refactor: move repo and delta in their own package

1 files changed, 0 insertions, 783 deletions

diff --git a/repo.go b/repo.go
deleted file mode 100644
index 543f6c3..0000000
--- a/repo.go
+++ /dev/null
@@ -1,783 +0,0 @@
-/*
-Manage a deduplicated versionned backups repository.
-
-Sample repository:
-
-```
-repo/
-├── 00000/
-│   ├── chunks/
-│   │   ├── 000000000000000
-│   │   ├── 000000000000001
-│   │   ├── 000000000000002
-│   │   └── 000000000000003
-│   ├── files
-│   ├── hashes
-│   └── recipe
-└── 00001/
-    ├── chunks/
-    │   ├── 000000000000000
-    │   └── 000000000000001
-    ├── files
-    ├── hashes
-    └── recipe
-```
-*/
-
-package main
-
-import (
-	"bufio"
-	"bytes"
-	"encoding/gob"
-	"fmt"
-	"io"
-	"io/fs"
-	"os"
-	"path/filepath"
-	"reflect"
-	"strings"
-
-	"github.com/chmduquesne/rollinghash/rabinkarp64"
-	"github.com/n-peugnet/dna-backup/cache"
-	"github.com/n-peugnet/dna-backup/logger"
-	"github.com/n-peugnet/dna-backup/sketch"
-	"github.com/n-peugnet/dna-backup/slice"
-	"github.com/n-peugnet/dna-backup/utils"
-)
-
-func init() {
-	// register chunk structs for encoding/decoding using gob
-	gob.RegisterName("*dna-backup.StoredChunk", &StoredChunk{})
-	gob.RegisterName("*dna-backup.TempChunk", &TempChunk{})
-	gob.RegisterName("*dna-backup.DeltaChunk", &DeltaChunk{})
-	gob.RegisterName("dna-backup.File", File{})
-}
-
-type FingerprintMap map[uint64]*ChunkId
-type SketchMap map[uint64][]*ChunkId
-
-func (m SketchMap) Set(key []uint64, value *ChunkId) {
-	for _, s := range key {
-		prev := m[s]
-		if contains(prev, value) {
-			continue
-		}
-		m[s] = append(prev, value)
-	}
-}
-
-type Repo struct {
-	path              string
-	chunkSize         int
-	sketchWSize       int
-	sketchSfCount     int
-	sketchFCount      int
-	pol               rabinkarp64.Pol
-	differ            Differ
-	patcher           Patcher
-	fingerprints      FingerprintMap
-	sketches          SketchMap
-	recipe            []Chunk
-	files             []File
-	chunkCache        cache.Cacher
-	chunkReadWrapper  utils.ReadWrapper
-	chunkWriteWrapper utils.WriteWrapper
-}
-
-type chunkHashes struct {
-	Fp uint64
-	Sk []uint64
-}
-
-type chunkData struct {
-	hashes  chunkHashes
-	content []byte
-	id      *ChunkId
-}
-
-type File struct {
-	Path string
-	Size int64
-	Link string
-}
-
-func NewRepo(path string) *Repo {
-	var err error
-	path, err = filepath.Abs(path)
-	if err != nil {
-		logger.Fatal(err)
-	}
-	err = os.MkdirAll(path, 0775)
-	if err != nil {
-		logger.Panic(err)
-	}
-	var seed int64 = 1
-	p, err := rabinkarp64.RandomPolynomial(seed)
-	if err != nil {
-		logger.Panic(err)
-	}
-	return &Repo{
-		path:              path,
-		chunkSize:         8 << 10,
-		sketchWSize:       32,
-		sketchSfCount:     3,
-		sketchFCount:      4,
-		pol:               p,
-		differ:            Fdelta{},
-		patcher:           Fdelta{},
-		fingerprints:      make(FingerprintMap),
-		sketches:          make(SketchMap),
-		chunkCache:        cache.NewFifoCache(10000),
-		chunkReadWrapper:  utils.ZlibReader,
-		chunkWriteWrapper: utils.ZlibWriter,
-	}
-}
-
-func (r *Repo) Differ() Differ {
-	return r.differ
-}
-
-func (r *Repo) Patcher() Patcher {
-	return r.patcher
-}
-
-func (r *Repo) Commit(source string) {
-	source, err := filepath.Abs(source)
-	if err != nil {
