neoneo-go/pkg/core/mempool/mem_pool.go
2020-06-05 19:20:16 +03:00

377 lines
11 KiB
Go

package mempool
import (
"errors"
"sort"
"sync"
"time"
"github.com/nspcc-dev/neo-go/pkg/core/transaction"
"github.com/nspcc-dev/neo-go/pkg/util"
)
var (
// ErrConflict is returned when transaction being added is incompatible
// with the contents of the memory pool (using the same inputs as some
// other transaction 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")
)
// item represents a transaction in the the Memory pool.
type item struct {
txn *transaction.Transaction
timeStamp time.Time
isLowPrio bool
}
// 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
}
// utilityBalanceAndFees stores sender's balance and overall fees of
// sender's transactions which are currently in mempool
type utilityBalanceAndFees struct {
balance util.Fixed8
feeSum util.Fixed8
}
// Pool stores the unconfirms transactions.
type Pool struct {
lock sync.RWMutex
verifiedMap map[util.Uint256]*item
verifiedTxes items
inputs []*transaction.Input
fees map[util.Uint160]utilityBalanceAndFees
capacity int
}
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 {
if otherP == nil {
return 1
}
if !p.isLowPrio && otherP.isLowPrio {
return 1
}
if p.isLowPrio && !otherP.isLowPrio {
return -1
}
// Fees sorted ascending.
if ret := p.txn.FeePerByte().CompareTo(otherP.txn.FeePerByte()); ret != 0 {
return ret
}
if ret := p.txn.NetworkFee.CompareTo(otherP.txn.NetworkFee); ret != 0 {
return ret
}
// Transaction hash sorted descending.
return otherP.txn.Hash().CompareTo(p.txn.Hash())
}
// 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
}
// findIndexForInput finds an index in a sorted Input pointers slice that is
// appropriate to place this input into (or which contains an identical Input).
func findIndexForInput(slice []*transaction.Input, input *transaction.Input) int {
return sort.Search(len(slice), func(n int) bool {
return input.Cmp(slice[n]) <= 0
})
}
// pushInputToSortedSlice pushes new Input into the given slice.
func pushInputToSortedSlice(slice *[]*transaction.Input, input *transaction.Input) {
n := findIndexForInput(*slice, input)
*slice = append(*slice, input)
if n != len(*slice)-1 {
copy((*slice)[n+1:], (*slice)[n:])
(*slice)[n] = input
}
}
// dropInputFromSortedSlice removes given input from the given slice.
func dropInputFromSortedSlice(slice *[]*transaction.Input, input *transaction.Input) {
n := findIndexForInput(*slice, input)
if n == len(*slice) || *input != *(*slice)[n] {
// Not present.
return
}
copy((*slice)[n:], (*slice)[n+1:])
*slice = (*slice)[:len(*slice)-1]
}
// tryAddSendersFee tries to add system fee and network fee to the total sender`s fee in mempool
// and returns false if sender has not enough GAS to pay
func (mp *Pool) tryAddSendersFee(tx *transaction.Transaction, feer Feer) bool {
if !mp.checkBalanceAndUpdate(tx, feer) {
return false
}
mp.addSendersFee(tx)
return true
}
// checkBalanceAndUpdate returns true in case when sender has enough GAS to pay for
// the transaction and sets sender's balance value in mempool in case if it was not set
func (mp *Pool) checkBalanceAndUpdate(tx *transaction.Transaction, feer Feer) bool {
senderFee, ok := mp.fees[tx.Sender]
if !ok {
senderFee.balance = feer.GetUtilityTokenBalance(tx.Sender)
mp.fees[tx.Sender] = senderFee
}
needFee := senderFee.feeSum + tx.SystemFee + tx.NetworkFee
if senderFee.balance < needFee {
return false
}
return true
}
// addSendersFee adds system fee and network fee to the total sender`s fee in mempool
func (mp *Pool) addSendersFee(tx *transaction.Transaction) {
senderFee := mp.fees[tx.Sender]
senderFee.feeSum += tx.SystemFee + tx.NetworkFee
mp.fees[tx.Sender] = senderFee
}
// Add tries to add given transaction to the Pool.
