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indexsorted.go
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/
indexsorted.go
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package index
import (
"bytes"
"encoding/binary"
"errors"
"fmt"
"io"
"sort"
internalio "github.com/ipld/go-car/v2/internal/io"
"github.com/multiformats/go-multicodec"
"github.com/ipfs/go-cid"
"github.com/multiformats/go-multihash"
)
var _ Index = (*multiWidthIndex)(nil)
type (
digestRecord struct {
digest []byte
index uint64
}
recordSet []digestRecord
singleWidthIndex struct {
width uint32
len uint64 // in struct, len is #items. when marshaled, it's saved as #bytes.
index []byte
}
multiWidthIndex map[uint32]singleWidthIndex
)
func (d digestRecord) write(buf []byte) {
n := copy(buf[:], d.digest)
binary.LittleEndian.PutUint64(buf[n:], d.index)
}
func (r recordSet) Len() int {
return len(r)
}
func (r recordSet) Less(i, j int) bool {
return bytes.Compare(r[i].digest, r[j].digest) < 0
}
func (r recordSet) Swap(i, j int) {
r[i], r[j] = r[j], r[i]
}
func (s *singleWidthIndex) Marshal(w io.Writer) (uint64, error) {
l := uint64(0)
if err := binary.Write(w, binary.LittleEndian, s.width); err != nil {
return 0, err
}
l += 4
if err := binary.Write(w, binary.LittleEndian, int64(len(s.index))); err != nil {
return l, err
}
l += 8
n, err := w.Write(s.index)
return l + uint64(n), err
}
func (s *singleWidthIndex) Unmarshal(r io.Reader) error {
var width uint32
if err := binary.Read(r, binary.LittleEndian, &width); err != nil {
if err == io.EOF {
return io.ErrUnexpectedEOF
}
return err
}
var dataLen uint64
if err := binary.Read(r, binary.LittleEndian, &dataLen); err != nil {
if err == io.EOF {
return io.ErrUnexpectedEOF
}
return err
}
if err := s.checkUnmarshalLengths(width, dataLen, 0); err != nil {
return err
}
buf := make([]byte, dataLen)
if _, err := io.ReadFull(r, buf); err != nil {
return err
}
s.index = buf
return nil
}
func (s *singleWidthIndex) checkUnmarshalLengths(width uint32, dataLen, extra uint64) error {
if width < 8 {
return errors.New("malformed index; width must be at least 8")
}
const maxWidth = 32 << 20 // 32MiB, to ~match the go-cid maximum
if width > maxWidth {
return errors.New("index too big; singleWidthIndex width is larger than allowed maximum")
}
oldDataLen, dataLen := dataLen, dataLen+extra
if oldDataLen > dataLen {
return errors.New("index too big; singleWidthIndex len is overflowing")
}
if int64(dataLen) < 0 {
return errors.New("index too big; singleWidthIndex len is overflowing int64")
}
s.width = width
s.len = dataLen / uint64(width)
return nil
}
func (s *singleWidthIndex) Less(i int, digest []byte) bool {
return bytes.Compare(digest[:], s.index[i*int(s.width):((i+1)*int(s.width)-8)]) <= 0
}
func (s *singleWidthIndex) GetAll(c cid.Cid, fn func(uint64) bool) error {
d, err := multihash.Decode(c.Hash())
if err != nil {
return err
}
return s.getAll(d.Digest, fn)
}
func (s *singleWidthIndex) getAll(d []byte, fn func(uint64) bool) error {
idx := sort.Search(int(s.len), func(i int) bool {
return s.Less(i, d)
})
var any bool
for ; uint64(idx) < s.len; idx++ {
digestStart := idx * int(s.width)
offsetEnd := (idx + 1) * int(s.width)
digestEnd := offsetEnd - 8
if bytes.Equal(d[:], s.index[digestStart:digestEnd]) {
any = true
offset := binary.LittleEndian.Uint64(s.index[digestEnd:offsetEnd])
if !fn(offset) {
// User signalled to stop searching; therefore, break.
break
}
} else {
// No more matches; therefore, break.