-		logger.Fatal(err)
-	}
-	versions := r.loadVersions()
-	newVersion := len(versions) // TODO: add newVersion functino
-	newPath := filepath.Join(r.path, fmt.Sprintf(versionFmt, newVersion))
-	newChunkPath := filepath.Join(newPath, chunksName)
-	os.Mkdir(newPath, 0775)      // TODO: handle errors
-	os.Mkdir(newChunkPath, 0775) // TODO: handle errors
-	logger.Info("listing files")
-	files := listFiles(source)
-	logger.Info("loading previous hashes")
-	r.loadHashes(versions)
-	logger.Info("loading previous file lists")
-	r.loadFileLists(versions)
-	logger.Info("loading previous recipies")
-	r.loadRecipes(versions)
-	storeQueue := make(chan chunkData, 32)
-	storeEnd := make(chan bool)
-	go r.storageWorker(newVersion, storeQueue, storeEnd)
-	var last, nlast, pass uint64
-	var recipe []Chunk
-	for ; nlast > last || pass == 0; pass++ {
-		logger.Infof("matcher pass number %d", pass+1)
-		last = nlast
-		reader, writer := io.Pipe()
-		go concatFiles(&files, writer)
-		recipe, nlast = r.matchStream(reader, storeQueue, newVersion, last)
-	}
-	close(storeQueue)
-	<-storeEnd
-	r.storeFileList(newVersion, unprefixFiles(files, source))
-	r.storeRecipe(newVersion, recipe)
-}
-
-func (r *Repo) Restore(destination string) {
-	versions := r.loadVersions()
-	logger.Info("loading previous file lists")
-	r.loadFileLists(versions)
-	logger.Info("loading previous recipies")
-	r.loadRecipes(versions)
-	reader, writer := io.Pipe()
-	logger.Info("restoring latest version")
-	go r.restoreStream(writer, r.recipe)
-	bufReader := bufio.NewReaderSize(reader, r.chunkSize*2)
-	for _, file := range r.files {
-		filePath := filepath.Join(destination, file.Path)
-		dir := filepath.Dir(filePath)
-		os.MkdirAll(dir, 0775) // TODO: handle errors
-		if file.Link != "" {
-			link := file.Link
-			if filepath.IsAbs(link) {
-				filepath.Join(destination, file.Link)
-			}
-			err := os.Symlink(link, filePath)
-			if err != nil {
-				logger.Errorf("restored symlink ", err)
-			}
-		} else {
-			f, _ := os.Create(filePath) // TODO: handle errors
-			n, err := io.CopyN(f, bufReader, file.Size)
-			if err != nil {
-				logger.Errorf("restored file, written %d/%d bytes: %s", filePath, n, file.Size, err)
-			}
-			if err := f.Close(); err != nil {
-				logger.Errorf("restored file ", err)
-			}
-		}
-	}
-}
-
-func (r *Repo) loadVersions() []string {
-	var versions []string
-	files, err := os.ReadDir(r.path)
-	if err != nil {
-		logger.Fatal(err)
-	}
-	for _, f := range files {
-		if !f.IsDir() {
-			continue
-		}
-		versions = append(versions, filepath.Join(r.path, f.Name()))
-	}
-	return versions
-}
-
-func listFiles(path string) []File {
-	var files []File
-	err := filepath.Walk(path, func(p string, i fs.FileInfo, err error) error {
-		if err != nil {
-			logger.Warning(err)
-			return nil
-		}
-		if i.IsDir() {
-			return nil
-		}
-		var file = File{Path: p, Size: i.Size()}
-		if i.Mode()&fs.ModeSymlink != 0 {
-			file, err = cleanSymlink(path, p, i)
-			if err != nil {
-				logger.Warning("skipping symlink ", err)
-				return nil
-			}
-		}
-		files = append(files, file)
-		return nil
-	})
-	if err != nil {
-		logger.Error(err)
-	}
-	return files
-}
-
-func cleanSymlink(root string, p string, i fs.FileInfo) (f File, err error) {
-	dir := filepath.Dir(p)
-	target, err := os.Readlink(p)
