302 lines
8.9 KiB
Go
302 lines
8.9 KiB
Go
package mempool
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import (
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"errors"
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"math/big"
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"sort"
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"sync"
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"time"
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"github.com/nspcc-dev/neo-go/pkg/core/transaction"
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"github.com/nspcc-dev/neo-go/pkg/util"
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)
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var (
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// ErrConflict is returned when transaction being added is incompatible
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// with the contents of the memory pool (Sender doesn't have enough GAS
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// to pay for all transactions in the pool).
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ErrConflict = errors.New("conflicts with the memory pool")
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// ErrDup is returned when transaction being added is already present
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// in the memory pool.
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ErrDup = errors.New("already in the memory pool")
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// ErrOOM is returned when transaction just doesn't fit in the memory
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// pool because of its capacity constraints.
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ErrOOM = errors.New("out of memory")
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)
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// item represents a transaction in the the Memory pool.
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type item struct {
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txn *transaction.Transaction
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timeStamp time.Time
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}
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// items is a slice of item.
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type items []*item
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// utilityBalanceAndFees stores sender's balance and overall fees of
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// sender's transactions which are currently in mempool
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type utilityBalanceAndFees struct {
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balance *big.Int
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feeSum int64
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}
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// Pool stores the unconfirms transactions.
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type Pool struct {
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lock sync.RWMutex
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verifiedMap map[util.Uint256]*item
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verifiedTxes items
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fees map[util.Uint160]utilityBalanceAndFees
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capacity int
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feePerByte int64
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}
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func (p items) Len() int { return len(p) }
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func (p items) Swap(i, j int) { p[i], p[j] = p[j], p[i] }
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func (p items) Less(i, j int) bool { return p[i].CompareTo(p[j]) < 0 }
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// CompareTo returns the difference between two items.
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// difference < 0 implies p < otherP.
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// difference = 0 implies p = otherP.
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// difference > 0 implies p > otherP.
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func (p *item) CompareTo(otherP *item) int {
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if otherP == nil {
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return 1
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}
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// Fees sorted ascending.
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if ret := int(p.txn.FeePerByte() - otherP.txn.FeePerByte()); ret != 0 {
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return ret
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}
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if ret := int(p.txn.NetworkFee - otherP.txn.NetworkFee); ret != 0 {
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return ret
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}
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// Transaction hash sorted descending.
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return otherP.txn.Hash().CompareTo(p.txn.Hash())
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}
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// Count returns the total number of uncofirm transactions.
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func (mp *Pool) Count() int {
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mp.lock.RLock()
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defer mp.lock.RUnlock()
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return mp.count()
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}
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// count is an internal unlocked version of Count.
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func (mp *Pool) count() int {
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return len(mp.verifiedTxes)
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}
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// ContainsKey checks if a transactions hash is in the Pool.
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func (mp *Pool) ContainsKey(hash util.Uint256) bool {
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mp.lock.RLock()
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defer mp.lock.RUnlock()
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return mp.containsKey(hash)
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}
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// containsKey is an internal unlocked version of ContainsKey.
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func (mp *Pool) containsKey(hash util.Uint256) bool {
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if _, ok := mp.verifiedMap[hash]; ok {
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return true
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}
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return false
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}
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// tryAddSendersFee tries to add system fee and network fee to the total sender`s fee in mempool
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// and returns false if both balance check is required and sender has not enough GAS to pay
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func (mp *Pool) tryAddSendersFee(tx *transaction.Transaction, feer Feer, needCheck bool) bool {
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senderFee, ok := mp.fees[tx.Sender()]
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if !ok {
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senderFee.balance = feer.GetUtilityTokenBalance(tx.Sender())
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mp.fees[tx.Sender()] = senderFee
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}
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if needCheck && !checkBalance(tx, senderFee) {
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return false
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}
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senderFee.feeSum += tx.SystemFee + tx.NetworkFee
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mp.fees[tx.Sender()] = senderFee
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return true
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}
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// checkBalance returns true in case when sender has enough GAS to pay for the
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// transaction
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func checkBalance(tx *transaction.Transaction, balance utilityBalanceAndFees) bool {
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needFee := balance.feeSum + tx.SystemFee + tx.NetworkFee
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return balance.balance.Cmp(big.NewInt(needFee)) >= 0
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}
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// Add tries to add given transaction to the Pool.
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func (mp *Pool) Add(t *transaction.Transaction, fee Feer) error {
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var pItem = &item{
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txn: t,
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timeStamp: time.Now().UTC(),
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}
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mp.lock.Lock()
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if !mp.checkTxConflicts(t, fee) {
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mp.lock.Unlock()
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return ErrConflict
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}
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if mp.containsKey(t.Hash()) {
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mp.lock.Unlock()
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return ErrDup
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}
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mp.verifiedMap[t.Hash()] = pItem
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// Insert into sorted array (from max to min, that could also be done
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// using sort.Sort(sort.Reverse()), but it incurs more overhead. Notice
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// also that we're searching for position that is strictly more
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// prioritized than our new item because we do expect a lot of
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// transactions with the same priority and appending to the end of the
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// slice is always more efficient.
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n := sort.Search(len(mp.verifiedTxes), func(n int) bool {
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return pItem.CompareTo(mp.verifiedTxes[n]) > 0
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})
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// We've reached our capacity already.
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if len(mp.verifiedTxes) == mp.capacity {
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// Less prioritized than the least prioritized we already have, won't fit.
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if n == len(mp.verifiedTxes) {
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mp.lock.Unlock()
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return ErrOOM
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}
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// Ditch the last one.
