Txpool is mainly used to store the currently committed transactions waiting to be written to the block, both remote and local. Txlist is more on the heap structure.
There are two types of transactions in txpool.
- Submitted but not yet executable, placed in the queue waiting to be executed (for example, nonce is too high).
- Waiting for execution, put it in pending and wait for execution.
From the test case of txpool, the main functions of txpool are as follows.
- The function of transaction verification, including insufficient balance, insufficient Gas, Nonce is too low, value is illegal, can not be negative.
- Ability to cache transactions where Nonce is in a higher state than the current local account. Stored in the queue field. If it is a transaction that can be executed, it is stored in the pending field.
- The same Nonce transaction for the same user will only retain the one with the largest GasPrice. Other inserts were unsuccessful.
- If the account has no money, the transaction of the corresponding account in queue and pending will be deleted.
- If the balance of the account is less than the amount of some transactions, the corresponding transaction will be deleted, and the valid transaction will be moved from pending to queue. Prevent being broadcast.
- txPool supports some restrictions on PriceLimit (remove the lowest GasPrice limit), PriceBump (the percentage of the price of the transaction that replaces the same Nonce) AccountSlots (the minimum value of the pending slot for each account) GlobalSlots (the maximum value of the global pending queue) AccountQueue ( The minimum value of the queue for each account) GlobalQueue (maximum value of global queueing) Lifetime (the longest waiting time in the queue)
- Replace with the priority of GasPrice in the case of limited resources.
- Local transactions will be stored on disk using the journal's functionality and will be re-imported after reboot. Remote transaction will not.
data structure
// TxPool contains all currently known transactions. Transactions
// enter the pool when they are received from the network or submitted
// locally. They exit the pool when they are included in the blockchain.
// The pool separates processable transactions (which can be applied to the
// current state) and future transactions. Transactions move between those
// two states over time as they are received and processed.
type TxPool struct {
config TxPoolConfig
chainconfig *params.ChainConfig
chain blockChain
gasPrice *big.Int
txFeed event.Feed
scope event.SubscriptionScope
chainHeadCh chan ChainHeadEvent // subscribed to the message of the block header, and will receive a notification here when a new block header is generated.
chainHeadSub event.Subscription
signer types.Signer // Encapsulate transaction signature processing.
mu sync.RWMutex
currentState *state.StateDB // Current state in the blockchain head
pendingState *state.ManagedState // Pending state tracking virtual nonces
currentMaxGas *big.Int // Current gas limit for transaction caps
locals *accountSet // Set of local transaction to exepmt from eviction rules
journal *txJournal // Journal of local transaction to back up to disk
pending map[common.Address]*txList // All currently processable transactions
queue map[common.Address]*txList // Queued but non-processable transactions
beats map[common.Address]time.Time // Last heartbeat from each known account
all map[common.Hash]*types.Transaction // All transactions to allow lookups
priced *txPricedList // All transactions sorted by price
wg sync.WaitGroup // for shutdown sync
homestead bool // home version
}Construct
// NewTxPool creates a new transaction pool to gather, sort and filter inbound
// trnsactions from the network.
func NewTxPool(config TxPoolConfig, chainconfig *params.ChainConfig, chain blockChain) *TxPool {
// Sanitize the input to ensure no vulnerable gas prices are set
config = (&config).sanitize()
// Create the transaction pool with its initial settings
pool := &TxPool{
config: config,
chainconfig: chainconfig,
chain: chain,
signer: types.NewEIP155Signer(chainconfig.ChainId),
pending: make(map[common.Address]*txList),
queue: make(map[common.Address]*txList),
beats: make(map[common.Address]time.Time),
all: make(map[common.Hash]*types.Transaction),
chainHeadCh: make(chan ChainHeadEvent, chainHeadChanSize),
gasPrice: new(big.Int).SetUint64(config.PriceLimit),
}
pool.locals = newAccountSet(pool.signer)
pool.priced = newTxPricedList(&pool.all)
pool.reset(nil, chain.CurrentBlock().Header())
// If local transactions and journaling is enabled, load from disk
// If the local transaction is allowed and the configured Journal directory is not empty, load the log from the specified directory.
