[PORT] Refactor the usage of batch catfile (gitea#31754)

When opening a repository, it will call `ensureValidRepository` and also
`CatFileBatch`. But sometimes these will not be used until repository
closed. So it's a waste of CPU to invoke 3 times git command for every
open repository.

This PR removed all of these from `OpenRepository` but only kept
checking whether the folder exists. When a batch is necessary, the
necessary functions will be invoked.

---
Conflict resolution: Because of the removal of go-git in (#4941)
`_nogogit.go` files were either renamed or merged into the 'common'
file. Git does handle the renames correctly, but for those that were
merged has to be manually copied pasted over. The patch looks the same,
201 additions 90 deletions as the original patch.

(cherry picked from commit c03baab678ba5b2e9d974aea147e660417f5d3f7)

modules/git/repo_base.go

@@ -21,15 +21,11 @@ type Repository struct {
 
 	gpgSettings *GPGSettings
 
-	batchInUse  bool
-	batchCancel context.CancelFunc
-	batchReader *bufio.Reader
-	batchWriter WriteCloserError
+	batchInUse bool
+	batch      *Batch
 
-	checkInUse  bool
-	checkCancel context.CancelFunc
-	checkReader *bufio.Reader
-	checkWriter WriteCloserError
+	checkInUse bool
+	check      *Batch
 
 	Ctx             context.Context
 	LastCommitCache *LastCommitCache
@@ -51,63 +47,75 @@ func OpenRepository(ctx context.Context, repoPath string) (*Repository, error) {
 		return nil, errors.New("no such file or directory")
 	}
 
-	// Now because of some insanity with git cat-file not immediately failing if not run in a valid git directory we need to run git rev-parse first!
-	if err := EnsureValidGitRepository(ctx, repoPath); err != nil {
-		return nil, err
-	}
-
-	repo := &Repository{
+	return &Repository{
 		Path:     repoPath,
 		tagCache: newObjectCache(),
 		Ctx:      ctx,
-	}
-
-	repo.batchWriter, repo.batchReader, repo.batchCancel = CatFileBatch(ctx, repoPath)
-	repo.checkWriter, repo.checkReader, repo.checkCancel = CatFileBatchCheck(ctx, repoPath)
-
-	return repo, nil
+	}, nil
 }
 
 // CatFileBatch obtains a CatFileBatch for this repository
-func (repo *Repository) CatFileBatch(ctx context.Context) (WriteCloserError, *bufio.Reader, func()) {
-	if repo.batchCancel == nil || repo.batchInUse {
-		log.Debug("Opening temporary cat file batch for: %s", repo.Path)
-		return CatFileBatch(ctx, repo.Path)
+func (repo *Repository) CatFileBatch(ctx context.Context) (WriteCloserError, *bufio.Reader, func(), error) {
+	if repo.batch == nil {
+		var err error
+		repo.batch, err = repo.NewBatch(ctx)
+		if err != nil {
+			return nil, nil, nil, err
+		}
 	}
-	repo.batchInUse = true
-	return repo.batchWriter, repo.batchReader, func() {
-		repo.batchInUse = false
+
+	if !repo.batchInUse {
+		repo.batchInUse = true
+		return repo.batch.Writer, repo.batch.Reader, func() {
+			repo.batchInUse = false
+		}, nil
 	}
+
+	log.Debug("Opening temporary cat file batch for: %s", repo.Path)
+	tempBatch, err := repo.NewBatch(ctx)
+	if err != nil {
+		return nil, nil, nil, err
+	}
+	return tempBatch.Writer, tempBatch.Reader, tempBatch.Close, nil
 }
 
 // CatFileBatchCheck obtains a CatFileBatchCheck for this repository
-func (repo *Repository) CatFileBatchCheck(ctx context.Context) (WriteCloserError, *bufio.Reader, func()) {
-	if repo.checkCancel == nil || repo.checkInUse {
-		log.Debug("Opening temporary cat file batch-check for: %s", repo.Path)
-		return CatFileBatchCheck(ctx, repo.Path)
+func (repo *Repository) CatFileBatchCheck(ctx context.Context) (WriteCloserError, *bufio.Reader, func(), error) {
+	if repo.check == nil {
+		var err error
+		repo.check, err = repo.NewBatchCheck(ctx)
+		if err != nil {
+			return nil, nil, nil, err
+		}
 	}
-	repo.checkInUse = true
-	return repo.checkWriter, repo.checkReader, func() {
-		repo.checkInUse = false
+
+	if !repo.checkInUse {
+		repo.checkInUse = true
+		return repo.check.Writer, repo.check.Reader, func() {
+			repo.checkInUse = false
+		}, nil
 	}
+
+	log.Debug("Opening temporary cat file batch-check for: %s", repo.Path)
+	tempBatchCheck, err := repo.NewBatchCheck(ctx)
+	if err != nil {
+		return nil, nil, nil, err
+	}
+	return tempBatchCheck.Writer, tempBatchCheck.Reader, tempBatchCheck.Close, nil
 }
 
 func (repo *Repository) Close() error {
 	if repo == nil {
 		return nil
 	}
-	if repo.batchCancel != nil {
-		repo.batchCancel()
-		repo.batchReader = nil
-		repo.batchWriter = nil
-		repo.batchCancel = nil
+	if repo.batch != nil {
+		repo.batch.Close()
+		repo.batch = nil
 		repo.batchInUse = false
 	}
-	if repo.checkCancel != nil {
-		repo.checkCancel()
-		repo.checkCancel = nil
-		repo.checkReader = nil
-		repo.checkWriter = nil
+	if repo.check != nil {
+		repo.check.Close()
+		repo.check = nil
 		repo.checkInUse = false
 	}
 	repo.LastCommitCache = nil