PackerManager: use tempfiles instead of memory buffers

src/restic/pack/pack.go

@@ -83,26 +83,26 @@ type Packer struct {
 
 	bytes uint
 	k     *crypto.Key
-	buf   *bytes.Buffer
+	wr    io.Writer
 
 	m sync.Mutex
 }
 
 // NewPacker returns a new Packer that can be used to pack blobs
-// together.
-func NewPacker(k *crypto.Key, buf []byte) *Packer {
-	return &Packer{k: k, buf: bytes.NewBuffer(buf)}
+// together. If wr is nil, a bytes.Buffer is used.
+func NewPacker(k *crypto.Key, wr io.Writer) *Packer {
+	return &Packer{k: k, wr: wr}
 }
 
 // Add saves the data read from rd as a new blob to the packer. Returned is the
 // number of bytes written to the pack.
-func (p *Packer) Add(t BlobType, id backend.ID, rd io.Reader) (int64, error) {
+func (p *Packer) Add(t BlobType, id backend.ID, data []byte) (int, error) {
 	p.m.Lock()
 	defer p.m.Unlock()
 
 	c := Blob{Type: t, ID: id}
 
-	n, err := io.Copy(p.buf, rd)
+	n, err := p.wr.Write(data)
 	c.Length = uint(n)
 	c.Offset = p.bytes
 	p.bytes += uint(n)
@@ -121,8 +121,9 @@ type headerEntry struct {
 }
 
 // Finalize writes the header for all added blobs and finalizes the pack.
-// Returned are all bytes written, including the header.
-func (p *Packer) Finalize() ([]byte, error) {
+// Returned are the number of bytes written, including the header. If the
+// underlying writer implements io.Closer, it is closed.
+func (p *Packer) Finalize() (uint, error) {
 	p.m.Lock()
 	defer p.m.Unlock()
 
@@ -131,37 +132,41 @@ func (p *Packer) Finalize() ([]byte, error) {
 	hdrBuf := bytes.NewBuffer(nil)
 	bytesHeader, err := p.writeHeader(hdrBuf)
 	if err != nil {
-		return nil, err
+		return 0, err
 	}
 
 	encryptedHeader, err := crypto.Encrypt(p.k, nil, hdrBuf.Bytes())
 	if err != nil {
-		return nil, err
+		return 0, err
 	}
 
 	// append the header
-	n, err := p.buf.Write(encryptedHeader)
+	n, err := p.wr.Write(encryptedHeader)
 	if err != nil {
-		return nil, err
+		return 0, err
 	}
 
 	hdrBytes := bytesHeader + crypto.Extension
 	if uint(n) != hdrBytes {
-		return nil, errors.New("wrong number of bytes written")
+		return 0, errors.New("wrong number of bytes written")
 	}
 
 	bytesWritten += hdrBytes
 
 	// write length
-	err = binary.Write(p.buf, binary.LittleEndian, uint32(uint(len(p.blobs))*entrySize+crypto.Extension))
+	err = binary.Write(p.wr, binary.LittleEndian, uint32(uint(len(p.blobs))*entrySize+crypto.Extension))
 	if err != nil {
-		return nil, err
+		return 0, err
 	}
 	bytesWritten += uint(binary.Size(uint32(0)))
 
 	p.bytes = uint(bytesWritten)
 
-	return p.buf.Bytes(), nil
+	if w, ok := p.wr.(io.Closer); ok {
+		return bytesWritten, w.Close()
+	}
+
+	return bytesWritten, nil
 }
 
 // writeHeader constructs and writes the header to wr.
@@ -208,6 +213,11 @@ func (p *Packer) Blobs() []Blob {
 	return p.blobs
 }
 
+// Writer return the underlying writer.
+func (p *Packer) Writer() io.Writer {
+	return p.wr
+}
+
 func (p *Packer) String() string {
 	return fmt.Sprintf("<Packer %d blobs, %d bytes>", len(p.blobs), p.bytes)
 }

src/restic/repository/packer_manager.go

@@ -1,6 +1,10 @@
 package repository
 
 import (
+	"fmt"
+	"io"
+	"io/ioutil"
+	"os"
 	"sync"
 
 	"restic/backend"
@@ -11,7 +15,7 @@ import (
 
 // Saver implements saving data in a backend.
 type Saver interface {
-	Save(h backend.Handle, p []byte) error
+	Save(h backend.Handle, jp []byte) error
 }
 
 // packerManager keeps a list of open packs and creates new on demand.
@@ -20,12 +24,30 @@ type packerManager struct {
 	key   *crypto.Key
 	pm    sync.Mutex
 	packs []*pack.Packer
+
+	tempdir string
 }
 
 const minPackSize = 4 * 1024 * 1024
 const maxPackSize = 16 * 1024 * 1024
 const maxPackers = 200
 