break
}
}
if !any {
return ErrNotFound
}
return nil
}
func (s *singleWidthIndex) Load(items []Record) error {
m := make(multiWidthIndex)
if err := m.Load(items); err != nil {
return err
}
if len(m) != 1 {
return fmt.Errorf("unexpected number of cid widths: %d", len(m))
}
for _, i := range m {
s.index = i.index
s.len = i.len
s.width = i.width
return nil
}
return nil
}
func (s *singleWidthIndex) forEachDigest(f func(digest []byte, offset uint64) error) error {
segmentCount := len(s.index) / int(s.width)
for i := 0; i < segmentCount; i++ {
digestStart := i * int(s.width)
offsetEnd := (i + 1) * int(s.width)
digestEnd := offsetEnd - 8
digest := s.index[digestStart:digestEnd]
offset := binary.LittleEndian.Uint64(s.index[digestEnd:offsetEnd])
if err := f(digest, offset); err != nil {
return err
}
}
return nil
}
func (m *multiWidthIndex) GetAll(c cid.Cid, fn func(uint64) bool) error {
d, err := multihash.Decode(c.Hash())
if err != nil {
return err
}
if s, ok := (*m)[uint32(len(d.Digest)+8)]; ok {
return s.getAll(d.Digest, fn)
}
return ErrNotFound
}
func (m *multiWidthIndex) Codec() multicodec.Code {
return multicodec.CarIndexSorted
}
func (m *multiWidthIndex) Marshal(w io.Writer) (uint64, error) {
l := uint64(0)
if err := binary.Write(w, binary.LittleEndian, int32(len(*m))); err != nil {
return l, err
}
l += 4
// The widths are unique, but ranging over a map isn't deterministic.
// As per the CARv2 spec, we must order buckets by digest length.
widths := make([]uint32, 0, len(*m))
for width := range *m {
widths = append(widths, width)
}
sort.Slice(widths, func(i, j int) bool {
return widths[i] < widths[j]
})
for _, width := range widths {
bucket := (*m)[width]
n, err := bucket.Marshal(w)
l += n
if err != nil {
return l, err
}
}
return l, nil
}
func (m *multiWidthIndex) Unmarshal(r io.Reader) error {
reader := internalio.ToByteReadSeeker(r)
var l int32
if err := binary.Read(reader, binary.LittleEndian, &l); err != nil {
if err == io.EOF {
return io.ErrUnexpectedEOF
}
return err
}
sum, err := reader.Seek(0, io.SeekCurrent)
if err != nil {
return err
}
if int32(l) < 0 {
return errors.New("index too big; multiWidthIndex count is overflowing int32")
}
for i := 0; i < int(l); i++ {
s := singleWidthIndex{}
if err := s.Unmarshal(r); err != nil {
return err
}
n, err := reader.Seek(0, io.SeekCurrent)
if err != nil {
return err
}
oldSum := sum
sum += n
if sum < oldSum {
return errors.New("index too big; multiWidthIndex len is overflowing int64")
}
(*m)[s.width] = s
}
return nil
}
func (m *multiWidthIndex) Load(items []Record) error {
// Split cids on their digest length
idxs := make(map[int][]digestRecord)
for _, item := range items {
decHash, err := multihash.Decode(item.Hash())
if err != nil {
return err
}
digest := decHash.Digest
idx, ok := idxs[len(digest)]
if !ok {
idxs[len(digest)] = make([]digestRecord, 0)
idx = idxs[len(digest)]
}
idxs[len(digest)] = append(idx, digestRecord{digest, item.Offset})
}
// Sort each list. then write to compact form.
for width, lst := range idxs {
sort.Sort(recordSet(lst))
rcrdWdth := width + 8
compact := make([]byte, rcrdWdth*len(lst))
for off, itm := range lst {
itm.write(compact[off*rcrdWdth : (off+1)*rcrdWdth])
}
s := singleWidthIndex{
width: uint32(rcrdWdth),
len: uint64(len(lst)),
index: compact,
}
(*m)[uint32(width)+8] = s
}
return nil
}
func (m *multiWidthIndex) forEachDigest(f func(digest []byte, offset uint64) error) error {
sizes := make([]uint32, 0, len(*m))
for k := range *m {
sizes = append(sizes, k)
}
sort.Slice(sizes, func(i, j int) bool { return sizes[i] < sizes[j] })
for _, s := range sizes {
swi := (*m)[s]
if err := swi.forEachDigest(f); err != nil {
return err
}
}
return nil
}
func newSorted() Index {
m := make(multiWidthIndex)
return &m
}