implement dagmodifier and tests.

.gitignore

@@ -3,3 +3,4 @@
 *.out
 *.test
 *.orig
+*~

blockservice/blockservice.go

@@ -36,7 +36,7 @@ func NewBlockService(d ds.Datastore, rem exchange.Interface) (*BlockService, err
 // AddBlock adds a particular block to the service, Putting it into the datastore.
 func (s *BlockService) AddBlock(b *blocks.Block) (u.Key, error) {
 	k := b.Key()
-	log.Debug("storing [%s] in datastore", k)
+	log.Debug("blockservice: storing [%s] in datastore", k.Pretty())
 	// TODO(brian): define a block datastore with a Put method which accepts a
 	// block parameter
 	err := s.Datastore.Put(k.DsKey(), b.Data)
@@ -53,7 +53,7 @@ func (s *BlockService) AddBlock(b *blocks.Block) (u.Key, error) {
 // GetBlock retrieves a particular block from the service,
 // Getting it from the datastore using the key (hash).
 func (s *BlockService) GetBlock(k u.Key) (*blocks.Block, error) {
-	log.Debug("BlockService GetBlock: '%s'", k)
+	log.Debug("BlockService GetBlock: '%s'", k.Pretty())
 	datai, err := s.Datastore.Get(k.DsKey())
 	if err == nil {
 		log.Debug("Blockservice: Got data in datastore.")

importer/dagwriter/dagmodifier.go

@@ -0,0 +1,190 @@
+package dagwriter
+
+import (
+	"errors"
+
+	"code.google.com/p/goprotobuf/proto"
+
+	imp "github.com/jbenet/go-ipfs/importer"
+	ft "github.com/jbenet/go-ipfs/importer/format"
+	mdag "github.com/jbenet/go-ipfs/merkledag"
+	u "github.com/jbenet/go-ipfs/util"
+)
+
+// DagModifier is the only struct licensed and able to correctly
+// perform surgery on a DAG 'file'
+// Dear god, please rename this to something more pleasant
+type DagModifier struct {
+	dagserv *mdag.DAGService
+	curNode *mdag.Node
+
+	pbdata *ft.PBData
+}
+
+func NewDagModifier(from *mdag.Node, serv *mdag.DAGService) (*DagModifier, error) {
+	pbd, err := ft.FromBytes(from.Data)
+	if err != nil {
+		return nil, err
+	}
+
+	return &DagModifier{
+		curNode: from.Copy(),
+		dagserv: serv,
+		pbdata:  pbd,
+	}, nil
+}
+
+// WriteAt will modify a dag file in place
+// NOTE: it currently assumes only a single level of indirection
+func (dm *DagModifier) WriteAt(b []byte, offset uint64) (int, error) {
+
+	// Check bounds
+	if dm.pbdata.GetFilesize() < offset {
+		return 0, errors.New("Attempted to perform write starting past end of file")
+	}
+
+	// This shouldnt be necessary if we do subblocks sizes properly
+	newsize := dm.pbdata.GetFilesize()
+	if uint64(len(b))+offset > dm.pbdata.GetFilesize() {
+		newsize = uint64(len(b)) + offset
+	}
+
+	// First need to find where we are writing at
+	end := uint64(len(b)) + offset
+	zeroblocklen := uint64(len(dm.pbdata.Data))
+	origlen := len(b)
+
+	if end <= zeroblocklen {
+		log.Debug("Writing into zero block.")
+		// Replacing zeroeth data block (embedded in the root node)
+		//TODO: check chunking here
+		copy(dm.pbdata.Data[offset:], b)
+		return len(b), nil
+	}
+
+	// Find where write should start
+	var traversed uint64
+	startsubblk := len(dm.pbdata.Blocksizes)
+	if offset < zeroblocklen {
+		dm.pbdata.Data = dm.pbdata.Data[:offset]
+		startsubblk = 0
+	} else {
+		traversed = uint64(zeroblocklen)
+		for i, size := range dm.pbdata.Blocksizes {
+			if uint64(offset) < traversed+size {
+				log.Debug("Starting mod at block %d. [%d < %d + %d]", i, offset, traversed, size)
+				// Here is where we start
+				startsubblk = i
+				lnk := dm.curNode.Links[i]
+				node, err := dm.dagserv.Get(u.Key(lnk.Hash))
+				if err != nil {
+					return 0, err
+				}
+				data, err := ft.UnwrapData(node.Data)
+				if err != nil {
+					return 0, err
+				}
+				b = append(data[:offset-traversed], b...)
+				break
+			}
+			traversed += size
+		}
+		if startsubblk == len(dm.pbdata.Blocksizes) {
+			// TODO: something?
+			/*
+				if traversed < offset {
+					return 0, errors.New("Tried to start write outside bounds of file.")
+				}
+			*/
+		}
+	}
+
+	// Find blocks that need to be overwritten
+	var changed []int
+	mid := -1
+	var midoff uint64
+	for i, size := range dm.pbdata.Blocksizes[startsubblk:] {
+		if end > traversed {
+			changed = append(changed, i+startsubblk)
+		} else if end == traversed {
+			break
+		} else {
+			break
+		}
+		traversed += size
+		if end < traversed {
+			mid = i + startsubblk
+			midoff = end - (traversed - size)
+			break
+		}
+	}
+
+	var midlnk *mdag.Link
+	if mid >= 0 {
+		midlnk = dm.curNode.Links[mid]
+		midnode, err := dm.dagserv.Get(u.Key(midlnk.Hash))
+		if err != nil {
+			return 0, err
+		}
+
+		// NOTE: this may have to be changed later when we have multiple
+		// layers of indirection
+		data, err := ft.UnwrapData(midnode.Data)
+		if err != nil {
+			return 0, err
+		}
+		b = append(b, data[midoff:]...)
+	}
+
+	// TODO: dont assume a splitting func here
+	subblocks := splitBytes(b, &imp.SizeSplitter2{512})
+	var links []*mdag.Link
+	var sizes []uint64
+	for _, sb := range subblocks {
+		n := &mdag.Node{Data: ft.WrapData(sb)}
+		_, err := dm.dagserv.Add(n)
+		if err != nil {
+			log.Error("Failed adding node to DAG service: %s", err)
+			return 0, err
+		}
+		lnk, err := mdag.MakeLink(n)
+		if err != nil {
+			return 0, err
+		}
+		links = append(links, lnk)
+		sizes = append(sizes, uint64(len(sb)))
+	}
+
+	// This is disgusting
+	if len(changed) > 0 {
+		dm.curNode.Links = append(dm.curNode.Links[:changed[0]], append(links, dm.curNode.Links[changed[len(changed)-1]+1:]...)...)
+		dm.pbdata.Blocksizes = append(dm.pbdata.Blocksizes[:changed[0]], append(sizes, dm.pbdata.Blocksizes[changed[len(changed)-1]+1:]...)...)
+	} else {
+		dm.curNode.Links = append(dm.curNode.Links, links...)
+		dm.pbdata.Blocksizes = append(dm.pbdata.Blocksizes, sizes...)
+	}
+	dm.pbdata.Filesize = proto.Uint64(newsize)
+
+	return origlen, nil
+}
+
+func splitBytes(b []byte, spl imp.StreamSplitter) [][]byte {
+	ch := make(chan []byte)
+	out := spl.Split(ch)
+	ch <- b
+	close(ch)
+	var arr [][]byte
+	for blk := range out {
+		arr = append(arr, blk)
+	}
+	return arr
+}
+
+func (dm *DagModifier) GetNode() (*mdag.Node, error) {
+	b, err := proto.Marshal(dm.pbdata)
+	if err != nil {
+		return nil, err
+	}
+	dm.curNode.Data = b
+	return dm.curNode.Copy(), nil
+}

importer/dagwriter/dagmodifier_test.go

@@ -0,0 +1,187 @@
+package dagwriter
+
+import (
+	"fmt"
+	"io"
+	"io/ioutil"
+	"math/rand"
+	"testing"
+	"time"
+
+	"github.com/jbenet/go-ipfs/Godeps/_workspace/src/github.com/op/go-logging"
+	bs "github.com/jbenet/go-ipfs/blockservice"
+	imp "github.com/jbenet/go-ipfs/importer"
+	ft "github.com/jbenet/go-ipfs/importer/format"
+	mdag "github.com/jbenet/go-ipfs/merkledag"
+
+	ds "github.com/jbenet/go-ipfs/Godeps/_workspace/src/github.com/jbenet/datastore.go"
+)
+
+type randGen struct {
+	src rand.Source
+}
+
+func newRand() *randGen {
+	return &randGen{rand.NewSource(time.Now().UnixNano())}
+}
+
+func (r *randGen) Read(p []byte) (n int, err error) {
+	todo := len(p)
+	offset := 0
+	for {
+		val := int64(r.src.Int63())
+		for i := 0; i < 8; i++ {
+			p[offset] = byte(val & 0xff)
+			todo--
+			if todo == 0 {
+				return len(p), nil
+			}
+			offset++
+			val >>= 8
+		}
+	}
+
+	panic("unreachable")
+}
+
+func getMockDagServ(t *testing.T) *mdag.DAGService {
+	dstore := ds.NewMapDatastore()
+	bserv, err := bs.NewBlockService(dstore, nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	return &mdag.DAGService{bserv}
+}
+
+func getNode(t *testing.T, dserv *mdag.DAGService, size int64) ([]byte, *mdag.Node) {
+	dw := NewDagWriter(dserv, &imp.SizeSplitter2{500})
+
+	n, err := io.CopyN(dw, newRand(), size)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if n != size {
+		t.Fatal("Incorrect copy amount!")
+	}
+
+	dw.Close()
+	node := dw.GetNode()
+
+	dr, err := mdag.NewDagReader(node, dserv)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	b, err := ioutil.ReadAll(dr)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	return b, node
+}
+
+func testModWrite(t *testing.T, beg, size uint64, orig []byte, dm *DagModifier) []byte {
+	newdata := make([]byte, size)
+	r := newRand()
+	r.Read(newdata)
+
+	if size+beg > uint64(len(orig)) {
+		orig = append(orig, make([]byte, (size+beg)-uint64(len(orig)))...)
+	}
+	copy(orig[beg:], newdata)
+
+	nmod, err := dm.WriteAt(newdata, uint64(beg))
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if nmod != int(size) {
+		t.Fatalf("Mod length not correct! %d != %d", nmod, size)
+	}
+
+	nd, err := dm.GetNode()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	rd, err := mdag.NewDagReader(nd, dm.dagserv)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	after, err := ioutil.ReadAll(rd)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	err = arrComp(after, orig)
+	if err != nil {
+		t.Fatal(err)
+	}
+	return orig
+}
+
+func TestDagModifierBasic(t *testing.T) {
+	logging.SetLevel(logging.CRITICAL, "blockservice")
+	logging.SetLevel(logging.CRITICAL, "merkledag")
+	dserv := getMockDagServ(t)
+	b, n := getNode(t, dserv, 50000)
+
+	dagmod, err := NewDagModifier(n, dserv)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// Within zero block
+	beg := uint64(15)
+	length := uint64(60)
+
+	t.Log("Testing mod within zero block")
+	b = testModWrite(t, beg, length, b, dagmod)
+
+	// Within bounds of existing file
+	beg = 1000
+	length = 4000
+	t.Log("Testing mod within bounds of existing file.")
+	b = testModWrite(t, beg, length, b, dagmod)
+
+	// Extend bounds
+	beg = 49500
+	length = 4000
+
+	t.Log("Testing mod that extends file.")
+	b = testModWrite(t, beg, length, b, dagmod)
+
+	// "Append"
+	beg = uint64(len(b))
+	length = 3000
+	b = testModWrite(t, beg, length, b, dagmod)
+
+	// Verify reported length
+	node, err := dagmod.GetNode()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	size, err := ft.DataSize(node.Data)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	expected := uint64(50000 + 3500 + 3000)
+	if size != expected {
+		t.Fatal("Final reported size is incorrect [%d != %d]", size, expected)
+	}
+}
+
+func arrComp(a, b []byte) error {
+	if len(a) != len(b) {
+		return fmt.Errorf("Arrays differ in length. %d != %d", len(a), len(b))
+	}
+	for i, v := range a {
+		if v != b[i] {
+			return fmt.Errorf("Arrays differ at index: %d", i)
+		}
+	}
+	return nil
+}

importer/dagwriter/dagwriter.go

@@ -32,10 +32,11 @@ func NewDagWriter(ds *dag.DAGService, splitter imp.StreamSplitter) *DagWriter {
 func (dw *DagWriter) startSplitter() {
 	blkchan := dw.splitter.Split(dw.splChan)
 	first := <-blkchan
+	mbf := new(ft.MultiBlock)
 	root := new(dag.Node)
-	fileSize := uint64(0)
+
 	for blkData := range blkchan {
-		fileSize += uint64(len(blkData))
+		mbf.AddBlockSize(uint64(len(blkData)))
 		node := &dag.Node{Data: ft.WrapData(blkData)}
 		_, err := dw.dagserv.Add(node)
 		if err != nil {
@@ -50,8 +51,16 @@ func (dw *DagWriter) startSplitter() {
 			return
 		}
 	}
-	root.Data = ft.FilePBData(first, fileSize)
-	_, err := dw.dagserv.Add(root)
+	mbf.Data = first
+	data, err := mbf.GetBytes()
+	if err != nil {
+		dw.seterr = err
+		log.Critical("Failed generating bytes for multiblock file: %s", err)
+		return
+	}
+	root.Data = data
+
+	_, err = dw.dagserv.Add(root)
 	if err != nil {
 		dw.seterr = err
 		log.Critical("Got error adding created node to dagservice: %s", err)

importer/dagwriter/dagwriter_test.go

@@ -100,3 +100,28 @@ func TestMassiveWrite(t *testing.T) {
 	}
 	dw.Close()
 }
+
+func BenchmarkDagWriter(b *testing.B) {
+	dstore := ds.NewNullDatastore()
+	bserv, err := bs.NewBlockService(dstore, nil)
+	if err != nil {
+		b.Fatal(err)
+	}
+	dag := &mdag.DAGService{bserv}
+
+	b.ResetTimer()
+	nbytes := int64(b.N)
+	for i := 0; i < b.N; i++ {
+		b.SetBytes(nbytes)
+		dw := NewDagWriter(dag, &imp.SizeSplitter2{4096})
+		n, err := io.CopyN(dw, &datasource{}, nbytes)
+		if err != nil {
+			b.Fatal(err)
+		}
+		if n != nbytes {
+			b.Fatal("Incorrect copy size.")
+		}
+		dw.Close()
+	}
+
+}

importer/format/format.go

@@ -8,6 +8,15 @@ import (
 	"code.google.com/p/goprotobuf/proto"
 )
 
+func FromBytes(data []byte) (*PBData, error) {
+	pbdata := new(PBData)
+	err := proto.Unmarshal(data, pbdata)
+	if err != nil {
+		return nil, err
+	}
+	return pbdata, nil
+}
+
 func FilePBData(data []byte, totalsize uint64) []byte {
 	pbfile := new(PBData)
 	typ := PBData_File
@@ -51,6 +60,15 @@ func WrapData(b []byte) []byte {
 	return out
 }
 
+func UnwrapData(data []byte) ([]byte, error) {
+	pbdata := new(PBData)
+	err := proto.Unmarshal(data, pbdata)
+	if err != nil {
+		return nil, err
+	}
+	return pbdata.GetData(), nil
+}
+
 func DataSize(data []byte) (uint64, error) {
 	pbdata := new(PBData)
 	err := proto.Unmarshal(data, pbdata)
@@ -69,3 +87,24 @@ func DataSize(data []byte) (uint64, error) {
 		return 0, errors.New("Unrecognized node data type!")
 	}
 }
+
+type MultiBlock struct {
+	Data       []byte
+	blocksizes []uint64
+	subtotal   uint64
+}
+
+func (mb *MultiBlock) AddBlockSize(s uint64) {
+	mb.subtotal += s
+	mb.blocksizes = append(mb.blocksizes, s)
+}
+
+func (mb *MultiBlock) GetBytes() ([]byte, error) {
+	pbn := new(PBData)
+	t := PBData_File
+	pbn.Type = &t
+	pbn.Filesize = proto.Uint64(uint64(len(mb.Data)) + mb.subtotal)
+	pbn.Blocksizes = mb.blocksizes
+	pbn.Data = mb.Data
+	return proto.Marshal(pbn)
+}

importer/importer.go

@@ -31,19 +31,23 @@ func NewDagFromReaderWithSplitter(r io.Reader, spl BlockSplitter) (*dag.Node, er
 	first := <-blkChan
 	root := &dag.Node{}
 
-	i := 0
-	totalsize := uint64(len(first))
+	mbf := new(ft.MultiBlock)
 	for blk := range blkChan {
-		totalsize += uint64(len(blk))
+		mbf.AddBlockSize(uint64(len(blk)))
 		child := &dag.Node{Data: ft.WrapData(blk)}
-		err := root.AddNodeLink(fmt.Sprintf("%d", i), child)
+		err := root.AddNodeLink("", child)
 		if err != nil {
 			return nil, err
 		}
-		i++
 	}
 
-	root.Data = ft.FilePBData(first, totalsize)
+	mbf.Data = first
+	data, err := mbf.GetBytes()
+	if err != nil {
+		return nil, err
+	}
+
+	root.Data = data
 	return root, nil
 }
 

merkledag/merkledag.go

@@ -34,9 +34,6 @@ type Link struct {
 	// cumulative size of target object
 	Size uint64
 
-	// cumulative size of data stored in object
-	DataSize uint64
-
 	// multihash of the target object
 	Hash mh.Multihash
 
@@ -44,45 +41,45 @@ type Link struct {
 	Node *Node
 }
 
-// AddNodeLink adds a link to another node.
-func (n *Node) AddNodeLink(name string, that *Node) error {
-	s, err := that.Size()
+func MakeLink(n *Node) (*Link, error) {
+	s, err := n.Size()
 	if err != nil {
-		return err
+		return nil, err
 	}
 
-	h, err := that.Multihash()
+	h, err := n.Multihash()
 	if err != nil {
-		return err
+		return nil, err
 	}
-
-	n.Links = append(n.Links, &Link{
-		Name: name,
+	return &Link{
 		Size: s,
 		Hash: h,
-		Node: that,
-	})
+	}, nil
+}
+
+// AddNodeLink adds a link to another node.
+func (n *Node) AddNodeLink(name string, that *Node) error {
+	lnk, err := MakeLink(that)
+	if err != nil {
+		return err
+	}
+	lnk.Name = name
+	lnk.Node = that
+
+	n.Links = append(n.Links, lnk)
 	return nil
 }
 
 // AddNodeLink adds a link to another node. without keeping a reference to
 // the child node
 func (n *Node) AddNodeLinkClean(name string, that *Node) error {
-	s, err := that.Size()
+	lnk, err := MakeLink(that)
 	if err != nil {
 		return err
 	}
+	lnk.Name = name
 
-	h, err := that.Multihash()
-	if err != nil {
-		return err
-	}
-
-	n.Links = append(n.Links, &Link{
-		Name: name,
-		Size: s,
-		Hash: h,
-	})
+	n.Links = append(n.Links, lnk)
 	return nil
 }