-	if err != nil {
-		return
-	}
-	isAbs := filepath.IsAbs(target)
-	cleaned := target
-	if !isAbs {
-		cleaned = filepath.Join(dir, cleaned)
-	}
-	cleaned = filepath.Clean(cleaned)
-	if !strings.HasPrefix(cleaned, root) {
-		err = fmt.Errorf("external %s -> %s", p, cleaned)
-		return
-	}
-	if isAbs {
-		f.Link, err = utils.Unprefix(cleaned, root)
-	} else {
-		f.Link, err = filepath.Rel(dir, filepath.Join(dir, target))
-	}
-	if err != nil {
-		return
-	}
-	if f.Link == "" {
-		err = fmt.Errorf("empty %s", p)
-		return
-	}
-	f.Path = p
-	f.Size = 0
-	return f, nil
-}
-
-func unprefixFiles(files []File, prefix string) (ret []File) {
-	var err error
-	ret = make([]File, len(files))
-	for i, f := range files {
-		if f.Path, err = utils.Unprefix(f.Path, prefix); err != nil {
-			logger.Warning(err)
-		} else {
-			ret[i] = f
-		}
-	}
-	return
-}
-
-// concatFiles reads the content of all the listed files into a continuous stream.
-// If any errors are encoutered while opening a file, it is then removed from the
-// list.
-//
-// If read is incomplete, then the actual read size is used.
-func concatFiles(files *[]File, stream io.WriteCloser) {
-	actual := make([]File, 0, len(*files))
-	for _, f := range *files {
-		if f.Link != "" {
-			actual = append(actual, f)
-			continue
-		}
-		file, err := os.Open(f.Path)
-		if err != nil {
-			logger.Warning(err)
-			continue
-		}
-		af := f
-		if n, err := io.Copy(stream, file); err != nil {
-			logger.Error("read ", n, " bytes, ", err)
-			af.Size = n
-		}
-		actual = append(actual, af)
-		if err = file.Close(); err != nil {
-			logger.Panic(err)
-		}
-	}
-	stream.Close()
-	*files = actual
-}
-
-func storeBasicStruct(dest string, wrapper utils.WriteWrapper, obj interface{}) {
-	file, err := os.Create(dest)
-	if err != nil {
-		logger.Panic(err)
-	}
-	out := wrapper(file)
-	encoder := gob.NewEncoder(out)
-	err = encoder.Encode(obj)
-	if err != nil {
-		logger.Panic(err)
-	}
-	if err = out.Close(); err != nil {
-		logger.Panic(err)
-	}
-	if err = file.Close(); err != nil {
-		logger.Panic(err)
-	}
-}
-
-func loadBasicStruct(path string, wrapper utils.ReadWrapper, obj interface{}) {
-	file, err := os.Open(path)
-	if err != nil {
-		logger.Panic(err)
-	}
-	in, err := wrapper(file)
-	if err != nil {
-		logger.Panic(err)
-	}
-	decoder := gob.NewDecoder(in)
-	err = decoder.Decode(obj)
-	if err != nil {
-		logger.Panic(err)
-	}
-	if err = in.Close(); err != nil {
-		logger.Panic(err)
-	}
-	if err = file.Close(); err != nil {
-		logger.Panic(err)
-	}
-}
-
-func (r *Repo) loadDeltas(versions []string, wrapper utils.ReadWrapper, name string) (ret slice.Slice) {
-	for _, v := range versions {
-		path := filepath.Join(v, name)
-		var delta slice.Delta
-		loadBasicStruct(path, wrapper, &delta)
-		ret = slice.Patch(ret, delta)
-	}
-	return
-}
-
-func fileList2slice(l []File) (ret slice.Slice) {
-	ret = make(slice.Slice, len(l))
-	for i := range l {
-		ret[i] = l[i]
-	}
-	return
-}
-
-func slice2fileList(s slice.Slice) (ret []File) {
-	ret = make([]File, len(s))
-	for i := range s {
-		if f, ok := s[i].(File); ok {
-			ret[i] = f
-		} else {
-			logger.Warningf("could not convert %s into a File", s[i])
-		}
-	}
-	return
-}
-
-// storeFileList stores the given list in the repo dir as a delta against the
-// previous version's one.
