neoneo-go/pkg/core/unspent_coin_state.go

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package core
import (
"fmt"
"github.com/CityOfZion/neo-go/pkg/core/storage"
"github.com/CityOfZion/neo-go/pkg/core/transaction"
"github.com/CityOfZion/neo-go/pkg/io"
"github.com/CityOfZion/neo-go/pkg/util"
)
// UnspentCoins is mapping between transactions and their unspent
// coin state.
type UnspentCoins map[util.Uint256]*UnspentCoinState
func (u UnspentCoins) getAndUpdate(s storage.Store, hash util.Uint256) (*UnspentCoinState, error) {
if unspent, ok := u[hash]; ok {
return unspent, nil
}
unspent := &UnspentCoinState{}
key := storage.AppendPrefix(storage.STCoin, hash.BytesReverse())
if b, err := s.Get(key); err == nil {
if err := unspent.DecodeBinary(io.NewBinReaderFromBuf(b)); err != nil {
return nil, fmt.Errorf("failed to decode (UnspentCoinState): %s", err)
}
} else {
unspent = &UnspentCoinState{
states: []CoinState{},
}
}
u[hash] = unspent
return unspent, nil
}
// UnspentCoinState hold the state of a unspent coin.
type UnspentCoinState struct {
states []CoinState
}
// NewUnspentCoinState returns a new unspent coin state with N confirmed states.
func NewUnspentCoinState(n int) *UnspentCoinState {
u := &UnspentCoinState{
states: make([]CoinState, n),
}
for i := 0; i < n; i++ {
u.states[i] = CoinStateConfirmed
}
return u
}
// commit writes all unspent coin states to the given Batch.
func (u UnspentCoins) commit(b storage.Batch) error {
buf := io.NewBufBinWriter()
for hash, state := range u {
if err := state.EncodeBinary(buf.BinWriter); err != nil {
return err
}
key := storage.AppendPrefix(storage.STCoin, hash.BytesReverse())
b.Put(key, buf.Bytes())
buf.Reset()
}
return nil
}
// EncodeBinary encodes UnspentCoinState to the given BinWriter.
func (s *UnspentCoinState) EncodeBinary(bw *io.BinWriter) error {
bw.WriteVarUint(uint64(len(s.states)))
for _, state := range s.states {
bw.WriteLE(byte(state))
}
return bw.Err
}
// DecodeBinary decodes UnspentCoinState from the given BinReader.
func (s *UnspentCoinState) DecodeBinary(br *io.BinReader) error {
lenStates := br.ReadVarUint()
s.states = make([]CoinState, lenStates)
for i := 0; i < int(lenStates); i++ {
var state uint8
br.ReadLE(&state)
s.states[i] = CoinState(state)
}
return br.Err
}
// IsDoubleSpend verifies that the input transactions are not double spent.
func IsDoubleSpend(s storage.Store, tx *transaction.Transaction) bool {
if len(tx.Inputs) == 0 {
return false
}
for prevHash, inputs := range tx.GroupInputsByPrevHash() {
unspent := &UnspentCoinState{}
key := storage.AppendPrefix(storage.STCoin, prevHash.BytesReverse())
if b, err := s.Get(key); err == nil {
if err := unspent.DecodeBinary(io.NewBinReaderFromBuf(b)); err != nil {
return false
}
if unspent == nil {
return true
}
for _, input := range inputs {
if int(input.PrevIndex) >= len(unspent.states) || unspent.states[input.PrevIndex] == CoinStateSpent {
return true
}
}
}
}
return false
}