// Then rotate the transaction log. Since the old transaction may have expired, the received transaction is written to the log after the add method is called.
if !config.NoLocals && config.Journal != "" {
pool.journal = newTxJournal(config.Journal)
if err := pool.journal.load(pool.AddLocal); err != nil {
log.Warn("Failed to load transaction journal", "err", err)
}
if err := pool.journal.rotate(pool.local()); err != nil {
log.Warn("Failed to rotate transaction journal", "err", err)
}
}
// Subscribe events from blockchain
pool.chainHeadSub = pool.chain.SubscribeChainHeadEvent(pool.chainHeadCh)
// Start the event loop and return
pool.wg.Add(1)
go pool.loop()
return pool
}The reset method retrieves the current state of the blockchain and ensures that the contents of the transaction pool are valid with respect to the current blockchain state. The main features include:
- Because the block header was replaced, some transactions in the original block were invalidated due to the replacement of the block header. This part of the transaction needs to be re-added to the txPool to wait for the new block to be inserted.
- Generate new currentState and pendingState
- Move some of the transactions in pending to the queue
- The transaction in the queue is moved into the pending.
reset code
// reset retrieves the current state of the blockchain and ensures the content
// of the transaction pool is valid with regard to the chain state.
func (pool *TxPool) reset(oldHead, newHead *types.Header) {
// If we're reorging an old state, reinject all dropped transactions
var reinject types.Transactions
if oldHead != nil && oldHead.Hash() != newHead.ParentHash {
// If the reorg is too deep, avoid doing it (will happen during fast sync)
oldNum := oldHead.Number.Uint64()
newNum := newHead.Number.Uint64()
if depth := uint64(math.Abs(float64(oldNum) - float64(newNum))); depth > 64 {
//If the old head and the new head are too far apart, then cancel the rebuild
log.Warn("Skipping deep transaction reorg", "depth", depth)
} else {
// Reorg seems shallow enough to pull in all transactions into memory
var discarded, included types.Transactions
var (
rem = pool.chain.GetBlock(oldHead.Hash(), oldHead.Number.Uint64())
add = pool.chain.GetBlock(newHead.Hash(), newHead.Number.Uint64())
)
// If the old height is greater than the new one, then you need to delete all of it.
for rem.NumberU64() > add.NumberU64() {
discarded = append(discarded, rem.Transactions()...)
if rem = pool.chain.GetBlock(rem.ParentHash(), rem.NumberU64()-1); rem == nil {
log.Error("Unrooted old chain seen by tx pool", "block", oldHead.Number, "hash", oldHead.Hash())
return
}
}
// If the new height is greater than the old one, then it needs to be increased.
for add.NumberU64() > rem.NumberU64() {
included = append(included, add.Transactions()...)
if add = pool.chain.GetBlock(add.ParentHash(), add.NumberU64()-1); add == nil {
log.Error("Unrooted new chain seen by tx pool", "block", newHead.Number, "hash", newHead.Hash())
return
}
}
// The height is the same. If the hashes are different, then you need to find them backwards and find the nodes have the same hash roots.
for rem.Hash() != add.Hash() {
discarded = append(discarded, rem.Transactions()...)
if rem = pool.chain.GetBlock(rem.ParentHash(), rem.NumberU64()-1); rem == nil {
log.Error("Unrooted old chain seen by tx pool", "block", oldHead.Number, "hash", oldHead.Hash())
return
}
included = append(included, add.Transactions()...)
if add = pool.chain.GetBlock(add.ParentHash(), add.NumberU64()-1); add == nil {
log.Error("Unrooted new chain seen by tx pool", "block", newHead.Number, "hash", newHead.Hash())
return
}
}
// Find out all the values that exist in the discard, but not in the included.