-func (r *Repo) storeFileList(version int, list []File) {
-	dest := filepath.Join(r.path, fmt.Sprintf(versionFmt, version), filesName)
-	delta := slice.Diff(fileList2slice(r.files), fileList2slice(list))
-	logger.Infof("files delta %s", delta.String())
-	storeBasicStruct(dest, r.chunkWriteWrapper, delta)
-}
-
-// loadFileLists loads incrementally the file lists' delta of each given version.
-func (r *Repo) loadFileLists(versions []string) {
-	r.files = slice2fileList(r.loadDeltas(versions, r.chunkReadWrapper, filesName))
-}
-
-// storageWorker is meant to be started in a goroutine and stores each new chunk's
-// data in the repo directory until the store queue channel is closed.
-//
-// it will put true in the end channel once everything is stored.
-func (r *Repo) storageWorker(version int, storeQueue <-chan chunkData, end chan<- bool) {
-	hashesFile := filepath.Join(r.path, fmt.Sprintf(versionFmt, version), hashesName)
-	file, err := os.Create(hashesFile)
-	if err != nil {
-		logger.Panic(err)
-	}
-	encoder := gob.NewEncoder(file)
-	for data := range storeQueue {
-		err = encoder.Encode(data.hashes)
-		r.StoreChunkContent(data.id, bytes.NewReader(data.content))
-		// logger.Debug("stored ", data.id)
-	}
-	if err = file.Close(); err != nil {
-		logger.Panic(err)
-	}
-	end <- true
-}
-
-func (r *Repo) StoreChunkContent(id *ChunkId, reader io.Reader) {
-	path := id.Path(r.path)
-	file, err := os.Create(path)
-	if err != nil {
-		logger.Panic("chunk store ", err)
-	}
-	wrapper := r.chunkWriteWrapper(file)
-	n, err := io.Copy(wrapper, reader)
-	if err != nil {
-		logger.Errorf("chunk store, %d written, %s", n, err)
-	}
-	if err := wrapper.Close(); err != nil {
-		logger.Warning("chunk store wrapper ", err)
-	}
-	if err := file.Close(); err != nil {
-		logger.Warning("chunk store ", err)
-	}
-}
-
-// LoadChunkContent loads a chunk from the repo directory.
-// If the chunk is in cache, get it from cache, else read it from drive.
-func (r *Repo) LoadChunkContent(id *ChunkId) *bytes.Reader {
-	value, exists := r.chunkCache.Get(id)
-	if !exists {
-		path := id.Path(r.path)
-		f, err := os.Open(path)
-		if err != nil {
-			logger.Panic("chunk load ", err)
-		}
-		wrapper, err := r.chunkReadWrapper(f)
-		if err != nil {
-			logger.Error("chunk load wrapper ", err)
-		}
-		value, err = io.ReadAll(wrapper)
-		if err != nil {
-			logger.Error("chunk load ", err)
-		}
-		if err = wrapper.Close(); err != nil {
-			logger.Warning("chunk load wrapper", err)
-		}
-		if err = f.Close(); err != nil {
-			logger.Warning("chunk load ", err)
-		}
-		r.chunkCache.Set(id, value)
-	}
-	return bytes.NewReader(value)
-}
-
-// TODO: use atoi for chunkid ?
