Avoid creating unnecessary temporary cat file sub process (#33942)

Extract from #33934 

In the same goroutine, we should reuse the exist cat file sub process
which exist in `git.Repository` to avoid creating a unnecessary
temporary subprocess.

This PR reuse the exist cate file writer and reader in
`getCommitFromBatchReader`.
It also move `prepareLatestCommitInfo` before creating dataRc which will
hold the writer so other git operation will create a temporary cat file
subprocess.

modules/git/repo_commit_nogogit.go

@@ -81,10 +81,10 @@ func (repo *Repository) getCommit(id ObjectID) (*Commit, error) {
 
 	_, _ = wr.Write([]byte(id.String() + "\n"))
 
-	return repo.getCommitFromBatchReader(rd, id)
+	return repo.getCommitFromBatchReader(wr, rd, id)
 }
 
-func (repo *Repository) getCommitFromBatchReader(rd *bufio.Reader, id ObjectID) (*Commit, error) {
+func (repo *Repository) getCommitFromBatchReader(wr WriteCloserError, rd *bufio.Reader, id ObjectID) (*Commit, error) {
 	_, typ, size, err := ReadBatchLine(rd)
 	if err != nil {
 		if errors.Is(err, io.EOF) || IsErrNotExist(err) {
@@ -112,7 +112,11 @@ func (repo *Repository) getCommitFromBatchReader(rd *bufio.Reader, id ObjectID)
 			return nil, err
 		}
 
-		commit, err := tag.Commit(repo)
+		if _, err := wr.Write([]byte(tag.Object.String() + "\n")); err != nil {
+			return nil, err
+		}
+
+		commit, err := repo.getCommitFromBatchReader(wr, rd, tag.Object)
 		if err != nil {
 			return nil, err
 		}

modules/git/repo_tag_nogogit.go

@@ -41,9 +41,12 @@ func (repo *Repository) GetTagType(id ObjectID) (string, error) {
 		return "", err
 	}
 	_, typ, _, err := ReadBatchLine(rd)
+	if err != nil {
 		if IsErrNotExist(err) {
 			return "", ErrNotExist{ID: id.String()}
 		}
+		return "", err
+	}
 	return typ, nil
 }
 

modules/git/repo_tree_nogogit.go

@@ -35,7 +35,11 @@ func (repo *Repository) getTree(id ObjectID) (*Tree, error) {
 		if err != nil {
 			return nil, err
 		}
-		commit, err := tag.Commit(repo)
+
+		if _, err := wr.Write([]byte(tag.Object.String() + "\n")); err != nil {
+			return nil, err
+		}
+		commit, err := repo.getCommitFromBatchReader(wr, rd, tag.Object)
 		if err != nil {
 			return nil, err
 		}

modules/git/tag.go

@@ -21,11 +21,6 @@ type Tag struct {
 	Signature *CommitSignature
 }
 
-// Commit return the commit of the tag reference
-func (tag *Tag) Commit(gitRepo *Repository) (*Commit, error) {
-	return gitRepo.getCommit(tag.Object)
-}
-
 func parsePayloadSignature(data []byte, messageStart int) (payload, msg, sign string) {
 	pos := messageStart
 	signStart, signEnd := -1, -1

modules/repository/repo.go

@@ -126,7 +126,7 @@ func PushUpdateAddTag(ctx context.Context, repo *repo_model.Repository, gitRepo
 	if err != nil {
 		return fmt.Errorf("unable to GetTag: %w", err)
 	}
-	commit, err := tag.Commit(gitRepo)
+	commit, err := gitRepo.GetTagCommit(tag.Name)
 	if err != nil {
 		return fmt.Errorf("unable to get tag Commit: %w", err)
 	}

routers/api/v1/repo/tag.go

@@ -110,7 +110,7 @@ func GetAnnotatedTag(ctx *context.APIContext) {
 	if tag, err := ctx.Repo.GitRepo.GetAnnotatedTag(sha); err != nil {
 		ctx.APIError(http.StatusBadRequest, err)
 	} else {
-		commit, err := tag.Commit(ctx.Repo.GitRepo)
+		commit, err := ctx.Repo.GitRepo.GetTagCommit(tag.Name)
 		if err != nil {
 			ctx.APIError(http.StatusBadRequest, err)
 		}

routers/web/repo/view_file.go

@@ -30,32 +30,31 @@ import (
 	"github.com/nektos/act/pkg/model"
 )
 