+// NewPackerManager returns an new packer manager which writes temporary files
+// to a temporary directory
+func NewPackerManager(be Saver, key *crypto.Key) (pm *packerManager, err error) {
+	pm = &packerManager{
+		be:  be,
+		key: key,
+	}
+
+	pm.tempdir, err = ioutil.TempDir("", fmt.Sprintf("restic-packs-%d-", os.Getpid()))
+	if err != nil {
+		return nil, err
+	}
+
+	return pm, nil
+}
+
 // findPacker returns a packer for a new blob of size bytes. Either a new one is
 // created or one is returned that already has some blobs.
 func (r *packerManager) findPacker(size uint) (*pack.Packer, error) {
@@ -47,7 +69,13 @@ func (r *packerManager) findPacker(size uint) (*pack.Packer, error) {
 
 	// no suitable packer found, return new
 	debug.Log("Repo.findPacker", "create new pack for %d bytes", size)
-	return pack.NewPacker(r.key, nil), nil
+	tmpfile, err := ioutil.TempFile(r.tempdir, "restic-pack-")
+	if err != nil {
+		return nil, err
+	}
+
+	fmt.Printf("tmpfile: %v, tempdir %v\n", tmpfile.Name(), r.tempdir)
+	return pack.NewPacker(r.key, tmpfile), nil
 }
 
 // insertPacker appends p to s.packs.
@@ -62,11 +90,28 @@ func (r *packerManager) insertPacker(p *pack.Packer) {
 // savePacker stores p in the backend.
 func (r *Repository) savePacker(p *pack.Packer) error {
 	debug.Log("Repo.savePacker", "save packer with %d blobs\n", p.Count())
-	data, err := p.Finalize()
+	n, err := p.Finalize()
 	if err != nil {
 		return err
 	}
 
+	tmpfile := p.Writer().(*os.File)
+	f, err := os.Open(tmpfile.Name())
+	if err != nil {
+		return err
+	}
+
+	data := make([]byte, n)
+	m, err := io.ReadFull(f, data)
+
+	if uint(m) != n {
+		return fmt.Errorf("read wrong number of bytes from %v: want %v, got %v", tmpfile.Name(), n, m)
+	}
+
+	if err = f.Close(); err != nil {
+		return err
+	}
+
 	id := backend.Hash(data)
 	h := backend.Handle{Type: backend.Data, Name: id.String()}
 
@@ -100,3 +145,10 @@ func (r *packerManager) countPacker() int {
 
 	return len(r.packs)
 }
+
+// removeTempdir deletes the temporary directory.
+func (r *packerManager) removeTempdir() error {
+	err := os.RemoveAll(r.tempdir)
+	r.tempdir = ""
+	return err
+}

src/restic/repository/packer_manager_test.go

@@ -3,6 +3,7 @@ package repository
 import (
 	"io"
 	"math/rand"
+	"os"
 	"restic/backend"
 	"restic/backend/mem"
 	"restic/crypto"
@@ -19,7 +20,39 @@ func randomID(rd io.Reader) backend.ID {
 	return id
 }
 
-func fillPacks(t testing.TB, rnd *rand.Rand, be Saver, pm *packerManager) (bytes int) {
+const maxBlobSize = 1 << 20
+
+func saveFile(t testing.TB, be Saver, filename string, n int) {
+	f, err := os.Open(filename)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	data := make([]byte, n)
+	m, err := io.ReadFull(f, data)
+
+	if m != n {
+		t.Fatalf("read wrong number of bytes from %v: want %v, got %v", filename, m, n)
+	}
+
+	if err = f.Close(); err != nil {
+		t.Fatal(err)
+	}
+
+	h := backend.Handle{Type: backend.Data, Name: backend.Hash(data).String()}
+
+	err = be.Save(h, data)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	err = os.Remove(filename)
+	if err != nil {
+		t.Fatal(err)
+	}
+}
+
+func fillPacks(t testing.TB, rnd *rand.Rand, be Saver, pm *packerManager, buf []byte) (bytes int) {
 	for i := 0; i < 100; i++ {
 		l := rnd.Intn(1 << 20)
 		seed := rnd.Int63()
@@ -31,9 +64,14 @@ func fillPacks(t testing.TB, rnd *rand.Rand, be Saver, pm *packerManager) (bytes
 
 		rd := rand.New(rand.NewSource(seed))
 		id := randomID(rd)
-		n, err := packer.Add(pack.Data, id, io.LimitReader(rd, int64(l)))
+		buf = buf[:l]
+		_, err = io.ReadFull(rd, buf)
+		if err != nil {
+			t.Fatal(err)
+		}
 
-		if n != int64(l) {
+		n, err := packer.Add(pack.Data, id, buf)
+		if n != l {
 			t.Errorf("Add() returned invalid number of bytes: want %v, got %v", n, l)
 		}
 		bytes += l
@@ -43,17 +81,13 @@ func fillPacks(t testing.TB, rnd *rand.Rand, be Saver, pm *packerManager) (bytes
 			continue
 		}
 
-		data, err := packer.Finalize()
+		bytesWritten, err := packer.Finalize()
 		if err != nil {
 			t.Fatal(err)
 		}
 
