neoneo-go/pkg/core/mempool/mem_pool.go
2021-02-02 22:01:32 +03:00

588 lines
19 KiB
Go

package mempool
import (
"errors"
"fmt"
"math/big"
"math/bits"
"sort"
"sync"
"github.com/nspcc-dev/neo-go/pkg/core/transaction"
"github.com/nspcc-dev/neo-go/pkg/util"
"go.uber.org/atomic"
)
var (
// ErrInsufficientFunds is returned when Sender is not able to pay for
// transaction being added irrespective of the other contents of the
// pool.
ErrInsufficientFunds = errors.New("insufficient funds")
// ErrConflict is returned when transaction being added is incompatible
// with the contents of the memory pool (Sender doesn't have enough GAS
// to pay for all transactions in the pool).
ErrConflict = errors.New("conflicts with the memory pool")
// ErrDup is returned when transaction being added is already present
// in the memory pool.
ErrDup = errors.New("already in the memory pool")
// ErrOOM is returned when transaction just doesn't fit in the memory
// pool because of its capacity constraints.
ErrOOM = errors.New("out of memory")
// ErrConflictsAttribute is returned when transaction conflicts with other transactions
// due to its (or theirs) Conflicts attributes.
ErrConflictsAttribute = errors.New("conflicts with memory pool due to Conflicts attribute")
// ErrOracleResponse is returned when mempool already contains transaction
// with the same oracle response ID and higher network fee.
ErrOracleResponse = errors.New("conflicts with memory pool due to OracleResponse attribute")
)
// item represents a transaction in the the Memory pool.
type item struct {
txn *transaction.Transaction
blockStamp uint32
data interface{}
}
// items is a slice of item.
type items []item
// utilityBalanceAndFees stores sender's balance and overall fees of
// sender's transactions which are currently in mempool
type utilityBalanceAndFees struct {
balance *big.Int
feeSum *big.Int
}
// Pool stores the unconfirms transactions.
type Pool struct {
lock sync.RWMutex
verifiedMap map[util.Uint256]*transaction.Transaction
verifiedTxes items
fees map[util.Uint160]utilityBalanceAndFees
// conflicts is a map of hashes of transactions which are conflicting with the mempooled ones.
conflicts map[util.Uint256][]util.Uint256
// oracleResp contains ids of oracle responses for tx in pool.
oracleResp map[uint64]util.Uint256
capacity int
feePerByte int64
payerIndex int
resendThreshold uint32
resendFunc func(*transaction.Transaction, interface{})
// subscriptions for mempool events
subscriptionsEnabled bool
subscriptionsOn atomic.Bool
stopCh chan struct{}
events chan Event
subCh chan chan<- Event // there are no other events in mempool except Event, so no need in generic subscribers type
unsubCh chan chan<- Event
}
func (p items) Len() int { return len(p) }
func (p items) Swap(i, j int) { p[i], p[j] = p[j], p[i] }
func (p items) Less(i, j int) bool { return p[i].CompareTo(p[j]) < 0 }
// CompareTo returns the difference between two items.
// difference < 0 implies p < otherP.
// difference = 0 implies p = otherP.
// difference > 0 implies p > otherP.
func (p item) CompareTo(otherP item) int {
pHigh := p.txn.HasAttribute(transaction.HighPriority)
otherHigh := otherP.txn.HasAttribute(transaction.HighPriority)
if pHigh && !otherHigh {
return 1
} else if !pHigh && otherHigh {
return -1
}
// Fees sorted ascending.
if ret := int(p.txn.FeePerByte() - otherP.txn.FeePerByte()); ret != 0 {
return ret
}
return int(p.txn.NetworkFee - otherP.txn.NetworkFee)
}
// Count returns the total number of uncofirm transactions.
func (mp *Pool) Count() int {
mp.lock.RLock()
defer mp.lock.RUnlock()
return mp.count()
}
// count is an internal unlocked version of Count.
func (mp *Pool) count() int {
return len(mp.verifiedTxes)
}
// ContainsKey checks if a transactions hash is in the Pool.
func (mp *Pool) ContainsKey(hash util.Uint256) bool {
mp.lock.RLock()
defer mp.lock.RUnlock()
return mp.containsKey(hash)
}
// containsKey is an internal unlocked version of ContainsKey.
func (mp *Pool) containsKey(hash util.Uint256) bool {
if _, ok := mp.verifiedMap[hash]; ok {
return true
}
return false
}
// HasConflicts returns true if transaction is already in pool or in the Conflicts attributes
// of pooled transactions or has Conflicts attributes for pooled transactions.