// Need to wait for these transactions to be reinserted into the pool.
reinject = types.TxDifference(discarded, included)
}
}
// Initialize the internal state to the current head
if newHead == nil {
newHead = pool.chain.CurrentBlock().Header() // Special case during testing
}
statedb, err := pool.chain.StateAt(newHead.Root)
if err != nil {
log.Error("Failed to reset txpool state", "err", err)
return
}
pool.currentState = statedb
pool.pendingState = state.ManageState(statedb)
pool.currentMaxGas = newHead.GasLimit
// Inject any transactions discarded due to reorgs
log.Debug("Reinjecting stale transactions", "count", len(reinject))
pool.addTxsLocked(reinject, false)
// validate the pool of pending transactions, this will remove
// any transactions that have been included in the block or
// have been invalidated because of another transaction (e.g.
// higher gas price)
pool.demoteUnexecutables()
// Update all accounts to the latest known pending nonce
for addr, list := range pool.pending {
txs := list.Flatten() // Heavy but will be cached and is needed by the miner anyway
pool.pendingState.SetNonce(addr, txs[len(txs)-1].Nonce()+1)
}
// Check the queue and move transactions over to the pending if possible
// or remove those that have become invalid
pool.promoteExecutables(nil)
}addTx
// addTx enqueues a single transaction into the pool if it is valid.
func (pool *TxPool) addTx(tx *types.Transaction, local bool) error {
pool.mu.Lock()
defer pool.mu.Unlock()
// Try to inject the transaction and update any state
replace, err := pool.add(tx, local)
if err != nil {
return err
}
// If we added a new transaction, run promotion checks and return
if !replace {
from, _ := types.Sender(pool.signer, tx) // already validated
pool.promoteExecutables([]common.Address{from})
}
return nil
}addTxsLocked
// addTxsLocked attempts to queue a batch of transactions if they are valid,
// whilst assuming the transaction pool lock is already held.
func (pool *TxPool) addTxsLocked(txs []*types.Transaction, local bool) error {
// Add the batch of transaction, tracking the accepted ones
dirty := make(map[common.Address]struct{})
for _, tx := range txs {
if replace, err := pool.add(tx, local); err == nil {
if !replace { // replace: if it is not a replacement, then it means that the status is updated, there is a possibility that it can be processed in the next step.
from, _ := types.Sender(pool.signer, tx) // already validated
dirty[from] = struct{}{}
}
}
}
// Only reprocess the internal state if something was actually added
if len(dirty) > 0 {
addrs := make([]common.Address, 0, len(dirty))
for addr, _ := range dirty {
addrs = append(addrs, addr)
}
// modified address
pool.promoteExecutables(addrs)
}
return nil
}demoteUnexecutables deletes invalid or processed transactions from pending, and other unexecutable transactions are moved to the future queue.
// demoteUnexecutables removes invalid and processed transactions from the pools
// executable/pending queue and any subsequent transactions that become unexecutable
// are moved back into the future queue.
func (pool *TxPool) demoteUnexecutables() {
// Iterate over all accounts and demote any non-executable transactions
for addr, list := range pool.pending {
nonce := pool.currentState.GetNonce(addr)
// Drop all transactions that are deemed too old (low nonce)
for _, tx := range list.Forward(nonce) {
hash := tx.Hash()
log.Trace("Removed old pending transaction", "hash", hash)
delete(pool.all, hash)
pool.priced.Removed()
}
// Drop all transactions that are too costly (low balance or out of gas), and queue any invalids back for later
drops, invalids := list.Filter(pool.currentState.GetBalance(addr), pool.currentMaxGas)
for _, tx := range drops {
hash := tx.Hash()
log.Trace("Removed unpayable pending transaction", "hash", hash)
delete(pool.all, hash)
pool.priced.Removed()
pendingNofundsCounter.Inc(1)
}
for _, tx := range invalids {
hash := tx.Hash()
log.Trace("Demoting pending transaction", "hash", hash)
pool.enqueueTx(hash, tx)
}
// If there's a gap in front, warn (should never happen) and postpone all transactions
// This step should indeed not happen because Filter has already processed invalids. There should be no transactions for invalids, that is, there are no holes.
