revert to using one open file for blob uploads

server/upload.go

@@ -36,6 +36,8 @@ type blobUpload struct {
 
 	context.CancelFunc
 
+	file *os.File
+
 	done       bool
 	err        error
 	references atomic.Int32
@@ -101,7 +103,7 @@ func (b *blobUpload) Prepare(ctx context.Context, requestURL *url.URL, opts *Reg
 		}
 
 		// set part.N to the current number of parts
-		b.Parts = append(b.Parts, blobUploadPart{blobUpload: b, N: len(b.Parts), Offset: offset, Size: size})
+		b.Parts = append(b.Parts, blobUploadPart{blobUpload: b, N: len(b.Parts), Hash: md5.New(), Offset: offset, Size: size})
 		offset += size
 	}
 
@@ -123,6 +125,19 @@ func (b *blobUpload) Run(ctx context.Context, opts *RegistryOptions) {
 	defer blobUploadManager.Delete(b.Digest)
 	ctx, b.CancelFunc = context.WithCancel(ctx)
 
+	p, err := GetBlobsPath(b.Digest)
+	if err != nil {
+		b.err = err
+		return
+	}
+
+	b.file, err = os.Open(p)
+	if err != nil {
+		b.err = err
+		return
+	}
+	defer b.file.Close()
+
 	g, inner := errgroup.WithContext(ctx)
 	g.SetLimit(numUploadParts)
 	for i := range b.Parts {
@@ -204,18 +219,8 @@ func (b *blobUpload) uploadChunk(ctx context.Context, method string, requestURL
 		headers.Set("Content-Range", fmt.Sprintf("%d-%d", part.Offset, part.Offset+part.Size-1))
 	}
 
-	p, err := GetBlobsPath(b.Digest)
+	sr := io.NewSectionReader(b.file, part.Offset, part.Size)
-	if err != nil {
+	resp, err := makeRequest(ctx, method, requestURL, headers, io.TeeReader(sr, part), opts)
-		return err
-	}
-
-	f, err := os.Open(p)
-	if err != nil {
-		return err
-	}
-	defer f.Close()
-
-	resp, err := makeRequest(ctx, method, requestURL, headers, io.TeeReader(io.NewSectionReader(f, part.Offset, part.Size), part), opts)
 	if err != nil {
 		return err
 	}
@@ -337,13 +342,7 @@ func (p *blobUploadPart) Write(b []byte) (n int, err error) {
 	n = len(b)
 	p.written += int64(n)
 	p.Completed.Add(int64(n))
-
-	if p.Hash == nil {
-		p.Hash = md5.New()
-	}
-
 	p.Hash.Write(b)
-
 	return n, nil
 }