func (mp *Pool) HasConflicts(t *transaction.Transaction, fee Feer) bool {
mp.lock.RLock()
defer mp.lock.RUnlock()
if mp.containsKey(t.Hash()) {
return true
}
if fee.P2PSigExtensionsEnabled() {
// do not check sender's signature and fee
if _, ok := mp.conflicts[t.Hash()]; ok {
return true
}
for _, attr := range t.GetAttributes(transaction.ConflictsT) {
if mp.containsKey(attr.Value.(*transaction.Conflicts).Hash) {
return true
}
}
}
return false
}
// tryAddSendersFee tries to add system fee and network fee to the total sender`s fee in mempool
// and returns false if both balance check is required and sender has not enough GAS to pay
func (mp *Pool) tryAddSendersFee(tx *transaction.Transaction, feer Feer, needCheck bool) bool {
payer := tx.Signers[mp.payerIndex].Account
senderFee, ok := mp.fees[payer]
if !ok {
senderFee.balance = feer.GetUtilityTokenBalance(payer)
senderFee.feeSum = big.NewInt(0)
mp.fees[payer] = senderFee
}
if needCheck {
newFeeSum, err := checkBalance(tx, senderFee)
if err != nil {
return false
}
senderFee.feeSum.Set(newFeeSum)
} else {
senderFee.feeSum.Add(senderFee.feeSum, big.NewInt(tx.SystemFee+tx.NetworkFee))
}
return true
}
// checkBalance returns new cumulative fee balance for account or an error in
// case sender doesn't have enough GAS to pay for the transaction.
func checkBalance(tx *transaction.Transaction, balance utilityBalanceAndFees) (*big.Int, error) {
txFee := big.NewInt(tx.SystemFee + tx.NetworkFee)
if balance.balance.Cmp(txFee) < 0 {
return nil, ErrInsufficientFunds
}
txFee.Add(txFee, balance.feeSum)
if balance.balance.Cmp(txFee) < 0 {
return nil, ErrConflict
}
return txFee, nil
}
// Add tries to add given transaction to the Pool.
func (mp *Pool) Add(t *transaction.Transaction, fee Feer, data ...interface{}) error {
var pItem = item{
txn: t,
blockStamp: fee.BlockHeight(),
}
if data != nil {
pItem.data = data[0]
}
mp.lock.Lock()
if mp.containsKey(t.Hash()) {
mp.lock.Unlock()
return ErrDup
}
conflictsToBeRemoved, err := mp.checkTxConflicts(t, fee)
if err != nil {
mp.lock.Unlock()
return err
}
if attrs := t.GetAttributes(transaction.OracleResponseT); len(attrs) != 0 {
id := attrs[0].Value.(*transaction.OracleResponse).ID
h, ok := mp.oracleResp[id]
if ok {
if mp.verifiedMap[h].NetworkFee >= t.NetworkFee {
mp.lock.Unlock()
return ErrOracleResponse
}
mp.removeInternal(h, fee)
}
mp.oracleResp[id] = t.Hash()
}
if fee.P2PSigExtensionsEnabled() {
// Remove conflicting transactions.
for _, conflictingTx := range conflictsToBeRemoved {
mp.removeInternal(conflictingTx.Hash(), fee)
}
}
// Insert into sorted array (from max to min, that could also be done
// using sort.Sort(sort.Reverse()), but it incurs more overhead. Notice
// also that we're searching for position that is strictly more
// prioritized than our new item because we do expect a lot of
// transactions with the same priority and appending to the end of the
// slice is always more efficient.
n := sort.Search(len(mp.verifiedTxes), func(n int) bool {
return pItem.CompareTo(mp.verifiedTxes[n]) > 0
})
// We've reached our capacity already.
if len(mp.verifiedTxes) == mp.capacity {
// Less prioritized than the least prioritized we already have, won't fit.
if n == len(mp.verifiedTxes) {
mp.lock.Unlock()
return ErrOOM
}
// Ditch the last one.
