mempool: return fee along with tx when requesting tx

Users of GetVerifiedTransactions() don't want to recalculate tx fee and it's
nice to have it returned from TryGetValue() also sometimes.

pkg/consensus/consensus.go

@@ -9,6 +9,7 @@ import (
 	"github.com/CityOfZion/neo-go/config"
 	"github.com/CityOfZion/neo-go/pkg/core"
 	coreb "github.com/CityOfZion/neo-go/pkg/core/block"
+	"github.com/CityOfZion/neo-go/pkg/core/mempool"
 	"github.com/CityOfZion/neo-go/pkg/core/transaction"
 	"github.com/CityOfZion/neo-go/pkg/crypto/hash"
 	"github.com/CityOfZion/neo-go/pkg/crypto/keys"
@@ -412,13 +413,13 @@ func (s *service) getBlock(h util.Uint256) block.Block {
 func (s *service) getVerifiedTx(count int) []block.Transaction {
 	pool := s.Config.Chain.GetMemPool()
 
-	var txx []*transaction.Transaction
+	var txx []mempool.TxWithFee
 
 	if s.dbft.ViewNumber > 0 {
-		txx = make([]*transaction.Transaction, 0, len(s.lastProposal))
+		txx = make([]mempool.TxWithFee, 0, len(s.lastProposal))
 		for i := range s.lastProposal {
-			if tx, ok := pool.TryGetValue(s.lastProposal[i]); ok {
-				txx = append(txx, tx)
+			if tx, fee, ok := pool.TryGetValue(s.lastProposal[i]); ok {
+				txx = append(txx, mempool.TxWithFee{Tx: tx, Fee: fee})
 			}
 		}
 
@@ -432,8 +433,8 @@ func (s *service) getVerifiedTx(count int) []block.Transaction {
 	res := make([]block.Transaction, len(txx)+1)
 	var netFee util.Fixed8
 	for i := range txx {
-		res[i+1] = txx[i]
-		netFee += s.Config.Chain.NetworkFee(txx[i])
+		res[i+1] = txx[i].Tx
+		netFee += txx[i].Fee
 	}
 
 	var txOuts []transaction.Output

pkg/core/blockchain.go

@@ -814,7 +814,7 @@ func (bc *Blockchain) headerListLen() (n int) {
 
 // GetTransaction returns a TX and its height by the given hash.
 func (bc *Blockchain) GetTransaction(hash util.Uint256) (*transaction.Transaction, uint32, error) {
-	if tx, ok := bc.memPool.TryGetValue(hash); ok {
+	if tx, _, ok := bc.memPool.TryGetValue(hash); ok {
 		return tx, 0, nil // the height is not actually defined for memPool transaction. Not sure if zero is a good number in this case.
 	}
 	return bc.dao.GetTransaction(hash)

pkg/core/mempool/mem_pool.go

@@ -35,6 +35,12 @@ type item struct {
 // items is a slice of item.
 type items []*item
 
+// TxWithFee combines transaction and its precalculated network fee.
+type TxWithFee struct {
+	Tx  *transaction.Transaction
+	Fee util.Fixed8
+}
+
 // Pool stores the unconfirms transactions.
 type Pool struct {
 	lock         sync.RWMutex
@@ -224,29 +230,28 @@ func NewMemPool(capacity int) Pool {
 	}
 }
 
-// TryGetValue returns a transaction if it exists in the memory pool.
-func (mp *Pool) TryGetValue(hash util.Uint256) (*transaction.Transaction, bool) {
+// TryGetValue returns a transaction and its fee if it exists in the memory pool.
+func (mp *Pool) TryGetValue(hash util.Uint256) (*transaction.Transaction, util.Fixed8, bool) {
 	mp.lock.RLock()
 	defer mp.lock.RUnlock()
 	if pItem, ok := mp.verifiedMap[hash]; ok {
-		return pItem.txn, ok
+		return pItem.txn, pItem.netFee, ok
 	}
 
-	return nil, false
+	return nil, 0, false
 }
 
 // GetVerifiedTransactions returns a slice of Input from all the transactions in the memory pool
 // whose hash is not included in excludedHashes.
-func (mp *Pool) GetVerifiedTransactions() []*transaction.Transaction {
+func (mp *Pool) GetVerifiedTransactions() []TxWithFee {
 	mp.lock.RLock()
 	defer mp.lock.RUnlock()
 
-	var t = make([]*transaction.Transaction, len(mp.verifiedTxes))
-	var i int
+	var t = make([]TxWithFee, len(mp.verifiedTxes))
 
-	for _, p := range mp.verifiedTxes {
-		t[i] = p.txn
-		i++
+	for i := range mp.verifiedTxes {
+		t[i].Tx = mp.verifiedTxes[i].txn
+		t[i].Fee = mp.verifiedTxes[i].netFee
 	}
 
 	return t

pkg/core/mempool/mem_pool_test.go

@@ -37,16 +37,16 @@ func (fs *FeerStub) SystemFee(*transaction.Transaction) util.Fixed8 {
 func testMemPoolAddRemoveWithFeer(t *testing.T, fs Feer) {
 	mp := NewMemPool(10)
 	tx := newMinerTX(0)
-	_, ok := mp.TryGetValue(tx.Hash())
+	_, _, ok := mp.TryGetValue(tx.Hash())
 	require.Equal(t, false, ok)
 	require.NoError(t, mp.Add(tx, fs))
 	// Re-adding should fail.
 	require.Error(t, mp.Add(tx, fs))
-	tx2, ok := mp.TryGetValue(tx.Hash())
+	tx2, _, ok := mp.TryGetValue(tx.Hash())
 	require.Equal(t, true, ok)
 	require.Equal(t, tx, tx2)
 	mp.Remove(tx.Hash())
-	_, ok = mp.TryGetValue(tx.Hash())
+	_, _, ok = mp.TryGetValue(tx.Hash())
 	require.Equal(t, false, ok)
 	// Make sure nothing left in the mempool after removal.
 	assert.Equal(t, 0, len(mp.verifiedMap))
@@ -173,8 +173,8 @@ func TestGetVerified(t *testing.T) {
 	require.Equal(t, mempoolSize, mp.Count())
 	verTxes := mp.GetVerifiedTransactions()
 	require.Equal(t, mempoolSize, len(verTxes))
-	for _, tx := range verTxes {
-		require.Contains(t, txes, tx)
+	for _, txf := range verTxes {
+		require.Contains(t, txes, txf.Tx)
 	}
 	for _, tx := range txes {
 		mp.Remove(tx.Hash())
@@ -210,8 +210,8 @@ func TestRemoveStale(t *testing.T) {
 	})
 	require.Equal(t, mempoolSize/2, mp.Count())
 	verTxes := mp.GetVerifiedTransactions()
-	for _, tx := range verTxes {
-		require.NotContains(t, txes1, tx)
-		require.Contains(t, txes2, tx)
+	for _, txf := range verTxes {
+		require.NotContains(t, txes1, txf.Tx)
+		require.Contains(t, txes2, txf.Tx)
 	}
 }