core/txpool, eth/catalyst: clear transaction pool in Rollback (#30534)

This adds an API method `DropTransactions` to legacy pool, blob pool and
txpool interface. This method removes all txs currently tracked in the
pools.

It modifies the simulated beacon to use the new method in `Rollback`
which removes previous hacky implementation that also erroneously reset
the gas tip to 1 gwei.

---------

Co-authored-by: Felix Lange <fjl@twurst.com>

core/txpool/blobpool/blobpool.go

@@ -1714,3 +1714,53 @@ func (p *BlobPool) Status(hash common.Hash) txpool.TxStatus {
 	}
 	return txpool.TxStatusUnknown
 }
+
+// Clear implements txpool.SubPool, removing all tracked transactions
+// from the blob pool and persistent store.
+func (p *BlobPool) Clear() {
+	p.lock.Lock()
+	defer p.lock.Unlock()
+
+	// manually iterating and deleting every entry is super sub-optimal
+	// However, Clear is not currently used in production so
+	// performance is not critical at the moment.
+	for hash := range p.lookup.txIndex {
+		id, _ := p.lookup.storeidOfTx(hash)
+		if err := p.store.Delete(id); err != nil {
+			log.Warn("failed to delete blob tx from backing store", "err", err)
+		}
+	}
+	for hash := range p.lookup.blobIndex {
+		id, _ := p.lookup.storeidOfBlob(hash)
+		if err := p.store.Delete(id); err != nil {
+			log.Warn("failed to delete blob from backing store", "err", err)
+		}
+	}
+
+	// unreserve each tracked account.  Ideally, we could just clear the
+	// reservation map in the parent txpool context.  However, if we clear in
+	// parent context, to avoid exposing the subpool lock, we have to lock the
+	// reservations and then lock each subpool.
+	//
+	// This creates the potential for a deadlock situation:
+	//
+	// * TxPool.Clear locks the reservations
+	// * a new transaction is received which locks the subpool mutex
+	// * TxPool.Clear attempts to lock subpool mutex
+	//
+	// The transaction addition may attempt to reserve the sender addr which
+	// can't happen until Clear releases the reservation lock.  Clear cannot
+	// acquire the subpool lock until the transaction addition is completed.
+	for acct, _ := range p.index {
+		p.reserve(acct, false)
+	}
+	p.lookup = newLookup()
+	p.index = make(map[common.Address][]*blobTxMeta)
+	p.spent = make(map[common.Address]*uint256.Int)
+
+	var (
+		basefee = uint256.MustFromBig(eip1559.CalcBaseFee(p.chain.Config(), p.head))
+		blobfee = uint256.NewInt(params.BlobTxMinBlobGasprice)
+	)
+	p.evict = newPriceHeap(basefee, blobfee, p.index)
+}

core/txpool/legacypool/legacypool.go

@@ -1961,3 +1961,44 @@ func (t *lookup) RemotesBelowTip(threshold *big.Int) types.Transactions {
 func numSlots(tx *types.Transaction) int {
 	return int((tx.Size() + txSlotSize - 1) / txSlotSize)
 }
+
+// Clear implements txpool.SubPool, removing all tracked txs from the pool
+// and rotating the journal.
+func (pool *LegacyPool) Clear() {
+	pool.mu.Lock()
+	defer pool.mu.Unlock()
+
+	// unreserve each tracked account.  Ideally, we could just clear the
+	// reservation map in the parent txpool context.  However, if we clear in
+	// parent context, to avoid exposing the subpool lock, we have to lock the
+	// reservations and then lock each subpool.
+	//
+	// This creates the potential for a deadlock situation:
+	//
+	// * TxPool.Clear locks the reservations
+	// * a new transaction is received which locks the subpool mutex
+	// * TxPool.Clear attempts to lock subpool mutex
+	//
+	// The transaction addition may attempt to reserve the sender addr which
+	// can't happen until Clear releases the reservation lock.  Clear cannot
+	// acquire the subpool lock until the transaction addition is completed.
+	for _, tx := range pool.all.remotes {
+		senderAddr, _ := types.Sender(pool.signer, tx)
+		pool.reserve(senderAddr, false)
+	}
+	for localSender, _ := range pool.locals.accounts {
+		pool.reserve(localSender, false)
+	}
+
+	pool.all = newLookup()
+	pool.priced = newPricedList(pool.all)
+	pool.pending = make(map[common.Address]*list)
+	pool.queue = make(map[common.Address]*list)
+
+	if !pool.config.NoLocals && pool.config.Journal != "" {
+		pool.journal = newTxJournal(pool.config.Journal)
+		if err := pool.journal.rotate(pool.local()); err != nil {
+			log.Warn("Failed to rotate transaction journal", "err", err)
+		}
+	}
+}

core/txpool/subpool.go

@@ -168,4 +168,7 @@ type SubPool interface {
 	// Status returns the known status (unknown/pending/queued) of a transaction
 	// identified by their hashes.
 	Status(hash common.Hash) TxStatus
+
+	// Clear removes all tracked transactions from the pool
+	Clear()
 }

core/txpool/txpool.go

@@ -497,3 +497,10 @@ func (p *TxPool) Sync() error {
 		return errors.New("pool already terminated")
 	}
 }
+
+// Clear removes all tracked txs from the subpools.
+func (p *TxPool) Clear() {
+	for _, subpool := range p.subpools {
+		subpool.Clear()
+	}
+}

eth/catalyst/simulated_beacon.go

@@ -21,7 +21,6 @@ import (
 	"crypto/sha256"
 	"errors"
 	"fmt"
-	"math/big"
 	"sync"
 	"time"
 
@@ -34,7 +33,6 @@ import (
 	"github.com/ethereum/go-ethereum/event"
 	"github.com/ethereum/go-ethereum/log"
 	"github.com/ethereum/go-ethereum/node"
-	"github.com/ethereum/go-ethereum/params"
 	"github.com/ethereum/go-ethereum/rpc"
 )
 
@@ -287,12 +285,7 @@ func (c *SimulatedBeacon) Commit() common.Hash {
 
 // Rollback un-sends previously added transactions.
 func (c *SimulatedBeacon) Rollback() {
-	// Flush all transactions from the transaction pools
-	maxUint256 := new(big.Int).Sub(new(big.Int).Lsh(common.Big1, 256), common.Big1)
-	c.eth.TxPool().SetGasTip(maxUint256)
-	// Set the gas tip back to accept new transactions
-	// TODO (Marius van der Wijden): set gas tip to parameter passed by config
-	c.eth.TxPool().SetGasTip(big.NewInt(params.GWei))
+	c.eth.TxPool().Clear()
 }
 
 // Fork sets the head to the provided hash.