unlucky := mp.verifiedTxes[len(mp.verifiedTxes)-1]
delete(mp.verifiedMap, unlucky.txn.Hash())
if fee.P2PSigExtensionsEnabled() {
mp.removeConflictsOf(unlucky.txn)
}
if attrs := unlucky.txn.GetAttributes(transaction.OracleResponseT); len(attrs) != 0 {
delete(mp.oracleResp, attrs[0].Value.(*transaction.OracleResponse).ID)
}
mp.verifiedTxes[len(mp.verifiedTxes)-1] = pItem
if mp.subscriptionsOn.Load() {
mp.events <- Event{
Type: TransactionRemoved,
Tx: unlucky.txn,
Data: unlucky.data,
}
}
} else {
mp.verifiedTxes = append(mp.verifiedTxes, pItem)
}
if n != len(mp.verifiedTxes)-1 {
copy(mp.verifiedTxes[n+1:], mp.verifiedTxes[n:])
mp.verifiedTxes[n] = pItem
}
mp.verifiedMap[t.Hash()] = t
if fee.P2PSigExtensionsEnabled() {
// Add conflicting hashes to the mp.conflicts list.
for _, attr := range t.GetAttributes(transaction.ConflictsT) {
hash := attr.Value.(*transaction.Conflicts).Hash
mp.conflicts[hash] = append(mp.conflicts[hash], t.Hash())
}
}
// we already checked balance in checkTxConflicts, so don't need to check again
mp.tryAddSendersFee(pItem.txn, fee, false)
updateMempoolMetrics(len(mp.verifiedTxes))
mp.lock.Unlock()
if mp.subscriptionsOn.Load() {
mp.events <- Event{
Type: TransactionAdded,
Tx: pItem.txn,
Data: pItem.data,
}
}
return nil
}
// Remove removes an item from the mempool, if it exists there (and does
// nothing if it doesn't).
func (mp *Pool) Remove(hash util.Uint256, feer Feer) {
mp.lock.Lock()
mp.removeInternal(hash, feer)
mp.lock.Unlock()
}
// removeInternal is an internal unlocked representation of Remove
func (mp *Pool) removeInternal(hash util.Uint256, feer Feer) {
if tx, ok := mp.verifiedMap[hash]; ok {
var num int
delete(mp.verifiedMap, hash)
for num = range mp.verifiedTxes {
if hash.Equals(mp.verifiedTxes[num].txn.Hash()) {
break
}
}
itm := mp.verifiedTxes[num]
if num < len(mp.verifiedTxes)-1 {
mp.verifiedTxes = append(mp.verifiedTxes[:num], mp.verifiedTxes[num+1:]...)
} else if num == len(mp.verifiedTxes)-1 {
mp.verifiedTxes = mp.verifiedTxes[:num]
}
payer := itm.txn.Signers[mp.payerIndex].Account
senderFee := mp.fees[payer]
senderFee.feeSum.Sub(senderFee.feeSum, big.NewInt(tx.SystemFee+tx.NetworkFee))
mp.fees[payer] = senderFee
if feer.P2PSigExtensionsEnabled() {
// remove all conflicting hashes from mp.conflicts list
mp.removeConflictsOf(tx)
}
if attrs := tx.GetAttributes(transaction.OracleResponseT); len(attrs) != 0 {
delete(mp.oracleResp, attrs[0].Value.(*transaction.OracleResponse).ID)
}
if mp.subscriptionsOn.Load() {
mp.events <- Event{
Type: TransactionRemoved,
Tx: itm.txn,
Data: itm.data,
}
}
}
updateMempoolMetrics(len(mp.verifiedTxes))
}
// RemoveStale filters verified transactions through the given function keeping
// only the transactions for which it returns a true result. It's used to quickly
// drop part of the mempool that is now invalid after the block acceptance.
func (mp *Pool) RemoveStale(isOK func(*transaction.Transaction) bool, feer Feer) {
mp.lock.Lock()
policyChanged := mp.loadPolicy(feer)
// We can reuse already allocated slice
// because items are iterated one-by-one in increasing order.
newVerifiedTxes := mp.verifiedTxes[:0]
mp.fees = make(map[util.Uint160]utilityBalanceAndFees) // it'd be nice to reuse existing map, but we can't easily clear it
if feer.P2PSigExtensionsEnabled() {
mp.conflicts = make(map[util.Uint256][]util.Uint256)
}
height := feer.BlockHeight()
var (
staleItems []item
)
for _, itm := range mp.verifiedTxes {
if isOK(itm.txn) && mp.checkPolicy(itm.txn, policyChanged) && mp.tryAddSendersFee(itm.txn, feer, true) {
newVerifiedTxes = append(newVerifiedTxes, itm)
if feer.P2PSigExtensionsEnabled() {
for _, attr := range itm.txn.GetAttributes(transaction.ConflictsT) {
hash := attr.Value.(*transaction.Conflicts).Hash
mp.conflicts[hash] = append(mp.conflicts[hash], itm.txn.Hash())
}
}
if mp.resendThreshold != 0 {
// item is resend at resendThreshold, 2*resendThreshold, 4*resendThreshold ...
