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utxo.go
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utxo.go
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package Blockchain
import (
"encoding/hex"
"github.com/dgraph-io/badger"
)
const (
utxoPrefix = "utxo-"
prefixLength = len(utxoPrefix)
)
type UTXOSet struct {
Blockchain *Blockchain
}
func (u UTXOSet) DeleteByPrefix(prefix []byte) {
deleteKeys := func(keysForDeletion [][]byte) error {
// if err := u.Blockchain.Database.Update(
// func(txn *badger.Txn) error{
// for _, key := range keysForDeletion{
// err := txn.Delete(key)
// Handle(err)
// }
// return nil
// }); err != nil{
// return err
// }
err := u.Blockchain.Database.Update(
func(txn *badger.Txn) error {
for _, key := range keysForDeletion {
err := txn.Delete(key)
Handle(err)
}
return nil
})
Handle(err)
return nil //leave
}
collectSize := 1000
u.Blockchain.Database.View(
func(txn *badger.Txn) error {
opts := badger.DefaultIteratorOptions
opts.PrefetchSize = collectSize
opts.PrefetchValues = false
var it *badger.Iterator = txn.NewIterator(opts)
defer it.Close()
keysForDeletion := make([][]byte, 0, collectSize)
keysCollected := 0
for it.Seek(prefix); /*all of the keys containing the prefix*/ it.ValidForPrefix(prefix); it.Next() {
var key []byte = it.Item().KeyCopy(nil)
keysForDeletion = append(keysForDeletion, key)
keysCollected++
if keysCollected == collectSize {
err := deleteKeys(keysForDeletion)
Handle(err) //yaha change
keysForDeletion = make([][]byte, 0, collectSize)
keysCollected = 0
}
}
if keysCollected > 0 {
err := deleteKeys(keysForDeletion)
Handle(err)
}
return nil
})
}
func (u UTXOSet) Reindex() {
var db *badger.DB = u.Blockchain.Database
u.DeleteByPrefix([]byte(utxoPrefix))
var UTXOs map[string]TxOutputs = u.Blockchain.FindUTXO()
var err error = db.Update(func(txn *badger.Txn) error {
for txID, outputs := range UTXOs {
key, err := hex.DecodeString(txID) //converting the hex string to byte array
Handle(err)
key = append([]byte(utxoPrefix), key...)
err = txn.Set(key, outputs.SerializeOutputs())
Handle(err)
}
return nil
})
Handle(err)
}
func (u UTXOSet) Update(block *Block) {
var db *badger.DB = u.Blockchain.Database
var err error = db.Update(func(txn *badger.Txn) error {
for _, tx := range block.Transactions {
if tx.Is_Coinbase() == false {
for _, input := range tx.Inputs {
var updatedOutputs TxOutputs
var inID []byte = append([]byte(utxoPrefix), input.ID...)
item, err := txn.Get(inID)
Handle(err)
value, err := item.ValueCopy([]byte{})
Handle(err)
var outputs TxOutputs = DeserializeOutputs(value)
for outIdx, output := range outputs.Outputs {
if outIdx != input.OutputIdx { //if the output is not the one being spent
updatedOutputs.Outputs = append(updatedOutputs.Outputs, output)
}
}
if len(updatedOutputs.Outputs) == 0 {
err := txn.Delete(inID)
Handle(err)
} else {
err := txn.Set(inID, updatedOutputs.SerializeOutputs())
Handle(err)
}
}
}
//change here if problem arises
var newOutputs TxOutputs
for _, output := range tx.Outputs {
newOutputs.Outputs = append(newOutputs.Outputs, output)
}
var txID []byte = append([]byte(utxoPrefix), tx.ID...)
err := txn.Set(txID, newOutputs.SerializeOutputs())
Handle(err)
}
return nil
})
Handle(err)
}
func (u UTXOSet) CountTransactions() int {
var db *badger.DB = u.Blockchain.Database
counter := 0
err := db.View(func(txn *badger.Txn) error {
var opts badger.IteratorOptions = badger.DefaultIteratorOptions
var it *badger.Iterator = txn.NewIterator(opts)
defer it.Close()
for it.Seek([]byte(utxoPrefix)); it.ValidForPrefix([]byte(utxoPrefix)); it.Next() {
counter++
}
return nil
})
Handle(err)
return counter
}
func (u UTXOSet) FindUnspentTransactions(pubKeyHash []byte) []TxOutput {
var UTXOs []TxOutput
var db *badger.DB = u.Blockchain.Database
err := db.View(func(txn *badger.Txn) error {
var opts badger.IteratorOptions = badger.DefaultIteratorOptions
var it *badger.Iterator = txn.NewIterator(opts)
defer it.Close()
for it.Seek([]byte(utxoPrefix)); it.ValidForPrefix([]byte(utxoPrefix)); it.Next(){
var item *badger.Item = it.Item()
value, err := item.ValueCopy([]byte{})
Handle(err)
var outputs TxOutputs = DeserializeOutputs(value)
for _, output := range outputs.Outputs{
if output.IsLockedWithKey(pubKeyHash){
UTXOs = append(UTXOs, output)
}
}
}
return nil
})
Handle(err)
return UTXOs
}
func (u UTXOSet) FindSpendableOutputs(pubKeyHash []byte, amount int) (int, map[string][]int) {
var unspentOutputs map[string][]int = make(map[string][]int)
var accumulated int = 0
var db *badger.DB = u.Blockchain.Database
err := db.View(func(txn *badger.Txn) error {
var opts badger.IteratorOptions = badger.DefaultIteratorOptions
var it *badger.Iterator = txn.NewIterator(opts)
defer it.Close()
for it.Seek([]byte(utxoPrefix)); it.ValidForPrefix([]byte(utxoPrefix)); it.Next(){
var item *badger.Item = it.Item()
var key []byte = item.Key()
value, err := item.ValueCopy([]byte{})
Handle(err)
key = key[prefixLength:] //removing the prefix
var txID string = hex.EncodeToString(key)
var outputs TxOutputs = DeserializeOutputs(value)
for outIdx, out := range outputs.Outputs {
if out.IsLockedWithKey(pubKeyHash) && accumulated < amount {
accumulated += out.Value
unspentOutputs[txID] = append(unspentOutputs[txID], outIdx)
}
}
}
return nil
})
Handle(err)
return accumulated, unspentOutputs
}