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unlucky := mp.verifiedTxes[len(mp.verifiedTxes)-1]
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delete(mp.verifiedMap, unlucky.txn.Hash())
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mp.verifiedTxes[len(mp.verifiedTxes)-1] = pItem
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} else {
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mp.verifiedTxes = append(mp.verifiedTxes, pItem)
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}
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if n != len(mp.verifiedTxes)-1 {
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copy(mp.verifiedTxes[n+1:], mp.verifiedTxes[n:])
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mp.verifiedTxes[n] = pItem
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}
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// we already checked balance in checkTxConflicts, so don't need to check again
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mp.tryAddSendersFee(pItem.txn, fee, false)
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updateMempoolMetrics(len(mp.verifiedTxes))
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mp.lock.Unlock()
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return nil
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}
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// Remove removes an item from the mempool, if it exists there (and does
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// nothing if it doesn't).
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func (mp *Pool) Remove(hash util.Uint256) {
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mp.lock.Lock()
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if it, ok := mp.verifiedMap[hash]; ok {
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var num int
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delete(mp.verifiedMap, hash)
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for num = range mp.verifiedTxes {
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if hash.Equals(mp.verifiedTxes[num].txn.Hash()) {
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break
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}
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}
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if num < len(mp.verifiedTxes)-1 {
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mp.verifiedTxes = append(mp.verifiedTxes[:num], mp.verifiedTxes[num+1:]...)
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} else if num == len(mp.verifiedTxes)-1 {
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mp.verifiedTxes = mp.verifiedTxes[:num]
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}
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senderFee := mp.fees[it.txn.Sender()]
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senderFee.feeSum -= it.txn.SystemFee + it.txn.NetworkFee
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mp.fees[it.txn.Sender()] = senderFee
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}
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updateMempoolMetrics(len(mp.verifiedTxes))
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mp.lock.Unlock()
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}
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// RemoveStale filters verified transactions through the given function keeping
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// only the transactions for which it returns a true result. It's used to quickly
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// drop part of the mempool that is now invalid after the block acceptance.
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func (mp *Pool) RemoveStale(isOK func(*transaction.Transaction) bool, feer Feer) {
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mp.lock.Lock()
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policyChanged := mp.loadPolicy(feer)
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// We can reuse already allocated slice
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// because items are iterated one-by-one in increasing order.
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newVerifiedTxes := mp.verifiedTxes[:0]
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mp.fees = make(map[util.Uint160]utilityBalanceAndFees) // it'd be nice to reuse existing map, but we can't easily clear it
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for _, itm := range mp.verifiedTxes {
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if isOK(itm.txn) && mp.checkPolicy(itm.txn, policyChanged) && mp.tryAddSendersFee(itm.txn, feer, true) {
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newVerifiedTxes = append(newVerifiedTxes, itm)
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} else {
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delete(mp.verifiedMap, itm.txn.Hash())
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}
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}
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mp.verifiedTxes = newVerifiedTxes
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mp.lock.Unlock()
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}
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// loadPolicy updates feePerByte field and returns whether policy has been
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// changed.
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func (mp *Pool) loadPolicy(feer Feer) bool {
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newFeePerByte := feer.FeePerByte()
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if newFeePerByte > mp.feePerByte {
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mp.feePerByte = newFeePerByte
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return true
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}
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return false
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}
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// checkPolicy checks whether transaction fits policy.
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func (mp *Pool) checkPolicy(tx *transaction.Transaction, policyChanged bool) bool {
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if !policyChanged || tx.FeePerByte() >= mp.feePerByte {
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return true
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}
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return false
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}
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// NewMemPool returns a new Pool struct.
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func NewMemPool(capacity int) Pool {
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return Pool{
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verifiedMap: make(map[util.Uint256]*item),
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verifiedTxes: make([]*item, 0, capacity),
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capacity: capacity,
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fees: make(map[util.Uint160]utilityBalanceAndFees),
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}
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}
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// TryGetValue returns a transaction and its fee if it exists in the memory pool.
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func (mp *Pool) TryGetValue(hash util.Uint256) (*transaction.Transaction, bool) {
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mp.lock.RLock()
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defer mp.lock.RUnlock()
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if pItem, ok := mp.verifiedMap[hash]; ok {
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return pItem.txn, ok
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}
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return nil, false
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}
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// GetVerifiedTransactions returns a slice of transactions with their fees.
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func (mp *Pool) GetVerifiedTransactions() []*transaction.Transaction {
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mp.lock.RLock()
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defer mp.lock.RUnlock()
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var t = make([]*transaction.Transaction, len(mp.verifiedTxes))
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for i := range mp.verifiedTxes {
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t[i] = mp.verifiedTxes[i].txn
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}
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return t
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}
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// checkTxConflicts is an internal unprotected version of Verify.
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func (mp *Pool) checkTxConflicts(tx *transaction.Transaction, fee Feer) bool {
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senderFee, ok := mp.fees[tx.Sender()]
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if !ok {
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senderFee.balance = fee.GetUtilityTokenBalance(tx.Sender())
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}
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return checkBalance(tx, senderFee)
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}
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// Verify checks if a Sender of tx is able to pay for it (and all the other
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// transactions in the pool). If yes, the transaction tx is a valid
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// transaction and the function returns true. If no, the transaction tx is
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// considered to be invalid the function returns false.
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func (mp *Pool) Verify(tx *transaction.Transaction, feer Feer) bool {
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mp.lock.RLock()
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defer mp.lock.RUnlock()
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return mp.checkTxConflicts(tx, feer)
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}
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