// so quotient must be a power of two.
diff := (height - itm.blockStamp)
if diff%mp.resendThreshold == 0 && bits.OnesCount32(diff/mp.resendThreshold) == 1 {
staleItems = append(staleItems, itm)
}
}
} else {
delete(mp.verifiedMap, itm.txn.Hash())
if attrs := itm.txn.GetAttributes(transaction.OracleResponseT); len(attrs) != 0 {
delete(mp.oracleResp, attrs[0].Value.(*transaction.OracleResponse).ID)
}
if mp.subscriptionsOn.Load() {
mp.events <- Event{
Type: TransactionRemoved,
Tx: itm.txn,
Data: itm.data,
}
}
}
}
if len(staleItems) != 0 {
go mp.resendStaleItems(staleItems)
}
mp.verifiedTxes = newVerifiedTxes
mp.lock.Unlock()
}
// loadPolicy updates feePerByte field and returns whether policy has been
// changed.
func (mp *Pool) loadPolicy(feer Feer) bool {
newFeePerByte := feer.FeePerByte()
if newFeePerByte > mp.feePerByte {
mp.feePerByte = newFeePerByte
return true
}
return false
}
// checkPolicy checks whether transaction fits policy.
func (mp *Pool) checkPolicy(tx *transaction.Transaction, policyChanged bool) bool {
if !policyChanged || tx.FeePerByte() >= mp.feePerByte {
return true
}
return false
}
// New returns a new Pool struct.
func New(capacity int, payerIndex int, enableSubscriptions bool) *Pool {
mp := &Pool{
verifiedMap: make(map[util.Uint256]*transaction.Transaction),
verifiedTxes: make([]item, 0, capacity),
capacity: capacity,
payerIndex: payerIndex,
fees: make(map[util.Uint160]utilityBalanceAndFees),
conflicts: make(map[util.Uint256][]util.Uint256),
oracleResp: make(map[uint64]util.Uint256),
subscriptionsEnabled: enableSubscriptions,
stopCh: make(chan struct{}),
events: make(chan Event),
subCh: make(chan chan<- Event),
unsubCh: make(chan chan<- Event),
}
mp.subscriptionsOn.Store(false)
return mp
}
// SetResendThreshold sets threshold after which transaction will be considered stale
// and returned for retransmission by `GetStaleTransactions`.
func (mp *Pool) SetResendThreshold(h uint32, f func(*transaction.Transaction, interface{})) {
mp.lock.Lock()
defer mp.lock.Unlock()
mp.resendThreshold = h
mp.resendFunc = f
}
func (mp *Pool) resendStaleItems(items []item) {
for i := range items {
mp.resendFunc(items[i].txn, items[i].data)
}
}
// TryGetValue returns a transaction and its fee if it exists in the memory pool.
func (mp *Pool) TryGetValue(hash util.Uint256) (*transaction.Transaction, bool) {
mp.lock.RLock()
defer mp.lock.RUnlock()
if tx, ok := mp.verifiedMap[hash]; ok {
return tx, ok
}
return nil, false
}
// TryGetData returns data associated with the specified transaction if it exists in the memory pool.
func (mp *Pool) TryGetData(hash util.Uint256) (interface{}, bool) {
mp.lock.RLock()
defer mp.lock.RUnlock()
if tx, ok := mp.verifiedMap[hash]; ok {
itm := item{txn: tx}
n := sort.Search(len(mp.verifiedTxes), func(n int) bool {
return itm.CompareTo(mp.verifiedTxes[n]) >= 0
})
if n < len(mp.verifiedTxes) {
for i := n; i < len(mp.verifiedTxes); i++ { // items may have equal priority, so `n` is the left bound of the items which are as prioritized as the desired `itm`.
if mp.verifiedTxes[i].txn.Hash() == hash {
return mp.verifiedTxes[i].data, ok
}
if itm.CompareTo(mp.verifiedTxes[i]) != 0 {
break
}
}
}
}
return nil, false
}
// GetVerifiedTransactions returns a slice of transactions with their fees.
