blockchain sandbox: UTXO chain, p2p mining, attacker node

chain/mempool.go

@@ -0,0 +1,87 @@
+package chain
+
+import (
+	"blockchain/config"
+	"crypto/ed25519"
+	"slices"
+	"sync"
+)
+
+type Mempool struct {
+	transations []*Transaction
+	mx          sync.Mutex
+}
+
+func NewMempool() *Mempool {
+	return &Mempool{}
+}
+
+func (m *Mempool) Add(tx *Transaction) {
+	if !tx.Verify() {
+		return
+	}
+	m.mx.Lock()
+	m.transations = append(m.transations, tx)
+	m.mx.Unlock()
+}
+
+func (m *Mempool) Len() int {
+	m.mx.Lock()
+	defer m.mx.Unlock()
+
+	return len(m.transations)
+}
+
+func (m *Mempool) CollectBlock(miner ed25519.PublicKey) []*Transaction {
+	m.mx.Lock()
+	defer m.mx.Unlock()
+
+	txs := []*Transaction{NewCoinbaseTransaction(miner, config.Default.Chain.MiningReward)}
+	spent := make(map[string]struct{})
+
+	isSpent := func(s CoinSpend) bool {
+		_, ok := spent[s.CoinID.Key()]
+		return ok
+	}
+
+	for _, tx := range m.transations {
+		if slices.ContainsFunc(tx.Spends, isSpent) {
+			continue
+		}
+
+		txs = append(txs, tx)
+
+		for _, s := range tx.Spends {
+			spent[s.CoinID.Key()] = struct{}{}
+		}
+	}
+
+	return txs
+}
+
+func (m *Mempool) RemoveMined(block *Block) {
+	spent := make(map[string]struct{})
+	for _, tx := range block.Transactions {
+		if tx.IsCoinbase() {
+			continue
+		}
+		for _, s := range tx.Spends {
+			spent[s.CoinID.Key()] = struct{}{}
+		}
+	}
+	if len(spent) == 0 {
+		return
+	}
+
+	m.mx.Lock()
+	defer m.mx.Unlock()
+
+	isSpent := func(s CoinSpend) bool {
+		_, ok := spent[s.CoinID.Key()]
+		return ok
+	}
+
+	m.transations = slices.DeleteFunc(m.transations, func(tx *Transaction) bool {
+		return slices.ContainsFunc(tx.Spends, isSpent)
+	})
+}