Add finalizers to ensure that repos are closed and blobreaders are closed (#19495) (#19496)

It may be prudent to add runtime finalizers to the git.Repository and
git.blobReader objects to absolutely ensure that these are both properly
cancelled, cleaned and closed out.

This commit is a backport of an extract from #19448

Signed-off-by: Andrew Thornton <art27@cantab.net>

Author: zeripath

modules/git/blob_nogogit.go

@@ -12,8 +12,11 @@ import (
 	"bytes"
 	"io"
 	"math"
+	"runtime"
+	"sync"
 
 	"code.gitea.io/gitea/modules/log"
+	"code.gitea.io/gitea/modules/process"
 )
 
 // Blob represents a Git object.
@@ -54,11 +57,15 @@ func (b *Blob) DataAsync() (io.ReadCloser, error) {
 		return io.NopCloser(bytes.NewReader(bs)), err
 	}
 
-	return &blobReader{
+	br := &blobReader{
+		repo:   b.repo,
 		rd:     rd,
 		n:      size,
 		cancel: cancel,
-	}, nil
+	}
+	runtime.SetFinalizer(br, (*blobReader).finalizer)
+
+	return br, nil
 }
 
 // Size returns the uncompressed size of the blob
@@ -86,6 +93,10 @@ func (b *Blob) Size() int64 {
 }
 
 type blobReader struct {
+	lock   sync.Mutex
+	closed bool
+
+	repo   *Repository
 	rd     *bufio.Reader
 	n      int64
 	cancel func()
@@ -104,27 +115,57 @@ func (b *blobReader) Read(p []byte) (n int, err error) {
 }
 
 // Close implements io.Closer
-func (b *blobReader) Close() error {
+func (b *blobReader) Close() (err error) {
+	b.lock.Lock()
+	defer b.lock.Unlock()
+	if b.closed {
+		return
+	}
+	return b.close()
+}
+
+func (b *blobReader) close() (err error) {
 	defer b.cancel()
+	b.closed = true
 	if b.n > 0 {
+		var n int
 		for b.n > math.MaxInt32 {
-			n, err := b.rd.Discard(math.MaxInt32)
+			n, err = b.rd.Discard(math.MaxInt32)
 			b.n -= int64(n)
 			if err != nil {
-				return err
+				return
 			}
 			b.n -= math.MaxInt32
 		}
-		n, err := b.rd.Discard(int(b.n))
+		n, err = b.rd.Discard(int(b.n))
 		b.n -= int64(n)
 		if err != nil {
-			return err
+			return
 		}
 	}
 	if b.n == 0 {
-		_, err := b.rd.Discard(1)
+		_, err = b.rd.Discard(1)
 		b.n--
-		return err
+		return
+	}
+	return
+}
+
+func (b *blobReader) finalizer() error {
+	if b == nil {
+		return nil
+	}
+	b.lock.Lock()
+	defer b.lock.Unlock()
+	if b.closed {
+		return nil
 	}
-	return nil
+
+	pid := ""
+	if b.repo.Ctx != nil {
+		pid = " from PID: " + string(process.GetPID(b.repo.Ctx))
+	}
+	log.Error("Finalizer running on unclosed blobReader%s: %s%s", pid, b.repo.Path)
+
+	return b.close()
 }

modules/git/repo_base_gogit.go

@@ -12,8 +12,12 @@ import (
 	"context"
 	"errors"
 	"path/filepath"
+	"runtime"
+	"sync"
 
+	"code.gitea.io/gitea/modules/log"
 	gitealog "code.gitea.io/gitea/modules/log"
+	"code.gitea.io/gitea/modules/process"
 	"code.gitea.io/gitea/modules/setting"
 
 	"github.com/go-git/go-billy/v5/osfs"
@@ -28,6 +32,9 @@ type Repository struct {
 
 	tagCache *ObjectCache
 
+	lock   sync.Mutex
+	closed bool
+
 	gogitRepo    *gogit.Repository
 	gogitStorage *filesystem.Storage
 	gpgSettings  *GPGSettings
@@ -63,23 +70,57 @@ func OpenRepositoryCtx(ctx context.Context, repoPath string) (*Repository, error
 		return nil, err
 	}
 
-	return &Repository{
+	repo := &Repository{
 		Path:         repoPath,
 		gogitRepo:    gogitRepo,
 		gogitStorage: storage,
 		tagCache:     newObjectCache(),
 		Ctx:          ctx,
-	}, nil
+	}
+
+	runtime.SetFinalizer(repo, (*Repository).finalizer)
+
+	return repo, nil
 }
 
