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 } // 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 } } // 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 } // 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.Lock() if _, ok := mp.unsortedTxn[hash]; ok { mp.lock.Unlock() return false } mp.unsortedTxn[hash] = pItem mp.lock.Unlock() 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, } } // TryGetValue returns a transaction if it exists in the memory pool. func (mp MemPool) TryGetValue(hash util.Uint256) (*transaction.Transaction, bool) { mp.lock.RLock() defer mp.lock.RUnlock() 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 } // 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.RLock() defer mp.lock.RUnlock() 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 }