-func (r *Repo) loadChunks(versions []string, chunks chan<- IdentifiedChunk) {
-	for i, v := range versions {
-		p := filepath.Join(v, chunksName)
-		entries, err := os.ReadDir(p)
-		if err != nil {
-			logger.Error("version dir ", err)
-		}
-		for j, e := range entries {
-			if e.IsDir() {
-				continue
-			}
-			id := &ChunkId{Ver: i, Idx: uint64(j)}
-			c := NewStoredChunk(r, id)
-			chunks <- c
-		}
-	}
-	close(chunks)
-}
-
-// loadHashes loads and aggregates the hashes stored for each given version and
-// stores them in the repo maps.
-func (r *Repo) loadHashes(versions []string) {
-	for i, v := range versions {
-		path := filepath.Join(v, hashesName)
-		file, err := os.Open(path)
-		if err != nil {
-			logger.Error("hashes ", err)
-		}
-		decoder := gob.NewDecoder(file)
-		for j := 0; err == nil; j++ {
-			var h chunkHashes
-			if err = decoder.Decode(&h); err == nil {
-				id := &ChunkId{i, uint64(j)}
-				r.fingerprints[h.Fp] = id
-				r.sketches.Set(h.Sk, id)
-			}
-		}
-		if err != nil && err != io.EOF {
-			logger.Panic(err)
-		}
-		if err = file.Close(); err != nil {
-			logger.Warning(err)
-		}
-	}
-}
-
-func (r *Repo) chunkMinLen() int {
-	return sketch.SuperFeatureSize(r.chunkSize, r.sketchSfCount, r.sketchFCount)
-}
-
-func contains(s []*ChunkId, id *ChunkId) bool {
-	for _, v := range s {
-		if v == id {
-			return true
-		}
-	}
-	return false
-}
-
-// findSimilarChunk looks in the repo sketch map for a match of the given sketch.
-//
-// There can be multiple matches but only the best one is returned. Indeed, the
-// more superfeature matches, the better the quality of the match. For now we
-// consider that a single superfeature match is enough to count it as valid.
-func (r *Repo) findSimilarChunk(sketch []uint64) (*ChunkId, bool) {
-	var similarChunks = make(map[ChunkId]int)
-	var max int
-	var similarChunk *ChunkId
-	for _, s := range sketch {
-		chunkIds, exists := r.sketches[s]
-		if !exists {
-			continue
-		}
-		for _, id := range chunkIds {
-			count := similarChunks[*id]
-			count += 1
-			logger.Debugf("found %d %d time(s)", id, count)
-			if count > max {
-				max = count
-				similarChunk = id
-			}
-			similarChunks[*id] = count
-		}
-	}
-	return similarChunk, max > 0
-}
-
-// encodeTempChunk first tries to delta-encode the given chunk before attributing
-// it an Id and saving it into the fingerprints and sketches maps.