 // Close this repository, in particular close the underlying gogitStorage if this is not nil
-func (repo *Repository) Close() {
-	if repo == nil || repo.gogitStorage == nil {
+func (repo *Repository) Close() (err error) {
+	if repo == nil {
+		return
+	}
+	repo.lock.Lock()
+	defer repo.lock.Unlock()
+	return repo.close()
+}
+
+func (repo *Repository) close() (err error) {
+	repo.closed = true
+	if repo.gogitStorage == nil {
 		return
 	}
-	if err := repo.gogitStorage.Close(); err != nil {
+	err = repo.gogitStorage.Close()
+	if err != nil {
 		gitealog.Error("Error closing storage: %v", err)
 	}
+	return
+}
+
+func (repo *Repository) finalizer() error {
+	if repo == nil {
+		return nil
+	}
+	repo.lock.Lock()
+	defer repo.lock.Unlock()
+	if !repo.closed {
+		pid := ""
+		if repo.Ctx != nil {
+			pid = " from PID: " + string(process.GetPID(repo.Ctx))
+		}
+		log.Error("Finalizer running on unclosed repository%s: %s%s", pid, repo.Path)
+	}
+
+	// We still need to run the close fn as it may be possible to reopen the gogitrepo after close
+	return repo.close()
 }
 
 // GoGitRepo gets the go-git repo representation

modules/git/repo_base_nogogit.go

@@ -13,8 +13,11 @@ import (
 	"context"
 	"errors"
 	"path/filepath"
+	"runtime"
+	"sync"
 
 	"code.gitea.io/gitea/modules/log"
+	"code.gitea.io/gitea/modules/process"
 )
 
 // Repository represents a Git repository.
@@ -25,6 +28,10 @@ type Repository struct {
 
 	gpgSettings *GPGSettings
 
+	lock sync.Mutex
+
+	closed bool
+
 	batchCancel context.CancelFunc
 	batchReader *bufio.Reader
 	batchWriter WriteCloserError
@@ -64,29 +71,57 @@ func OpenRepositoryCtx(ctx context.Context, repoPath string) (*Repository, error
 	repo.batchWriter, repo.batchReader, repo.batchCancel = CatFileBatch(ctx, repoPath)
 	repo.checkWriter, repo.checkReader, repo.checkCancel = CatFileBatchCheck(ctx, repo.Path)
 
+	runtime.SetFinalizer(repo, (*Repository).finalizer)
+
 	return repo, nil
 }
 
 // CatFileBatch obtains a CatFileBatch for this repository
 func (repo *Repository) CatFileBatch(ctx context.Context) (WriteCloserError, *bufio.Reader, func()) {
-	if repo.batchCancel == nil || repo.batchReader.Buffered() > 0 {
+	repo.lock.Lock()
+	defer repo.lock.Unlock()
+
+	if repo.closed || repo.batchReader.Buffered() > 0 {
 		log.Debug("Opening temporary cat file batch for: %s", repo.Path)
 		return CatFileBatch(ctx, repo.Path)
 	}
+
+	if repo.batchCancel == nil {
+		repo.batchWriter, repo.batchReader, repo.batchCancel = CatFileBatch(ctx, repo.Path)
+	}
+
 	return repo.batchWriter, repo.batchReader, func() {}
 }
 
 // CatFileBatchCheck obtains a CatFileBatchCheck for this repository
 func (repo *Repository) CatFileBatchCheck(ctx context.Context) (WriteCloserError, *bufio.Reader, func()) {
-	if repo.checkCancel == nil || repo.checkReader.Buffered() > 0 {
+	repo.lock.Lock()
+	defer repo.lock.Unlock()
+
+	if repo.closed || repo.checkReader.Buffered() > 0 {
 		log.Debug("Opening temporary cat file batch-check: %s", repo.Path)
 		return CatFileBatchCheck(ctx, repo.Path)
 	}
+
+	if repo.checkCancel == nil {
+		repo.checkWriter, repo.checkReader, repo.checkCancel = CatFileBatchCheck(ctx, repo.Path)
+	}
+
 	return repo.checkWriter, repo.checkReader, func() {}
 }
 
 // Close this repository, in particular close the underlying gogitStorage if this is not nil
-func (repo *Repository) Close() {
+func (repo *Repository) Close() (err error) {
+	if repo == nil {
+		return
+	}
+	repo.lock.Lock()
+	defer repo.lock.Unlock()
+
+	return repo.close()
+}
+
+func (repo *Repository) close() (err error) {
 	if repo == nil {
 		return
 	}
@@ -102,4 +137,26 @@ func (repo *Repository) Close() {
 		repo.checkReader = nil
 		repo.checkWriter = nil
 	}
+	repo.closed = true
+	return
+}
+
+func (repo *Repository) finalizer() (err error) {
+	if repo == nil {
+		return
+	}
+	repo.lock.Lock()
+	defer repo.lock.Unlock()
+	if repo.closed {
+		return nil
+	}
+
+	if repo.batchCancel != nil || repo.checkCancel != nil {
+		pid := ""
+		if repo.Ctx != nil {
+			pid = " from PID: " + string(process.GetPID(repo.Ctx))
+		}
+		log.Error("Finalizer running on unclosed repository%s: %s%s", pid, repo.Path)
+	}
+	return repo.close()
 }