if list.Len() > 0 && list.txs.Get(nonce) == nil {
for _, tx := range list.Cap(0) {
hash := tx.Hash()
log.Error("Demoting invalidated transaction", "hash", hash)
pool.enqueueTx(hash, tx)
}
}
// Delete the entire queue entry if it became empty.
if list.Empty() {
delete(pool.pending, addr)
delete(pool.beats, addr)
}
}
}enqueueTx inserts a new transaction into the future queue. This method assumes that the pool's lock has been acquired.
// enqueueTx inserts a new transaction into the non-executable transaction queue.
// Note, this method assumes the pool lock is held!
func (pool *TxPool) enqueueTx(hash common.Hash, tx *types.Transaction) (bool, error) {
// Try to insert the transaction into the future queue
from, _ := types.Sender(pool.signer, tx) // already validated
if pool.queue[from] == nil {
pool.queue[from] = newTxList(false)
}
inserted, old := pool.queue[from].Add(tx, pool.config.PriceBump)
if !inserted {
// An older transaction was better, discard this
queuedDiscardCounter.Inc(1)
return false, ErrReplaceUnderpriced
}
// Discard any previous transaction and mark this
if old != nil {
delete(pool.all, old.Hash())
pool.priced.Removed()
queuedReplaceCounter.Inc(1)
}
pool.all[hash] = tx
pool.priced.Put(tx)
return old != nil, nil
}The promoteExecutables method inserts transactions that have become executable from the future queue into the pending queue. Through this process, all invalid transactions (nonce too low, insufficient balance) will be deleted.
// promoteExecutables moves transactions that have become processable from the
// future queue to the set of pending transactions. During this process, all
// invalidated transactions (low nonce, low balance) are deleted.
func (pool *TxPool) promoteExecutables(accounts []common.Address) {
// Gather all the accounts potentially needing updates
// accounts store all the accounts that need to be updated. If the account is passed in as nil, it represents all known accounts.
if accounts == nil {
accounts = make([]common.Address, 0, len(pool.queue))
for addr, _ := range pool.queue {
accounts = append(accounts, addr)
}
}
// Iterate over all accounts and promote any executable transactions
for _, addr := range accounts {
list := pool.queue[addr]
if list == nil {
continue // Just in case someone calls with a non existing account
}
// Drop all transactions that are deemed too old (low nonce)
for _, tx := range list.Forward(pool.currentState.GetNonce(addr)) {
hash := tx.Hash()
log.Trace("Removed old queued transaction", "hash", hash)
delete(pool.all, hash)
pool.priced.Removed()
}
// Drop all transactions that are too costly (low balance or out of gas)
drops, _ := list.Filter(pool.currentState.GetBalance(addr), pool.currentMaxGas)
for _, tx := range drops {
hash := tx.Hash()
log.Trace("Removed unpayable queued transaction", "hash", hash)
delete(pool.all, hash)
pool.priced.Removed()
queuedNofundsCounter.Inc(1)
}
// Gather all executable transactions and promote them
for _, tx := range list.Ready(pool.pendingState.GetNonce(addr)) {
hash := tx.Hash()
log.Trace("Promoting queued transaction", "hash", hash)
pool.promoteTx(addr, hash, tx)
}
// Drop all transactions over the allowed limit
if !pool.locals.contains(addr) {
for _, tx := range list.Cap(int(pool.config.AccountQueue)) {
hash := tx.Hash()
delete(pool.all, hash)
pool.priced.Removed()
queuedRateLimitCounter.Inc(1)
log.Trace("Removed cap-exceeding queued transaction", "hash", hash)
}
}
// Delete the entire queue entry if it became empty.
if list.Empty() {
delete(pool.queue, addr)
}
}
// If the pending limit is overflown, start equalizing allowances
pending := uint64(0)
for _, list := range pool.pending {
pending += uint64(list.Len())
}
// If the total number of pending exceeds the configuration of the system.
if pending > pool.config.GlobalSlots {
pendingBeforeCap := pending
// Assemble a spam order to penalize large transactors first
spammers := prque.New()
for addr, list := range pool.pending {
// Only evict transactions from high rollers
// First record all accounts larger than the minimum value of AccountSlots, and some transactions will be removed from these accounts.
