neo-go/pkg/core/mem_pool.go

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package core
import (
"sort"
"sync"
"time"
"github.com/CityOfZion/neo-go/pkg/core/transaction"
"github.com/CityOfZion/neo-go/pkg/util"
)
// PoolItem represents a transaction in the the Memory pool.
type PoolItem struct {
txn *transaction.Transaction
timeStamp time.Time
fee Feer
}
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// PoolItems slice of PoolItem.
type PoolItems []*PoolItem
// MemPool stores the unconfirms transactions.
type MemPool struct {
lock *sync.RWMutex
unsortedTxn map[util.Uint256]*PoolItem
unverifiedTxn map[util.Uint256]*PoolItem
sortedHighPrioTxn PoolItems
sortedLowPrioTxn PoolItems
unverifiedSortedHighPrioTxn PoolItems
unverifiedSortedLowPrioTxn PoolItems
capacity int
}
func (p PoolItems) Len() int { return len(p) }
func (p PoolItems) Swap(i, j int) { p[i], p[j] = p[j], p[i] }
func (p PoolItems) Less(i, j int) bool { return p[i].CompareTo(p[j]) < 0 }
// CompareTo returns the difference between two PoolItems.
// difference < 0 implies p < otherP.
// difference = 0 implies p = otherP.
// difference > 0 implies p > otherP.
func (p PoolItem) CompareTo(otherP *PoolItem) int {
if otherP == nil {
return 1
}
if p.fee.IsLowPriority(p.txn) && p.fee.IsLowPriority(otherP.txn) {
thisIsClaimTx := p.txn.Type == transaction.ClaimType
otherIsClaimTx := otherP.txn.Type == transaction.ClaimType
if thisIsClaimTx != otherIsClaimTx {
// This is a claim Tx and other isn't.
if thisIsClaimTx {
return 1
}
// The other is claim Tx and this isn't.
return -1
}
}
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// Fees sorted ascending.
pFPB := p.fee.FeePerByte(p.txn)
otherFPB := p.fee.FeePerByte(otherP.txn)
if ret := pFPB.CompareTo(otherFPB); ret != 0 {
return ret
}
pNF := p.fee.NetworkFee(p.txn)
otherNF := p.fee.NetworkFee(otherP.txn)
if ret := pNF.CompareTo(otherNF); ret != 0 {
return ret
}
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// Transaction hash sorted descending.
return otherP.txn.Hash().CompareTo(p.txn.Hash())
}
// Count returns the total number of uncofirm transactions.
func (mp MemPool) Count() int {
mp.lock.RLock()
defer mp.lock.RUnlock()
return len(mp.unsortedTxn) + len(mp.unverifiedTxn)
}
// ContainsKey checks if a transactions hash is in the MemPool.
func (mp MemPool) ContainsKey(hash util.Uint256) bool {
mp.lock.RLock()
defer mp.lock.RUnlock()
if _, ok := mp.unsortedTxn[hash]; ok {
return true
}
if _, ok := mp.unverifiedTxn[hash]; ok {
return true
}
return false
}
// TryAdd try to add the PoolItem to the MemPool.
func (mp MemPool) TryAdd(hash util.Uint256, pItem *PoolItem) bool {
var pool PoolItems
mp.lock.RLock()
if _, ok := mp.unsortedTxn[hash]; ok {
mp.lock.RUnlock()
return false
}
mp.unsortedTxn[hash] = pItem
mp.lock.RUnlock()
if pItem.fee.IsLowPriority(pItem.txn) {
pool = mp.sortedLowPrioTxn
} else {
pool = mp.sortedHighPrioTxn
}
mp.lock.Lock()
pool = append(pool, pItem)
sort.Sort(pool)
mp.lock.Unlock()
if mp.Count() > mp.capacity {
(&mp).RemoveOverCapacity()
}
mp.lock.RLock()
_, ok := mp.unsortedTxn[hash]
updateMempoolMetrics(len(mp.unsortedTxn), len(mp.unverifiedTxn))
mp.lock.RUnlock()
return ok
}
// Remove removes an item from the mempool, if it exists there (and does
// nothing if it doesn't).
func (mp *MemPool) Remove(hash util.Uint256) {
var mapAndPools = []struct {
unsortedMap map[util.Uint256]*PoolItem
sortedPools []*PoolItems
}{
{unsortedMap: mp.unsortedTxn, sortedPools: []*PoolItems{&mp.sortedHighPrioTxn, &mp.sortedLowPrioTxn}},
{unsortedMap: mp.unverifiedTxn, sortedPools: []*PoolItems{&mp.unverifiedSortedHighPrioTxn, &mp.unverifiedSortedLowPrioTxn}},
}
mp.lock.Lock()
for _, mapAndPool := range mapAndPools {
if _, ok := mapAndPool.unsortedMap[hash]; ok {
delete(mapAndPool.unsortedMap, hash)
for _, pool := range mapAndPool.sortedPools {
var num int
var item *PoolItem
for num, item = range *pool {
if hash.Equals(item.txn.Hash()) {
break
}
}
if num < len(*pool)-1 {
*pool = append((*pool)[:num], (*pool)[num+1:]...)
