repository: Use object reader to read gitattributes file

We're currently using the deprecated Batch interface to read information
about the gitattributes file we're about to apply. Currently, we're
using it for three steps: first, we check whether the source commit
exists at all via `Info()`, then we retrieve object info of the blob via
`Info()`, and then we retrieve the blob reader via `Blob()`. We cannot
skip the first step, but doing this via `localrepo.ResolveRevision()` is
much more straight-forward. The second and third steps can be combined
into a single step though by just using `Object()` directly, avoiding
one needless roundtrip.

1 files changed, 9 insertions, 13 deletions

diff --git a/internal/gitaly/service/repository/apply_gitattributes.go b/internal/gitaly/service/repository/apply_gitattributes.go
index 00d3c2bf7..011e363d5 100644
--- a/internal/gitaly/service/repository/apply_gitattributes.go
+++ b/internal/gitaly/service/repository/apply_gitattributes.go
@@ -10,6 +10,7 @@ import (
 
 	"gitlab.com/gitlab-org/gitaly/v14/internal/git"
 	"gitlab.com/gitlab-org/gitaly/v14/internal/git/catfile"
+	"gitlab.com/gitlab-org/gitaly/v14/internal/git/localrepo"
 	"gitlab.com/gitlab-org/gitaly/v14/internal/gitaly/transaction"
 	"gitlab.com/gitlab-org/gitaly/v14/internal/helper"
 	"gitlab.com/gitlab-org/gitaly/v14/internal/safe"
@@ -20,25 +21,25 @@ import (
 
 const attributesFileMode os.FileMode = 0o644
 
-func (s *server) applyGitattributes(ctx context.Context, c catfile.Batch, repoPath string, revision []byte) error {
+func (s *server) applyGitattributes(ctx context.Context, repo *localrepo.Repo, objectReader catfile.ObjectReader, repoPath string, revision []byte) error {
 	infoPath := filepath.Join(repoPath, "info")
 	attributesPath := filepath.Join(infoPath, "attributes")
 
-	_, err := c.Info(ctx, git.Revision(revision))
+	_, err := repo.ResolveRevision(ctx, git.Revision(revision)+"^{commit}")
 	if err != nil {
-		if catfile.IsNotFound(err) {
+		if errors.Is(err, git.ErrReferenceNotFound) {
 			return helper.ErrInvalidArgumentf("revision does not exist")
 		}
 
 		return err
 	}
 
-	blobInfo, err := c.Info(ctx, git.Revision(fmt.Sprintf("%s:.gitattributes", revision)))
+	blobObj, err := objectReader.Object(ctx, git.Revision(fmt.Sprintf("%s:.gitattributes", revision)))
 	if err != nil && !catfile.IsNotFound(err) {
 		return err
 	}
 
-	if catfile.IsNotFound(err) || blobInfo.Type != "blob" {
+	if catfile.IsNotFound(err) || blobObj.Type != "blob" {
 		// If there is no gitattributes file, we simply use the ZeroOID
 		// as a placeholder to vote on the removal.
 		if err := s.vote(ctx, git.ZeroOID); err != nil {
@@ -58,11 +59,6 @@ func (s *server) applyGitattributes(ctx context.Context, c catfile.Batch, repoPa
 		return err
 	}
 
-	blobObj, err := c.Blob(ctx, git.Revision(blobInfo.Oid))
-	if err != nil {
-		return err
-	}
-
 	writer, err := safe.NewLockingFileWriter(attributesPath, safe.LockingFileWriterConfig{
 		FileWriterConfig: safe.FileWriterConfig{FileMode: attributesFileMode},
 	})
@@ -71,7 +67,7 @@ func (s *server) applyGitattributes(ctx context.Context, c catfile.Batch, repoPa
 	}
 	defer writer.Close()
 
-	if _, err := io.CopyN(writer, blobObj.Reader, blobInfo.Size); err != nil {
+	if _, err := io.Copy(writer, blobObj.Reader); err != nil {
 		return err
 	}
 
@@ -116,12 +112,12 @@ func (s *server) ApplyGitattributes(ctx context.Context, in *gitalypb.ApplyGitat
 		return nil, helper.ErrInvalidArgumentf("revision: %v", err)
 	}
 
-	c, err := s.catfileCache.BatchProcess(ctx, repo)
+	objectReader, err := s.catfileCache.ObjectReader(ctx, repo)
 	if err != nil {
 		return nil, err
 	}
 
-	if err := s.applyGitattributes(ctx, c, repoPath, in.GetRevision()); err != nil {
+	if err := s.applyGitattributes(ctx, repo, objectReader, repoPath, in.GetRevision()); err != nil {
 		return nil, err
 	}