// Note that spammers are a priority queue, which is sorted by the number of transactions from large to small.
if !pool.locals.contains(addr) && uint64(list.Len()) > pool.config.AccountSlots {
spammers.Push(addr, float32(list.Len()))
}
}
// Gradually drop transactions from offenders
offenders := []common.Address{}
for pending > pool.config.GlobalSlots && !spammers.Empty() {
// Simulate changes in the number of account transactions in the offenders queue.
// First cycle [10] end of cycle [10]
// Second cycle [10, 9] End of cycle [9,9]
// Third cycle [9, 9, 7] End of cycle [7, 7, 7]
// Fourth cycle [7, 7 , 7 , 2] End of cycle [2, 2 , 2, 2]
// Retrieve the next offender if not local address
offender, _ := spammers.Pop()
offenders = append(offenders, offender.(common.Address))
// Equalize balances until all the same or below threshold
if len(offenders) > 1 { // When entering this loop for the first time, there are two accounts with the largest number of transactions in the offenders queue.
// Calculate the equalization threshold for all current offenders
// The transaction amount of the last added account is the threshold of the cost
threshold := pool.pending[offender.(common.Address)].Len()
// Iteratively reduce all offenders until below limit or threshold reached
for pending > pool.config.GlobalSlots && pool.pending[offenders[len(offenders)-2]].Len() > threshold {
// Traverse all accounts except the last one, and subtract the number of their transactions by 1.
for i := 0; i < len(offenders)-1; i++ {
list := pool.pending[offenders[i]]
for _, tx := range list.Cap(list.Len() - 1) {
// Drop the transaction from the global pools too
hash := tx.Hash()
delete(pool.all, hash)
pool.priced.Removed()
// Update the account nonce to the dropped transaction
if nonce := tx.Nonce(); pool.pendingState.GetNonce(offenders[i]) > nonce {
pool.pendingState.SetNonce(offenders[i], nonce)
}
log.Trace("Removed fairness-exceeding pending transaction", "hash", hash)
}
pending--
}
}
}
}
// If still above threshold, reduce to limit or min allowance
// After the above loop, the number of transactions for all accounts that exceed AccountSlots has changed to the previous minimum.
// If the threshold is still exceeded, then continue to delete one from the offenders each time.
if pending > pool.config.GlobalSlots && len(offenders) > 0 {
for pending > pool.config.GlobalSlots && uint64(pool.pending[offenders[len(offenders)-1]].Len()) > pool.config.AccountSlots {
for _, addr := range offenders {
list := pool.pending[addr]
for _, tx := range list.Cap(list.Len() - 1) {
// Drop the transaction from the global pools too
hash := tx.Hash()
delete(pool.all, hash)
pool.priced.Removed()
// Update the account nonce to the dropped transaction
if nonce := tx.Nonce(); pool.pendingState.GetNonce(addr) > nonce {
pool.pendingState.SetNonce(addr, nonce)
}
log.Trace("Removed fairness-exceeding pending transaction", "hash", hash)
}
pending--
}
}
}
pendingRateLimitCounter.Inc(int64(pendingBeforeCap - pending))
}
// end if pending > pool.config.GlobalSlots
// If we've queued more transactions than the hard limit, drop oldest ones
// We have dealt with the restriction of pending, and we need to deal with the limitations of the future queue.
