Reject transactions that have already been submitted to the tx pool

api/utils.go

@@ -29,9 +29,6 @@ func resolveBlockTag(
 	if number, ok := blockNumberOrHash.Number(); ok {
 		height, err := resolveBlockNumber(number, blocksDB)
 		if err != nil {
-			logger.Error().Err(err).
-				Stringer("block_number", number).
-				Msg("failed to resolve block by number")
 			return 0, err
 		}
 		return height, nil
@@ -40,9 +37,6 @@ func resolveBlockTag(
 	if hash, ok := blockNumberOrHash.Hash(); ok {
 		height, err := blocksDB.GetHeightByID(hash)
 		if err != nil {
-			logger.Error().Err(err).
-				Stringer("block_hash", hash).
-				Msg("failed to resolve block by hash")
 			return 0, err
 		}
 		return height, nil

models/errors/errors.go

@@ -28,9 +28,8 @@ var (
 
 	// Transaction errors
 
-	ErrFailedTransaction    = errors.New("failed transaction")
-	ErrInvalidTransaction   = fmt.Errorf("%w: %w", ErrInvalid, ErrFailedTransaction)
-	ErrDuplicateTransaction = fmt.Errorf("%w: %s", ErrInvalid, "transaction already in pool")
+	ErrFailedTransaction  = errors.New("failed transaction")
+	ErrInvalidTransaction = fmt.Errorf("%w: %w", ErrInvalid, ErrFailedTransaction)
 
 	// Storage errors
 

services/requester/batch_tx_pool.go

@@ -18,39 +18,45 @@ import (
 	"github.com/onflow/flow-evm-gateway/config"
 	"github.com/onflow/flow-evm-gateway/metrics"
 	"github.com/onflow/flow-evm-gateway/models"
-	errs "github.com/onflow/flow-evm-gateway/models/errors"
 	"github.com/onflow/flow-evm-gateway/services/requester/keystore"
 )
 
-const eoaActivityCacheSize = 10_000
+const (
+	eoaActivityCacheSize     = 10_000
+	maxTrackedTxNoncesPerEOA = 30
+)
 
 type pooledEvmTx struct {
 	txPayload cadence.String
-	txHash    gethCommon.Hash
 	nonce     uint64
 }
 
-// BatchTxPool is a `TxPool` implementation that collects and groups
-// transactions based on their EOA signer, and submits them for execution
-// using a batch.
+type eoaActivityMetadata struct {
+	lastSubmission time.Time
+	txNonces       []uint64
+}
+
+// BatchTxPool is a `TxPool` implementation that groups incoming transactions
+// based on their EOA signer, and submits them for execution using a batch.
 //
 // The underlying Cadence EVM API used, is `EVM.batchRun`, instead of the
 // `EVM.run` used in `SingleTxPool`.
 //
 // The main advantage of this implementation over the `SingleTxPool`, is the
-// guarantee that transactions originated from the same EOA address, which
-// arrive in a short time interval (about the same as Flow's block production rate),
-// will be executed in the same order their arrived.
-// This helps to reduce the nonce mismatch errors which mainly occur from the
-// re-ordering of Cadence transactions that happens from Collection nodes.
+// guarantee that transactions originating from the same EOA address, which
+// arrive in a short time interval (configurable by the node operator),
+// will be executed in the same order they arrived.
+// This helps to reduce the execution errors which may occur from the
+// re-ordering of Cadence transactions that happens on Collection nodes.
 type BatchTxPool struct {
 	*SingleTxPool
-	pooledTxs   map[gethCommon.Address][]pooledEvmTx
-	txMux       sync.Mutex
-	eoaActivity *expirable.LRU[gethCommon.Address, time.Time]
+
+	pooledTxs        map[gethCommon.Address][]pooledEvmTx
+	txMux            sync.Mutex
+	eoaActivityCache *expirable.LRU[gethCommon.Address, eoaActivityMetadata]
 }
 
-var _ TxPool = &BatchTxPool{}
+var _ TxPool = (*BatchTxPool)(nil)
 
 func NewBatchTxPool(
 	ctx context.Context,
@@ -77,16 +83,16 @@ func NewBatchTxPool(
 		return nil, err
 	}
 
-	eoaActivity := expirable.NewLRU[gethCommon.Address, time.Time](
+	eoaActivityCache := expirable.NewLRU[gethCommon.Address, eoaActivityMetadata](
 		eoaActivityCacheSize,
 		nil,
 		config.EOAActivityCacheTTL,
 	)
 	batchPool := &BatchTxPool{
-		SingleTxPool: singleTxPool,
-		pooledTxs:    make(map[gethCommon.Address][]pooledEvmTx),
-		txMux:        sync.Mutex{},
-		eoaActivity:  eoaActivity,
+		SingleTxPool:     singleTxPool,
+		pooledTxs:        make(map[gethCommon.Address][]pooledEvmTx),
+		txMux:            sync.Mutex{},
+		eoaActivityCache: eoaActivityCache,
 	}
 
 	go batchPool.processPooledTransactions(ctx)
@@ -104,11 +110,6 @@ func (t *BatchTxPool) Add(
 ) error {
 	t.txPublisher.Publish(tx) // publish pending transaction event
 
