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177 lines
3.6 KiB
177 lines
3.6 KiB
package consensus
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import (
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"bytes"
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"crypto/sha256"
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"errors"
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"io"
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"sync"
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. "github.com/tendermint/tendermint/binary"
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. "github.com/tendermint/tendermint/common"
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"github.com/tendermint/tendermint/merkle"
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)
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const (
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partSize = 4096 // 4KB
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)
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var (
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ErrPartSetUnexpectedIndex = errors.New("Error part set unexpected index")
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ErrPartSetInvalidTrail = errors.New("Error part set invalid trail")
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)
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type Part struct {
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Index uint16
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Trail [][]byte
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Bytes []byte
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// Cache
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hash []byte
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}
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func ReadPart(r io.Reader, n *int64, err *error) *Part {
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return &Part{
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Index: ReadUInt16(r, n, err),
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Trail: ReadByteSlices(r, n, err),
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Bytes: ReadByteSlice(r, n, err),
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}
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}
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func (b *Part) WriteTo(w io.Writer) (n int64, err error) {
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WriteUInt16(w, b.Index, &n, &err)
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WriteByteSlices(w, b.Trail, &n, &err)
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WriteByteSlice(w, b.Bytes, &n, &err)
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return
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}
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func (pt *Part) Hash() []byte {
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if pt.hash != nil {
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return pt.hash
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} else {
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hasher := sha256.New()
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_, err := hasher.Write(pt.Bytes)
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if err != nil {
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panic(err)
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}
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pt.hash = hasher.Sum(nil)
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return pt.hash
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}
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}
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//-------------------------------------
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type PartSet struct {
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rootHash []byte
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total uint16
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mtx sync.Mutex
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parts []*Part
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partsBitArray BitArray
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count uint16
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}
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// Returns an immutable, full PartSet.
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func NewPartSetFromData(data []byte) *PartSet {
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// divide data into 4kb parts.
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total := (len(data) + partSize - 1) / partSize
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parts := make([]*Part, total)
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parts_ := make([]merkle.Hashable, total)
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partsBitArray := NewBitArray(uint(total))
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for i := 0; i < total; i++ {
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part := &Part{
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Index: uint16(i),
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Bytes: data[i*partSize : MinInt(len(data), (i+1)*partSize)],
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}
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parts[i] = part
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parts_[i] = part
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partsBitArray.SetIndex(uint(i), true)
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}
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// Compute merkle trails
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hashTree := merkle.HashTreeFromHashables(parts_)
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for i := 0; i < total; i++ {
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parts[i].Trail = merkle.HashTrailForIndex(hashTree, i)
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}
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return &PartSet{
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parts: parts,
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partsBitArray: partsBitArray,
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rootHash: hashTree[len(hashTree)/2],
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total: uint16(total),
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count: uint16(total),
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}
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}
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// Returns an empty PartSet ready to be populated.
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func NewPartSetFromMetadata(total uint16, rootHash []byte) *PartSet {
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return &PartSet{
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parts: make([]*Part, total),
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partsBitArray: NewBitArray(uint(total)),
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rootHash: rootHash,
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total: total,
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count: 0,
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}
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}
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func (ps *PartSet) BitArray() BitArray {
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ps.mtx.Lock()
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defer ps.mtx.Unlock()
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return ps.partsBitArray.Copy()
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}
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func (ps *PartSet) RootHash() []byte {
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return ps.rootHash
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}
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func (ps *PartSet) Total() uint16 {
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if ps == nil {
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return 0
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}
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return ps.total
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}
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func (ps *PartSet) AddPart(part *Part) (bool, error) {
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ps.mtx.Lock()
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defer ps.mtx.Unlock()
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// Invalid part index
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if part.Index >= ps.total {
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return false, ErrPartSetUnexpectedIndex
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}
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// If part already exists, return false.
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if ps.parts[part.Index] != nil {
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return false, nil
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}
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// Check hash trail
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if !merkle.VerifyHashTrailForIndex(int(part.Index), part.Hash(), part.Trail, ps.rootHash) {
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return false, ErrPartSetInvalidTrail
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}
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// Add part
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ps.parts[part.Index] = part
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ps.partsBitArray.SetIndex(uint(part.Index), true)
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ps.count++
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return true, nil
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}
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func (ps *PartSet) GetPart(index uint16) *Part {
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ps.mtx.Lock()
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defer ps.mtx.Unlock()
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return ps.parts[index]
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}
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func (ps *PartSet) IsComplete() bool {
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return ps.count == ps.total
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}
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func (ps *PartSet) GetReader() io.Reader {
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if !ps.IsComplete() {
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panic("Cannot GetReader() on incomplete PartSet")
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}
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buf := []byte{}
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for _, part := range ps.parts {
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buf = append(buf, part.Bytes...)
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}
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return bytes.NewReader(buf)
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}
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