-func (r *Repo) encodeTempChunk(temp BufferedChunk, version int, last *uint64, storeQueue chan<- chunkData) (Chunk, bool) {
-	sk, _ := sketch.SketchChunk(temp.Reader(), r.pol, r.chunkSize, r.sketchWSize, r.sketchSfCount, r.sketchFCount)
-	id, found := r.findSimilarChunk(sk)
-	if found {
-		var buff bytes.Buffer
-		if err := r.differ.Diff(r.LoadChunkContent(id), temp.Reader(), &buff); err != nil {
-			logger.Error("trying delta encode chunk:", temp, "with source:", id, ":", err)
-		} else {
-			logger.Debugf("add new delta chunk of size %d", len(buff.Bytes()))
-			return &DeltaChunk{
-				repo:   r,
-				Source: id,
-				Patch:  buff.Bytes(),
-				Size:   temp.Len(),
-			}, true
-		}
-	}
-	if temp.Len() == r.chunkSize {
-		id := &ChunkId{Ver: version, Idx: *last}
-		*last++
-		hasher := rabinkarp64.NewFromPol(r.pol)
-		io.Copy(hasher, temp.Reader())
-		fp := hasher.Sum64()
-		r.fingerprints[fp] = id
-		r.sketches.Set(sk, id)
-		storeQueue <- chunkData{
-			hashes:  chunkHashes{fp, sk},
-			content: temp.Bytes(),
-			id:      id,
-		}
-		r.chunkCache.Set(id, temp.Bytes())
-		logger.Debug("add new chunk ", id)
-		return NewStoredChunk(r, id), false
-	}
-	logger.Debug("add new partial chunk of size: ", temp.Len())
-	return temp, false
-}
-
-// encodeTempChunks encodes the current temporary chunks based on the value of the previous one.
-// Temporary chunks can be partial. If the current chunk is smaller than the size of a
-// super-feature and there exists a previous chunk, then both are merged before attempting
-// to delta-encode them.
-func (r *Repo) encodeTempChunks(prev BufferedChunk, curr BufferedChunk, version int, last *uint64, storeQueue chan<- chunkData) []Chunk {
-	if reflect.ValueOf(prev).IsNil() {
-		c, _ := r.encodeTempChunk(curr, version, last, storeQueue)
-		return []Chunk{c}
-	} else if curr.Len() < r.chunkMinLen() {
-		tmp := NewTempChunk(append(prev.Bytes(), curr.Bytes()...))
-		c, success := r.encodeTempChunk(tmp, version, last, storeQueue)
-		if success {
-			return []Chunk{c}
-		}
-	}
-	prevD, _ := r.encodeTempChunk(prev, version, last, storeQueue)
-	currD, _ := r.encodeTempChunk(curr, version, last, storeQueue)
-	return []Chunk{prevD, currD}
-}
-
-// matchStream is the heart of DNA-backup. Thus, it sounded rude not to add some comment to it.
-//
-// It applies a rolling hash on the content of a given stream to look for matching fingerprints
-// in the repo. If no match is found after the equivalent of three chunks of data are processed,
-// then the first unmatched chunk sketch is checked to see if it could be delta-encoded.
-// If not, the chunk is then stored as a new chunk for this version and its fingerprint and
-// sketch are added to the repo maps.
-//
-// If a match happens during the processing of the third chunk, then, if possible, the remaining
-// of the second chunk is merged with the first one to try to delta encode it at once.
-//
-// Each time a new chunk is added it is sent to the store worker through the store queue.
-func (r *Repo) matchStream(stream io.Reader, storeQueue chan<- chunkData, version int, last uint64) ([]Chunk, uint64) {
-	var b byte
-	var chunks []Chunk
-	var prev *TempChunk
-	var err error
-	bufStream := bufio.NewReaderSize(stream, r.chunkSize*2)
-	buff := make([]byte, r.chunkSize, r.chunkSize*2)
-	if n, err := io.ReadFull(stream, buff); n < r.chunkSize {
-		if err == io.ErrUnexpectedEOF {
-			c, _ := r.encodeTempChunk(NewTempChunk(buff[:n]), version, &last, storeQueue)
-			chunks = append(chunks, c)
-			return chunks, last
-		} else {
-			logger.Panicf("matching stream, read only %d bytes with error '%s'", n, err)
-		}
-	}
-	hasher := rabinkarp64.NewFromPol(r.pol)
-	hasher.Write(buff)
-	for err != io.EOF {
-		h := hasher.Sum64()
-		chunkId, exists := r.fingerprints[h]
-		if exists {
-			if len(buff) > r.chunkSize && len(buff) <= r.chunkSize*2 {
-				size := len(buff) - r.chunkSize
-				temp := NewTempChunk(buff[:size])
-				chunks = append(chunks, r.encodeTempChunks(prev, temp, version, &last, storeQueue)...)