-	// tx adding should be blocking, so we don't have races when
-	// pooled transactions are being processed in the background.
-	t.txMux.Lock()
-	defer t.txMux.Unlock()
-
 	from, err := models.DeriveTxSender(tx)
 	if err != nil {
 		return err
@@ -123,6 +124,20 @@ func (t *BatchTxPool) Add(
 		return err
 	}
 
+	eoaActivity, found := t.eoaActivityCache.Get(from)
+	nonce := tx.Nonce()
+
+	// Skip transactions that have been already submitted,
+	// as they are *likely* to fail.
+	if found && slices.Contains(eoaActivity.txNonces, nonce) {
+		t.logger.Info().
+			Str("evm_tx", tx.Hash().Hex()).
+			Str("from", from.Hex()).
+			Uint64("nonce", nonce).
+			Msg("tx with same nonce has been already submitted")
+		return nil
+	}
+
 	// Scenarios
 	// 1. EOA activity not found:
 	// => We send the transaction individually, without adding it
@@ -140,27 +155,59 @@ func (t *BatchTxPool) Add(
 	// For all 3 cases, we record the activity time for the next
 	// transactions that might come from the same EOA.
 	// [X] is equal to the configured `TxBatchInterval` duration.
-	lastActivityTime, found := t.eoaActivity.Get(from)
-
 	if !found {
 		// Case 1. EOA activity not found:
 		err = t.submitSingleTransaction(ctx, hexEncodedTx)
-	} else if time.Since(lastActivityTime) > t.config.TxBatchInterval {
-		// Case 2. EOA activity found AND it was more than [X] seconds ago:
-		err = t.submitSingleTransaction(ctx, hexEncodedTx)
+	} else if time.Since(eoaActivity.lastSubmission) > t.config.TxBatchInterval {
+		// If the EOA has pooled transactions, which are not yet processed,
+		// due to congestion or anything, make sure to include the current
+		// tx on that batch.
+		t.txMux.Lock()
+		hasBatch := len(t.pooledTxs[from]) > 0
+		if hasBatch {
+			userTx := pooledEvmTx{txPayload: hexEncodedTx, nonce: nonce}
+			t.pooledTxs[from] = append(t.pooledTxs[from], userTx)
+		}
+		t.txMux.Unlock()
+
+		// If it wasn't batched, submit individually
+		if !hasBatch {
+			// Case 2. EOA activity found AND it was more than [X] seconds ago:
+			err = t.submitSingleTransaction(ctx, hexEncodedTx)
+		}
 	} else {
 		// Case 3. EOA activity found AND it was less than [X] seconds ago:
-		userTx := pooledEvmTx{txPayload: hexEncodedTx, txHash: tx.Hash(), nonce: tx.Nonce()}
-		// Prevent submission of duplicate transactions, based on their tx hash
-		if slices.Contains(t.pooledTxs[from], userTx) {
-			return errs.ErrDuplicateTransaction
-		}
+		t.txMux.Lock()
+		userTx := pooledEvmTx{txPayload: hexEncodedTx, nonce: nonce}
 		t.pooledTxs[from] = append(t.pooledTxs[from], userTx)
+		t.txMux.Unlock()
 	}
 
-	t.eoaActivity.Add(from, time.Now())
+	if err != nil {
+		t.logger.Error().Err(err).Msgf(
+			"failed to submit single Flow transaction for EOA: %s",
+			from.Hex(),
+		)
+		return err
+	}
+
+	t.txMux.Lock()
+	defer t.txMux.Unlock()
 
-	return err
+	// Update metadata for the last EOA activity only on successful add/submit.
+	eoaActivity, _ = t.eoaActivityCache.Get(from)
+	eoaActivity.lastSubmission = time.Now()
+	eoaActivity.txNonces = append(eoaActivity.txNonces, nonce)
+	// To avoid the slice of nonces from growing indefinitely,
+	// keep only the last `maxTrackedTxNoncesPerEOA` nonces.
+	if len(eoaActivity.txNonces) > maxTrackedTxNoncesPerEOA {
+		firstKeep := len(eoaActivity.txNonces) - maxTrackedTxNoncesPerEOA
+		eoaActivity.txNonces = eoaActivity.txNonces[firstKeep:]
+	}
+
+	t.eoaActivityCache.Add(from, eoaActivity)
+
+	return nil
 }
 
 func (t *BatchTxPool) processPooledTransactions(ctx context.Context) {
@@ -188,10 +235,14 @@ func (t *BatchTxPool) processPooledTransactions(ctx context.Context) {
 				)
 				if err != nil {
 					t.logger.Error().Err(err).Msgf(
-						"failed to submit Flow transaction from BatchTxPool for EOA: %s",
+						"failed to submit batch Flow transaction for EOA: %s",
 						address.Hex(),
 					)
-					continue
+					// In case of any error, add the transactions back to the pool,
+					// as a retry mechanism.
+					t.txMux.Lock()
+					t.pooledTxs[address] = append(t.pooledTxs[address], pooledTxs...)
+					t.txMux.Unlock()
 				}
 			}
 		}
@@ -235,6 +286,9 @@ func (t *BatchTxPool) batchSubmitTransactionsForSameAddress(
 	}
 
 	if err := t.client.SendTransaction(ctx, *flowTx); err != nil {
+		// If there was any error while sending the transaction,
+		// we record all transactions as dropped.
+		t.collector.TransactionsDropped(len(hexEncodedTxs))
 		return err
 	}
 