} else if num == len(*pool)-1 {
*pool = (*pool)[:num]
}
}
}
}
updateMempoolMetrics(len(mp.unsortedTxn), len(mp.unverifiedTxn))
mp.lock.Unlock()
}
// RemoveOverCapacity removes transactions with lowest fees until the total number of transactions
// in the MemPool is within the capacity of the MemPool.
func (mp *MemPool) RemoveOverCapacity() {
for mp.Count()-mp.capacity > 0 {
mp.lock.Lock()
if minItem, argPosition := getLowestFeeTransaction(mp.sortedLowPrioTxn, mp.unverifiedSortedLowPrioTxn); minItem != nil {
if argPosition == 1 {
// minItem belongs to the mp.sortedLowPrioTxn slice.
// The corresponding unsorted pool is is mp.unsortedTxn.
delete(mp.unsortedTxn, minItem.txn.Hash())
mp.sortedLowPrioTxn = append(mp.sortedLowPrioTxn[:0], mp.sortedLowPrioTxn[1:]...)
} else {
// minItem belongs to the mp.unverifiedSortedLowPrioTxn slice.
// The corresponding unsorted pool is is mp.unverifiedTxn.
delete(mp.unverifiedTxn, minItem.txn.Hash())
mp.unverifiedSortedLowPrioTxn = append(mp.unverifiedSortedLowPrioTxn[:0], mp.unverifiedSortedLowPrioTxn[1:]...)
}
} else if minItem, argPosition := getLowestFeeTransaction(mp.sortedHighPrioTxn, mp.unverifiedSortedHighPrioTxn); minItem != nil {
if argPosition == 1 {
// minItem belongs to the mp.sortedHighPrioTxn slice.
// The corresponding unsorted pool is is mp.unsortedTxn.
delete(mp.unsortedTxn, minItem.txn.Hash())
mp.sortedHighPrioTxn = append(mp.sortedHighPrioTxn[:0], mp.sortedHighPrioTxn[1:]...)
} else {
// minItem belongs to the mp.unverifiedSortedHighPrioTxn slice.
// The corresponding unsorted pool is is mp.unverifiedTxn.
delete(mp.unverifiedTxn, minItem.txn.Hash())
mp.unverifiedSortedHighPrioTxn = append(mp.unverifiedSortedHighPrioTxn[:0], mp.unverifiedSortedHighPrioTxn[1:]...)
}
}
updateMempoolMetrics(len(mp.unsortedTxn), len(mp.unverifiedTxn))
mp.lock.Unlock()
}
}
// NewPoolItem returns a new PoolItem.
func NewPoolItem(t *transaction.Transaction, fee Feer) *PoolItem {
return &PoolItem{
txn: t,
timeStamp: time.Now().UTC(),
fee: fee,
}
}
// NewMemPool returns a new MemPool struct.
func NewMemPool(capacity int) MemPool {
return MemPool{
lock: new(sync.RWMutex),
unsortedTxn: make(map[util.Uint256]*PoolItem),
unverifiedTxn: make(map[util.Uint256]*PoolItem),
capacity: capacity,
}
}
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// TryGetValue returns a transaction if it exists in the memory pool.
func (mp MemPool) TryGetValue(hash util.Uint256) (*transaction.Transaction, bool) {
mp.lock.Lock()
defer mp.lock.Unlock()
if pItem, ok := mp.unsortedTxn[hash]; ok {
return pItem.txn, ok
}
if pItem, ok := mp.unverifiedTxn[hash]; ok {
return pItem.txn, ok
}
return nil, false
}
// getLowestFeeTransaction returns the PoolItem with the lowest fee amongst the "verifiedTxnSorted"
// and "unverifiedTxnSorted" PoolItems along with a integer. The integer can assume two values, 1 and 2 which indicate
// that the PoolItem with the lowest fee was found in "verifiedTxnSorted" respectively in "unverifiedTxnSorted".
// "verifiedTxnSorted" and "unverifiedTxnSorted" are sorted slice order by transaction fee ascending. This means that
// the transaction with lowest fee start at index 0.
// Reference: GetLowestFeeTransaction method in C# (https://github.com/neo-project/neo/blob/master/neo/Ledger/MemoryPool.cs)
func getLowestFeeTransaction(verifiedTxnSorted PoolItems, unverifiedTxnSorted PoolItems) (*PoolItem, int) {
minItem := min(unverifiedTxnSorted)
verifiedMin := min(verifiedTxnSorted)
if verifiedMin == nil || (minItem != nil && verifiedMin.CompareTo(minItem) >= 0) {
return minItem, 2
}
minItem = verifiedMin
return minItem, 1
}
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// min returns the minimum item in a ascending sorted slice of pool items.
// The function can't be applied to unsorted slice!
func min(sortedPool PoolItems) *PoolItem {
if len(sortedPool) == 0 {
return nil
}
return sortedPool[0]
}
// GetVerifiedTransactions returns a slice of Input from all the transactions in the memory pool
// whose hash is not included in excludedHashes.
func (mp *MemPool) GetVerifiedTransactions() []*transaction.Transaction {
var t []*transaction.Transaction
mp.lock.Lock()
defer mp.lock.Unlock()
for _, p := range mp.unsortedTxn {
t = append(t, p.txn)
}
return t
}
// 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 MemPool) Verify(tx *transaction.Transaction) bool {
count := 0
inputs := make([]*transaction.Input, 0)
for _, item := range mp.GetVerifiedTransactions() {
if tx.Hash().Equals(item.Hash()) {
inputs = append(inputs, item.Inputs...)
}
}
for i := 0; i < len(inputs); i++ {
for j := 0; j < len(tx.Inputs); j++ {
if inputs[i].PrevHash.Equals(tx.Inputs[j].PrevHash) {
count++
}
}
}
return count == 0
}