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