-		h := backend.Handle{Type: backend.Data, Name: randomID(rd).String()}
-
-		err = be.Save(h, data)
-		if err != nil {
-			t.Fatal(err)
-		}
+		tmpfile := packer.Writer().(*os.File)
+		saveFile(t, be, tmpfile.Name(), int(bytesWritten))
 	}
 
 	return bytes
@@ -62,18 +96,14 @@ func fillPacks(t testing.TB, rnd *rand.Rand, be Saver, pm *packerManager) (bytes
 func flushRemainingPacks(t testing.TB, rnd *rand.Rand, be Saver, pm *packerManager) (bytes int) {
 	if pm.countPacker() > 0 {
 		for _, packer := range pm.packs {
-			data, err := packer.Finalize()
+			n, err := packer.Finalize()
 			if err != nil {
 				t.Fatal(err)
 			}
-			bytes += len(data)
+			bytes += int(n)
 
-			h := backend.Handle{Type: backend.Data, Name: randomID(rnd).String()}
-
-			err = be.Save(h, data)
-			if err != nil {
-				t.Fatal(err)
-			}
+			tmpfile := packer.Writer().(*os.File)
+			saveFile(t, be, tmpfile.Name(), bytes)
 		}
 	}
 
@@ -90,33 +120,45 @@ func TestPackerManager(t *testing.T) {
 	rnd := rand.New(rand.NewSource(23))
 
 	be := mem.New()
-	pm := &packerManager{
-		be:  be,
-		key: crypto.NewRandomKey(),
+	pm, err := NewPackerManager(be, crypto.NewRandomKey())
+	if err != nil {
+		t.Fatal(err)
 	}
 
-	bytes := fillPacks(t, rnd, be, pm)
+	blobBuf := make([]byte, maxBlobSize)
+
+	bytes := fillPacks(t, rnd, be, pm, blobBuf)
 	bytes += flushRemainingPacks(t, rnd, be, pm)
 
 	t.Logf("saved %d bytes", bytes)
+	err = pm.removeTempdir()
+	if err != nil {
+		t.Fatal(err)
+	}
 }
 
 func BenchmarkPackerManager(t *testing.B) {
 	rnd := rand.New(rand.NewSource(23))
 
 	be := &fakeBackend{}
-	pm := &packerManager{
-		be:  be,
-		key: crypto.NewRandomKey(),
+	pm, err := NewPackerManager(be, crypto.NewRandomKey())
+	if err != nil {
+		t.Fatal(err)
 	}
+	blobBuf := make([]byte, maxBlobSize)
 
 	t.ResetTimer()
 
 	bytes := 0
 	for i := 0; i < t.N; i++ {
-		bytes += fillPacks(t, rnd, be, pm)
+		bytes += fillPacks(t, rnd, be, pm, blobBuf)
 	}
 
 	bytes += flushRemainingPacks(t, rnd, be, pm)
 	t.Logf("saved %d bytes", bytes)
+
+	err = pm.removeTempdir()
+	if err != nil {
+		t.Fatal(err)
+	}
 }

src/restic/repository/repository.go

@@ -27,14 +27,19 @@ type Repository struct {
 }
 
 // New returns a new repository with backend be.
-func New(be backend.Backend) *Repository {
-	return &Repository{
-		be:  be,
-		idx: NewMasterIndex(),
-		packerManager: &packerManager{
-			be: be,
-		},
+func New(be backend.Backend) (*Repository, error) {
+	pm, err := NewPackerManager(be, nil)
+	if err != nil {
+		return nil, err
 	}
+
+	repo := &Repository{
+		be:            be,
+		idx:           NewMasterIndex(),
+		packerManager: pm,
+	}
+
+	return repo, nil
 }
 
 // Find loads the list of all blobs of type t and searches for names which start
@@ -195,7 +200,7 @@ func (r *Repository) SaveAndEncrypt(t pack.BlobType, data []byte, id *backend.ID
 	}
 
 	// save ciphertext
-	_, err = packer.Add(t, *id, bytes.NewReader(ciphertext))
+	_, err = packer.Add(t, *id, ciphertext)
 	if err != nil {
 		return backend.ID{}, err
 	}

src/restic/test/backend.go

@@ -61,7 +61,10 @@ func SetupRepo() *repository.Repository {
 		panic(err)
 	}
 
-	repo := repository.New(b)
+	repo, err := repository.New(b)
+	if err != nil {
+		panic(err)
+	}
 	err = repo.Init(TestPassword)
 	if err != nil {
 		panic(err)

src/restic/test/helpers.go

@@ -213,7 +213,10 @@ func OpenLocalRepo(t testing.TB, dir string) *repository.Repository {
 	be, err := local.Open(dir)
 	OK(t, err)
 
-	repo := repository.New(be)
+	repo, err := repository.New(be)
+	if err != nil {
+		t.Fatal(err)
+	}
 	err = repo.SearchKey(TestPassword)
 	OK(t, err)