queued := uint64(0)
for _, list := range pool.queue {
queued += uint64(list.Len())
}
if queued > pool.config.GlobalQueue {
// Sort all accounts with queued transactions by heartbeat
addresses := make(addresssByHeartbeat, 0, len(pool.queue))
for addr := range pool.queue {
if !pool.locals.contains(addr) { // don't drop locals
addresses = append(addresses, addressByHeartbeat{addr, pool.beats[addr]})
}
}
sort.Sort(addresses)
// Drop transactions until the total is below the limit or only locals remain
// From now on, the more the heartbeat is new, the more it will be deleted.
for drop := queued - pool.config.GlobalQueue; drop > 0 && len(addresses) > 0; {
addr := addresses[len(addresses)-1]
list := pool.queue[addr.address]
addresses = addresses[:len(addresses)-1]
// Drop all transactions if they are less than the overflow
if size := uint64(list.Len()); size <= drop {
for _, tx := range list.Flatten() {
pool.removeTx(tx.Hash())
}
drop -= size
queuedRateLimitCounter.Inc(int64(size))
continue
}
// Otherwise drop only last few transactions
txs := list.Flatten()
for i := len(txs) - 1; i >= 0 && drop > 0; i-- {
pool.removeTx(txs[i].Hash())
drop--
queuedRateLimitCounter.Inc(1)
}
}
}
}promoteTx adds a transaction to the pending queue. This method assumes that a lock has been obtained.
// promoteTx adds a transaction to the pending (processable) list of transactions.
// Note, this method assumes the pool lock is held!
func (pool *TxPool) promoteTx(addr common.Address, hash common.Hash, tx *types.Transaction) {
// Try to insert the transaction into the pending queue
if pool.pending[addr] == nil {
pool.pending[addr] = newTxList(true)
}
list := pool.pending[addr]
inserted, old := list.Add(tx, pool.config.PriceBump)
if !inserted {
// If there is no replacement, there is already an old transaction. Delete.
// An older transaction was better, discard this
delete(pool.all, hash)
pool.priced.Removed()
pendingDiscardCounter.Inc(1)
return
}
// Otherwise discard any previous transaction and mark this
if old != nil {
delete(pool.all, old.Hash())
pool.priced.Removed()
pendingReplaceCounter.Inc(1)
}
// Failsafe to work around direct pending inserts (tests)
if pool.all[hash] == nil {
pool.all[hash] = tx
pool.priced.Put(tx)
}
// Set the potentially new pending nonce and notify any subsystems of the new tx
// Add the transaction to the queue and send a message to tell all subscribers that the subscriber is inside the eth protocol. It will receive the message and broadcast the message over the network.
pool.beats[addr] = time.Now()
pool.pendingState.SetNonce(addr, tx.Nonce()+1)
go pool.txFeed.Send(TxPreEvent{tx})
}removeTx, delete a transaction, and move all subsequent transactions to the future queue
// removeTx removes a single transaction from the queue, moving all subsequent
// transactions back to the future queue.
func (pool *TxPool) removeTx(hash common.Hash) {
// Fetch the transaction we wish to delete
tx, ok := pool.all[hash]
if !ok {
return
}
addr, _ := types.Sender(pool.signer, tx) // already validated during insertion
// Remove it from the list of known transactions
delete(pool.all, hash)
pool.priced.Removed()
// Remove the transaction from the pending lists and reset the account nonce
// Remove the transaction from pending and put the transaction that was invalidated due to the deletion of this transaction into the future queue, then update the state of pendingState
if pending := pool.pending[addr]; pending != nil {
if removed, invalids := pending.Remove(tx); removed {
// If no more transactions are left, remove the list
if pending.Empty() {
delete(pool.pending, addr)
delete(pool.beats, addr)
} else {
// Otherwise postpone any invalidated transactions
for _, tx := range invalids {
pool.enqueueTx(tx.Hash(), tx)
}
}
// Update the account nonce if needed
if nonce := tx.Nonce(); pool.pendingState.GetNonce(addr) > nonce {
pool.pendingState.SetNonce(addr, nonce)
}
return
}
}
// Transaction is in the future queue
if future := pool.queue[addr]; future != nil {
future.Remove(tx)
if future.Empty() {
delete(pool.queue, addr)
}
}
}Loop is a goroutine of txPool. It is also the main event loop. Waiting and responding to external blockchain events and various report and transaction eviction events.