func (mp *Pool) Add(t *transaction.Transaction, fee Feer) error {
var pItem = &item{
txn: t,
timeStamp: time.Now().UTC(),
}
pItem.isLowPrio = fee.IsLowPriority(pItem.txn.NetworkFee)
mp.lock.Lock()
if !mp.checkTxConflicts(t, fee) {
mp.lock.Unlock()
return ErrConflict
}
if mp.containsKey(t.Hash()) {
mp.lock.Unlock()
return ErrDup
}
mp.verifiedMap[t.Hash()] = pItem
// 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())
mp.verifiedTxes[len(mp.verifiedTxes)-1] = pItem
} 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.addSendersFee(pItem.txn)
// For lots of inputs it might be easier to push them all and sort
// afterwards, but that requires benchmarking.
for i := range t.Inputs {
pushInputToSortedSlice(&mp.inputs, &t.Inputs[i])
}
updateMempoolMetrics(len(mp.verifiedTxes))
mp.lock.Unlock()
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) {
mp.lock.Lock()
if it, 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
}
}
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]
}
senderFee := mp.fees[it.txn.Sender]
senderFee.feeSum -= it.txn.SystemFee + it.txn.NetworkFee
mp.fees[it.txn.Sender] = senderFee
for i := range it.txn.Inputs {
dropInputFromSortedSlice(&mp.inputs, &it.txn.Inputs[i])
}
}
updateMempoolMetrics(len(mp.verifiedTxes))
mp.lock.Unlock()
}
// 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()
// We can reuse already allocated slice
// because items are iterated one-by-one in increasing order.
newVerifiedTxes := mp.verifiedTxes[:0]
newInputs := mp.inputs[:0]
mp.fees = make(map[util.Uint160]utilityBalanceAndFees) // it'd be nice to reuse existing map, but we can't easily clear it
for _, itm := range mp.verifiedTxes {
if isOK(itm.txn) && mp.tryAddSendersFee(itm.txn, feer) {
newVerifiedTxes = append(newVerifiedTxes, itm)
for i := range itm.txn.Inputs {
newInputs = append(newInputs, &itm.txn.Inputs[i])
}
} else {
delete(mp.verifiedMap, itm.txn.Hash())
}
}
sort.Slice(newInputs, func(i, j int) bool {
return newInputs[i].Cmp(newInputs[j]) < 0
})
mp.verifiedTxes = newVerifiedTxes
mp.inputs = newInputs
mp.lock.Unlock()
}
// NewMemPool returns a new Pool struct.
func NewMemPool(capacity int) Pool {
return Pool{
verifiedMap: make(map[util.Uint256]*item),
verifiedTxes: make([]*item, 0, capacity),
capacity: capacity,
fees: make(map[util.Uint160]utilityBalanceAndFees),
}
}
// 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, pItem.txn.NetworkFee, ok
}
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() []TxWithFee {
mp.lock.RLock()
defer mp.lock.RUnlock()
var t = make([]TxWithFee, len(mp.verifiedTxes))
for i := range mp.verifiedTxes {
t[i].Tx = mp.verifiedTxes[i].txn
t[i].Fee = mp.verifiedTxes[i].txn.NetworkFee
}
return t
}
// areInputsInPool tries to find inputs in a given sorted pool and returns true
// if it finds any.
func areInputsInPool(inputs []transaction.Input, pool []*transaction.Input) bool {
for i := range inputs {
n := findIndexForInput(pool, &inputs[i])
if n < len(pool) && *pool[n] == inputs[i] {
return true
}
}
return false
}
// checkTxConflicts is an internal unprotected version of Verify.
func (mp *Pool) checkTxConflicts(tx *transaction.Transaction, fee Feer) bool {
if areInputsInPool(tx.Inputs, mp.inputs) {
return false
}
if !mp.checkBalanceAndUpdate(tx, fee) {
return false
}
switch tx.Type {
case transaction.IssueType:
// It's a hack, because technically we could check for
// available asset amount, but these transactions are so rare
// that no one really cares about this restriction.
for i := range mp.verifiedTxes {
if mp.verifiedTxes[i].txn.Type == transaction.IssueType {
return false
}
}
}
return true
}
// Verify verifies if the inputs of a transaction tx are already used in any other transaction in the memory pool.
// If yes, the transaction tx is not a valid transaction and the function return false.
// If no, the transaction tx is a valid transaction and the function return true.
func (mp *Pool) Verify(tx *transaction.Transaction, feer Feer) bool {
mp.lock.RLock()
defer mp.lock.RUnlock()
return mp.checkTxConflicts(tx, feer)
}