Refactor cat-file batch operations and support --batch-command approach

modules/git/blob_nogogit.go

@@ -6,8 +6,6 @@
 package git
 
 import (
-	"bufio"
-	"bytes"
 	"io"
 
 	"code.gitea.io/gitea/modules/log"
@@ -25,39 +23,28 @@ type Blob struct {
 
 // DataAsync gets a ReadCloser for the contents of a blob without reading it all.
 // Calling the Close function on the result will discard all unread output.
-func (b *Blob) DataAsync() (io.ReadCloser, error) {
+func (b *Blob) DataAsync() (_ io.ReadCloser, retErr error) {
 	batch, cancel, err := b.repo.CatFileBatch(b.repo.Ctx)
 	if err != nil {
 		return nil, err
 	}
+	defer func() {
+		// if there was an error, cancel the batch right away,
+		// otherwise let the caller close it
+		if retErr != nil {
+			cancel()
+		}
+	}()
 
-	rd := batch.Reader()
-	_, err = batch.Writer().Write([]byte(b.ID.String() + "\n"))
-	if err != nil {
-		cancel()
-		return nil, err
-	}
-	_, _, size, err := ReadBatchLine(rd)
+	info, contentReader, err := batch.QueryContent(b.ID.String())
 	if err != nil {
-		cancel()
 		return nil, err
 	}
 	b.gotSize = true
-	b.size = size
-
-	if size < 4096 {
-		bs, err := io.ReadAll(io.LimitReader(rd, size))
-		defer cancel()
-		if err != nil {
-			return nil, err
-		}
-		_, err = rd.Discard(1)
-		return io.NopCloser(bytes.NewReader(bs)), err
-	}
-
+	b.size = info.Size
 	return &blobReader{
-		rd:     rd,
-		n:      size,
+		rd:     contentReader,
+		n:      info.Size,
 		cancel: cancel,
 	}, nil
 }
@@ -68,30 +55,24 @@ func (b *Blob) Size() int64 {
 		return b.size
 	}
 
-	batch, cancel, err := b.repo.CatFileBatchCheck(b.repo.Ctx)
+	batch, cancel, err := b.repo.CatFileBatch(b.repo.Ctx)
 	if err != nil {
 		log.Debug("error whilst reading size for %s in %s. Error: %v", b.ID.String(), b.repo.Path, err)
 		return 0
 	}
 	defer cancel()
-	_, err = batch.Writer().Write([]byte(b.ID.String() + "\n"))
+	info, err := batch.QueryInfo(b.ID.String())
 	if err != nil {
 		log.Debug("error whilst reading size for %s in %s. Error: %v", b.ID.String(), b.repo.Path, err)
 		return 0
 	}
-	_, _, b.size, err = ReadBatchLine(batch.Reader())
-	if err != nil {
-		log.Debug("error whilst reading size for %s in %s. Error: %v", b.ID.String(), b.repo.Path, err)
-		return 0
-	}
-
 	b.gotSize = true
-
+	b.size = info.Size
 	return b.size
 }
 
 type blobReader struct {
-	rd     *bufio.Reader
+	rd     BufferedReader
 	n      int64
 	cancel func()
 }