@@ -266,6 +320,9 @@ func (t *BatchTxPool) submitSingleTransaction(
 	}
 
 	if err := t.client.SendTransaction(ctx, *flowTx); err != nil {
+		// If there was any error while sending the transaction,
+		// we record it as a dropped transaction.
+		t.collector.TransactionsDropped(1)
 		return err
 	}
 

services/requester/requester.go

@@ -238,7 +238,7 @@ func (e *EVM) SendRawTransaction(ctx context.Context, data []byte) (common.Hash,
 	}
 
 	e.logger.Info().
-		Str("evm-id", tx.Hash().Hex()).
+		Str("evm_tx", tx.Hash().Hex()).
 		Str("to", to).
 		Str("from", from.Hex()).
 		Str("value", tx.Value().String()).

services/requester/single_tx_pool.go

@@ -31,7 +31,6 @@ type SingleTxPool struct {
 	pool        *sync.Map
 	txPublisher *models.Publisher[*gethTypes.Transaction]
 	config      config.Config
-	mux         sync.Mutex
 	keystore    *keystore.KeyStore
 	collector   metrics.Collector
 	// referenceBlockHeader is stored atomically to avoid races
@@ -40,7 +39,7 @@ type SingleTxPool struct {
 	// todo add methods to inspect transaction pool state
 }
 
-var _ TxPool = &SingleTxPool{}
+var _ TxPool = (*SingleTxPool)(nil)
 
 func NewSingleTxPool(
 	ctx context.Context,
@@ -96,6 +95,11 @@ func (t *SingleTxPool) Add(
 ) error {
 	t.txPublisher.Publish(tx) // publish pending transaction event
 
+	from, err := models.DeriveTxSender(tx)
+	if err != nil {
+		return err
+	}
+
 	txData, err := tx.MarshalBinary()
 	if err != nil {
 		return err
@@ -121,10 +125,21 @@ func (t *SingleTxPool) Add(
 		// If there was any error during the transaction build
 		// process, we record it as a dropped transaction.
 		t.collector.TransactionsDropped(1)
+		t.logger.Error().Err(err).Msgf(
+			"failed to build Flow transaction for EOA: %s",
+			from.Hex(),
+		)
 		return err
 	}
 
 	if err := t.client.SendTransaction(ctx, *flowTx); err != nil {
+		// If there was any error while sending the transaction,
+		// we record it as a dropped transaction.
+		t.collector.TransactionsDropped(1)
+		t.logger.Error().Err(err).Msgf(
+			"failed to submit Flow transaction for EOA: %s",
+			from.Hex(),
+		)
 		return err
 	}
 
@@ -150,8 +165,8 @@ func (t *SingleTxPool) Add(
 				}
 
 				t.logger.Error().Err(res.Error).
-					Str("flow-id", flowTx.ID().String()).
-					Str("evm-id", tx.Hash().Hex()).
+					Str("flow_tx", flowTx.ID().String()).
+					Str("evm_tx", tx.Hash().Hex()).
 					Msg("flow transaction error")
 
 				// hide specific cause since it's an implementation issue
@@ -188,7 +203,11 @@ func (t *SingleTxPool) buildTransaction(
 		}
 	}
 
-	accKey, err := t.fetchSigningAccountKey()
+	// getting an account key from the `KeyStore` for signing transactions,
+	// *does not* need to be lock-protected, as the keys are read from a
+	// channel. No two go-routines will end up getting the same account
+	// key at the same time.
+	accKey, err := t.keystore.Take()
 	if err != nil {
 		return nil, err
 	}
@@ -211,16 +230,6 @@ func (t *SingleTxPool) buildTransaction(
 	return flowTx, nil
 }
 
-func (t *SingleTxPool) fetchSigningAccountKey() (*keystore.AccountKey, error) {
-	// getting an account key from the `KeyStore` for signing transactions,
-	// should be lock-protected, so that we don't sign any two Flow
-	// transactions with the same account key
-	t.mux.Lock()
-	defer t.mux.Unlock()
-
-	return t.keystore.Take()
-}
-
 func (t *SingleTxPool) getReferenceBlock() *flow.BlockHeader {
 	if v := t.referenceBlockHeader.Load(); v != nil {
 		return v.(*flow.BlockHeader)