this.opts.MaxThumbSizeBytes {
 		return errors.New("Don't want to thumbnail very large files, sorry")
 	}
 
-	var filePath string
-
-	if this.opts.StorageType == STORAGE_LOCAL {
-		filePath = filepath.Join(this.opts.DataDirectory, m.FileHash)
-
-	} else if this.opts.StorageType == STORAGE_S3 {
-		// Need to temporarily download it for thumbnailing (slow and costs money)
-
-		destFh, err := os.CreateTemp("", "contented-thumbcache-*")
-		defer os.Remove(destFh.Name())
-
-		srcFh, err := this.store.ReadFile(ctx, m.FileHash)
-		if err != nil {
-			return err
-		}
-
-		_, err = io.CopyN(destFh, srcFh, m.FileSize)
-		srcFh.Close()
-		if err != nil {
-			return err
-		}
-
-		destFh.Seek(0, io.SeekStart)
-		filePath = destFh.Name()
-
-	} else {
-		panic("bad StorageType")
+	// Some storage backends can supply a local filepath immediately for thumbnailing
+	// Others (s3, tiered) need to download the file temporarily first
+	filePath, cleanup, err := this.store.TempLocalFilepath(ctx, m.FileHash)
+	if err != nil {
+		return fmt.Errorf("TempLocalFilepath: %w", err)
 	}
 
+	defer func() {
+		// delete temporary file, if necessary
+		if cleanupErr := cleanup(); cleanupErr != nil {
+			log.Printf("cleaning up temporary thumbnail file: %v", cleanupErr)
+		}
+	}()
+
 	thumb, err := t.RenderFileAs(filePath, m.MimeType)
 	if err != nil {
-		return err
+		return fmt.Errorf("RenderFileAs: %w", err)
 	}
 
 	w.Header().Set(`Cache-Control`, `max-age=31536000, immutable`)