From cc39d831d37e691d4d3061cc560c4cde32697848 Mon Sep 17 00:00:00 2001
From: CHAMI Rachid <chamirachid1@gmail.com>
Date: Mon, 4 Dec 2023 14:09:32 +0100
Subject: [PATCH] feat: speed up transactions if they don't get included
 initially (#636)

* feat: support transaction speed up

* chore: better logs

* chore: better logs

* chore: not send transaction if new gas price is lower than current one
---
 evm/evm_client.go  |  1 -
 relayer/errors.go  |  1 +
 relayer/relayer.go | 57 ++++++++++++++++++++++++++++++++++++++++++++--
 3 files changed, 56 insertions(+), 3 deletions(-)

diff --git a/evm/evm_client.go b/evm/evm_client.go
index f5d1647b..7aba080f 100644
--- a/evm/evm_client.go
+++ b/evm/evm_client.go
@@ -241,7 +241,6 @@ func (ec *Client) WaitForTransaction(
 		ec.logger.Info("transaction confirmed", "hash", tx.Hash().String(), "block", receipt.BlockNumber.Uint64())
 		return receipt, nil
 	}
-	ec.logger.Error("transaction failed", "hash", tx.Hash().String())
 
 	return receipt, err
 }
diff --git a/relayer/errors.go b/relayer/errors.go
index 6326049d..8e2fff62 100644
--- a/relayer/errors.go
+++ b/relayer/errors.go
@@ -9,4 +9,5 @@ var (
 	ErrAttestationNotDataCommitmentRequest = errors.New("attestation is not a data commitment request")
 	ErrAttestationNotFound                 = errors.New("attestation not found")
 	ErrValidatorSetMismatch                = errors.New("p2p validator set is different from the trusted contract one")
+	ErrTransactionStillPending             = errors.New("evm transaction still pending")
 )
diff --git a/relayer/relayer.go b/relayer/relayer.go
index a79ea0bf..db8e2937 100644
--- a/relayer/relayer.go
+++ b/relayer/relayer.go
@@ -4,11 +4,14 @@ import (
 	"bytes"
 	"context"
 	"encoding/hex"
+	stderrors "errors"
 	"fmt"
 	"math/big"
 	"strconv"
 	"time"
 
+	"github.com/ethereum/go-ethereum/ethclient"
+
 	"github.com/ipfs/go-datastore"
 	badger "github.com/ipfs/go-ds-badger2"
 
@@ -113,8 +116,7 @@ func (r *Relayer) Start(ctx context.Context) error {
 					return err
 				}
 
-				// wait for transaction to be mined
-				_, err = r.EVMClient.WaitForTransaction(ctx, ethClient, tx, r.RetryTimeout)
+				err = r.waitForTransactionAndRetryIfNeeded(ctx, ethClient, tx)
 				if err != nil {
 					return err
 				}
@@ -373,6 +375,57 @@ func (r *Relayer) SaveDataCommitmentSignaturesToStore(ctx context.Context, att c
 	return batch.Commit(ctx)
 }
 
+// waitForTransactionAndRetryIfNeeded waits for transaction to be mined. If it's not mined in the provided timeout, it will
+// attempt to speed it up via updating the gas price.
+func (r *Relayer) waitForTransactionAndRetryIfNeeded(ctx context.Context, ethClient *ethclient.Client, tx *coregethtypes.Transaction) error {
+	r.logger.Debug("submitted transaction", "hash", tx.Hash().Hex(), "gas_price", tx.GasPrice().Uint64())
+	newTx := tx
+	for i := 0; i < 10; i++ {
+		_, err := r.EVMClient.WaitForTransaction(ctx, ethClient, newTx, r.RetryTimeout)
+		if err != nil {
+			if stderrors.Is(err, context.DeadlineExceeded) {
+				newGasPrice, err := ethClient.SuggestGasPrice(ctx)
+				if err != nil {
+					return err
+				}
+				if newGasPrice.Uint64() <= newTx.GasPrice().Uint64() {
+					// no need to resend the transaction if the suggested gas price is lower than the original one
+					continue
+				}
+				legacyTx := toLegacyTransaction(newTx)
+				legacyTx.GasPrice = newGasPrice
+				newTx = coregethtypes.NewTx(legacyTx)
+				r.logger.Debug("transaction still not included. updating the gas price", "retry_number", i)
+				err = ethClient.SendTransaction(ctx, newTx)
+				r.logger.Info("submitted speed up transaction", "hash", newTx.Hash().Hex(), "new_gas_price", newTx.GasPrice().Uint64())
+				if err != nil {
+					r.logger.Debug("response of sending speed up transaction", "resp", err.Error())
+				}
+			} else {
+				return err
+			}
+		} else {
+			return nil
+		}
+	}
+	return ErrTransactionStillPending
+}
+
+func toLegacyTransaction(tx *coregethtypes.Transaction) *coregethtypes.LegacyTx {
+	v, r, s := tx.RawSignatureValues()
+	return &coregethtypes.LegacyTx{
+		Nonce:    tx.Nonce(),
+		GasPrice: tx.GasPrice(),
+		Gas:      tx.Gas(),
+		To:       tx.To(),
+		Value:    tx.Value(),
+		Data:     tx.Data(),
+		V:        v,
+		R:        r,
+		S:        s,
+	}
+}
+
 // matchAttestationConfirmSigs matches and sorts the confirm signatures with the valset
 // members as expected by the Blobstream contract.
 // Also, it leaves the non provided signatures as nil in the `sigs` slice: