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set.go
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set.go
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package pin
import (
"bytes"
"context"
"encoding/binary"
"errors"
"fmt"
"hash/fnv"
"sort"
"github.com/ipfs/go-ipfs/merkledag"
"github.com/ipfs/go-ipfs/pin/internal/pb"
"gx/ipfs/QmZ4Qi3GaRbjcx28Sme5eMH7RQjGkt8wHxt2a65oLaeFEV/gogo-protobuf/proto"
cid "gx/ipfs/QmcZfnkapfECQGcLZaf9B79NRg7cRa9EnZh4LSbkCzwNvY/go-cid"
ipld "gx/ipfs/Qme5bWv7wtjUNGsK2BNGVUFPKiuxWrsqrtvYwCLRw8YFES/go-ipld-format"
)
const (
// defaultFanout specifies the default number of fan-out links per layer
defaultFanout = 256
// maxItems is the maximum number of items that will fit in a single bucket
maxItems = 8192
)
func hash(seed uint32, c *cid.Cid) uint32 {
var buf [4]byte
binary.LittleEndian.PutUint32(buf[:], seed)
h := fnv.New32a()
_, _ = h.Write(buf[:])
_, _ = h.Write(c.Bytes())
return h.Sum32()
}
type itemIterator func() (c *cid.Cid, ok bool)
type keyObserver func(*cid.Cid)
type sortByHash struct {
links []*ipld.Link
}
func (s sortByHash) Len() int {
return len(s.links)
}
func (s sortByHash) Less(a, b int) bool {
return bytes.Compare(s.links[a].Cid.Bytes(), s.links[b].Cid.Bytes()) == -1
}
func (s sortByHash) Swap(a, b int) {
s.links[a], s.links[b] = s.links[b], s.links[a]
}
func storeItems(ctx context.Context, dag ipld.DAGService, estimatedLen uint64, depth uint32, iter itemIterator, internalKeys keyObserver) (*merkledag.ProtoNode, error) {
links := make([]*ipld.Link, 0, defaultFanout+maxItems)
for i := 0; i < defaultFanout; i++ {
links = append(links, &ipld.Link{Cid: emptyKey})
}
// add emptyKey to our set of internal pinset objects
n := &merkledag.ProtoNode{}
n.SetLinks(links)
internalKeys(emptyKey)
hdr := &pb.Set{
Version: proto.Uint32(1),
Fanout: proto.Uint32(defaultFanout),
Seed: proto.Uint32(depth),
}
if err := writeHdr(n, hdr); err != nil {
return nil, err
}
if estimatedLen < maxItems {
// it'll probably fit
links := n.Links()
for i := 0; i < maxItems; i++ {
k, ok := iter()
if !ok {
// all done
break
}
links = append(links, &ipld.Link{Cid: k})
}
n.SetLinks(links)
// sort by hash, also swap item Data
s := sortByHash{
links: n.Links()[defaultFanout:],
}
sort.Stable(s)
}
hashed := make([][]*cid.Cid, defaultFanout)
for {
// This loop essentially enumerates every single item in the set
// and maps them all into a set of buckets. Each bucket will be recursively
// turned into its own sub-set, and so on down the chain. Each sub-set
// gets added to the dagservice, and put into its place in a set nodes
// links array.
//
// Previously, the bucket was selected by taking an int32 from the hash of
// the input key + seed. This was erroneous as we would later be assigning
// the created sub-sets into an array of length 256 by the modulus of the
// int32 hash value with 256. This resulted in overwriting existing sub-sets
// and losing pins. The fix (a few lines down from this comment), is to
// map the hash value down to the 8 bit keyspace here while creating the
// buckets. This way, we avoid any overlapping later on.
k, ok := iter()
if !ok {
break
}
h := hash(depth, k) % defaultFanout
hashed[h] = append(hashed[h], k)
}
for h, items := range hashed {
if len(items) == 0 {
// recursion base case
continue
}
childIter := getCidListIterator(items)
// recursively create a pinset from the items for this bucket index
child, err := storeItems(ctx, dag, uint64(len(items)), depth+1, childIter, internalKeys)
if err != nil {
return nil, err
}
size, err := child.Size()
if err != nil {
return nil, err
}
err = dag.Add(ctx, child)
if err != nil {
return nil, err
}
childKey := child.Cid()
internalKeys(childKey)
// overwrite the 'empty key' in the existing links array
n.Links()[h] = &ipld.Link{
Cid: childKey,
Size: size,
}
}
return n, nil
}
func readHdr(n *merkledag.ProtoNode) (*pb.Set, error) {
hdrLenRaw, consumed := binary.Uvarint(n.Data())
if consumed <= 0 {
return nil, errors.New("invalid Set header length")
}
pbdata := n.Data()[consumed:]
if hdrLenRaw > uint64(len(pbdata)) {
return nil, errors.New("impossibly large Set header length")
}
// as hdrLenRaw was <= an int, we now know it fits in an int
hdrLen := int(hdrLenRaw)
var hdr pb.Set
if err := proto.Unmarshal(pbdata[:hdrLen], &hdr); err != nil {
return nil, err
}
if v := hdr.GetVersion(); v != 1 {
return nil, fmt.Errorf("unsupported Set version: %d", v)
}
if uint64(hdr.GetFanout()) > uint64(len(n.Links())) {
return nil, errors.New("impossibly large Fanout")
}
return &hdr, nil
}
func writeHdr(n *merkledag.ProtoNode, hdr *pb.Set) error {
hdrData, err := proto.Marshal(hdr)
if err != nil {
return err
}
// make enough space for the length prefix and the marshalled header data
data := make([]byte, binary.MaxVarintLen64, binary.MaxVarintLen64+len(hdrData))
// write the uvarint length of the header data
uvarlen := binary.PutUvarint(data, uint64(len(hdrData)))
// append the actual protobuf data *after* the length value we wrote
data = append(data[:uvarlen], hdrData...)
n.SetData(data)
return nil
}
type walkerFunc func(idx int, link *ipld.Link) error
func walkItems(ctx context.Context, dag ipld.DAGService, n *merkledag.ProtoNode, fn walkerFunc, children keyObserver) error {
hdr, err := readHdr(n)
if err != nil {
return err
}
// readHdr guarantees fanout is a safe value
fanout := hdr.GetFanout()
for i, l := range n.Links()[fanout:] {
if err := fn(i, l); err != nil {
return err
}
}
for _, l := range n.Links()[:fanout] {
c := l.Cid
children(c)
if c.Equals(emptyKey) {
continue
}
subtree, err := l.GetNode(ctx, dag)
if err != nil {
return err
}
stpb, ok := subtree.(*merkledag.ProtoNode)
if !ok {
return merkledag.ErrNotProtobuf
}
if err := walkItems(ctx, dag, stpb, fn, children); err != nil {
return err
}
}
return nil
}
func loadSet(ctx context.Context, dag ipld.DAGService, root *merkledag.ProtoNode, name string, internalKeys keyObserver) ([]*cid.Cid, error) {
l, err := root.GetNodeLink(name)
if err != nil {
return nil, err
}
lnkc := l.Cid
internalKeys(lnkc)
n, err := l.GetNode(ctx, dag)
if err != nil {
return nil, err
}
pbn, ok := n.(*merkledag.ProtoNode)
if !ok {
return nil, merkledag.ErrNotProtobuf
}
var res []*cid.Cid
walk := func(idx int, link *ipld.Link) error {
res = append(res, link.Cid)
return nil
}
if err := walkItems(ctx, dag, pbn, walk, internalKeys); err != nil {
return nil, err
}
return res, nil
}
func getCidListIterator(cids []*cid.Cid) itemIterator {
return func() (c *cid.Cid, ok bool) {
if len(cids) == 0 {
return nil, false
}
first := cids[0]
cids = cids[1:]
return first, true
}
}
func storeSet(ctx context.Context, dag ipld.DAGService, cids []*cid.Cid, internalKeys keyObserver) (*merkledag.ProtoNode, error) {
iter := getCidListIterator(cids)
n, err := storeItems(ctx, dag, uint64(len(cids)), 0, iter, internalKeys)
if err != nil {
return nil, err
}
err = dag.Add(ctx, n)
if err != nil {
return nil, err
}
internalKeys(n.Cid())
return n, nil
}