func (mp *Pool) GetVerifiedTransactions() []*transaction.Transaction {
mp.lock.RLock()
defer mp.lock.RUnlock()
var t = make([]*transaction.Transaction, len(mp.verifiedTxes))
for i := range mp.verifiedTxes {
t[i] = mp.verifiedTxes[i].txn
}
return t
}
// checkTxConflicts is an internal unprotected version of Verify. It takes into
// consideration conflicting transactions which are about to be removed from mempool.
func (mp *Pool) checkTxConflicts(tx *transaction.Transaction, fee Feer) ([]*transaction.Transaction, error) {
payer := tx.Signers[mp.payerIndex].Account
actualSenderFee, ok := mp.fees[payer]
if !ok {
actualSenderFee.balance = fee.GetUtilityTokenBalance(payer)
actualSenderFee.feeSum = big.NewInt(0)
}
var expectedSenderFee utilityBalanceAndFees
// Check Conflicts attributes.
var conflictsToBeRemoved []*transaction.Transaction
if fee.P2PSigExtensionsEnabled() {
// Step 1: check if `tx` was in attributes of mempooled transactions.
if conflictingHashes, ok := mp.conflicts[tx.Hash()]; ok {
for _, hash := range conflictingHashes {
existingTx := mp.verifiedMap[hash]
if existingTx.HasSigner(payer) && existingTx.NetworkFee > tx.NetworkFee {
return nil, fmt.Errorf("%w: conflicting transaction %s has bigger network fee", ErrConflictsAttribute, existingTx.Hash().StringBE())
}
conflictsToBeRemoved = append(conflictsToBeRemoved, existingTx)
}
}
// Step 2: check if mempooled transactions were in `tx`'s attributes.
for _, attr := range tx.GetAttributes(transaction.ConflictsT) {
hash := attr.Value.(*transaction.Conflicts).Hash
existingTx, ok := mp.verifiedMap[hash]
if !ok {
continue
}
if !tx.HasSigner(existingTx.Signers[mp.payerIndex].Account) {
return nil, fmt.Errorf("%w: not signed by the sender of conflicting transaction %s", ErrConflictsAttribute, existingTx.Hash().StringBE())
}
if existingTx.NetworkFee >= tx.NetworkFee {
return nil, fmt.Errorf("%w: conflicting transaction %s has bigger or equal network fee", ErrConflictsAttribute, existingTx.Hash().StringBE())
}
conflictsToBeRemoved = append(conflictsToBeRemoved, existingTx)
}
// Step 3: take into account sender's conflicting transactions before balance check.
expectedSenderFee = utilityBalanceAndFees{
balance: new(big.Int).Set(actualSenderFee.balance),
feeSum: new(big.Int).Set(actualSenderFee.feeSum),
}
for _, conflictingTx := range conflictsToBeRemoved {
if conflictingTx.Signers[mp.payerIndex].Account.Equals(payer) {
expectedSenderFee.feeSum.Sub(expectedSenderFee.feeSum, big.NewInt(conflictingTx.SystemFee+conflictingTx.NetworkFee))
}
}
} else {
expectedSenderFee = actualSenderFee
}
_, err := checkBalance(tx, expectedSenderFee)
return conflictsToBeRemoved, err
}
// Verify checks if a Sender of tx is able to pay for it (and all the other
// transactions in the pool). If yes, the transaction tx is a valid
// transaction and the function returns true. If no, the transaction tx is
// considered to be invalid the function returns false.
func (mp *Pool) Verify(tx *transaction.Transaction, feer Feer) bool {
mp.lock.RLock()
defer mp.lock.RUnlock()
_, err := mp.checkTxConflicts(tx, feer)
return err == nil
}
// removeConflictsOf removes hash of the given transaction from the conflicts list
// for each Conflicts attribute.
func (mp *Pool) removeConflictsOf(tx *transaction.Transaction) {
// remove all conflicting hashes from mp.conflicts list
for _, attr := range tx.GetAttributes(transaction.ConflictsT) {
conflictsHash := attr.Value.(*transaction.Conflicts).Hash
if len(mp.conflicts[conflictsHash]) == 1 {
delete(mp.conflicts, conflictsHash)
continue
}
for i, existingHash := range mp.conflicts[conflictsHash] {
if existingHash == tx.Hash() {
// tx.Hash can occur in the conflicting hashes array only once, because we can't add the same transaction to the mempol twice
mp.conflicts[conflictsHash] = append(mp.conflicts[conflictsHash][:i], mp.conflicts[conflictsHash][i+1:]...)
break
}
}
}
}