-				prev = nil
-			} else if prev != nil {
-				c, _ := r.encodeTempChunk(prev, version, &last, storeQueue)
-				chunks = append(chunks, c)
-				prev = nil
-			}
-			logger.Debugf("add existing chunk: %d", chunkId)
-			chunks = append(chunks, NewStoredChunk(r, chunkId))
-			buff = make([]byte, 0, r.chunkSize*2)
-			for i := 0; i < r.chunkSize && err == nil; i++ {
-				b, err = bufStream.ReadByte()
-				if err != io.EOF {
-					hasher.Roll(b)
-					buff = append(buff, b)
-				}
-			}
-			continue
-		}
-		if len(buff) == r.chunkSize*2 {
-			if prev != nil {
-				chunk, _ := r.encodeTempChunk(prev, version, &last, storeQueue)
-				chunks = append(chunks, chunk)
-			}
-			prev = NewTempChunk(buff[:r.chunkSize])
-			tmp := buff[r.chunkSize:]
-			buff = make([]byte, r.chunkSize, r.chunkSize*2)
-			copy(buff, tmp)
-		}
-		b, err = bufStream.ReadByte()
-		if err != io.EOF {
-			hasher.Roll(b)
-			buff = append(buff, b)
-		}
-	}
-	if len(buff) > 0 {
-		var temp *TempChunk
-		if len(buff) > r.chunkSize {
-			if prev != nil {
-				chunk, _ := r.encodeTempChunk(prev, version, &last, storeQueue)
-				chunks = append(chunks, chunk)
-			}
-			prev = NewTempChunk(buff[:r.chunkSize])
-			temp = NewTempChunk(buff[r.chunkSize:])
-		} else {
-			temp = NewTempChunk(buff)
-		}
-		chunks = append(chunks, r.encodeTempChunks(prev, temp, version, &last, storeQueue)...)
-	}
-	return chunks, last
-}
-
-func (r *Repo) restoreStream(stream io.WriteCloser, recipe []Chunk) {
-	for _, c := range recipe {
-		if n, err := io.Copy(stream, c.Reader()); err != nil {
-			logger.Errorf("copying to stream, read %d bytes from chunk: %s", n, err)
-		}
-	}
-	stream.Close()
-}
-
-func recipe2slice(r []Chunk) (ret slice.Slice) {
-	ret = make(slice.Slice, len(r))
-	for i := range r {
-		ret[i] = r[i]
-	}
-	return
-}
-
-func slice2recipe(s slice.Slice) (ret []Chunk) {
-	ret = make([]Chunk, len(s))
-	for i := range s {
-		if c, ok := s[i].(Chunk); ok {
-			ret[i] = c
-		} else {
-			logger.Warningf("could not convert %s into a Chunk", s[i])
-		}
-	}
-	return
-}
-
-func (r *Repo) storeRecipe(version int, recipe []Chunk) {
-	dest := filepath.Join(r.path, fmt.Sprintf(versionFmt, version), recipeName)
-	delta := slice.Diff(recipe2slice(r.recipe), recipe2slice(recipe))
-	logger.Infof("recipe delta %s", delta.String())
-	storeBasicStruct(dest, r.chunkWriteWrapper, delta)
-}
-
-func (r *Repo) loadRecipes(versions []string) {
-	recipe := slice2recipe(r.loadDeltas(versions, r.chunkReadWrapper, recipeName))
-	for _, c := range recipe {
-		if rc, isRepo := c.(RepoChunk); isRepo {
-			rc.SetRepo(r)
-		}
-	}
-	r.recipe = recipe
-}
-
-func extractDeltaChunks(chunks []Chunk) (ret []*DeltaChunk) {
-	for _, c := range chunks {
-		tmp, isDelta := c.(*DeltaChunk)
-		if isDelta {
-			ret = append(ret, tmp)
-		}
-	}
-	return
-}