// loop is the transaction pool's main event loop, waiting for and reacting to
// outside blockchain events as well as for various reporting and transaction
// eviction events.
func (pool *TxPool) loop() {
defer pool.wg.Done()
// Start the stats reporting and transaction eviction tickers
var prevPending, prevQueued, prevStales int
report := time.NewTicker(statsReportInterval)
defer report.Stop()
evict := time.NewTicker(evictionInterval)
defer evict.Stop()
journal := time.NewTicker(pool.config.Rejournal)
defer journal.Stop()
// Track the previous head headers for transaction reorgs
head := pool.chain.CurrentBlock()
// Keep waiting for and reacting to the various events
for {
select {
// Handle ChainHeadEvent
// Listen to the event at the block header and get the new block header.
case ev := <-pool.chainHeadCh:
if ev.Block != nil {
pool.mu.Lock()
if pool.chainconfig.IsHomestead(ev.Block.Number()) {
pool.homestead = true
}
pool.reset(head.Header(), ev.Block.Header())
head = ev.Block
pool.mu.Unlock()
}
// Be unsubscribed due to system stopped
case <-pool.chainHeadSub.Err():
return
// Handle stats reporting ticks
case <-report.C:
pool.mu.RLock()
pending, queued := pool.stats()
stales := pool.priced.stales
pool.mu.RUnlock()
if pending != prevPending || queued != prevQueued || stales != prevStales {
log.Debug("Transaction pool status report", "executable", pending, "queued", queued, "stales", stales)
prevPending, prevQueued, prevStales = pending, queued, stales
}
// Handle inactive account transaction eviction
case <-evict.C:
pool.mu.Lock()
for addr := range pool.queue {
// Skip local transactions from the eviction mechanism
if pool.locals.contains(addr) {
continue
}
// Any non-locals old enough should be removed
if time.Since(pool.beats[addr]) > pool.config.Lifetime {
for _, tx := range pool.queue[addr].Flatten() {
pool.removeTx(tx.Hash())
}
}
}
pool.mu.Unlock()
// Handle local transaction journal rotation
// rotate regenerates the transaction journal based on the current contents of the transaction pool.
case <-journal.C:
if pool.journal != nil {
pool.mu.Lock()
if err := pool.journal.rotate(pool.local()); err != nil {
log.Warn("Failed to rotate local tx journal", "err", err)
}
pool.mu.Unlock()
}
}
}
}The add method, validates the transaction and inserts it into the future queue. If the transaction replaces a currently existing transaction, it returns the previous transaction so that the external method does not call the promote method. If a newly added transaction is Marked as local, then its sending account will enter the white list, the associated transaction of this account will not be deleted due to price restrictions or other restrictions.
// add validates a transaction and inserts it into the non-executable queue for
// later pending promotion and execution. If the transaction is a replacement for
// an already pending or queued one, it overwrites the previous and returns this
// so outer code doesn't uselessly call promote.
//
// If a newly added transaction is marked as local, its sending account will be
// whitelisted, preventing any associated transaction from being dropped out of
// the pool due to pricing constraints.