+func prepareLatestCommitInfo(ctx *context.Context) bool {
+	commit, err := ctx.Repo.Commit.GetCommitByPath(ctx.Repo.TreePath)
+	if err != nil {
+		ctx.ServerError("GetCommitByPath", err)
+		return false
+	}
+
+	return loadLatestCommitData(ctx, commit)
+}
+
 func prepareToRenderFile(ctx *context.Context, entry *git.TreeEntry) {
 	ctx.Data["IsViewFile"] = true
 	ctx.Data["HideRepoInfo"] = true
-	blob := entry.Blob()
-	buf, dataRc, fInfo, err := getFileReader(ctx, ctx.Repo.Repository.ID, blob)
-	if err != nil {
-		ctx.ServerError("getFileReader", err)
+
+	if !prepareLatestCommitInfo(ctx) {
 		return
 	}
-	defer dataRc.Close()
+
+	blob := entry.Blob()
 
 	ctx.Data["Title"] = ctx.Tr("repo.file.title", ctx.Repo.Repository.Name+"/"+path.Base(ctx.Repo.TreePath), ctx.Repo.RefFullName.ShortName())
 	ctx.Data["FileIsSymlink"] = entry.IsLink()
 	ctx.Data["FileName"] = blob.Name()
 	ctx.Data["RawFileLink"] = ctx.Repo.RepoLink + "/raw/" + ctx.Repo.RefTypeNameSubURL() + "/" + util.PathEscapeSegments(ctx.Repo.TreePath)
 
-	commit, err := ctx.Repo.Commit.GetCommitByPath(ctx.Repo.TreePath)
-	if err != nil {
-		ctx.ServerError("GetCommitByPath", err)
-		return
-	}
-
-	if !loadLatestCommitData(ctx, commit) {
-		return
-	}
-
 	if ctx.Repo.TreePath == ".editorconfig" {
 		_, editorconfigWarning, editorconfigErr := ctx.Repo.GetEditorconfig(ctx.Repo.Commit)
 		if editorconfigWarning != nil {
@@ -90,6 +89,15 @@ func prepareToRenderFile(ctx *context.Context, entry *git.TreeEntry) {
 	isDisplayingSource := ctx.FormString("display") == "source"
 	isDisplayingRendered := !isDisplayingSource
 
+	// Don't call any other repository functions depends on git.Repository until the dataRc closed to
+	// avoid create unnecessary temporary cat file.
+	buf, dataRc, fInfo, err := getFileReader(ctx, ctx.Repo.Repository.ID, blob)
+	if err != nil {
+		ctx.ServerError("getFileReader", err)
+		return
+	}
+	defer dataRc.Close()
+
 	if fInfo.isLFSFile {
 		ctx.Data["RawFileLink"] = ctx.Repo.RepoLink + "/media/" + ctx.Repo.RefTypeNameSubURL() + "/" + util.PathEscapeSegments(ctx.Repo.TreePath)
 	}

services/repository/push.go

@@ -385,7 +385,7 @@ func pushUpdateAddTags(ctx context.Context, repo *repo_model.Repository, gitRepo
 		if err != nil {
 			return fmt.Errorf("GetTag: %w", err)
 		}
-		commit, err := tag.Commit(gitRepo)
+		commit, err := gitRepo.GetTagCommit(tag.Name)
 		if err != nil {
 			return fmt.Errorf("Commit: %w", err)
 		}