291 lines
7.7 KiB
Go
291 lines
7.7 KiB
Go
package mempool
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import (
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"errors"
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"sort"
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"sync"
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"time"
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"github.com/CityOfZion/neo-go/pkg/core/transaction"
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"github.com/CityOfZion/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 (using the same inputs as some
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// other transaction 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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perByteFee util.Fixed8
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netFee util.Fixed8
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isLowPrio bool
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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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// 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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capacity int
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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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if !p.isLowPrio && otherP.isLowPrio {
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return 1
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}
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if p.isLowPrio && !otherP.isLowPrio {
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return -1
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}
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if p.isLowPrio && otherP.isLowPrio {
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thisIsClaimTx := p.txn.Type == transaction.ClaimType
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otherIsClaimTx := otherP.txn.Type == transaction.ClaimType
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if thisIsClaimTx != otherIsClaimTx {
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// This is a claim Tx and other isn't.
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if thisIsClaimTx {
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return 1
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}
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// The other is claim Tx and this isn't.
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return -1
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}
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}
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// Fees sorted ascending.
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if ret := p.perByteFee.CompareTo(otherP.perByteFee); ret != 0 {
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return ret
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}
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if ret := p.netFee.CompareTo(otherP.netFee); 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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// 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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perByteFee: fee.FeePerByte(t),
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netFee: fee.NetworkFee(t),
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isLowPrio: fee.IsLowPriority(t),
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}
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mp.lock.Lock()
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if !mp.verifyInputs(t) {
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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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mp.verifiedTxes = append(mp.verifiedTxes, pItem)
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if n != len(mp.verifiedTxes) {
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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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mp.lock.Unlock()
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if mp.Count() > mp.capacity {
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mp.RemoveOverCapacity()
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}
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mp.lock.RLock()
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_, ok := mp.verifiedMap[t.Hash()]
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updateMempoolMetrics(len(mp.verifiedTxes))
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mp.lock.RUnlock()
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if !ok {
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return ErrOOM
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}
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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 _, 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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}
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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) {
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mp.lock.Lock()
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// We expect a lot of changes, so it's easier to allocate a new slice
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// rather than move things in an old one.
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newVerifiedTxes := make([]*item, 0, mp.capacity)
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for _, itm := range mp.verifiedTxes {
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if isOK(itm.txn) {
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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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// RemoveOverCapacity removes transactions with lowest fees until the total number of transactions
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// in the Pool is within the capacity of the Pool.
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func (mp *Pool) RemoveOverCapacity() {
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mp.lock.Lock()
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num := mp.count() - mp.capacity
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for i := 1; i <= num; i++ {
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txToDrop := mp.verifiedTxes[len(mp.verifiedTxes)-num].txn
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delete(mp.verifiedMap, txToDrop.Hash())
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}
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mp.verifiedTxes = mp.verifiedTxes[:len(mp.verifiedTxes)-num]
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updateMempoolMetrics(mp.count())
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mp.lock.Unlock()
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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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}
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}
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// TryGetValue returns a transaction 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 Input from all the transactions in the memory pool
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// whose hash is not included in excludedHashes.
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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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var i int
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for _, p := range mp.verifiedTxes {
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t[i] = p.txn
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i++
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}
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return t
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}
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// verifyInputs is an internal unprotected version of Verify.
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func (mp *Pool) verifyInputs(tx *transaction.Transaction) bool {
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if len(tx.Inputs) == 0 {
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return true
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}
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for num := range mp.verifiedTxes {
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txn := mp.verifiedTxes[num].txn
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for i := range txn.Inputs {
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for j := 0; j < len(tx.Inputs); j++ {
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if txn.Inputs[i] == tx.Inputs[j] {
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return false
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}
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}
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}
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}
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return true
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}
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// Verify verifies if the inputs of a transaction tx are already used in any other transaction in the memory pool.
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// If yes, the transaction tx is not a valid transaction and the function return false.
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// If no, the transaction tx is a valid transaction and the function return true.
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func (mp *Pool) Verify(tx *transaction.Transaction) bool {
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mp.lock.RLock()
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defer mp.lock.RUnlock()
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return mp.verifyInputs(tx)
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}
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