func (pool *TxPool) add(tx *types.Transaction, local bool) (bool, error) {
// If the transaction is already known, discard it
hash := tx.Hash()
if pool.all[hash] != nil {
log.Trace("Discarding already known transaction", "hash", hash)
return false, fmt.Errorf("known transaction: %x", hash)
}
// If the transaction fails basic validation, discard it
if err := pool.validateTx(tx, local); err != nil {
log.Trace("Discarding invalid transaction", "hash", hash, "err", err)
invalidTxCounter.Inc(1)
return false, err
}
// If the transaction pool is full, discard underpriced transactions
if uint64(len(pool.all)) >= pool.config.GlobalSlots+pool.config.GlobalQueue {
// If the new transaction is underpriced, don't accept it
if pool.priced.Underpriced(tx, pool.locals) {
log.Trace("Discarding underpriced transaction", "hash", hash, "price", tx.GasPrice())
underpricedTxCounter.Inc(1)
return false, ErrUnderpriced
}
// New transaction is better than our worse ones, make room for it
drop := pool.priced.Discard(len(pool.all)-int(pool.config.GlobalSlots+pool.config.GlobalQueue-1), pool.locals)
for _, tx := range drop {
log.Trace("Discarding freshly underpriced transaction", "hash", tx.Hash(), "price", tx.GasPrice())
underpricedTxCounter.Inc(1)
pool.removeTx(tx.Hash())
}
}
// If the transaction is replacing an already pending one, do directly
from, _ := types.Sender(pool.signer, tx) // already validated
if list := pool.pending[from]; list != nil && list.Overlaps(tx) {
// Nonce already pending, check if required price bump is met
inserted, old := list.Add(tx, pool.config.PriceBump)
if !inserted {
pendingDiscardCounter.Inc(1)
return false, ErrReplaceUnderpriced
}
// New transaction is better, replace old one
if old != nil {
delete(pool.all, old.Hash())
pool.priced.Removed()
pendingReplaceCounter.Inc(1)
}
pool.all[tx.Hash()] = tx
pool.priced.Put(tx)
pool.journalTx(from, tx)
log.Trace("Pooled new executable transaction", "hash", hash, "from", from, "to", tx.To())
return old != nil, nil
}
// New transaction isn't replacing a pending one, push into queue
replace, err := pool.enqueueTx(hash, tx)
if err != nil {
return false, err
}
// Mark local addresses and journal local transactions
if local {
pool.locals.add(from)
}
// If it is a local transaction, it will be recorded into journalTx
pool.journalTx(from, tx)
log.Trace("Pooled new future transaction", "hash", hash, "from", from, "to", tx.To())
return replace, nil
}validateTx uses consistency rules to check if a transaction is valid and uses some heuristic restrictions on the local node.
// validateTx checks whether a transaction is valid according to the consensus
// rules and adheres to some heuristic limits of the local node (price and size).
func (pool *TxPool) validateTx(tx *types.Transaction, local bool) error {
// Heuristic limit, reject transactions over 32KB to prevent DOS attacks
if tx.Size() > 32*1024 {
return ErrOversizedData
}
// Transactions can't be negative. This may never happen using RLP decoded
// transactions but may occur if you create a transaction using the RPC.
if tx.Value().Sign() < 0 {
return ErrNegativeValue
}
// Ensure the transaction doesn't exceed the current block limit gas.
// currentMaxGas is GasLimit of currentBlock
if pool.currentMaxGas.Cmp(tx.Gas()) < 0 {
return ErrGasLimit
}
// Make sure the transaction is signed properly
from, err := types.Sender(pool.signer, tx)
if err != nil {
return ErrInvalidSender
}
// Drop non-local transactions under our own minimal accepted gas price
local = local || pool.locals.contains(from) // account may be local even if the transaction arrived from the network
// If it is not a local transaction and GasPrice is below our setting, it will not be received.
if !local && pool.gasPrice.Cmp(tx.GasPrice()) > 0 {
return ErrUnderpriced
}
// Ensure the transaction adheres to nonce ordering
if pool.currentState.GetNonce(from) > tx.Nonce() {
return ErrNonceTooLow
}
// Transactor should have enough funds to cover the costs
// cost == V - Value + GP - GasPrice * GL - GasLimit
if pool.currentState.GetBalance(from).Cmp(tx.Cost()) < 0 {
return ErrInsufficientFunds
}
intrGas := IntrinsicGas(tx.Data(), tx.To() == nil, pool.homestead)
// If the transaction is a contract creation or call. Then see if there is enough initial Gas.
if tx.Gas().Cmp(intrGas) < 0 {
return ErrIntrinsicGas
}
return nil
}